Diesel thermostat definative answer

[philjudo]

Thanks for that, I suspect mine is starting to run cold.

[Thomas]

Originally Posted by wuzerk

DAVID: As Mintee says there is a very small relief in the Chevy rim, so small that I didn't spot it and drilled experimental holes on the first attempt.(Meziere themselves advised me to drill two 4mm holes in it)You can see it if you hold it up to the light.
PAUL: If you are using the British housing them you have to be careful if using a different thermostat to the one supplied. If the new 'stat has a thinner
profile around the edge then it may allow coolant to seep through when it is closed, I did say, several pages ago that it might be necessary to use some sealer on the rim. The Meziere housing comes with a gasket which sits over the rim of the stat so there is no problem there.

Mine seeps through very very slightly as I noticed the other day a small weep off collant from it ! now in my rush to get the new stat in I didnt use any sealer so will have to reopen it and use some sealer, now an update on mine guys is that even with the QTH107 stat my temperature is still dropping , ambient temp seems to affect my car pretty bad and tonight after doing 30 miles the temperature of the engine went from 80 down to 72 so not great even after switching the heater off, that was at 40mph in top gear on a average speed camera section which last for about ten miles, as soon as I was out that I managed to get the temp back up but it didnt exceed 80oc

(ps exterior temp was -1)

[Number 6]

As mentioned on a previous thread I went to Wales for a couple of days and at the same time I tested the in line thermostat I had previousley fitted

The out side temp varied between +3c and -3c

when the car reached its normal temp after about 1/2 to 2miles the temp averaged between 85 and 90 degrees c
It was quite noticable when the stat opened as you could see the temp drop,but went back up very quickley
The speed averaged about 55-60 mph with an occasional burst to 70 when the temp went to 93c but then returned to average 85/90c

The fuel consumption possibly had improved by about 1 to 2 mile per gallon
Another thing I noted was even on a very long down hill run the temp did not drop below 83c

So all in all it would seem that there is an improvement using an inline stat of some sort,what will happen in the warmer weather remains to be seen.

[Mintee]

Originally Posted by Number 6

...what will happen in the warmer weather remains to be seen.

What are you expecting, the thermostat not to work in hot weather?

[Mintee]

Originally Posted by David Lawrence

yes I am using the 195F chevy stat. I'll try drilling a small hole first, nothing to lose. Meziere suggest two 4mm holes, but that seems a bit drastic.

I wouldn't drill any at this stage. If your other 'stat doesn't work stick an 88°C one in and see if it is some flow issue with your car. You would expect that to run a little cooler if it doesn't you might need to look elsewhere for a problem.

If it does you could perhaps post your unmodified 'stat to myself (or wezerk) and let us use it for a while and see how it works in our car? Just an idea. It will be immediately obvious to us if it is different to the ones we have fitted.

[PaulR]

Originally Posted by Thomas

Mine seeps through very very slightly as I noticed the other day a small weep off collant from it ! now in my rush to get the new stat in I didnt use any sealer so will have to reopen it and use some sealer, now an update on mine guys is that even with the QTH107 stat my temperature is still dropping , ambient temp seems to affect my car pretty bad and tonight after doing 30 miles the temperature of the engine went from 80 down to 72 so not great even after switching the heater off, that was at 40mph in top gear on a average speed camera section which last for about ten miles, as soon as I was out that I managed to get the temp back up but it didnt exceed 80oc

(ps exterior temp was -1)

I haven't driven mine very far since fitting the stat yesterday, but I suspect I will get very similar results. I don't know whether the new batch has a hole drilled in the stat or not. I will try to find time to check today and if so I will seal it. The outlet pipe was warm yesterday whilst the engine side was hot so there must be some leakage.

There seem to be widely varying results and there are also varying MPG figures. I wonder whether those getting higher temperatures are also getting lower MPG figures. In other words are their engines producing more heat because they are using more fuel either because of driving habits or some other engine problems.

Paul

[wuzerk]

Originally Posted by Thomas

Mine seeps through very very slightly as I noticed the other day a small weep off collant from it ! now in my rush to get the new stat in I didnt use any sealer so will have to reopen it and use some sealer, now an update on mine guys is that even with the QTH107 stat my temperature is still dropping , ambient temp seems to affect my car pretty bad and tonight after doing 30 miles the temperature of the engine went from 80 down to 72 so not great even after switching the heater off, that was at 40mph in top gear on a average speed camera section which last for about ten miles, as soon as I was out that I managed to get the temp back up but it didnt exceed 80oc

(ps exterior temp was -1)

THOMAS: I cannot see any other explanation for your low temperatures other than a 'stat which opens too early or a faulty temperature sensor. After all, if you only saw 80C then the stat should not have opened and the temperature should have continued to rise. If you are going to work on the
housing perhaps you could check the stat in a pan of water? (if you have a suitable thermometer). regarding the housing needing a sealant, I meant around the lip of the actual thermostat where it sits in the recess.
If the profile of your new stat is different from the original then it might need the sealant. The british housing is meant to be bolted up tight
without a gasket as the seal is actually between the lip of the stat itself
and the recess.

PAUL: you will always get some warmth on the radiator side due to heat transfer.

[Mintee]

Originally Posted by PaulR

There seem to be widely varying results and there are also varying MPG figures. I wonder whether those getting higher temperatures are also getting lower MPG figures. In other words are their engines producing more heat because they are using more fuel either because of driving habits or some other engine problems.

Quite the opposite. I used to drive about in the low 60's, now it is at the high 80's and my fuel consumption has improved a little. Only by a couple of MPG so far and that over a half a dozen tank-fills so far - but I seem to have been getting a 'better' mileage in the cold weather than I did last year.

[rossocorsa]

I would imagine that in warmer weather the performance of the stat will be more stable as the water in the radiator will be higher so temp drop will be less dramatic but still more than cool enough to keep the engine cool.

[PaulR]

Yes, you seem to have the hoped for solution, Mintee - a reasonable operating temperature and subsequent increase in MPG.

I seem to remember that some were having temperatures higher than this and I just wondered whether that went with previously low MPG figures and whether the two were linked in some way.

Paul