Ah Ha! Thermostat stuck open - Page 8 - The Unofficial BMW M5 Messageboard (m5board.com)

gsfent · 1st April 2008, 23:36

Quote:

Originally Posted by jcdavis

Dealer said if they replaced the MAF and it didnt fix the problem I would still be charged for the sensor.

Why? Sounds like a scam to replace perfectly good parts.

I would charge that back against my credit card and then report it to the BBB and the Attorney General. I would think they would take a dim view of consumer fraud.

And if they diagnosed it wrong, should you have to pay for that too?

Regards,
Jerry

jcdavis · 2nd April 2008, 01:01

I was thinking the same too. I called them back and wanted to know why I should pay for a misdiagnosis. They replied that the MAF was contributing to the problem. I replied that I thought the bad MAF is a result of the problem. Their reply was "it is easier to fix a car when it is under warranty because the technicians can throw new parts at the car at BMW's expense. If your car isn't under warranty, the technicians can't throw parts at the car at the owners expense ,which makes it harder to fix the car." Why do they have all of that fancy equipment? This is why I have gone to an indy. I hope I have better luck.

BTW the last problem I had with my 540i took 3 trips to the dealer before the finally foud a vacuum leak in the CCV. Paying the dealer sucks. Wasting 3 days of my time is even worse.

J Irwan · 3rd April 2008, 05:01

Quote:

Originally Posted by everycredit

Thermostat is under $40 from pelicanparts.com. I don't recall the P/N, but look it up at realoem.com

Here's what you need to do.

Wait for car to cool down.

Jack car up.

Open expansion tank cap.

Remove underarmor of car, both front and back.

Pull blue plug from radiator (driver's side on lhd). This turns and pulls out after a hard tug (make sure it's turned all the way--no real tricks).

Catch ~ 1 gal of fluid.

Replace o-ring on plug and reinsert plug.

Remove heat shield blocking left side coolant plug (8 mm hex screws x 3 behind the tie rod)

With extension, remove left side coolant plug (13 mm, blue loctite)

Catch ~ 0.5 gal of fluid.

Replace copper crush washer, blue loctite, and reinsert bolt.

Remove right side coolant plug (13 mm, blue loctite)

Catch ~0.5 gal of fluid.

Replace copper crush washer, blue loctite, and reinsert bolt.

Thermostat

Remove L & R airbox top and pipes into intake (protect MAF from contamination)

Disconnect two radiator hoses going to thermostat housing (right in the middle of car)

Remove two 10 mm bolts holding down VANOS sending unit to thermostat housing.

Remove coolant temp sensor from thermostat housing (21 mm?)

Remove three 10 mm bolts holding down thermostat housing (all different lengths--note which bolt came from where)

Remove thermostat housing (tug it! hard because VANSO sending unit in the way and doesn't like to move due to SS hoses)

Remove and replace thermostat--note orientation of thermostat.

Remove and replace the three o-rings.

Reinstall in reverse order.

Mixture of 50/50 coolant/water. Potable water okay (if soft), deionized preferred. Slowly fill until 1 cm above minimum cold level in expansion tank (capacity about 13 liters).

Tighten cap on expansion tank.

Vent system--start engine, turn heater all the way up, turn fan on lowest setting (so it's still running). Run until engine reaches operating temperature.

Check for leaks.

When at operating temperature, check fluid level.

Add fluid if necessary (wait for fluid to cool!)

If no leaks, replace underarmor.

Lower car.

Reset DME.

Drive.

Sorry if I asked the obvious, when you say "When at operating temperature, check fluid level...." Do you kill the engine and immediately open the
caps to inspec the fluid level or you just see the fluid level from the outside.

Sometime its not easy to see the fluid level from the outside.

Regardz,

J Irwan

jcdavis · 3rd April 2008, 13:20

If you open the cap on your radiator when at operating temp you are in for a very nasty suprise(bad burns). Just look at the fill line on your expantion tank.

jcdavis · 6th April 2008, 15:18

I changed out the TPS on Saturday. The ECU is now reading the right bank MAF. I did the on board MAF test and came up with 120 for three pulls in third gear. The last pulls I did came up with 109. This is a little better, but still has not fixed my problem. I am leaning more towards a vacuum leak maybe. I have had my car to an indy to diagnose. I am having a hard time leaving my car for the indy to perform maintenance. They wanted 3 hrs labor to replace the TPS that took me about 1 hr to do myself. They also wanted 2 hrs labor to change out an ignition coil. I know these are probably book times on replacement, but I can save hundreds by doing it myself. Besides, for the 20 min he had the car, he stripped on of my plenum screws completely off. Oh well, if anyone has anymore ideas I would be glad to hear them.

Kelleyo · 6th April 2008, 18:00

One way to detect a vacuum leak is to spray carb or brake clean under the plenum while the car is running. If there is a leak (and the chemical gets sucked in) the idle revs will shoot up when this chemical hits the combustion chamber.

Don't need a lot. Just some short bursts.

xr4tic · 6th April 2008, 18:28

I like to use Ether (Starting Fluid) for checking for leaks.

Although, on some cars, I've seen the idle drop when it sucked in the fluid.

You probably already have, but have you changed the fuel filter? How about checking the fuel pressure?

When you press on the throttle, there is a change in vacuum in the intake manifold, and should be a corresponding change in fuel pressure. Maybe it's not changing fast enough (clog) or not at all (bad pump)

gsfent · 6th April 2008, 19:31

Quote:

Originally Posted by jcdavis

I changed out the TPS on Saturday. The ECU is now reading the right bank MAF. I did the on board MAF test and came up with 120 for three pulls in third gear. The last pulls I did came up with 109. This is a little better, but still has not fixed my problem. I am leaning more towards a vacuum leak maybe. I have had my car to an indy to diagnose. I am having a hard time leaving my car for the indy to perform maintenance. They wanted 3 hrs labor to replace the TPS that took me about 1 hr to do myself. They also wanted 2 hrs labor to change out an ignition coil. I know these are probably book times on replacement, but I can save hundreds by doing it myself. Besides, for the 20 min he had the car, he stripped on of my plenum screws completely off. Oh well, if anyone has anymore ideas I would be glad to hear them.

120 is not bad, I used to run low 120's before I added the bigger MAF housing. My numbers were on the low end of the scale compared to board members, but my car runs fine and AFAIK I have my original MAF's.

More importantly, how does the car run?? Remember, the MAF dynamic test is really a diagnostic tool, not an end in itself.

Regards,
Jerry

jcdavis · 6th April 2008, 19:42

The car seems to run better at hight rpm's, but the problem is still there. Do you happen to know if the TPS has to be set with a voltometer or something of the like? Or is it more of a plug-n-play?

gsfent · 6th April 2008, 22:57

Quote:

Originally Posted by jcdavis

The car seems to run better at hight rpm's, but the problem is still there. Do you happen to know if the TPS has to be set with a voltometer or something of the like? Or is it more of a plug-n-play?

I don't know. If I had to guess, a TPS should be plug and play.

Strange how it is better at high rpms. I seem to remember a discussion a long time ago that the idle circuit actually runs the car up to a ridicuously high rpm before the throttle bodies actually take over (maybe I am hallucinating from another board, but I think it was shadowman who provided that info). In my mind, it is well over 2000 rpm. I thought it strange, as there is nothing noticable from driving to give that indication, but then there is a lot of throttle by wire, so the computer would mask that anyway.

In any event, if there is some transition, then I would focus on that piece of equipment that operates in transition from low to medium or high rpms. One part would be throttle bodies. Have your throttle bodies ever been checked to make sure they are operating properly, including that they are properly synchronized?

BTW, have you dynoed yet to get AFR's or emissions results? Both could help pinpoint what is wrong.

Regards,
Jerry