Cooling system problems :(

[Kalevera]

Hi guys.

Last weekend, I changed the tstat and most of the hoses on my car. I flushed the system and radiator with a hose, hylomar'd all of the new connections, and mixed 50/50 distilled water and BMW cool blue. I filled the system with the bleeder screw open, although I didn't have the heater controls on high/the key in the "on" position.

After filling the system and initially bleeding it, everything seemed to be fine, although, upon first running it and letting it warm up, a little bit of smoke appeared around the block, which I attributed to water and coolant vapor. The temp gauge stayed on the middle and the pisser line intermittantly worked.

So I bled, bled and bled some more (all with the coolant cap off), and eventually got the pisser to work reliably. As I shut the car off with the expansion tank cap off, it overflowed with coolant. I cleaned it up, poured new coolant mix in, and the car was still running fine.

Over the past two days, the car has been overheating. I have only been driving it in 1 mile increments. It goes to ~ 12 o clock, sits there, and then goes up to ~ 3/4, where it stays (to the best of my knowlege). If I try to open the expansion tank cap after running it at that temp, it overflows and I can hear a "gargling" sound in the radiator to thermostat housing pipe. While running, there is sometimes a constant pisser stream, sometimes it's a lot less than others. If I manipulate the heater, it usually comes back. Opening the bleeder screw gets a lot of bubbles and froth. If I let it sit and bleed it later, the coolant comes out fine with no air bubbles.

I checked the fan clutch: it blows a lot of air and stops rather abruptly when the engine is shut off. The water pump appears to be newer.

I also checked the oil and coolant for signs of intermixing; they don't appear to be doing that, and while the exhuast smells a little sweet, it doesn't seem to be moreso than it was before.

EDIT: the upper radiator hose is hot to the touch when doing this -- tstat appears to be working, and I *haven't* reinstalled the fan shroud (does it really matter!?).


So I'm at a loss of ideas -- what do I do next?


Best, Whit

[Javier]

Javier

[Kalevera]

"Pisser" line, as Winfred calls it, runs from the top of the radiator back to the expansion tank. I think it's technically called the "coolant return line". They commonly get clogged, but I don't think mine is clogged as I replaced the entire thing (and the rubber hose intermediary between it and the radiator) last month.

What a pain in the ass that was.

best, whit

[Javier]

and the cooling system was a mess, until I read about it in Bruno's site, and found out. It was curious, the dirt in there was acting as a check valve, when I blew from radiator to expansion tank, it was closed, when I sucked, it was open. Bruno's site suggests enlarging the tiny hole at the expansion tank, I didn't, but cleaned carefully. At that time, I noticed that bleeding this car is a pain in the ass, get used to loose a bit the bleeding screw every time I turned off the engine, and after cooled, opened and refill coolant if needed. I kept doing this for more than a week. Don't understand why you are opening the expansion tank wile hot, are you sure there are no leaks? When the temperature rises, do you check temperature at the hoses (coolant flow). Is your radiator hot, electro fan blowing? Are you getting hot air to the cabin? Is all air out of the heater core?

Hot engine, cool radiator means no flow, either pump or tsat. Air in the housing of tsat prevents proper operation, tsat has only one position and the tiny hole helps with the air bleeding.

I'm curious, know how you feel, hope it is not head gasket.

Javier

[Kalevera]

Yes, the heat works fine (although it didn't work at all when I first filled the system).

I've been opening the cap to release the pressure so that I can bleed the system (nothing comes out if the cap is on, unless the temp is at the 3/4 mark, in which case I get boiling froth).

Yes, certain that there are no leaks. I had to tighten up two clamps, now the only place it's losing coolant is through the bleeder screw or the overflow pipe (when I de-pressurize the system when it's at 3/4).

Radiator appears to be hot - the upper pipe is hot. I've pulled the big (M20?) bolt between the sensors on the tstat housing a number of times and gotten coolant; and I drilled a 1/16" bleeder hole on the upper part of the new tstat below the rubber gasket.

I feel like **** because I've sunk about $5000 into this car in the past two months that I've owned it, and have gotten very little utility out of it beyond the learning experience. Yes, I hope it's not the head gasket, as well...but I don't know how to check that...

Thanks for your help, Javier :)

Best, whit

[Kalevera]

Edit: after checking the expansion tank for like the 5 millionth time tonight, I noted a lot of specks of brown. Does mobil 1 look brown when it's floating on top of a lot of cool blue?

best, whit

[Javier]

Forget about bleeding with an open expansion tank, without pressure in the system, you may have boiling and the process becomes a mess. Just fill up to the neck, close the expansion tank, run the engine, and keep opening and closing the bleeder, keep it open as long as you feel air bubbles coming out, close immediately if no pressure or coolant stream. Repeat at infinitum; don't let the bleeder loose coolant unnecessarily. As long as the system get hot, it will build up pressure to help you bleed, be patient, wait for the tsat to open, feel the temperature change in radiator upper hose when tsat opens, open full heat to the cabin to flush heat core. And be sure that electro fan turns on if temperature rises. If you feel you have lost too much coolant in the process, just turn off the engine, wait to cool down and refill the system up to the neck. When you fill coolant, squeeze the hoses to force air out to the expansion tank.

Javier

[Javier]

bubbles there? This sure looks suspicious. If you get oil in the coolant, at 3/4 of the dial, you should be loosing coolant to the crankcase.

Javier

[Kalevera]

Javier - the oil stick looks fine, so far as I can tell, with no bubbles. Just those few floating brown spots in the expansion tank...

Don't know about the electro fan - I'll check it out. I don't remember it being on, but I wasn't really paying attention to it.

best, whit

[Kalevera]

And also - It doesn't appear to be losing any coolant, beyond what I bleed out of it or it sent out the overflow pipe.

best, whit

[Javier]

but you will need it. Check this link at Bruno's site

http://www.bmwe34.net/e34main/trouble/overheating.htm

Javier

[Robin-535im]

But did you try bleeding it at full cold, parked nose-up on an incline, with the heater on and key in at position 2?

(knock on wood) I've never had a problem bleeding using that procedure, but I've only done it 3 or 4 times so far. I start full cold with the car as described above, fill from the expansion tank with the bleeder valve open, and squeeze the radiator hoses to help get the air out. Once the blue juice starts coming out the bleeder valve, I close it, start the car, and let it run until it reaches normal operating temperature. Then I open the bleeder valve for a sec (with some cardboard there to keep it from spraying onto the fan) and let it spit out for 1-2 seconds, then close her up. I'll top it off next time it's cold, but I don't ever open it up while the system is hot.

The behavior does sound like an air bubble to me, but you might check that you have the upgraded expansion tank cap. One has a 170 on it, the other has a 220, or something like that. (Someone here should know). It was a recall item IIRC, and the earlier version didn't hold pressure enough and it would overheat. Something to check anyway. Bruno's site might have something on it.

HTH

Robin

[Kalevera]

Hey Robin - Yes, I did mine the exact same way only with the heater off and no key. The more I think about it, the more concerned I am that I "burned out" the head gasket -- how else can I explain the few whifts of smoke that came up from around the engine block at operating temperature? The weird thing is, it didn't overheat then...dead on in the middle...and everything was fine until I took it for a spin last night and it went above the 1/2 mark.

I'm tempted to drain the coolant from the radiator, refill it, and see what happens. It'd be nice if it's just an air bubble and I don't have to do a head gasket :)

My cap has "240" or "260" on it....definitely 2 something ,though.

Best, Whit

[Dave535Phoenix]

My 535 is quite finicky about the bleeding. I've refilled twice in my tenure in the car, and neither time did the standard bleeding techniques entirely work.

After filling and doing the standard bleeding steps, I drive around for the next couple days with a 8mm wrench near at hand and one eye on the temp gauge. When it starts to head for red, I get to the side of the road and open the bleed screw a few times. Careful here - it'll spray hot coolant into the fan and splash a bit.

In my experience a bit of bleeding will curb that incident of overheating, and after 4 or 5 repetitions the car stops overheating altogether.

Theorizing now - I think air bubbles collect and meet at the thermostat. When enough get there the thermostat is no longer entirely immersed in hot coolant so closes. That causes the temp to rise so quickly. Opening the bleed screw allows the air to escape, re-immersing the thermostat and letting it work as it should. The hot coolant gets to the radiator and things return to normal until the next batch of air bubbles have their party. After a few incidents, there are no air bubbles left and you're home free for another couple years.

One note - as advised somewhere on this board, I did drill a small hole in the top part of the thermostat to aid bleeding. It lets air through, but is small enough not to affect coolant flow.

Good Luck

Dave

[Kalevera]

Dave, do you bleed the car on the side of the road while it's running?

I tried that...it spits out a lot of hot foam and air, and the temp gauge doesn't seem to change.

I just can't figure out where all this air is coming from...The thing bleeds a steady stream of cool blue when it's at normal operating temps (although I'm STILL seeing pockets of air coming out with the coolant through the pisser line).

best, whit

[Javier]

may be its a climate difference. As Dave told, I do usually keep bleeding the car for a wile, about one week after system repairs. Every morning, during that week, WHEN COLD, I open the cap and refill to the neck, then start the engine, make a slow walk to my trunk tool set, get the smallest wrench, open the bleeder a bit, see what is coming out, bubbles? keep open, nothing or steady stream? close immediately (engine running, of course). As Dave told you, it sprays a little bit, not only that, coolant in front of the engine keep things noisy for a wile, but, need to get out all that air! I have a small trip to the office, when arrive there, again, before turning off the engine, open the bleeder and check. At the noon, car already cold, open cap and check level, and repeat bleeding as above. I see no other way to do it, as it is not possible to keep the system open wile the engine is running, without loosing huge amounts of coolant and letting air back in. Need Cold-Hot-Cold... cycles to fill-bleed-fill... and I'm not that patient to do all them in a row. Again, do not open the system HOT.

Avoid the temp gauge going too far up, if system temperature is too high, as soon as you open the bleeder you have a sudden low pressure that makes the system boil, then you get foamy vapor coming out of the bleeder, and will never get a steady coolant stream. Optimum temperature to bleed is needle on the center (or immediately after the tsat opens, if rising from cold). Guess this is the reason that Dave told to side right away and bleed as son as you notice a temperature increase, typically caused by an air bubble in the tsat housing.

Keep the heater operating all the time, you need all the air in there to come up to the bleeder.

Believe me, my first time I did also though my head gasket blew up, until I understood how unpleasant this bleeding operation can be. Just be patient.

Javier

[Kalevera]

God, it is unpleasant :)

I'm still hoping that it's not the head gasket, and I still have a few specks of brown floating around in the expansion tank, but no smoke and the oil is still clear.

Today I bled it after it made it up to about one mark above 12O, and when I opened the bleeder screw, the boiling foam/air stuff came out. So I let it cool down a bit, and then the steady stream of cool blue came out with no bubbles. argh.

I'll give it a few days and see what happens...let's hope for the best :)

Thanks for all of your help, Javier...what ever happened with your transmission issues? Did you end up getting a ZF reman?

Best, Whit

[Javier]

I'll try to book a date next week. I intend to have a chat with the chief of mechanics to listen his opinion on the issue. If he convinces me, I will take a jump and leave the car.

My God how I hate this, wonder how many original bolts and nuts will be lost when I got my car back. The car has never been to nobody but me for repairs, even when paint refinishing were needed, I disassemble my self all the trims, register and stored every screw, clip or nut, took the car for refinishing job only, and got it back for re-assembly. Only oil service at its very early days were done by estrangers. Now this issue on the transmission has been above my capabilities.

Javier

[Kalevera]

I'm telling you - you should just convert it to a manual while you can :)

I know the parts are hard to find down there, but I'm sure you could obtain them...

Lowell

[Javier]

also Caracas is not a typical USA city, think of it like the traffic of Manhattan, or Miami. To be standing 45 minutes in traffic, advancing couple meters per clutch release, is just unbearable. Cannot convert.

Javier

[Dave535Phoenix]

Sorry for the late reply,

Yes, I do. At the first sign of the temp gauge creeping up I pulled off as soon as I could and hit the bleed screw. I opened it several times, getting quite a bit of spray (foam doesn't ring a bell though). It hisses and spits a for about 5-15 seconds, then calms down and mostly coolant trickles out. I closed the bleeder for 10-20 seconds then did it again, repeating until there was very little hissing. I think I'd open/close the bleed screw 5-6 times per session. It took about 4 sessions before the temp gauge stabilized.

One note - I did mostly freeway driving during that stretch. 20 miles at 70mph without any issues - the problem only cropped up after I was off the freeway and idling at a light or something. I do remember my car overheating on the freeway before - when I had a blown head gasket.

I don't have any advice after that - others on this board seem to be saying anything I could come up with.

Good luck.

[Kalevera]

UPDATE - (Javier, Dave...anyone else who might know something about this -- please read!)

I took the car out on the highway today. Recently, although it's been a little colder, it's taken LONGER to warm up versus earlier in the week. I was able to make some observations:

- The "brown specks" in the coolant appear to be a mixture of rust/dirt and old green coolant (what was previously in the car).

- I thought the fan(s) were OK, but now I'm beginning to wonder. The mechanical fan spins up fine on starting, but then spins slowly at higher RPMS (when in PARK). When it's cold, it stops quickly after shutting off...when HOT, it runs away. So it looks like the VC is gone and I'm going to replace that.

- The Aux fan doesn't run at all. Not when the AC is turned on (which doesn't work, by the way), not when the car is past the 12o mark. Could be the resistor? I guess I'll have to look into that -- but it apparently has been a long term problem, as I've NEVER noticed it working. Also something to fix.

- In stop and go traffic, with the heat on FULL, it stays around 3/4, usually a little below. On the highway, also with the heat on FULL, it will bring the temp down a bit, but not to anything like comfortable levels.

- As I was driving on a crowded highway when it started to creep past 12o, I waited until the next exit (3 miles total on the HW) to bleed it. By that time, it was ~ 3/4 and it boiled out with lots of hot air. I also inspected the oil cap and dipstick and found some white looking residue on them. Upon letting the engine cool further, the residue disappeared on both accounts. The oil at the bottom of the dipstick still looks normal, as does the valvetrain.

- Punching on the gas from a stoplight will give temporary relief - it drops about a needle length....also with full heat on.

And finally, the WEIRDEST for last:

- After returning home (and praying all the way that I wasn't doing more damage than already existed), I shut the engine off and popped the hood and opened the bleeder screw for a few seconds to get steam/boiling coolant. Upon turning the car on again (less than a few seconds later), the temp gauge had returned to normal.

So it seems like it's a combination of massive FAN failure, and residual air in the system... I'm not really sure how the VC is supposed to work, but I assume that when the engine is idling hot, it should be kicking up at least as much air as it does when the car is first started.

Best, Whit

[Robin-535im]

Okay, so take what I say with a grain of salt (WAGOS) because I'm not a mechanic by trade.

A bad fan (fan clutch or electric) should only matter mostly at idle, and even then for this time of year I would expect it to go only a few needles higher than half for any reasonable amount of regular traffic idle time.

If it gets hot while driving down the road, I think it's definitely not the fans b/c all they really do is move the air while you're still - car motion should be enough to flow sufficient air even without a fan.

You said when you gunned it the temp came down. That's the kind of thing that would happen if the water pump were barely working. And I didn't make that up, I heard it on Car Talk or from Winfred or something. :)

However I don't know how to check the pump besides getting a new one - so keep it on your shopping list if nothing else works.

- Robin

[Kalevera]

Robin - oh, I've already got one sitting here in a box :)

I would've replaced it when I had the system apart last week, but the clowns at Park Tool don't know how to follow their own policies and incorrectly shipped my 32mm wrench.

When I had the system apart, the old pump looked FINE/like new, and spun well, too. The interior looked very clean.I was thinking it could be some kind of cavitation, but I think that'dve destroyed the motor by now.

Once the wrench shows up, I guess I'll drain the radiator again and put the new one in...see what happens...

More info: I just checked the aux fan per Gale's page. The radiator temp sensor appears to be bad, as does the ballast resistor (fan only works on HIGH when jumping the harness).

Best, Whit

[Javier]

the water inside the radiator was that hot? I mean, enough to turn on auxiliary fan or the VC? Having the gauge that high does not necessarily means radiator is hot, actually, the most probable cause of overheating is that water is not going trough the radiator, then it is not getting cooled! Question is why? Bad pump, may be, but think you took a look at it and seems to be OK, closed tsat? Probably, easy check if you have the proper feeling in the hoses, the auxiliary fan not going on is very revealing, too much bugs together to be trusted, A/C, ballast, radiator thermo-switch, let's debug first the thermo switch, its an easy job, pull it out, go to kitchen stove and boil it, hook at continuity probe between terminals 1 and 2 (pins close to the mark) and when closed switch to 1 (or2) and 3, they will close soon after as the water reach boiling point. Take it from boiling water to cool water, and both switches go open, again to boiling water and click-click. If you take the plug to the thermo switch at radiator and jump 1-2 or 1-3, will also debug for K21 and K22 relays and auxiliary fan. That I did in a situation similar than yours, and confirmed me that the radiator was cool wile the engine was hot. My case needed more bleeding.

Have you taken a look at Bruno's site regarding blown head gasket, it is interesting info there. **** I don't want to be the messenger on bad news, but white residues in oil, does not look good.

http://www.bmwe34.net/e34main/trouble/headgasket.htm

If tsat gets air, it does not open, then fan gets cold air from radiator and does not work properly. Also thermo switch see less than 91/99 degrees C (two stages) and does not start auxiliary fan.

If auxiliary fan system debugs to be OK, at least at the High speed stage (burned resistor), you are not getting the water trough the radiator, I would say either you sill have much air in the system (bleed and be sure pissing is not cloged again), or you have a blown gasket (getting exhaust gases on the system).

Wish you good luck. Javier

[Kalevera]

Javier - Yes, I've read Bruno's site a bunch of times on the topic. I haven't ruled out the head gasket, but I still think that there'd be other signs -- the exhaust is completely normal, and I'm not losing coolant beyond what I bleed out of it. I pulled out a lot of the residue floating around in the expansion tank and realized that it is old coolant in globs (yuck) or bits of rusty water. I think the white residue on the oil cap was from the oil getting really hot, but I'm not sure. It disappeared as the engine cooled down, and there wasn't any when I returned home with the car (with full heat on, thereby, hopefully -- a lesser temp).

I tested the fan and the relays already - both checked out fine, beyond the ballast resistor. I haven't tested the temp switch -- I'm just going to replace the thing because I don't have a multimeter handy. I suppose the thermostat that I installed could be bad? I didn't check it, and I think I threw away the old (working) one.

Once I get the new fan clutch, wrench, and other misc parts, I'll take it all apart again and see what I find. A friend of mine really thinks it's the water pump; it doesn't hurt to just change it, I guess, since I have a new one sitting right here...so I'll fix all of that stuff and then see where we are...

thanks, again, for all of your help!

best, whit

[Kalevera]

Oh - and I'm assuming right now that the TSTAT is OK as the upper hose is HOT to the touch and the lower hose is cool. I think that's how it's supposed to be?

[Dave535Phoenix]

I'm with Robin on this one. If it's 3/4 up the gauge cruising at freeway speeds, the fans aren't in the picture. It sounds like it's a coolant flow problem, not a fan problem.

You sure you didn't install the themostat backwards? Easy to do, and may cause some of the symptoms you're describing.

Without the system bled, my car would go from normal to 'bing' in about 45 seconds. It'd never have a problem on the freeway, only when I stopped or slowed. On the other hand, when my head gasket was blown, it'd overheat on the freeway.

Look at flow. The water pump - the belt? That nice and tight? The thermostat - bad out of the package? Backwards?


Good luck

[KeithW '91 535i]

I have an '89 735il and '91 535ia. I am VERY familiar with the cooling system and the frustrations.
IF your upper hose gets hot and the lower hose is cold, the tstat is not opening properly or at all. The lower hose SHOULD be a bit cooler (40-50 degrees or so) as the rad is doing its job, but not cold. So, the lower hose will feel pretty warm, near hot to touch if the stat is working well. I use a 71 degree stat all year here in Scottsdale, AZ. Like Javier said, a stuck stat will not circulate the coolant thru the rad and the fan clutch will not hook-up as it needs heat from the rad to do so. Just this week I was involved in similar issue. With the system drained, The stat drilled on the arrow and the stat installed with the arrow at 12 o'clock, the bleeder open, I poured some 1.5 gallons into the system until the expansion tank was full and it poured out the bleeder bolt. Tighten the bleeder bolt. Next, cap the expansion tank. Start the engine, turn heater valves to high, fan to med or high. Watched the guage slowly climb to midway. Then I grab the upper hose..it's hot. Next the lower hose...it's hot now, too. Still running, burp the system at the bleed bolt. Still midway at the guage. Test drove for 10 minutes. Back to the garage and idled for 10 more...still perfect. IF you have a bad head gasket, a common symptom would include: White smoke/steam out the tail pipe and/or expanded and hard cooling hoses from the pressure of exhaust seeping past the head gasket into the coolant jacket. Plus, the thing would probably not stop at 3/4 but would just go into the red. FAn clutch issues are typical at very slow speed and idle. Water pump issues tend to be 1- Leaking and 2- the shaft or pulley mount comes apart after the bearing pukes. By grabbing the fan blade at the top and pulling fore and aft, there should be little play, hence a tight healthy bearing. The fact that the car ran 'normal' before you worked on it indicates the stat may be bad/defective or by improperly bleeding initially, there is air in the system. The pissing return line is a sly dog to the uneducated. I was nailed by that darn thing once and that was enough! These things are touchey, but not to the extent you are experiencing. Last, make sure you have the correct rad cap installed. BMW recalled them a few years ago and provided replacements for free. Old caps do not release high pressure at a low enough pressure, and BMW says that the heater core could blow resulting in your getting burned by the hot coolant in the passenger compartment. Hang in there!

Keith in AZ.
'89 735il 243K miles
'91 535ia 192K miles

[Kalevera]

Thanks for all of that info, keith!

Yes, I'm wondering about this Tstat that I installed. This particular one (Vernet from BMA -- patrick said it was an OEM 88 degree, but the thing has every indication that it's an 80 degree) has no arrow on it. I drilled the 1/16" bleeder hole right below where the rubber gasket sits.

I'm going to pull it apart once my 32 mm wrench shows up. I'm pretty sure it's not the head gasket (yet), as the hoses (which are new), don't seem to be overpressurizing, and the exhaust is acting as it should.

My expansion tank cap reads "260" or "2GO" -- Javier mentioned, I think, that he has the same.

And the water pump...well, it looks fine, doesn't leak, and there's no play in the bearings....but I might as well replace it since I'm going to be messing around with that part of the system again...

Thanks! I'll let you guys know what I find out...when this wrench shows up.

Best, whit

[Kalevera]

I think I figured it out!

Well, time will tell. But I've been noticing that like...HALF of the radiator will be warm (the part closest to the upper hose) while the other will be cold, as well as the lower coolant hose. I haven't taken it apart yet...because I'm still waiting on Park Tool and that 32mm wrench :(

Today I drove the car about 2 miles, and as I was coming back, it was creeping up past the 12o mark. I shut it down in my driveway and started tinkering with the rear suspension. After I'd done that, I thought I'd turn it on and see what the temp was doing while I had a look under the hood. To my surprise, the lower coolant hose was WARM, as was the rest of the radiator, and the temp was dead on where it used to be before two weeks ago!

I decided to take a spin and see what happened. I started driving around and the temp was maintaining. I live on the edge of the city so I was able to do about ~65mph/100+kmh on the local country roads. After about three minutes of this, the temp started *dropping* until it hit 1/4 mark. I stopped at a turn in to see what would happen at idle, and sure enough it returned to normal and didn't overheat.

Well, I drove around some more, at more or less the same speeds, and it kept on dropping back to 1/4. I decided to do some quick starts to diagnose an unknown sound somewhere in the suspension, afterwhich it returned to normal and started overheating again, so I went home. Popped the hood and once again, 1/2 the radiator was cold, as was the lower coolant hose.

Here's what I think happened: the tstat has been closed all along. For some reason, it opened all the way while I was working on the car, and then stayed open until it dropped below 1/4 or whatever it was while I was driving around the second time. Afterwards, it didn't open again, hence the overheating returned, as did the cold radiator and lower hose.

My .02c says I got a defective tstat. What do you guys think?

Best, whit

[KeithW '91 535i]

If you read my post, the first line diagnosed the problem to be the stat and how to prove it.. I went on to tell you why the rest of the guesses were not right.
Regarding the wrench...I just went to the local bicycle shop and bought a head wrench with a 32mm size on it for $14.00. Works fine, and it is very thin.
So, change that stat and report back. Hope your problems are gone, Whit!

[Dave535Phoenix]

That's some good info. The most important step in troubleshooting any problem is getting specific about the symptoms. It is sounding like a flow problem...

Here's a whacky idea. Try removing the tstat altogether and driving around some. You can do that while waiting on the wrench. The car may never get to operating temperature, but at least you'll know one way or the other if the tstat is the problem.

I drove my '87 Accord around for two years (in Arizona) with a stuck open thermostat. Well, it wasn't exactly stuck open, it more disintigrated from corrosion. The car was a beater that never skipped a beat. At 178k miles the motor was still going strong. I say this to allay fears of damage from running too cool. Insert disclaimer here.

Good luck

[Kalevera]

Lol...yeah. Keith - I agree with you, but I just wasn't knowlegable enough in the workings of this cooling system to know for sure whether the flow was correct.

Dave - I'm too freaked out at this point about ruining some internal engine part(s) to run it with no tstat, so I guess I'll just call BMA tomorrow and ask patrick for a working one. I sure wish I'd kept my old *working* one.

best, whit

[rot535i]

Just a thought about your temperature sensors. There are two near the thermostat one is more off of the head and the other is closer the the t-stat if they are plugged in to the correct sensors. try swapping them and see what it is reading.

[Kalevera]

What would this determine?!

[rot535i]

What would this determine?!
I mistakenly switched them once and I had the temp guage reading 3/4. When I saw the mistake I corrected it the guage went back to just under the 1/2 mark.

[FSures]

If your coolant return line is clogged or not flowing properly, the car will overheat. There should be a good volume of coolant flowing back into the holding tank when the engine is at moderate rpm,s.

[Javier]

way selector, it opens one line wile closing the other. It is no good idea to simply remove it.

Why don't you just pull out the tsat and take a look, I found one just broken apart. You can also boil it (Pan, water, and kitchen stove, I'm not insinuating you are ignorant, I'm english ignorant, so just not sure if the term boiling means that in this context), even more if you have a 0-120 degrees C thermometer, you can also record opening temp.

I just refuse to keep changing parts without being sure I have to. Better save money for when it is needed.

For me it is clear tsat is not operating properly, this do not necessarily means it is the culprit.

Javier

[Kalevera]

Problem solved!

First, a BIG THANKS goes out to Javier, Dave, Keith, Robin, and everyone else who contributed tidbits (or bucketloads) of info.

What happened:

My 32 mm wrench showed up today (sweet!) so I was able to remove the VC and had more room to work around the front of the engine. Drained the radiator and as I was removing the tstat cover, heard a "thunk" from within.

Got the tstat out, looked okay. Took it into the house and messed around with it. It opened faithfully at ~ 80/88 degrees (I was using a not quite accurate digital meat thermometer). Everything looked fine. I put it back together, this time with the rubber gasket on the tstat cover side, replaced the aux fan switch on the radiator while I was at it. Filled up the coolant, burped and bled...went for a drive, where it went to a tick less than 12 and stayed there, even when running around for a while at ~4000/5000 rpm :)

Got home, noticed that some coolant was leaking from the aux fan switch (didn't tighten it enough, I guess) even after hylomaring it. So I tightened the heck out of that thing...hoping all along that the plastic radiator would stay intact.

Conclusion: I installed the TSTAT/gasket incorrectly, and this inhibited the tstat's ability to operate correctly. The old one had the gasket on the HOUSING side; apparently, on this tstat, it makes it not work. installing the gasket on the COVER side fixed everything :)

Thanks again, guys!! Couldn'tve done it without you!

Best, whit

[Javier]

Javier

[Robin-535im]

Javier

Congratulations, you are now the designated expert on cooling issues!

[Dave535Phoenix]

Congrats Lowell, cooling system problems can be agonizing - and expensive. Glad the issue was simple to fix, if hard to find.

I think I may have one of my own. I've just reinstalled my cylinder head after getting a valve job and replacing the rocker arms - motivated because 2 of 'em broke.

The car seemed okay for a couple weeks, but after a 30-mile freeway drive, some coolant started dribbling from the top tstat hose. This is the way my blown head gasket started :(

Apparently this can happen if exhaust gases leak into the cooling system and cause the pressure to rise. I'm worried to death that I somehow pinched the head gasket or something. I'll figure it out....but I may be tapping your newfound knowledge pretty soon - in a new thread of course. This one can close now.

Dave

[uscharalph]

I love this post. While some of it doesn't apply to my car, I've learned a lot. I'm sure I've got a lot more to learn, but that doesn't freak me out.

[Kalevera]

:)

M20 is a bit different with cooling issues than the M30, but yeah -- I learned a lot myself thanks to Javier, Dave, Keith & others....

best, whit