Can you tell if your HG is blown?

[Rob]

Howzit Guys,

While inspecting my coolant level on Sunday, I notice to what looks like, dirt or rust in the coolant expansion tank. Could be oil. So I thought maybe the HG is blown. However I checked the oil cap on the engine block, no white stuff there at all. She doesn't smoke at all, no white smoke, no smell. So I'm guessing that because the engine stood still for nine months and again for a month last month, so could be rust or something. I'm going to completly drain the whole cooling system, bleed and refill. Will do more checks then.

How else can I tell if the HG is blown? Oh and I don't see any leaks around the HG or any oil dripping anywhere. All seems fine. Only thing that has made me ask this question and suspect the HG is gone is the coolant colour.

Also when I filled it up on Sunday to the COOL Mark on the expansion take it still gave me a coolant low warning. Check it again today and she's back down to the bottom of the tank, very low. How is this possible?

Thanks guys!

Oh, if you're all sick to death about hearing about my poor, sick E34, don't worry about this problem just yet. I'm going to focus on the power issue first get engine power back then tackel everything else.

:(

Thank you.

Rob.

[cschollum]

well you say its loosing water, that could be a sign of a blown gasket, however rusty water would be quite normal in a 1990 engine, a few flushes should cure that for a while

i would fill it up again, then monitor the operating temperature on a normal drive, make sure it doesnt go over half way on the guage, then reasses the water level when you get back after its cooled - if its lost more and youre sure there are no leaks, then I would suspect head gasket

[Rob]

Damn, I really hope not. Will get the system flushed and re checked. By the way is the HG hard to replace?

Oh and it lost water when I didn't even drive it at all. just ran the engine, It over heats while idleing! :(

[cschollum]

i wouldnt bother flushing it, untill you have established if the gasket has gone, 1 it will be a waste of time and 2 in the process of bleeding the system you may further damage the head

id see what others have to say at this point, the m20 engine is quite trigger happy in blowing gaskets, it certainly seems like that is the issue, overheating and loosing coolent.

the gasket isnt that difficult but it is to do right, depends on your experience and you must get the belt and tensioner back on correctly or it will smash the valves - plus the head nmay be warped and require skimming - as I say it depends on what your experience is

when you say it overheated while idling, how long did it idle for?

[Rob]

Idling for about 30 mins then will start to get hot. No the car has always had a overheating problem. My old man had the car before me and said its always got hot only when standing still really.

[cschollum]

you should never let the car idle for that long, really doesnt do it any good, plus you have no rush of air running past the radiator

take it for a run with a full coolent level and see how it behaves, keep an eye on the temperature and check level when cooled back down

but never idle for so long

[Rob]

See I have to wait for my pump to come next week, before I can take her out. But I don't think the HG is gone as the motor was recently re done. After a cam belt snapped.

[schematic]

You can get a pressure check done to check for leaks also another check would be a compression check on engine but you need the proper gauges should not cost too much to have tested
Howzit Guys,

While inspecting my coolant level on Sunday, I notice to what looks like, dirt or rust in the coolant expansion tank. Could be oil. So I thought maybe the HG is blown. However I checked the oil cap on the engine block, no white stuff there at all. She doesn't smoke at all, no white smoke, no smell. So I'm guessing that because the engine stood still for nine months and again for a month last month, so could be rust or something. I'm going to completly drain the whole cooling system, bleed and refill. Will do more checks then.

How else can I tell if the HG is blown? Oh and I don't see any leaks around the HG or any oil dripping anywhere. All seems fine. Only thing that has made me ask this question and suspect the HG is gone is the coolant colour.

Also when I filled it up on Sunday to the COOL Mark on the expansion take it still gave me a coolant low warning. Check it again today and she's back down to the bottom of the tank, very low. How is this possible?

Thanks guys!

Oh, if you're all sick to death about hearing about my poor, sick E34, don't worry about this problem just yet. I'm going to focus on the power issue first get engine power back then tackel everything else.

:(

Thank you.

Rob.

[joshua43214]

I would respectively like to make a few corrections. You should be able to safely idle the car for days with no ill effects concerning the heating, this is harder on the catalyst than any other part. There is a huge difference between runing hot and over heating, please don't confuse them and interchange the words. Running hot is whenthe gauge goes high on the gauge, overheating is when the coolent become hot enough to boil and the gauge goes into the red. ALL cars will run slightly hotter if left to idle, this is normal and is not a concern. If your car overheats at idle and not while cruising, you probably have a fan issue ie. loose belt, bad clutch, cloged radiator fins etc. If you have a overheat problem at all speeds, you probably have a waterflow problem ie. bad T-stat,cloged radiator etc.

If the car runs hot at idle and not at cruise, once again its probably an airflow probem, but could be a waterflow problem as well. If it runs hot at all speeds, it is also still probably a waterflow problem, but a bad radiator can cause this too.

Bleeding the system will absolutley no effect on the head, you simply can not do more damage to the engine bleeding it.

Please give us a proper description;
How high does the gauge get?
What is your ambient temp?
How long does it take to get there?(short time=waterflow)
Does the fan clutch engage?(air flow)
Does the aux fan come on?(air flow)
Does it cool back down when driven?(air and water flow)
Does it cool back down when idle is raised slightly?(water flow)
Does it cool back down when idle is raised to 1500rpm?(air and water flow)

Answer all of these questions to yourself, then ask yourself what the common demoninator is. Diagnosing most cooling sustem problems is straightforward, but people seem to think its voodoo. I see people toss parts at cars with overheating problems almost as much as they toss parts at cars for driveability issues.

Report back with your findings, don't use words like "overheat" unless the car is going into the red. it just raises red flags with people and you will get flooded with guesses about the cuprit.

Here is how the cooling system works;
As the car heats up, the water absorbs the heat from the engine and is circulated through the engine. When the water gets hot enough, the T-stat opens, and allows cold water from the radiator to enter the engine, this cool charge of water will then close the T-stat. The water then transfers its heat to the radiator allowing it to radiate off, while the water in the engine heats up again. This process is repeated until an equilibrium is established, this equilibrium is dependant on ambient temp. In very cold weather, the T-stat will just open and close as described above until the car is turned off. In warmer weather, the radiator will not be able to shed heat fast enough to keep up with the engine. At this point the T-stat will remain open(or partly open) constantly alowing a constant enchange of heat from the engine to water to radiator. The hot air coming ouf of the radiator is drawn accross the fan, when the thermocouple get hot enough, the fan clutch will engage, increaseing the air flow through the radiator and increasing its efficiency. In very hot ambient temps, the air flow at idle will be insufficient to maintain safe temps and a safety circuit will cut in causing the auxiliary fan to start. This fan will then bring the temp down to a safe level and then turn off.

If every thing is working properly, you the car will idle at a safe temp for as long as you like. This maybe about 3/4 gauge in very hot areas as the car cycles the aux fan on and off. So if its 105 degrees out and the gauge goes up to 3/4 or even higher when left to idle, but does not go into the red, its working as intended. Higher temps do mean increased pressure, so this can be hard on older weaker systems.

[Tiger]

Simple CO test will determine if you got blown headgasket. Mechanic should have this tool.

Check for coolant leak... like at your thermostat housing... heater core, etc. DO a pressure test and you should be able to find the leak.

[Jon K]

For what its worth i thought I blew my headgasket a few years ago because i saw coolant at the bottom front of the head. Turns out it was just my water pump leaking. I was losing cooland and thought oh noes. Just the water pump leak.

A headgasket on an M20 isn't too bad actually... if you are mechanically inclined I am sure you can do it yourself. Set a weekend aside.

[cschollum]

I would respectively like to make a few corrections. You should be able to safely idle the car for days with no ill effects concerning the heating, this is harder on the catalyst than any other part. There is a huge difference between runing hot and over heating, please don't confuse them and interchange the words. Running hot is whenthe gauge goes high on the gauge, overheating is when the coolent become hot enough to boil and the gauge goes into the red. ALL cars will run slightly hotter if left to idle, this is normal and is not a concern. If your car overheats at idle and not while cruising, you probably have a fan issue ie. loose belt, bad clutch, cloged radiator fins etc. If you have a overheat problem at all speeds, you probably have a waterflow problem ie. bad T-stat,cloged radiator etc.

If the car runs hot at idle and not at cruise, once again its probably an airflow probem, but could be a waterflow problem as well. If it runs hot at all speeds, it is also still probably a waterflow problem, but a bad radiator can cause this too.

Bleeding the system will absolutley no effect on the head, you simply can not do more damage to the engine bleeding it.

Please give us a proper description;
How high does the gauge get?
What is your ambient temp?
How long does it take to get there?(short time=waterflow)
Does the fan clutch engage?(air flow)
Does the aux fan come on?(air flow)
Does it cool back down when driven?(air and water flow)
Does it cool back down when idle is raised slightly?(water flow)
Does it cool back down when idle is raised to 1500rpm?(air and water flow)

Answer all of these questions to yourself, then ask yourself what the common demoninator is. Diagnosing most cooling sustem problems is straightforward, but people seem to think its voodoo. I see people toss parts at cars with overheating problems almost as much as they toss parts at cars for driveability issues.

Report back with your findings, don't use words like "overheat" unless the car is going into the red. it just raises red flags with people and you will get flooded with guesses about the cuprit.

Here is how the cooling system works;
As the car heats up, the water absorbs the heat from the engine and is circulated through the engine. When the water gets hot enough, the T-stat opens, and allows cold water from the radiator to enter the engine, this cool charge of water will then close the T-stat. The water then transfers its heat to the radiator allowing it to radiate off, while the water in the engine heats up again. This process is repeated until an equilibrium is established, this equilibrium is dependant on ambient temp. In very cold weather, the T-stat will just open and close as described above until the car is turned off. In warmer weather, the radiator will not be able to shed heat fast enough to keep up with the engine. At this point the T-stat will remain open(or partly open) constantly alowing a constant enchange of heat from the engine to water to radiator. The hot air coming ouf of the radiator is drawn accross the fan, when the thermocouple get hot enough, the fan clutch will engage, increaseing the air flow through the radiator and increasing its efficiency. In very hot ambient temps, the air flow at idle will be insufficient to maintain safe temps and a safety circuit will cut in causing the auxiliary fan to start. This fan will then bring the temp down to a safe level and then turn off.

If every thing is working properly, you the car will idle at a safe temp for as long as you like. This maybe about 3/4 gauge in very hot areas as the car cycles the aux fan on and off. So if its 105 degrees out and the gauge goes up to 3/4 or even higher when left to idle, but does not go into the red, its working as intended. Higher temps do mean increased pressure, so this can be hard on older weaker systems.

dissregard this bloke, running the car on idle for extended periods like half an hour or days! does the engine no good whatsoever, it fouls the plugs up amoungst other things

[joshua43214]

dissregard this bloke, running the car on idle for extended periods like half an hour or days! does the engine no good whatsoever, it fouls the plugs up amoungst other things

Yes it causes the car to run rich, which has the biggest effect on the cats, the plugs should clear back up after you drive the car. The point is, that nothing adverse will happen to the engine. Yes, It serves no purpose to allow the car to warm up more than a few minutes before driving, but to imply that it does damage to the engine to allow it to idle is false. Stating that bleeding the system can cause engine damage is also false. If you are unable to idle your car for an extended period of time, something is wrong, period.

Telling someone not to allow the car to idle to check an overheat problem is like telling someone not to drive the car up a driveway in order to check a front end noise since it may damage something. Parts should be tested before they are replaced or you are tossing money on senseless guessing, if someone is not qualified to test, then they will either learn from others or they should go to a shop and let a qualified person do it. Providing false information only makes things worse for every one.

[cschollum]

Yes it causes the car to run rich, which has the biggest effect on the cats, the plugs should clear back up after you drive the car. The point is, that nothing adverse will happen to the engine. Yes, It serves no purpose to allow the car to warm up more than a few minutes before driving, but to imply that it does damage to the engine to allow it to idle is false. Stating that bleeding the system can cause engine damage is also false. If you are unable to idle your car for an extended period of time, something is wrong, period.

Telling someone not to allow the car to idle to check an overheat problem is like telling someone not to drive the car up a driveway in order to check a front end noise since it may damage something. Parts should be tested before they are replaced or you are tossing money on senseless guessing, if someone is not qualified to test, then they will either learn from others or they should go to a shop and let a qualified person do it. Providing false information only makes things worse for every one.


youre arguing for the sake of it, not reading what I have said, bleading the system in itself will not damage the system, however while you are refilling the coolent and running the engine it can overheat while youre not watching the temp gauge, plus I was saying there is no point in bleeding the coolent if you suspect the head gasket has gone, why bother you will only have to do it again.

leaving the car idling for half an hour doesnt do it any good, im not saying it will explode! i am just stating that 1 there is no point in doing it, and 2 it doesnt do the engine any good

[joshua43214]

I'll not drag this topic farther OT than this.


i wouldnt bother flushing it, untill you have established if the gasket has gone, 1 it will be a waste of time and 2 in the process of bleeding the system you may further damage the head

Thanks for the clarification, I thought I read that you stated that bleeding could cause damage to the head, I see now you meant further damage to the head, which is also false assuming any damage in the first place. Rob has been posting a nice stream of car issues, so running the car at idle for exteded periods is to be expected both to diagnose problems and verify repairs. Far better to break down in the driveway than on the side of the road.

Rob please report back with your findings =).

[genphreak]

youre arguing for the sake of it...take a chill pill. There is nothing wrong with anything either of you are saying. Joshua has at least gone to the effort of describing some correct theory and some good tips for testing. The fact is, if you are testing a cooling system we ALL know one should keep an eye on the gauge AND to shut it down if it looks like overheating. Also, witha little patience, and even with a blown head gasket, you can play with pressurising the cooling system, bleeding it and etc. without having to risk any (real) overheating. There is another thread describing how to force bleed the system using your own mouth over the overflow tank... it was good advice too.

If the car has tended to run hot for a while (without overheating in clouds of steam) then the chances are the cooling system has a faulty fan. Could be a switch, either themrostat or a fan motor or fan clutch. A thorough check of the operation of all these items, inc the water pump can be made very simply.

Maybe more than one item is faulty- or maybe a cooling system overhaul (inc. hoses and coolant) is often warranted. Either way its no biggie if you have a Bently manual. :) Nick

[Kalevera]

It's news to me that these cars run rich at idle. I, for one, have never heard of or seen any motronic BMW do so without an existing issue.


best, whit

[AllGo'n'Show]

One question...

My guage stays at the warm/perfect temp *right in the middle* all the time. Idle or driving.
Doesn't vary whether its idling or driving down the road or driving hard.
I do smell coolant sometimes, I am thinking heatercore but thats quite the undertaking it seems for E32's.

I'm slowly burning Coolant or loosing Coolant somewhere along the lines. I don't noticed white smoke out of my tail pipes and haven't had anyone I drive infront of mention it to me, don't see it while idling after its warmed up either.

Possible HG or is it that damn heater core? Its a slow leak or slow burn somewhere, I get the wanring message on the dash probably every 2 months.

Thanks everyone!

[joshua43214]

One question...

My guage stays at the warm/perfect temp *right in the middle* all the time. Idle or driving.
Doesn't vary whether its idling or driving down the road or driving hard.
I do smell coolant sometimes, I am thinking heatercore but thats quite the undertaking it seems for E32's.

I'm slowly burning Coolant or loosing Coolant somewhere along the lines. I don't noticed white smoke out of my tail pipes and haven't had anyone I drive infront of mention it to me, don't see it while idling after its warmed up either.

Possible HG or is it that damn heater core? Its a slow leak or slow burn somewhere, I get the wanring message on the dash probably every 2 months.

Thanks everyone!

MY first suspect for very small leaks is either a loose clamp or a bad radiator, look for staining, and dampness rather than liquid. There may be white residue as well. The radiator commonly seeps along the seem where the side tanks join the metal part, you may have to tip the top of the radiator rearward to inspect it. Drive the car hard, park in it an area with still air and follow your nose. Good luck.

[Beemr750]

There is an easy way to check for blown HG.If no visible leaks occur and the temp stays normal but still experience water "loss" in the system,it's most likely the HG.Top off the fillerneck till it overflows, keep idling the engine,after the initial air displaced is gone there should NO bubbles come out of the water ever. The level may rise while it gets hotter but no bubbles should follow.If the bubbles don't stop.... you will have to get busy.

What's happening blowby compression will build up till the cap releases to overflow.You will also notice the hoses will absorbe the higher pressure by getting harder to the touch and swell some what.

It happened to my 535,when taking it to the dealer for a CO2 check,it tested negative, but suggested a new waterpump and a fan clutch.I did not think for a minute about his suggestion,because it never overheated on me.The only worry was the loss of water and the bubbles never stopping.

Btw I took a pressure reading of the cooling system when the hose got hard.It read 28 PSI that meant my 2 bar cap was working OK but also I stopped everything and ordred me a gasket kit.

[genphreak]

It's news to me that these cars run rich at idle. I, for one, have never heard of or seen any motronic BMW do so without an existing issue. best, whitOK, perhaps not much wrong with what was said... :D

[Rob]

Wow, didn't expect this thread to still be here. Sorry if I've caused an argument.

Okay, well I've determend that the head gasket is actually fine. What's in the expansion tank is bits of dirt/rust as fas as I can tell. No oil in there at all.

I'm hopfully getting my new pump on Friday. Will fit Monday and let you guys know how that goes.

I checked the rad and it is covered! in thick dirt on the front. This may be the cause to overheating?

Sorry about the whole long post guys. :(