Low temperature thermostat

[deanmr2]

Hi guys I will be putting my Boxster off the road for winter at the end of this month, one of my winter projects is to change the coolant and thermostat. I have read all sorts on the internet about the pros and cons of a low temp thermostat that starts to open at 73 degrees as opposed the OEM stat that starts to open at 83 degrees, I was leaning towards the low temp stat but now I am not too sure. Anyone have actual experience of this or if anyone has an opinion I would love to hear about it 

Cheers Dean 

[Menoporsche]

I only heard this was to protect the bores of the 3.4, not sure I've heard of a compelling reason to do it on a 3.2.  But it's inexpensive and reversible if you want to.

[Ninesomething]

I read a lot about this although I never did it because I have a 987 2.7. Seems a very popular mod in the US - possibly because of temperatures. I think that most people that have a rebuild do it which is very much locking the stable door when the horse is halfway up 40 acre field. Not an expensive mod - might help.

[edc]

I've had one on for several years now. Done at the same time as waterpump on a preventative basis. 

[joeluth]

I just got one mainly as it was the only one available from spyderperformance when I ordered a few bits, from what little research I did it seems it's a good thing?

Certainly presented that way in my 101 Boxster projects book where it states that the lower 71 degrees thermostat results in lower oil temps giving a +5bhp dyno test, and that originally Porsche designed the thermostat to open later at 82 degrees to  help with emissions.     the 71 degree stat helps with engine longevity. 

 

 

Edited September 27, 2021 by joeluth

[deanmr2]

5 hours ago, joeluth said:

I just got one mainly as it was the only one available from spyderperformance when I ordered a few bits, from what little research I did it seems it's a good thing?

Certainly presented that way in my 101 Boxster projects book where it states that the lower 71 degrees thermostat results in lower oil temps giving a +5bhp dyno test, and that originally Porsche designed the thermostat to open later at 82 degrees to  help with emissions.     the 71 degree stat helps with engine longevity. 

 

 

Yeah what you have said is pretty much what I have read on different forums the one concern I have is if Porsche fitted an 83 degree thermostat to help with emissions does that mean if you fit the 71 degree stat you could have problems with emissions at MOT time?

[edc]

26 minutes ago, deanmr2 said:

Yeah what you have said is pretty much what I have read on different forums the one concern I have is if Porsche fitted an 83 degree thermostat to help with emissions does that mean if you fit the 71 degree stat you could have problems with emissions at MOT time?

If you want it, just do it and don't over think it. When was the last time you read a post that said MOT emissions failed due to thermostat? Probably none as it's nearly always an exhaust problem! 

[Menoporsche]

37 minutes ago, deanmr2 said:

concern I have is if Porsche fitted an 83 degree thermostat to help with emissions does that mean if you fit the 71 degree stat you could have problems with emissions at MOT time?

I always run mine down the motorway just before the test, I’ve understood it reads better when hot. Stat would be well open then. 

[joeluth]

11 hours ago, deanmr2 said:

Yeah what you have said is pretty much what I have read on different forums the one concern I have is if Porsche fitted an 83 degree thermostat to help with emissions does that mean if you fit the 71 degree stat you could have problems with emissions at MOT time?

Who knows what they go through when they design and test a car for all the different regions, but surely we'd have heard about it causing issues by now as it's been available for at least 10 years,    I'm going ahead and fitting my one, if it fails next year on emissions I'll be sure to report it! 

 

 

Edited September 28, 2021 by joeluth

[Paul P]

Type approval for new cars - and the emission checks associated with that aren't the same as the checks on MOT. 

That's what "dieselgate" was all about - cheating the type approval.

Low temp thermostat just opens sooner, so the engine theoretically doesn't warm up as quick ( coolant moves through rads sooner )  - but coolant starts to flow around it all sooner - so if you were to have a design where by a "hot spot" could form in one part in some circumstances before the thermostat thought it was time to open - then a thermostat that was more eager to open would go someway to mitigating that.

Do cars with low temp thermostats run any cooler once up to temp ? or does the temp gauge stay in the same place as "normal cars" ?

From what I have read - it's a common thing on 911's as a bore score risk mitigation - but not something that is a goto for boxsters - whilst they engines are "the same" - they are installed the other way round, in a different place on the 911 - so perhaps the boxsters lucked into not having the unfortunate circumstances occur as often.

 

 

[bally4563]

1 hour ago, Paul P said:

Type approval for new cars - and the emission checks associated with that aren't the same as the checks on MOT. 

That's what "dieselgate" was all about - cheating the type approval.

Low temp thermostat just opens sooner, so the engine theoretically doesn't warm up as quick ( coolant moves through rads sooner )  - but coolant starts to flow around it all sooner - so if you were to have a design where by a "hot spot" could form in one part in some circumstances before the thermostat thought it was time to open - then a thermostat that was more eager to open would go someway to mitigating that.

Do cars with low temp thermostats run any cooler once up to temp ? or does the temp gauge stay in the same place as "normal cars" ?

From what I have read - it's a common thing on 911's as a bore score risk mitigation - but not something that is a goto for boxsters - whilst they engines are "the same" - they are installed the other way round, in a different place on the 911 - so perhaps the boxsters lucked into not having the unfortunate circumstances occur as often.

 

 

That’s how I understand it , and although the Cayman is the same lay out as a Boxster , air flow around the engine is not as good , hence more Caymans have fallen foul with BS

[Menoporsche]

Surprised to hear that bally, I heard Caymans were more susceptible just because they sold a lot more (remember when Cayman got 3.4 a year or two before the Boxster, I think). Is there really a significant difference in airflow? I find that odd. 

[Menoporsche]

2 hours ago, Paul P said:

Do cars with low temp thermostats run any cooler once up to temp ?

Yes to me this assumption is illogical. 

[RalphyBMW]

I’ve also got the low temp (986 2.7), similar to above got it from Spyder along with water pump.

No difference in use as far as I can tell. My cabin was cold, but this was a dodgy interior temp sensor.

I hadn’t had mine for long before the change (noisy WP), but I do notice that the temp gauge moves a lot more on the Boxster than other cars. Seems more to do with airflow that anything else.

[edc]

In theory no as the cooling then is provided by the system and rad capacity. But in practice various users 

[½cwt]

2 hours ago, Menoporsche said:

Yes to me this assumption is illogical. 

I agree, the engine will still ahve the same heat rejection characteristics, assuming nothing else has changed, so it will just allow cooler water at 71°C  to circulate sooner thus taking longer to get up to normal working temp rather than keeping the water just in the engine until 83°C.

Have to admit I was confused by the earlier comment about fans running less.  They are activated by a high temp sensor at around 95°C way after either type of 'stat would have opened so they could have no influence on this.  Thinking of the fans, remember they are also switched in by a/c requirement so often kick in in traffic way before the engine would need extra cooling, but they are creating airflow over the condensers to keep you cool rather than the engine, cloud it have jsut been a cooler day when the comparison was noted?

[beicmynydd]

I think I read about it on the Hartech web site, google "hartech engine rebuilds interim" it's a pdf report  around page 33 there is an detailed explanation of the cooling system of the m96.