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Old 10-12-2012, 09:15 AM
robertobaggio20 robertobaggio20 is offline
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Originally Posted by Larrick View Post
Thanks for the information. It is 5:30 am. I can not sleep thinking about it! A few more question please.
Is there any reason that a cooling system will not be able to eliminate all the air?
If there is a head gasket problem, can air be being introduced into the system as it trying to be bled?
I researched a "ticking" sound coming from the top,front of the engine. Most popular explanation is a loose spark plug followed by lifter, loose belt, lose pulley and water pump going bad.
If it were the valves, common opinion (internet) says that it is not a problem and some suggest a 5W50 oil to cure the noise.
The spark plug is easy to check.
How much slack should be in the belt? Isn't there just one adjustment position?
I have always thought that the exhaust contained my vapor than I liked but it has been doing that for a long, long time.
It was cool and we had some rain and mist conditions yesterday but the BMW did it much more than my truck.
Wouldn't I need to loose considerable coolant to make the car overheat? Assuming I have the air out of the system.
Why can the engine run for more than an hour at idle (as I tried to bleed it) with the temp gauged pinned at the 1/2 mark but run a little hotter when on the road (and eventually overheat)?
I would think that the engine would cool better while while being driven gently. (more air flow and coolant flow) Is that situation an indicator of a bad water pump?
The pump can not keep up? Will a bad (weak) water pump make it harder to bleed the system also?
I will report back. Thanks again

Hi Larrick. Here are some answers to the questions you asked earlier. I guess you'll only read this when you're back from running your car.

FYI a cooling system will never be able to eliminate all the air that it has. Engines are designed with that in mind. Only large air pockets will cause damage to the cylinder head. There are tiny ones being created and collapsing all the time in the extremely hot environment of the cylinder head. All of that is factored in. Normal bleeding as described here and/or the Bentley manual, by normal people, and without special equipment, is all that a normal cooling system requires to be happy.

Hmmmm no HG issues do not introduce air into the cooling system, but cracks in the cylinder head might. With the rad cap off and the engine at idle, do you see little bubbles appear in the expansion tank (not the bleed screw) ? If so, those bubbles are from combustion gases being squeezed through a crack in the combustion chamber that leads to a coolant passage.

The ticking sound that you're referring to could be your vanos unit being temperamental. Belts generally cause squeaky sounds, and even if they are ticking sounds, they will sound kinda squeaky. lol. It is very very unlikely for a spark plug to get loose once installed. I've never heard of that. Anyway, if your car drives well, it is unlikely that anything related to the spark plugs, ignition coils, etc, is at fault.

You do not have valve lifters as you're using a twin cam engine. The M20 E34s had that. The solution to valve lifter noise is not to change the engine oil, but to have the valve lifters tightened down to correct tolerances using a feeler gauge. This needs to be done every 50k I believe.

A water pump going bad is unlikely to generate alot of noise that you cannot easily trace to the water pump itself while standing over the engine. I could be wrong here though but I would think so.

It is not logical for the engine to be fine at idle but overheat while driving. The cooling effect of onrushing air is far far greater while driving and more than compensates for the higher rpms. If this is happening, and you're not losing coolant , then its fair to say that your water pump or thermostat is busted and insufficient heated coolant is circulating out of the head into the radiator to be cooled. Check if you're losing coolant when you stop the car after it overheats, then gently loosen the rad cap by 1/4 turn, and then another 1/4, to relieve the pressure, wait 5 minutes and loosen more, and eventually you'll be able to remove it without everything spilling out, and you can see how much coolant you've got left. If you've not lost any, then its a simple matter of the water pump or the thermostat. I would advise that you change both for peace of mind.

Yes, a bad water pump will make it harder to expel air from the cooling system. But sir, please, don't worry about air in the system. It is very rare from what I've observed. I've done substandard bleeding of my radiator before, driven it for a week, done another bleeding and noticed TONS of bubbles, and I had no problems for that week.

The exhaust is not supposed to contain any vapour at all, especially after you stop the car after a drive. If its always been that way...hmm.

Please do the stomp test and see if there's any interesting error codes stored on your computer. Who knows ? Something relevant might be there.

The belt should have no slack whatsoever. It should feel tight to the touch, you almost shouldn't be able to move it laterally or upwards (just the tiniest movement). You should be able to flick it with your thumb and it will feel sharp. If you don't have that, you've got a problem. Not a big one, but fixing it will improve your drivability. The problem may be buggy pulleys (not likely), buggy tensioners (probable) and old belts (probable). One simple way to tell if your engine belt system is working perfectly is to use fan belt spray on it. Spray it everywhere with the engine off and when the engine is on (be very careful). See if any noises that you mentioned earlier have disappeared. If they have, then you've got something to look at there. Your car will also drive better with the fan belt spray on it.

I'm not sure what you mean by "adjustment position". You must refer to the tensioners over there. I believe that there are at least two automatic tensioners in the E34 (m50) and may be more...not sure. If they are in good shape, the belts will become tight once the tensioners are released. If they are in good shape but the belts are loose, the belts are the problem, and you might have the wrong belt on your car (it happens).

Yes you would need to lose a fair bit of coolant before overheating sets in, assuming that there are no large air pockets left, and that your water pump and thermostat are working correctly. Any one of those elements being busted can easily lead to overheating situations.

Last edited by robertobaggio20; 10-12-2012 at 09:19 AM.
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