Bri Bro

I needed to test my oil cooler thermostat and I didn't find much with the search and I don't remember a write-uo on how to test the part so here it goes.

The first thing I ran into was getting the plug off to get to the thermostat. I purchased a set of metric 1/2 drive Hex bit set made by GreatNeck at Autozone. I took off the oil filter and the metal water line that attaches to the cam housing to get access to the plug. It required the 17mm Hex bit and a lot of force to break it loose. I had to use a five foot torque wrench to get it to pop loose. I also had to use a couple of wobble extensions to get the extension to snap on the the plug. I would have had to remove the distrubitor housing to get a better angle. After taking off the plug the first thing to look at is if the seal is still on the plug. Then, extract the large spring and you can see the bulb of the thermostat. I needed to use a long nose pliers and gently grab the bulb and pull out the thermostat from the sleeve.

The thermostat has a bulb with a small plunger coming out the bottom side. The spring keeps the thermostat seated down in the sleeve. As the oil heats up above 105C, the plunger starts to move out and the entire thermostat moves up in the sleeve allowing oil to flow through a slot in the thermostat housing and then down the oil cooler lines.

Testing. I stated with boiling water but looking at the bulb it had a 105C stamp on it. I switched to oil in a small steel cup on low heat on the stove to get above 100C. The bottom of the thermostat has a small pin that extracts from the bulb when heated to a length of around 3/4 in. At 105C the pin started to move and by 110C it is fully extended. I allowed to oil to cool and at around 75C the plunger started to retract (need to push it down) and by 60C it could be pushed all the way back into the bulb. So, it passed the test.

I found a replacement set at 944online for under $100. Items 13-16 in the diagram.
http://www.944online.com/cgi-bin/ASI...kukey_20052965

Jeff N.

Also, there's a 95 degree C option. My understanding is that the 105 was on the earlier models and the 95 was on the later models.

I swapped my 105 for a 95 to help manage oil temps. Keeps it lower a bit longer but doesn't impact the top end temp. Adding another cooler for that.

F18Rep

Good info, I've been meaning to check mine too. Bruce

Bri Bro

Jeff, I have not had any luck finding a source for a lower temperature thermostat. The part number I come up with is 951 107 155 01.

Some more sources for the thermostat. Do a search on this P/N 951-107-155-01
http://www.lindseyracing.com/LR/Pors...07-155-01.html
http://germanimportedparts.com/Order...px?mode=search

Oddjob

Fairly certain the only oil therm available from porsche is the low temp unit. I have bought 3 of these over the past several years and all three have been the 95C therms.

Bri Bro

Thanks Jim, maybe the original 951 107 155 00 is the 105C and the 951 107 155 01 is the 95C.

Ski

There was some earlier discussion about the lower thermostat that was put into the S2 IIRC but it's been a while since it came up because I wanted to put the lower thermostat in the track car. I'm overseas but if someone can come up with the correct part number and verify, maybe through Sunset and if it's available, I would be most appreciative and buy one. TIA

Jeff N.

I believe the lower unit has superseded the higher temp unit.

I got mine used from dc auto. I think it was like $30 or something.

Thom

During the assembly of my next engine I had 3 complete thermostat housings at disposal and noticed that '86 & '88 951 had the 105°C unit while the '93 968 had the 95°C unit.
All 3 thermostats were tested and I decided to use the 95°C thermostat (with a 951 housing in order to avoid messing up with the lines to the cooler that are different between 968 and 951).

333pg333

We also switched to the lower temp ones. Makes good sense.

Sysgen

Could someone enlighten me as to how this small plunger can push against the spring and the oil pressure. I understand that's what's happening but I do not understand how this small plunger works. What's in that thing? Anyone knows?

We pulled one out of a car last night and the plunger was stuck inside. We had to use plyers to pull it out and then it worked flawlessly, it would move freely when I pushed on it.

Is this something that happens often?

fbgh2o

Potentially a dumb question.

I am running a oil temperature gauge (connected to the drain plug in the sump). I rarely see temperatures over 88C (190F) in around town driving and regularly at cruise see about 170F (77C) (water temp is very steady at 75 to 80C). Is this because the cooler is doing its job or is the oil not getting hot enough to even run through the cooler?

Sysgen

Sounds to me that it's doing it's job, as you say, it gets cooler when cruising. It would get a lot hotter if the thermonstat wasn't working.

fbgh2o

True, but if the oil cooler t-stat only open at 105C and my oil nevers get that hot, I assume nothing flows through it... Therefore should I have a concern?

Sysgen

Could it be because your gauge is at the bottom of the oil pan where it might be cooler than where the oil t-stat is sitting? Just guessing, I don't know.

I just read that some coolant thermostat use wax to open and close. Anyone knows what makes the oil t-stat open and close like that?