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DISCUSSION => Engine + Driveline => Topic started by: jrw21 on October 05, 2009, 12:48:19 PM

Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 05, 2009, 12:48:19 PM
If someone could let me know the correct torque specs for the t-stat housing bolts on my m42 I would greatly appreciate it. Thanks in advance.
Title: Torque Specs for m42 Thermostat Housing
Post by: rob_e30 on October 05, 2009, 01:40:02 PM
Not much.  The head is aluminum so DO NOT over tighten.

Check out this reference:

http://www.bmw-m.net/TechData/torq/bmw_torq.pdf (http://www.bmw-m.net/TechData/torq/bmw_torq.pdf)
Title: Torque Specs for m42 Thermostat Housing
Post by: kenika65 on October 05, 2009, 06:09:10 PM
I torqued mine down to spec and it still leaked so what i did is fill with fluid and as it was leaking i would slowly tighten the bolts till the leak stopped and just keep a close eye on it.


Dont over tighten it because the thermostat housing will break and or the threads will pull out of the head.
Title: Torque Specs for m42 Thermostat Housing
Post by: iamcreepingdeath on October 05, 2009, 06:22:05 PM
and that would SUCK.
Title: Torque Specs for m42 Thermostat Housing
Post by: RED IS 91 on October 05, 2009, 06:24:18 PM
Bentley states

10Nm or 89 inch pounds
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 05, 2009, 08:59:47 PM
Thanks for the info. Got it bolted down, no leaks after about 75 miles of driving today.

However, runs very cool. I tapped the thermostat housing for a vdo water temp gauge. I didn't trust the stock vdo gauge in the cluster, the needle was well short of the half way point. But, the standalone gauge is pegging 180 degrees to confirm a cool engine temp. Running without the mechanical fan too. Do these engines just run cool?
Title: Torque Specs for m42 Thermostat Housing
Post by: johnwoo on October 06, 2009, 12:23:44 AM
Quote from: jrw21;79469
Thanks for the info. Got it bolted down, no leaks after about 75 miles of driving today.

However, runs very cool. I tapped the thermostat housing for a vdo water temp gauge. I didn't trust the stock vdo gauge in the cluster, the needle was well short of the half way point. But, the standalone gauge is pegging 180 degrees to confirm a cool engine temp. Running without the mechanical fan too. Do these engines just run cool?


no quite the contrary you see a bunch of people running hot me included whether its the gauge or sensor

do you have a pic of your vdo setup and how you taped the housing?  im interested in running a more reliable gauge also.
Title: Torque Specs for m42 Thermostat Housing
Post by: 91 318is on October 06, 2009, 06:09:11 AM
Quote from: jrw21;79469
Thanks for the info. Got it bolted down, no leaks after about 75 miles of driving today.

However, runs very cool. I tapped the thermostat housing for a vdo water temp gauge. I didn't trust the stock vdo gauge in the cluster, the needle was well short of the half way point. But, the standalone gauge is pegging 180 degrees to confirm a cool engine temp. Running without the mechanical fan too. Do these engines just run cool?


Hmmm, so the new thermostat makes the engine run cooler?  What temp thermostat is it?
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 06, 2009, 08:18:41 AM
I did not install a new thermostat. I assumed it was the stock thermostat, I didn't pull it out to check.

Basically, all I did was remove the housing to tap the housing for a new temp sender. I did this because I thought the oem instrument cluster gauge was faulty. It turns out that the car just runs cool, both the oem gauge and the aftermarket gauge read the same values.

Quote from: johnwoo;79480
no quite the contrary you see a bunch of people running hot me included whether its the gauge or sensor

do you have a pic of your vdo setup and how you taped the housing?  im interested in running a more reliable gauge also.


You will want to tap the exit side of the housing. The new sender and gauge are 250F VDO vision.

(http://img.photobucket.com/albums/v83/whitebred21/100_2083.jpg)
Title: Torque Specs for m42 Thermostat Housing
Post by: johnwoo on October 06, 2009, 06:15:07 PM
how did you tap it? just with a drill?  and did you run the wire through the glovebox?  any interior pics.

looks like you did a great job
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 06, 2009, 08:47:32 PM
Quote from: johnwoo;79513
how did you tap it? just with a drill?  and did you run the wire through the glovebox?  any interior pics.

looks like you did a great job


Yep, used a drill to make the hole. Then used a tap to create the threads for the sender. I went a step further and applied some jb weld on the last thread of the sender. I don't plan on taking the sender back out, so I used the JB weld as a preventative in case of future leaking.

The yellow signal wire was ran through the firewall at the glovebox location. Pulled power and ground from the panel for the gauge.

Drove the beast ~180 miles today, not a drop of leakeage. Temp stayed at 180F or less the entire trip. I still don't quite understand why my engine runs so cool.
Title: Torque Specs for m42 Thermostat Housing
Post by: johnwoo on October 06, 2009, 09:03:13 PM
you should do a writeup on how you did it.  showing how you tapped the housing, powering it and mounting it.  im sure there would be lots of people here that wants to run an aftermarket temp gauge since the one on the cluster is complete shit somtimes

you could be running colder based on your tstat.  do you have 88 or 75 degree tstat?
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 06, 2009, 09:21:45 PM
Quote from: johnwoo;79520
you should do a writeup on how you did it.  showing how you tapped the housing, powering it and mounting it.  im sure there would be lots of people here that wants to run an aftermarket temp gauge since the one on the cluster is complete shit somtimes

you could be running colder based on your tstat.  do you have 88 or 75 degree tstat?


I should have checked the thermostat type while I was in there, however, I did not. So, I am unaware if it has an aftermarket "colder" thermostat. I thought for sure removing the mechanical fan would warm it up a bit. But, it didn't. Just free'd up a tiny bit of power and mpg.

As far as the write up, I didn't take any picutures of the process, or I would make a nice detailed write up.

I plan on putting a new fuel filter on it tomorrow, I will snap a few pictures of the interior gauge and where the wire is passing through the firewall.
Title: Torque Specs for m42 Thermostat Housing
Post by: johnwoo on October 07, 2009, 01:08:02 AM
Quote from: jrw21;79524
I should have checked the thermostat type while I was in there, however, I did not. So, I am unaware if it has an aftermarket "colder" thermostat. I thought for sure removing the mechanical fan would warm it up a bit. But, it didn't. Just free'd up a tiny bit of power and mpg.

As far as the write up, I didn't take any picutures of the process, or I would make a nice detailed write up.

I plan on putting a new fuel filter on it tomorrow, I will snap a few pictures of the interior gauge and where the wire is passing through the firewall.


yes do. eventually i am going to get an aftermarket gauge. im going to switch out the sensors and the tstat for a lower one because where i live it gets pretty hot in the summer times and would like my car to run at a lower temp.

there is actually i believe three temp tstats a 92, 88, and a 75.  i believe stock was 88. not sure. if you go to pelican bmaparts it lists all three.  im going to switch out my 88 to 75 so if your running a lower temp one i might have a 88 tstat available.
Title: Torque Specs for m42 Thermostat Housing
Post by: monty23psk on October 07, 2009, 08:52:38 AM
88 is stock.
Title: Torque Specs for m42 Thermostat Housing
Post by: johnwoo on October 08, 2009, 01:42:39 AM
Quote from: jrw21;79524
I should have checked the thermostat type while I was in there, however, I did not. So, I am unaware if it has an aftermarket "colder" thermostat. I thought for sure removing the mechanical fan would warm it up a bit. But, it didn't. Just free'd up a tiny bit of power and mpg.

As far as the write up, I didn't take any picutures of the process, or I would make a nice detailed write up.

I plan on putting a new fuel filter on it tomorrow, I will snap a few pictures of the interior gauge and where the wire is passing through the firewall.


or maybe your tstat is stuck open.  not allowing your car to get up to operation temp
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 08, 2009, 09:56:03 PM
Quote from: johnwoo;79597
or maybe your tstat is stuck open.  not allowing your car to get up to operation temp


I thought of that as well, but I checked and it does open and close.
Title: Torque Specs for m42 Thermostat Housing
Post by: iamcreepingdeath on October 08, 2009, 10:27:41 PM
you must have 75 degree t-stat.  180 F is about 82 C, which seems about right.  the temp at the t-stat being 75 degrees would probably heat up to 82 degrees after flowing through the engine block.

btw i am running a 75 deg stat, and i do recommend.

And yes, everyone else's M42s on here seem to have overheating problems.  Consider yourself lucky.  

I may do something similar to what you did, and if i do, i will make a write-up with lots of pretty pictures.
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 08, 2009, 10:47:19 PM
Quote from: iamcreepingdeath;79656
you must have 75 degree t-stat.  180 F is about 82 C, which seems about right.  the temp at the t-stat being 75 degrees would probably heat up to 82 degrees after flowing through the engine block.

btw i am running a 75 deg stat, and i do recommend.

And yes, everyone else's M42s on here seem to have overheating problems.  Consider yourself lucky.  

I may do something similar to what you did, and if i do, i will make a write-up with lots of pretty pictures.


I agree, sometime in its life someone must have swapped out the stock t-stat for a 75 t-stat. Bring on the DIY, I feel bad now for not taking the time to write one up :p
Title: Torque Specs for m42 Thermostat Housing
Post by: iamcreepingdeath on October 08, 2009, 10:52:32 PM
im also attempting to make a DIY on fabricating a self-bleeding system for the M42 radiator. (see the other post in this section)

And if my engine explodes as a result of that, I will document that too.
Title: Torque Specs for m42 Thermostat Housing
Post by: jrw21 on October 09, 2009, 09:15:25 AM
Quote from: iamcreepingdeath;79661
im also attempting to make a DIY on fabricating a self-bleeding system for the M42 radiator. (see the other post in this section)

And if my engine explodes as a result of that, I will document that too.


Mine bled very easily, I just unscrewed the "bleeder" screw at the top of the expansion tank then closed it up when fluid started spewing out.