I just had the cylinder head gasket on my 3.8 replaced. It seems like a good job no oil leaks and seem to run as well as it ever did.
The problem is that the car seems to be running hotter as the oil and water temprature report higher levels. I have checked the fan clutch, radiator, thermostat (newly replaced) and hoses for signs of leakage. I have found none. I have not had the car a week yet but in addition to this after a drive of any real distance (say 20 kilometers in city traffic) I stop, pop the bonnet and feel the hoses. Each time they are hard to the touch. Indicating thay the car is running hotter than it should.
If I allow the engine to cool, this "hardness" dissapears.
I have even tried the obviously dangerous maneuver of opening the radiator cap while the engine is still hot. I get a gust of compressed air coming out and the hardness ceases.
My mecahanic says we should wait awhile and let the gasket bed properly. I do not think this is the answer. Does anyone have any ideas. The valve clearances are ok.
I understood that the coolant system in the M5 was self pressurising.
That`s why there`s a valve on top of the coolant level box. I thought that the system operated at pressure, the pressure generated by the heat of the engine expanding the coolant and the bit of air in the system.
(I understand the valve is either a no-longer-generally-used place to pressurise it, or is a emergency pressure relief valve, I`m not sure.)
Logically then, the hoses would be hard when the car is up to temp. Just like a coca-cola plastic bottle goes harder when heated or shaken.
If you release the pressure by undoing the radiator cap, then pressure lost, hoses go soft.
IIRC, very early cars were rumoured to have to be pressurised manually, later cars auto pressurise. I personally haven`t seen this written down, so I think it`s an urban myth, and they all self pressurise.
Back to your problem. How far does the water and oil needle go?
If I remember right, (I`m at work), my oil temp goes to about 7mm before the halfway line, and can go up to and just about halfway with hard driving, and 2mm past the halfway with very "spirited" driving in hot weather.
The water temp goes to mid-way, but I`m not so sure about this, so I`ll measure it tonight and update this post.
If your water is going very hot, 3/4 or higher, does it come down to halfway when driving constantly at 40mph+ ?
If so, it`s likely to be a failing/failed viscous fan coupling, ie fan not going around at low mph to cool engine radiator.
Ivan.
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Last edited by IvanDias; 7th October 2003 at 19:54.
It sounds like you may have air in the system. When the coolant is cool, remove the expansion tank cap and start the car. be sure to turn the a/c dials so the heat is on. Once the temp guage has gone out of the blue and approaching a normal temp the thermostat has opened. Keep an eye on the coolant level, it should drop once all the air has been circulated out. Fill the expansion tank to a slightly higher level, replace the cap and pressurize the system to 7psi. That may do the trick. If the problem persists then it may be a fan clutch on it's way out. Either way you will have gotten the air out of your coolant system and can rule out that possibility. Good luck
Could it be possible that the head gasket is fitted incorrectly (or the wrong one used) and is blocking some of the water cooing ports - i.e. stopping the water from flowing properly around then engine?
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Check the gasket. Nothing else on your car has been changed? Or has it? If you were not heating up before the gasket was changed then if that was all that was done it has got to be the gasket.
What your mechanic says is rubbish. A gasket is either correctly fitted or it is not.
ralph (vadas1)
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To Ivandais:
My car is a 3.8 and does not have a nipple for pressurisation.
I understand there should be some hardness but it is in my opinion too hard.
Before I had the gasket changed, the oil temprature gauge hovered about 5mm to the left of the midway point and stays around there unless I was driving very fast (say 240kph and above) then it would creep to about 5-7 mm past midway.
Yes the water temp gauge rises if I am sitting in traffic for anything more then say 15-20 minutes with the a/c on. I live in a very hot country.
We have tested the fan clutch and it seems ok.
To: Mmm-Five. I do not think the gasket was fitted wrong, firstly I was there and secondly it is difficult to fit it wrong as if it is so, the water holes will be covered by parts of gasket and we won't be talking about a gently heating up.
Toteven. I too suspect there is air in the system and that this is what is making the car get hot earlier than normal and hardening the hoses unduly. I will try your procedure but as I said earlier, my car has no pressure nipple on the coolanr tank.
To: Vadas1. I agree that a gasket is either in or not but I changed the gasket because the car overheated and I found traces of water in the dip stick.
I tried to bleed the air out of the system yesterday and it seems to be better. That is the oil and water temprature seems back to what I knew to be normal for me and for my clime. When I take it out and about today, I should know.
I very much doubt the gasket is installed incorrectly, all moder engines are designed so that the gaskets only fit one way to prevent this type of problem from hapening.
The hoses wil go hard because the cooling system is designed to operate under pressure, the pressure that the cooling system runs at is dictated by the valve inside the filler cap of the header tank, has this cap been changed, I doubt it.
Water temp running hotter than normal would suggest a problem with cooling system, the most common occurence is to have an air lock in the cooling system that prevents the water from reaching all the parts of the engine and from circulating correctly, you should try, turning the heater in the car to max heat, with the fan on the minimun speed, and run the engine for while, including giving it a good few revs a couple of times to try and shift any air pockets in the system.
other posibilities is a thermostat fitted the wrong way round ç8 not quite sure what symptoms this would produce, a lazy viscous fan coupling which would show up as the engine runing hot in traffic but cooling down when driving on the open road. May a water pump which has a damaged impeler, and therefore is not pumping the water round the engine, this would make the engine overheat under load, but would probably be ok if driven slowly or left to idle, and the last thing I could think of is the rad being blocked with the sludge and emulsion from water and oil having mixed before when the head gasket failed, but this would show as the coolant looking really shitty inside the header the tank.
Hello Enjoymentman,
I have had a similar problem. Engine getting very hot when driving in warm conditions. Had to open the bonnet and put the heating on (making it 35 degrees+ in the car). I finally over heated the engine going 250 Km/h on the Autobahn.
Before going to Germany I had BMW check the cooling system but they could not find anything technically wrong with it. In reality they were right.
The problem was that the radiator was filled with dried sand where the air should pass thru!!! Not that easy to spot since the clogged sand was not visible from the engine side.
The previous owner had hosed the "radiator" when cleaning the car, he thought. He had cleaned the A/C condensor and flushed all the sand and everything that got stuck in the condesor on to the radiator. The condensor is located in front of the radiatior and that is what you see when you look into the radiator grill from the front of the car.
The result was a complete re-build of the engine.
My advice: Flush the radiator with a hose from the engine side for 10 minutes. That should get any sand or blocking out of the way.
Thanks for all the replies. I had the air bled out of the engine again and it seem to have "cured" it. It is back to normal. That is the oil temprature gauge stays on the last marker before the mid point and the water temprature is a fraction over the mid point. I will still keep an eye on it though. The main thing is I have my car back and I have rediscovered what the reason why I am smitten with the car.
This is not the place for it but I will sure buy the E60 M5 although I think its ugly.
teven. I too suspect there is air in the system and that this is what is making the car get hot earlier than normal and hardening the hoses unduly. I will try your procedure but as I said earlier, my car has no pressure nipple on the coolanr tank.
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