540iA - How do I know is it thermostat or water pump?

lutasa · 12-13-2010, 08:45 PM

I got my first dream machine - 2001 540iA M-pkg 3 months ago with 180kms. Previous owner apparently replaced WP, fan clutch and belts/tensioners in May this year (I believe he did) and car is overall in great shape. Here's what's happening: I see no obvious coolant leaks, after 10 min of engine running, temp goes past the middle mark, top radiator hose is warm but bottom one (coming out of the radiator) is dead cold and I have no warm air in the cabin no matter what temp I set in the cabin. Is this the thermostat issue or the WP? How do I tell?

blk3 · 12-13-2010, 08:48 PM

if its a waterpump issue you will have no coolant flow. you could pull off any coolant hose and start the car and you will see no coolant flying out of the hose. more than likely its a thermostate issue

lutasa · 12-13-2010, 09:03 PM

Quote:

Originally Posted by blk3

if its a waterpump issue you will have no coolant flow. you could pull off any coolant hose and start the car and you will see no coolant flying out of the hose. more than likely its a thermostate issue

Thanks blk3, that's what I'm hoping to be. From what I've found in the posts, replacing thermostat/housing is fairly simple DIY procedure. Shell I replace anything else while I'm doing the thermostat?

Dado 540 · 12-13-2010, 10:02 PM

Loss of heat in the cabin could be an eazy fix as adding coolant to the reservoir and/or releasing any build up air pockets.

Next step could be the thermostat or heater core,....

If the thermostat is gone it will go into the manual mode and stay open as a failsafe not to overheat the engine so your engine would actually be cooler than normal.

This car and its never ending cooling issues aghhhh! Do the whole overhaul and be at peace. Get the all aluminum rad with built in tank, water pump with metal propelers, bulletproof thermostat.

lutasa · 12-13-2010, 11:37 PM

Quote:

Originally Posted by Dado 540

Loss of heat in the cabin could be an eazy fix as adding coolant to the reservoir and/or releasing any build up air pockets.

Next step could be the thermostat or heater core,....

If the thermostat is gone it will go into the manual mode and stay open as a failsafe not to overheat the engine so your engine would actually be cooler than normal.

This car and its never ending cooling issues aghhhh! Do the whole overhaul and be at peace. Get the all aluminum rad with built in tank, water pump with metal propelers, bulletproof thermostat.

Looks like you've been there already

Do you have any idea what the cost of complete overhaul be in GTA? Here in London, I'm pretty much stuck with local dealership

I know that rad has been already replaced by BMW (it was ex CPO car) and as I've mentioned, previous owner replaced wp, pulleys, fan clutch and belts approx 6 monhts ago...

Eurostyle · 12-14-2010, 01:36 AM

Why not just replace the thermostat and see what happens! It's not a milion dollar item, and pretty good to do if you dont have any records of when it was replaced.

The cheap way of testing it will be to take the Tstat out, and run the system without it. If problem goes away, then you know what was wrong!

The other way of testing (without running the car) is placing the Tstat in boiling water (or heat up with a torche) and see if it opens, or stays closed (stuck!)...

lutasa · 12-14-2010, 02:41 PM

Ok - I just ordered new Behr thermostat/housing and will be replacing it tomomorrow. Seems to be that replacing it annualy is almost the safest thing! I will let you know the outcome....

Thanks everyone for tips and suggestions, it's highly appreciated!

daveyto · 12-21-2010, 07:30 PM

Quote:

Originally Posted by lutasa

Ok - I just ordered new Behr thermostat/housing and will be replacing it tomomorrow. Seems to be that replacing it annualy is almost the safest thing! I will let you know the outcome....

Thanks everyone for tips and suggestions, it's highly appreciated!

Replacing it annually is fine for GM and ford but many of the import Tstats last a very long time.

My question is are you getting heat in the car? If the needle is over the middle but not buried far to the right it is prob ok. The gauge is just a general indicator. Again if it is buried to the right you may have a problem. Although it does appear from what you are saying that your Tstat may be stuck or opening slowly.

You can take the old one out and boil it in water and see if it opens quickly enough.

Again my Tstat in my e39 is almost 7 years old...my subaru Tstat was over 11 years old and no issues.its possible also the coolant wasn't filled properly.

Refer to the proper procedure from the manual...I can't remember what it is but somebody can chime in. Try this before you take everything apart.

lutasa · 01-07-2011, 08:47 PM

Hey guys - I had my car fixed by BMW dealership afterall and here's what happened - it may help somebody else with similar symptoms as mine.
Before replacing the thermostat, I decided to try air-bleeding my system first. Jacked the car, put the heat on highest and ran the cabin fan on slowest all while adding the coolant and checking the bleeding screw. It some 20-30 min. Tried starting the car - and found drained battery. Called CAA and they said that battery is dead and needs to be replaced. Although skeptical about CAA diagnosis, at that point I had the car towed ('flatbed-ed') to local BMW dealership. Final word - replaced battery and overflow bottle sensor and bleeding screw. Got my car back next day. Knowing this, replacing the overflow bottle set DIY would fix the problem.
Thanks everyone for input and help!

Mike e39 · 12-27-2011, 02:08 AM

...I'm resurrecting this tread, but just to make sure that those who will read it will have an idea what happened.... -you can correct me if i'm not right. - cause thats what happened to me..

... so we have an owner who has no heat and is overheating the engine. Being specified he is boiling hes coolant.
As the level of coolant was low, he lost heating, as the coolant was low, due to crack in expansion tank - usually were level sensor is attached - not noticeable until is too late.
that small crack prevent buildup of proper pressure,( ~ 32psi) that cause coolant boiling, as engine runs at 105*C. with no pressure in system temperature strikes immediately to 120*C witch was shown on temperature gage . When gage is past 12 o'clock you MUST STOP ENGINE IMMEDIATELY ! Unless you are fully aware of the problem, and you can roll the car on the engine off for most of the time and start it just for a moment. At least in this case.
For those interested, temperature gage stays at 12 o'clock from 75*C to 120 or 125 i don't remember now. So i guess you understand what it is mean, when it passes vertical position......
So next time when you have no heat, stop wait some time to cool down the engine and check coolant level. most time is too low. if you have your temp. gage past vertical STOP !!!! and do same as above.....

MLue1 · 12-27-2011, 10:39 AM

The temp gage is buffered so at 12 o clock or 1/2 or vertial, the engine temp is between 75-115 degrees, I've only seen my temp gage go past 12 o clock when running at the track and even then only up to 3/5 no higher.

According to Jim Cash on Bimmerboard (he works for a dealer), the E39 540 cooling system is designed to regulate at 109-110 degrees. The tstat has a heater on it (prolly why it cost so much) that it uses to pre heat the tstat to open earlier during spitited driving or when the computer sees something odd with the rate of cooling.

Some guys say that there was a bad batch of after market expansion tanks that cracked or cause overheating, I haven't seen any tho as I buy my expansion tanks through Mike at Maranello BMW, they are a site sponsor and give discounts on parts when you mention the Max forum.