Mysterious Loss of Coolant

[E34Freak]

Can anyone help me, I have tried everything and not even the Dealer has given my the correct answer. My car is a 1992 E34 525i.

This one is kind of a long term problem. I have tried everything. First the dealer changed the radiator, thermostat, water pump, heater core and several more trips to check the problem. They have done compression tests and everything. This is over a 1 year period.

It doesn't overheat and every time I ask them to check the head gasket they come back telling me it is not the problem. I went to another mechanic, since now I no longer trust the Dealer, and he said it could be a small leak in the head gasket and one that is not noticable by tests. No signs of oil or coolant in either side. Just the coolant level will not hold for more than two days now. Before, I was only adding coolant every month, which I thought was due to the age of the car and possible leaks in other parts of the system. Now it is getting worse and nobody can figure it out.

The funny thing is, it runs like a champion. Any opinions. Any help. I would like to try the CarGo Seal Up but not sure if it is sold in Japan where I live.

Thanks for any help.

[Scott C]

Check the hose clamps real well? Check the aux pump? I found I had a poor fitting and was very hesitant to tighten the clamp for fear of breaking the plastic. Check with white paper under the engine? Are you using BMW coolant (Blue - relatively easy to see)

Scott

[gale]

The head can crack between the water jacket and an exhaust port, hence no mixing of coolant & oil, and no possible leak diagnosis with a compression test or leakdown test. The only evidence is the odor of anti-freeze from the tailpipe or abnormal amount of vapor. They may be able to wipe a sample of soot from the tailpipe & have it analyzed for coolant.

Perhaps have them do a static pressure test of the coolant system & look for drips. Be careful not to exceed say 15 psi or it could put the heater core at risk. Look for wet carpet as well and fogging of the windshield which would be indications of a leaking heater core or associated plumbing.

[niall]

when a car is loosing coolant, there is 2 ways it can leak, internally or externally now externally is easiest to check, just put some paper under the car and run it up to temp and you will know if it is leaking, if there is nothing on the paper the our powers of deduction will tell us that it is leaking internally ie. throught the cylinder head gasket, just because it doesnt leak into the oil gallery doesnt mean the gasket hasnt failed, the coolant can leak into the combustion chamber and go out through the exhaust .

[niall]

Look for wet carpet as well and fogging of the windshield which would be indications of a leaking heater core or associated plumbing.

forgot to put that in myself!

[winfred]

one common leak place that a lot of people overlook is the auxilery water pump below the heater valves, it can crack and leak but usually it gets worse over time, leaking over a year with no trace is odd, if it's ingesting it there would be some sign, if it's going through the combustion chamber the cooling system would be over pressureized and there would probably be a slight miss at start up from water leaking into the cylinder, you could see the leak from the fact that the leaking cylinder's spark plug would be steam cleaned, in two or three dozen m50 head jobs i've yet to see one that went slowly from a crack or gasket, a quick dirty test is start it with the coolent cap off and if it blows out coolent/air without the engine actually getting hot theres something up, a little better test is top off the cooling system all the way up to the top and do a leak down test on the engine watching the coolent level to see if it rises

[winfred]

every cracked m50/52 head i've seen has ether been cracked between the valves or from the chamber across the surface of the head to a head bolt hole or coolent passage

[shogun]

Whow, another member located in Japan. We should get together. But I live in Tokyo and that is about 550 km away from Osake.
I got your PM, but all is already said be the excellent experts here.
Unfortunately I do not know any shop in Osaka/Kobe area. But I will go to the E32 meeting mid this months. Sometimes 1 or 2 people from Kobe come. If they are there, I will ask them for a reputed shop.
There is a good repair shop in Yokohama, mainly E34 and E32. They also have used parts. Their homepage is all in Japanese. But maybe you ask ask a friend if you cannot read Japanese.
http://www.poleposition.co.jp/framepage.htm
Some more pages for used parts in Japan:
Yahoo auctions E34 parts
http://search1.auctions.yahoo.co.jp/...ale=0jp&mode=2
Yahoo auctions E32 parts, many parts fit and are interchangeable
http://search1.auctions.yahoo.co.jp/...ale=0jp&mode=2
Part numbers you can get from the online ETK, just use the search to find it here.

[winfred]

http://babelfish.altavista.com/babelfish/tr

[Dash01]

The aux water pump on mine was leaking, though you'd never know it to look around the engine bay.

If leaking, you can 1.) Disconnect the hose that feeds the aux water pump, and re-install that hose to the heater control manifold just above, thereby bypassing the aux water pump. This works and costs nothing. The cabin heat still works, but is a bit slower to come on when the car is cold. Be sure to unplug the electric wire that feeds the aux water pump, so it doen't spin needlessly. Or, 2.) Replace the aux water pump, for ~$105 from BMA, or for price of shipping if your very good friend offers you his old one. Thanks, Duey! (I'm doing step 1 until I get around to step 2.)

Also, I found small a leak in my 7 month old upper water pump hose, right beneath (caused by?) the clamp. The hose was torn on the inside surface, but only had a tiny hole on the outside surface, beneath and hidden by the clamp. Steam would squirt out when the system ran hot, and was not particulaly visible except by shining flashlight on it in a dark garage or at night. Pretty subtle, this escaped notice for longer than I care to admit. Somebody else had a similar problem recently, so perhaps the 90 degree hose has quality issues. I'd saved my old lower rad hose as a spare, and its mid-section has a 90 degree bend and perfect offset, so I pared it down with a fishing knife and replaced the defective upper WP hose, pending a new one from BMA.

one common leak place that a lot of people overlook is the auxilery water pump below the heater valves, it can crack and leak but usually it gets worse over time, leaking over a year with no trace is odd, if it's ingesting it there would be some sign, if it's going through the combustion chamber the cooling system would be over pressureized and there would probably be a slight miss at start up from water leaking into the cylinder, you could see the leak from the fact that the leaking cylinder's spark plug would be steam cleaned, in two or three dozen m50 head jobs i've yet to see one that went slowly from a crack or gasket, a quick dirty test is start it with the coolent cap off and if it blows out coolent/air without the engine actually getting hot theres something up, a little better test is top off the cooling system all the way up to the top and do a leak down test on the engine watching the coolent level to see if it rises