Author Topic: Thermostat housing (Read 4882 times)

oldtimer · « **on:** April 30, 2007, 01:54:41 PM »

1991 318is. One of the initial baseline I like to do is replace the thermostat on the car, which probably needed to be replace since the car does not heat up. I figured the thermostat was open. When I removed the housing it did not have one installed or it had the groove for the "o-ring" I got and what the manuals calls for. Instead it had your standard flat paper gasket. I couldn't even find it in my 101 project book. My question is. Is the another version of this 318is that calls for a regular thermostat housing gasket? Or do I have wierd model?

Ben

RED IS 91 · « **Reply #1 on:** April 30, 2007, 08:04:05 PM »

check out the link. this is how it should look . I believe all M42's are alike in this respect .It should be installed exactly like the diagram.
good luck

http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_0559&hg=11&fg=35

oldtimer · « **Reply #2 on:** April 30, 2007, 08:20:54 PM »

Well, I envisioned that's how it should look basing my vision from illustration similar the one in the link. However, if I was to install that "o-ring" there's no room for it, once the thermostat is placed in the cavity the groove it sits on is filled by the thickness of the thermostat. I will reverse my installation tomorrow and re-investigate.

Ben

Choking Hazard · « **Reply #3 on:** April 30, 2007, 10:24:15 PM »

IIRC, it doesn't sit all the way in. Does the thermostat have a gasket of some kind already? If not, try bolting it up...I know that o-ring gets pretty squished- I remember taking out a really flattened one. Didja take off the fan shroud? Makes it alot easier to get to the bolts on the bottom of the housing.

oldtimer · « **Reply #4 on:** April 30, 2007, 10:50:09 PM »

Warm spring night and late car maintenance. I remove the housing again and re-investigate my problem or what I think is a problem. I noticed that the thermostat has a lip around it once I re-install it back in the cavity I notice how the "o-ring" will fit, it fits on the thermostat itself. I was looking for a groove on the area where the housing mates to. The "o-ring's is now installed. Now I just need to sold why the temp gauge keeps jumping around. I bleed the system several times now. Not much bubbles comes out and the coolant in the resecvior is barely being sucked in.

Ben

ak96ss · « **Reply #5 on:** May 01, 2007, 07:19:45 AM »

I had to put the front of the car up on ramps to get a decent bleed.

You did remember to turn on the heater in the car, right?

oldtimer · « **Reply #6 on:** May 01, 2007, 07:37:10 AM »

Putting it on the ramp? Is that so the bubbles will rise up? Yes, I had the heat and fan going.

Ben

RED IS 91 · « **Reply #7 on:** May 01, 2007, 11:15:17 AM »

When you first start the car (cold) the top hose shouldn't have any pressure to it . When it reaches temp. the thermostat will open and the top hose should get hot and be pressurized .
When I bleed my system I get the thermostat to open .Have the heat on and fan speed to #2. Rev the motor while I open the bleed screw. when I have only coolant coming out I close the bleed screw .I then run the car around the block a couple of times while watching the temp guage .Pop the hood and re bleed if necessary.
Works for me.........

Also check your connections to the temp guage .
1st check the one on the motor . It will be the brown sensor to the rear of the motor on the drivers side.It may also be your connection at the back of the cluster .If it's jumping around then it probably the connections somewhere.
good luck

oldtimer · « **Reply #8 on:** May 01, 2007, 01:46:22 PM »

Well, I look for the coolant sensor according to your description. I did not see one, however there is one under the breather hose from the valve cover foward of the engine. It looks blue, faded blue. I have not received the book for this car so I am lost as to where things are located. Just started the car minutes ago and tried your method of bleeding got solid coolant no bubbles. The gauge jumped around.

Ben

Choking Hazard · « **Reply #9 on:** May 01, 2007, 04:15:43 PM »

buy a candy thermometer and check the temp of the coolant. It should be around 190. The ground for the guage is crappy and causes the erratic behavior and phantom overheating. Do a search or scan back a few pages for "operating temperature". I just replaced all the cooling stuff before I found out it was bad readings.

RED IS 91 · « **Reply #10 on:** May 01, 2007, 07:59:45 PM »

Quote from: oldtimer;24955

Well, I look for the coolant sensor according to your description. I did not see one, however there is one under the breather hose from the valve cover foward of the engine. It looks blue, faded blue. I have not received the book for this car so I am lost as to where things are located. Just started the car minutes ago and tried your method of bleeding got solid coolant no bubbles. The gauge jumped around.

Ben

It is number 6 in the diagram.Number 8(the blue one) sends temperature info to the ECU.
http://www.realoem.com/bmw/showparts.do?model=AF93&mospid=47305&btnr=11_1505&hg=11&fg=15

ak96ss · « **Reply #11 on:** May 01, 2007, 08:28:07 PM »

Quote from: oldtimer;24930

Putting it on the ramp? Is that so the bubbles will rise up? Yes, I had the heat and fan going.

Ben

The ramps just 'encourage' the system to let go of the air, since they raise the exit point (the bleed valve) higher in relation to the rest of the system. I don't think it's a requirement, and, honestly, it was mostly because I already had the car on the ramps...

oldtimer · « **Reply #12 on:** May 01, 2007, 09:35:08 PM »

Wow that sensor is well hidden, because after reading these responses I still didn't see it. I am going to take the cluster out and swap out the temp gauge. My 1984 318i was doing the same when I swap out the temp guage it was normal I didn't think I will be dealing with the same thing with this new project since I was focused on the inproper bleeding of the system. Now I know why the previous owner removed the thermostat thinking it was overheating when it was not. With all this inputs I think the cooling system is well bleed as many times I did it.

Gentlemen thank for all the inputs and the education. Wish me luck tomorrow finding the sensor and getting it out, it looks very tight in that area.

Ben

oldtimer · « **Reply #13 on:** May 03, 2007, 11:55:41 AM »

Just an update and maybe my final response to this thread. I replaced the coolant senson but did not fix the gauge jumping around. Decided to pull the cluster out and swap out a new gauge, when I was about to loosen the nut that holds the gauge to board I discovered it was loose. Tighten and and re-install cluster. Temperature gauge is now normal and functioning accordingly. So those of you who notice your gauge jumping around you might want to pull the cluster and check the nut for tightness, by the way the gas gauge was loose also. Thanks for all the inputs it sure made me think to get the job done.

Ben

Choking Hazard · « **Reply #14 on:** May 03, 2007, 02:27:55 PM »

I had to double nut mine because it backed off again after a year. Also, there are two grounding attachments like that, and either one can come loose and cause the same problem.