Thermostat "upgrade"

Mixerfistit · 2023-10-01 13:17:27

Has anyone dabbled with swapping the thermostat for one that kicks in a bit warmer?

My 2.0 HDi seems to sit cooler than any of my other HDIs have done in the past including a 2.0 807.

Seems the dial pointing off to the left is normal for our vehicles whether they're 1.9,td or hdi - I'd replaced my old one when I first got the van as I didn't know any better and no change.
Wouldn't there be a fuel saving for getting the engine a bit warmer?

I've only ever got the needle slightly past 12 o'clock by driving her hard up an inclined dual carriageway over about 15 miles in the few warm days of summer we had above 25C.
Clearly, the engine has bags of cooling power at it's disposal and it's my understanding a later thermostat wouldn't cause any issue with unwanted higher temps as once it's on it's on. Surely ~85 C would be a bit better than 79C or whatever it is now.

A side question on a similar topic, does anyone block their grille up in winter? I know the xsara picasso (or was it the C4 Pic) had a snow grille for 10C and below

AlvyLad · 2023-10-01 14:48:36

Those engines (any) as a matter of fact are designed and tested to operate in in -20°C - +45°C. Thermostat temperature is only the part of temperature management, there's also the shape and positioning of hotter and colder parts of the engine, oil does the other main cooling- circulation- (lubrication) funcion.
As for the expectation to change coolant temperature to have an effect on diesel "ignition" - hardly, if anything cooling the air intake (making it denser- bigger volume) perhaps could make an impact, but we are talking about 5° degrees change out of 65° operating temperature, never mind other parameters compensating itself to minimise it anyway.
Would lowering coolant temperature make engine more efficient ("work better") - not really
Would increasing coolant temperature make engine work better, more efficient? - not at all, as it wouldn't have no measurable impact on fuel ignition temperature. If anything you would increase a chance for a fluid to boil up at the points where it is getting much hotter, than thermostat housing is.
That applies to all internal combustion engines... at least most off the liquid cooled ones...

Or, as someone on here said : "aren't broke - don't fix it" or "(keep on) fixing it until broke" big_smile

JohnDragonMan · 2023-10-01 22:38:21

AlvyLad wrote:

"aren't broke - don't fix it" or "(keep on) fixing it until broke"

though there's always room for improvement, i'm saying nothing.

AlvyLad · 2023-10-02 21:37:20

JohnDragonMan wrote:

AlvyLad wrote:
"aren't broke - don't fix it" or "(keep on) fixing it until broke"
though there's always room for improvement, i'm saying nothing.

and I bet, you sleep like a baby roll

Mixerfistit · 2023-10-02 22:13:27

JohnDragonMan wrote:

AlvyLad wrote:
"aren't broke - don't fix it" or "(keep on) fixing it until broke"
though there's always room for improvement, i'm saying nothing.

If anyone had changed it, you'd have been my first guess haha

JohnDragonMan · 2023-10-02 22:25:13

though i have replaced it, i have not modified it. it kinda works perfectly, i dont need to modify it really.

now if i install the hot water system to the van maybe.. but for now i am working on other projects.

OAT · 2023-10-02 22:59:59

They do need to allow for both extremes of usage too.

Try climbing Hardknott or Applecross and you will see the needle moving uncomfortably past 12 0'clock.

(Interesting summary Avy, cheers.)

JohnDragonMan · 2023-10-02 23:32:54

hmm ive not done Hardknott in my van, but i have in my little 1991 fiat panda 4x4 loaded with camping gear and a month's worth of food and drink. that got a bit hot. made use of its low ratio first gear and just crawled up the hill. thankfully it was in winter and no one was about!
be interesting in 30.c heat..

spent a month in Scotland and took the back roads all the way never touched a dual carriageway or motorway on the whole trip. well besides crossing them. lived in the car stopping at pubs to ask if i can have a shower. it worked well!

cars been in storage for 8 and a bit years and ive only just got it out. well been able to get to it.. its been boxed in by 3 cars a large van and a 7.5 ton lorry!

Last edited by JohnDragonMan (2023-10-02 23:34:55)

Mixerfistit · 2023-10-04 23:09:22

I understand the need to cater to extremes and leaving the pointlessness of fiddling for diminishing returns aside, wouldn't a warmer thermostat not make a difference at the top end?

Whether it engages at 77 or 87, by the time they're getting into the high 90s they'd both have long been fully open and the rad/fans doing their thing. (I'm not 100% sure on what the half and full open temps are but I'm sure you get what I mean).

At least that's my logic anyway
The only thing I can think that would play differently is if a modified and unmodified otherwise equally engine claimed the same hill I suppose one has an x degree head start over the other, but on a long enough hill, I'd guess they'd soon equal out at a given higher temp

FWIW, Just took mine on the dual carriage way for several miles and with no heating on it maxed at 78C with 12C ambient (EGR status undisclosed...)

AlvyLad · 2023-10-05 12:58:57

Not 100% certain, but flow direction goes through the engine (hot and vv hot), then thermostat, then radiator, so it opens only once it's warm (whole engine). If the design is allowing near cylinders to get whatever temp it's mean, it also has certain volume to heat up, that might end too late, if temp is set higher...
I could still be wrong

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#1 2023-10-01 13:17:27

Thermostat "upgrade"

#2 2023-10-01 14:48:36

Re: Thermostat "upgrade"

#3 2023-10-01 22:38:21

Re: Thermostat "upgrade"

#4 2023-10-02 21:37:20

Re: Thermostat "upgrade"

#5 2023-10-02 22:13:27

Re: Thermostat "upgrade"

#6 2023-10-02 22:25:13

Re: Thermostat "upgrade"

#7 2023-10-02 22:59:59

Re: Thermostat "upgrade"

#8 2023-10-02 23:32:54

Re: Thermostat "upgrade"

#9 2023-10-04 23:09:22

Re: Thermostat "upgrade"

#10 2023-10-05 12:58:57

Re: Thermostat "upgrade"

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