Overheating Diagnostics - Continued...

[Mitch90535im]

Decided to start a new thread on this one -

Replaced the fan clutch ("borrowed" the tool from Autozone to hold the waterpump pulley)

Now the bad news - the fan clutch was not my problem.

Back to diagnostics.

1) I believe the thermostat is OK based on the fact that the top radiator hose is hot. Is that a valid assumption?

2) Is there any sure way to test the water-pump on while on the vehicle?
Bentley says to take the belt off and spin and check for play. I'm not sure that is a complete test. I'm looking for a way to tell if it is actually pumping coolant.

3) I'm going to test the aux. fan this evening. I'm really not sure if it is working or not. Question - With the air compressor on should the aux fan run regardless of whether the aux switch on the radiator is bad or not?

4) I'm looking for someone to do a coolant system pressure test (my luck it is a head gasket) but I'm having trouble finding a mechanic willing to diagnois problem unless I'm willing to let him do the work.)


Any other suggestions would be appreciated.

MB

[Mitch90535im]

Looks like "cooling system week" on the board. (bump)

[632 Regal]

if the switch is bad they wont come on.

[Mitch90535im]

Based on that I believe I should test the switch/fan low and high speeds by jumpering the plug. Sound reasonable?

[632 Regal]

Based on that I believe I should test the switch/fan low and high speeds by jumpering the plug. Sound reasonable?

[Derek A.]

The a/c turn on for the aux fan operates independantly of the thermo switch in the radiator. If the a/c compressor is running the fan should be on, if its not there is a problem. Generally an aux fan problem will not cause on overheat problem. Its only when you are in a super hot climate sitting still that it kicks in. Are you comsuming coolant ? when does it overheat ? Its possible tha the thermostat is open enough to allow some coolant flow but not enough to cool the engine when it get hot.

[Dan in NZ]

I replaced my fan clutch and still had overheating, same as you. It turned out my radiator was 75% blocked, so I took it out and had it cleaned out by a specialist, then re-installed. Good as new.

[Mitch90535im]

Its only when you are in a super hot climate sitting still that it kicks in. Are you comsuming coolant ? when does it overheat ? Its possible tha the thermostat is open enough to allow some coolant flow but not enough to cool the engine when it get hot.


Not consuming coolant. It overheats in slow traffic after it has warmed up and the needle has remained steady at 1/2 for 5-6 minutes. I guess the thermostat is a possibility, top hose is plenty hot. I didn't get a chance to test the aux fan yet, but I'm glad someome qualified the fact that the AC controlled fan switch is independent of the radiator switch. (got bad advise on that one earlier). Earlier was told that if the radiator switch was bad, the A/C switch would not work either. That should be quick enough to test this morning before work.

I suspect either:

1) Aux Fan (or related switches/resistors)
2) Water Pump (still haven't seen any advise on how to determine if it is actually pumping coolant)
3) Thermostat
4) Head gasket or crack

The odd thing is that this all started just after a coolant drain, flush, and fill. That's obviously why I suspected trapped air, but I've bled dozens of times, and there really doesn't appear to be any trapped air at this point.

[Mitch90535im]

Update - Aux fan runs on low speed with A/C on. Drove to work with compressor on this morning and temp still wanted to creep up above 1/2 mark. I'll test radiator switch this evening.

Beginning now to suspect either the water pump, or thermostat that is only partially opening.

Any recommendations from you guys at this point?

[Derek A.]

Can you feel hot air being pumped by the fan when the car is running ? How old is the radiator on the car ? After you shut the car off how long does the cooling system hold pressure ? If the top hose collapses quickly I would guess that you have a leak somewhere. How does the engine oil look ? Does the car make steam a lot out the exhuast ?

[Mitch90535im]

Can you feel hot air being pumped by the fan when the car is running ? How old is the radiator on the car ? After you shut the car off how long does the cooling system hold pressure ? If the top hose collapses quickly I would guess that you have a leak somewhere. How does the engine oil look ? Does the car make steam a lot out the exhuast ?


Can you feel hot air being pumped by the fan when the car is running ? Which fan? Heater fan inside - yes. Main radiator fan - yes, but it doesn't appear to increase when hot (that's why I replaced the fan clutch to begin with, plus it spun a few turns, didn't come to an "abrupt" stop, when the engine is turned off hot) Aux radiator fan runs with A/C on. Temp still wanted to creep over 1/2 even with aux fan on.

How old is the radiator on the car? 2 months

After you shut the car off how long does the cooling system hold pressure ? Not sure, but it does seem to be pressurized when I remove the overflow tank cap, or open the bleed screw.

How does the engine oil look ? Good and clean

If the top hose collapses quickly I would guess that you have a leak somewhere. (Hard as a rock)

Does the car make steam a lot out the exhuast? It always has - no more than usual.

[George Davis]

"The odd thing is that this all started just after a coolant drain, flush, and fill. That's obviously why I suspected trapped air, but I've bled dozens of times, and there really doesn't appear to be any trapped air at this point."

Too much of a coincidence. I'd suggest bleeding again, with the engine hot so you're sure the t-stat is open. I think it's also a good idea to have the nose of the car higher than the tail, like on a slope or ramps, that way any air bubbles move (upward) toward the t-stat end of the engine.

There are probably some creative ways to test water pumps in place, but it will be messy. One way would be to pull off the heater supply hose from the block outlet, block the hose end, then install a length of hose from the block heater outlet and into the radiator fill hole so you don't lose all your coolant. (I'm guessing about the heater hose because I don't know how your engine is configured.) Start the engine and it should pump coolant out of the hose if it's pumping. If you only have access to the heater return hose, the same should work but run the extra hose from the heater outlet to the rad filler and block the heater return fitting on the block, and be sure your heater is full on. Alternatively, remove the pump and make sure it's definitely in one piece. If it isn't broken and the belt turns it, it's a pretty good bet it's pumping.

[JonE]

Can you feel hot air being pumped by the fan when the car is running ? Which fan? Heater fan inside - yes. Main radiator fan - yes, but it doesn't appear to increase when hot (that's why I replaced the fan clutch to begin with, plus it spun a few turns, didn't come to an "abrupt" stop, when the engine is turned off hot) Aux radiator fan runs with A/C on. Temp still wanted to creep over 1/2 even with aux fan on.

Are you sure that new clutch is good? Some people have reported getting a bad one. I could tell the difference right away when I changed mine, the sound was much louder as that fan started to really push the air around, kinda like a big truck, sorta like a "roaring" sound. Either that or there is something else not allowing that clutch to get hot enough to lock up. George Davis's suggestions sound good. I assume that it was bled properly with the heater on high while bleeding? T-stat is good and inserted properly? Hopefully others will have better advice for you, too.

[632 Regal]

blown head gasket??

I hate to say it but since this started right after you flushed and bled it quite coincidental. Just an option.

Back to basics here...T-stat, trapped air, water pump, radiator or clutch fan.

Elimination says rad is OK,

T-stat hasnt been replaced...replace that and the pump if it hasn't and go from there.

[Mitch90535im]

blown head gasket??

I hate to say it but since this started right after you flushed and bled it quite coincidental. Just an option.

Back to basics here...T-stat, trapped air, water pump, radiator or clutch fan.

Elimination says rad is OK,

T-stat hasnt been replaced...replace that and the pump if it hasn't and go from there.

What is about drain, flush, and fill that would lead you to think Head gasket?

[632 Regal]

overheated the **** outta it?

Doubt it thats whay I said back to basics.

[Mitch90535im]

I try to be really careful to avoid that. It scares me to drive it when it creeps barely past 1/2. I thought I might try jumping the fan switch plug to make it run on high, but since it still wanted to overheat with the aux fan running via the A/C switch, I really don't think that will make a difference.

My guess (and that's all I'm qualified to do at this point) is that either:

1) the thermostat is not opening fully
2) the water ppump is not moving coolant
3) trapped air
4) head gasket or crack
5) bad fan clutch from BMA? New one appears and feels just like the old one, which doesn't seem to increase air flow when increasing rpm's when hot, nor does it come to an "abrupt" stop when hot. Of course that all depends on the exact definition of "abrupt"? It spins by hand about the same, whether cold, or hot and to me that just doesn't sound right? Should I maybe talk to Patrick/Yeves about a return/replacement? Without seeing one on a car that we know is good, I just don't know how to gauge if this clutch is good or not.

The fact that the heater works, and blows warm air - does that indicate either that the water pump is ok or that the thermostat is ok? Or does it not really tell me anything?

Did I mention I'm a complete novice at this?

[632 Regal]

it should make a lot of noise, kinda like a schoolbus accelerating. When they are cold they will be tight as when they are warm so that isnt a test.

[Derek A.]

If the cooling system is not full of water then the radiator will not radiate warm air and it will not allow the viscous fluid in the clutch to lock up and pull the air. Can you see coolant squirting through the recovery tank on the firewall ?

[Mitch90535im]

"...it should make a lot of noise, kinda like a schoolbus accelerating"

It really doesn't seem to make any difference with it hot vs cold. Now I'm beginning to wonder if I received a bad clutch from BMA?

[632 Regal]

Derek has a point.

[Mitch90535im]

Yes, and I think it is full of water now. How would I tell?

[George Davis]

Did you bleed it after the engine was fully up to operating temperature and the thermostat definitely open?

[Mitch90535im]

Did you bleed it after the engine was fully up to operating temperature and the thermostat definitely open?

I definitley bled it and topped off with the engine running, after the engine was fully up to operating temp, and I assume the thermostat was open (but I'm basing that simply on the fact that the top hose is hot and stiff, not that I was able to visually see the thermostat or anything). I've bled it a couple dozen times, and for the past 22, there hasnt "appeared" (to my novice eye) to be any air in the system. At least none that is working its way out of the bleed hole. It's blowing a steady stream of coolant/water.

I'm thinking next:

1 - test aux fan and switch at both speeds
2 - replace the thermostat
3 - try to figure out if the water pump is moving coolant
4 - replace the water pump
5 - explore with Patrick the possibility that the new fan clutch is bad
6 - replace the fan clutch
7 - pay the service guy $60 to test the pressure

Sounds like a f&%#ed up Saturday ahead.

[632 Regal]

I definitley bled it and topped off with the engine running, after the engine was fully up to operating temp, and I assume the thermostat was open (but I'm basing that simply on the fact that the top hose is hot and stiff, not that I was able to visually see the thermostat or anything). I've bled it a couple dozen times, and for the past 22, there hasnt "appeared" (to my novice eye) to be any air in the system. At least none that is working its way out of the bleed hole. It's blowing a steady stream of coolant/water.

I'm thinking next:

1 - test aux fan and switch at both speeds
2 - replace the thermostat
3 - try to figure out if the water pump is moving coolant
4 - replace the water pump
5 - explore with Patrick the possibility that the new fan clutch is bad
6 - replace the fan clutch
7 - pay the service guy $60 to test the pressure

Sounds like a f&%#ed up Saturday ahead.

[Mitch90535im]

Not the thermostat.

Have water pump on order.

[liquidtiger720]

sorry to go a little off topic- but, my temp gauge is about one needle width over the 1/2 point. does this mean i still have a little air in my system?