LexVan

It will leak again in about 2 years. Just replace with the Porsche one then.

docdrs

Looks like it has a 180 degree Tstat in it. Thats when it begins to open and by the time its 200 its wide open letting all the hot coolant out and cool coolant in via the circ pump. JMO

user 72902

Agree. I have a 160 T-stat and my temp stabilizes at 189.

Petza914

The low temp thermostat is what should be used in these cars because as jkw states, a 160 degree thermostat doesn't make your engine run at 160 degrees, it means it opens a 160 degrees and the engine temperature will stabilize quite a bit above the opening temperature. There is data from the most reputable M96/M97 engine guru that shows these cars make more power and run better when they're in the temperature range achieved with the 160 thermostat. Using the standard 180 thermostat makes the engine run hotter and a stock motor at this temperature has been shown to produce 12-15 fewer HP.

Back to the OP, Porsche coolant is pink - I've not seen a 997 that had yellowish/green coolant in it, but that's not to say it's completely impossible - just seem like that wasn't a factory fill color and maybe someone has been in that system before.

The car will actually burp itself over time, even if the burp valve isn't manually opened - opening it just makes it occur sooner/faster. If the temp gauge needle is jumping from time to time, that's air or boiling coolant going past the sender/guage pickup - you might even be able to hear the air or coolant moving around / boiling in the system with the car off. Parking the car on an incline with the rear higher than the front while it's running with the burp valve open and fully warmed up so the thermostat is open, will help evacuate some of that air from the system. Put a bottle of mixed coolant in the car as you drive it around. If you park it somewhere long enough for it to cool down where you can open the cap without it lowering the boiling point and overflowing, check the coolant and add as necessary. After a few days you'll have it topped up and stabilized. Then you can check your temps again via the OBD2 port like you did before. If you still see a graph similar to the previous one you posted, it looks like you don't have a 160 degree thermostat and any higher temps witnessed are likely attributable to the non OEM water pump.

Get your water pumps from the P-car dealers or from LN Engineering and your 160 degree thermostats from LN, and as another poster commented, make sure any water pump has the composite impeller so you don't will into your block when the bearing wears. There are some lower quality low-temp thermostats on the market, but LN has never had a failure on one of their new low temp versions right out of the box.

Let us know how you make out.

jchapura

Thank you Pete.

I agree, that's why I switched over to one.


My concern is, after installing the new pump and (probably Motorad) low temperature thermostat insert, during non-spirited cool (60 degF) ambient temperature driving, the oil temperature ran 10 degrees hotter, not the 10-20 degrees cooler (a delta of 20-30 degrees in my mind), I was expecting. Essentially, no other variables. I did collect some more data (IMO, confirming data) - posted here: http://www.renntech.org/forums/topic...at-change-why/

I'm thinking I got a mislabeled or dud low temp tstat. Bad luck. But not as bad as getting a dud water pump - much more effort to recover from that.


The coolant level really hasn't changed since "day 1" post-change-out. The AirLift and naturally burping worked in my opinion. I burped manually because I was fervently searching for the explanation of why the low temp tstat wasn't acting like a low temp tstat. There has been no needle jumping since the initial heat-up/cool-down cycle.

Do you really mean pump (and not thermostat)?

Next time... (and current one, Pierburg, has composite impeller)

I just ordered an LNE low temp thermostat insert from Pelican and will throw it in and capture the coolant temp data...

Definitely.

Petza914

Once we've eliminated all the other variables (thermostat, air trapped in the system, homogeneity of the coolant / distilled water mix, etc), then yes, it could be the pump itself if the impeller is somehow different and less efficient) or even possibly the circumference of the pulley slightly larger (turns slower) but I think you'd detect this when trying to install the drive belt.

It's a PITA when you complete a DIY job and don't get the results you were expecting and have to dig back into it. Just happened to me with something as simple as hard-wiring a radar detector into a Cayenne - turns out the normal lighter plug cord and the hardwire cord although they had the same 4 color wires in them, had them in different positions in the modular plug - black in the one cord had to become green in the other to be the ground, but took about 2 hours of troubleshooting with different wires, different connectors, and different detectors to figure it out.

Anyway, I digress. Good luck with the cooling system.

jchapura

It better not be the pump... . Not the best of memories getting access to pull the old one out...

Here's to hoping that it's only that the tstat was a dud...

jchapura

It was raining and about 62 degrees F today. After being driven, and then parked for about an hour, and then driven again, I captured this info.

I do have a new (LNE) low thermostat on order. But I may delay putting it in. Bruce had an idea - put the old thermostat back in and capture the data. Then, there will only be the one variable in play - the thermostat.

I'm still trying to find the explanation for why the new low temp thermostat gave me a steady state oil temperature that was 10 degrees warmer than the old thermostat (for the same conditions; and as seen on the dash gage). But in the end, I really just want the engine protection that the lower temperature thermostat provides.

docdrs

before you put the new one in, place them in a pot of water on your stove with a thermometer and see ate what temp they begin to open. aA hot engine will see a temp spike as in your graph when it is turned off as there is no coolant flow and the engine act as a heat sink.

gpjli2

So here is my problem with 160 thermostat: as I understand it it begins to open sooner. This helps prevent rapid temp spikes when folks get on the throttle before engine is at full running temps. Once you are at 200-210 degrees (which I believe is necessary to boil condensation out of oil ie 212 deg and all that) both thermostats are fully open. Since that is the case, what do you expect to gain under running conditions?

I think 160 t is hype and if it lengthens warm up and contributes to contaminated oil may do more harm than good. As to car making more hp, (someone did say that right or am I hallucinating again?) gmab. A full warmed up engine running WFO at 220 degrees or so does not see whether it has a 160 or 180 deg thermostat.

Just stay off the throttle until you see 200+ oil temps. But you all know that already.

Have fun out there.
G

user 72902

I have a 160 thermostat and I've been sending my oil samples to Blackstone for several years. No contaminates - perfect DT40 oil. I'd suspect driving habits (short runs not allowing proper engine warming) contribute to oil contamination.

gpjli2

The real test would be to prove statistically that it reduced incidence of #6 cylinder/piston failure and the like. That was the theoretical goal as I understood it: to have the cooling system respond more quickly when large amounts of throttle was applied suddenly before oem thermostat was fully open. That is thought by some to cause a temperature spike and fry the cylinder over time because of a design problem which limits coolant flow to that part of the motor.

I don't know that the frequency of this type of failure is high enough to allow this sort of study. Most folks seem happy because 160 is lower than 180 and on the face of it that is a good thing. If it gives you peace of mind then so be it.

I did see a post by a LI driver who said his warm up times were longer despite manufacturers claim that would not happen. That would worry me over time. Oil is designed to work at certain temps and lower is not always better.

Glad your motor is healthy

Petza914

Jake & Tony recommend the 160 thermostat. Not understanding all the reasons why, that's good enough for me, so that's what's in both my 997s.

jchapura

This past weekend I changed out the new thermostat that was giving me even warmer oil temperatures than the original regular temp thermostat.

The new low temperature thermostat acted like I expected to. It gave me oil temps about 8 deg F cooler than the original regular temp tstat. The first low temperature thermostat must have been a dud. Attached is an image of the old and new tstat coolant temp graphs clearly showing the approximate 20 degree difference in the temperature at the plateau (after warmup).

I did boil all the tstats - they did open pretty close to what I read should be expected.

I'm happy it's resolved. I hated to have to spend another half-day to change it out again. I'm hoping it does its job to protect the engine just that little bit more.

Thanks everyone for chiming in.

Petza914

Would've sucked if you did the changeout and had the same issue. Glad you didn't and it's resolved for you.