# 2000 BMW 740il coolant leak



## rservati (Feb 3, 2009)

My 2000 740 with 58,000 miles is leaking antifreeze at the back of the engine on the top. I have to add about 1 cup of antifreeze every 1-2 weeks or so. Mechanic tells me it is an intake manifold gasket and wants $500 for repair. He did not do a pressure test. Does this sound right? I this serious enough to get repaired now or could I wait until it gets worse? It's been leaking for over a year now.


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## M.Wong (Jan 9, 2003)

You posted this in the new member into page first. Hopefully here, you will find better results. 

A coolant leak is almost always critical. If you do not trust the mechanic to locate the leak, you may want to have a pressure test done elsewhere to verify. If the source is high, I would check those heater hoses first. Here are some posts that might help:

Hoses

Water valve

Intake gasket, valve cover gasket

Valley pan gasket


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## crewdog843 (Mar 15, 2006)

You specify 'back of the engine on the top', which sounds like the valley pan gasket. This is something you definitely want to get looked at and fixed quickly, especially since your car has such low mileage for the production year. If in fact it is the valley pan, you may want to consider a new OSV at the same time as the upper quarter of the engine will have to be removed to get to the valley pan. If you are handy with tools, this is a job which you can do yourself and is well documented on many forums.

I just had mine done....it started with a SES light caused by the OSV and they found a valley pan leak in the process. Some other things to look for: Seeping valve cover gaskets and leaking heater hoses on the firewall.

jake


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## rservati (Feb 3, 2009)

*Valley Pan Leak*

What did it cost you to repair the valley pan leak?


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## crewdog843 (Mar 15, 2006)

Hard to say as the valley pan leak was in conjunction with all the other work performed.

It started out with an SES which did not seem to affect the overall running of the engine, as it remained powerful, smooth and responsive. I took it in the next day and they determined the cause to be a lean condition caused by too much vacuum in the engine, in turn caused by an OSV going south. In the process, they noted the signs of leakage in the valley pan. To replace the OSV, they had to take the entire intake manifold off, thus exposing the valley pan so it was as no brainer to replace the valley pan as well. 

They replaced the valley pan and buttoned up the engine, and it passed the pressure test but failed the road test. They had to take the top apart again and put a new valley pan in, which fared better. In conjunction with all this, I replaced the fuel filter and the MAF, as once the OSV was replaced, fuel adaptation values went in the other direction resulting in a MAF replacement.

All in all: $2131.19

Labor was $1153.56, parts only $907.31. Car out of commission for four days. Odometer 80732 miles.

jake


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## rservati (Feb 3, 2009)

*Coolent leak on 2000 740 il*

Well I was told today the leak is in he valley pan gasket. They want around $500 for parts sand labor. I also noticed that the driviers side of my heating system is pulsating air that is hot then cold and cycles like this evey 2 seconds. The passenger side works fine. They think it's related to the coolent leak and think air could be getting into the system. Who knows. This car is too complicated.


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## crewdog843 (Mar 15, 2006)

They are probably going to find a leak at that cluster of rubber hoses on the firewall....have them take a look at it when they get the top off the engine. You may also want them to do a 'slack tube manometer' test on the car to determine if the OSV is working properly. If it has never been replaced on your car, it should be as it will fail soon(er or later). 

It is easier to replace the OSV while the intake manifold is off to service the valley pan than the other way around.

jake


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## sleepymartini (Oct 27, 2008)

Crew dog is right about the OSV, if it needs replacing. Its better to do it after you take the entire manifold off. I replaced mine before I realized I needed to replace the valley pan gasket.

Fair warning, unless your are Better than average DIY mechanic, dont attempt the valley pan gasket.


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## rservati (Feb 3, 2009)

*2000 740 with valley pan leak*

Could the valley pan leak also cause the driver's side heating system to cycle hot then cold air every few seconds? I have the water vavlve replaced 2 years ago for a different problema nd I hope that hasn't failed again.


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## crewdog843 (Mar 15, 2006)

I don't have any basis for saying 'I don't think so', only that it sounds like a sensor. In other words, under normal circumstances, a sensor would 'sense' that the internal cabin temperature was either too high or too low for the preset temp shown on the dash and adjust the output accordingly, especially if you are set on 'Auto'.

I haven't driven any long distances in my '01 in quite a while, but I remember the air conditioning cycling on and off in response to vacillating cabin temperatures....I would have to assume that the heater would as well. In your case, however, the cycling seems to be abnormally fast.

jake


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