2.5 DI running cool

[sam l]

Hi people. My MKII CI was re-engined with a 2.5DI before I got it. It's always run with the temp needle at the lowest end of the normal scale. The temp gauge works, and the thermostat is not stuck open, although it may be operating too soon. The steel bolts on the thermostat have fused the the aluminium and give the impression that they will shear off if I really give them some welly.

This has never been a problem until now (except that the engine won't run at it's best too cold I suppose) when I've fitted a heat exchanger for veg-oil conversion purposes. The heat exchanger doesn't get hot enough really.

SO - is the old gauge for a petrol engine calibrated differently? Do petrols run hotter than diesels? How cheap and easy is it to replace the thermostat housing if I shear the bolts off it?

The heat exchanger gets too hot to hold but the 60deg C thermostatic switch I have on it does not switch - have I got a dodgy switch maybe.

Has anyone else on here done a 2-tank veg oil conversion on a 2.5DI?

Hope you can help - as you always seem to!

Cheers

[FredTransit]

it sounds like you need to change the temp sender switch in the block. They are colour coded and there are so many I couldn't tell you which one you need!

[sam l]

Oh dear. What's the sender wire by the thermostat for? Someone told me but I forgot . . . I can see the one on the block.

If the gauge is just reading low I'm not arsed about that.

edited to add

Anyone know where I can get hold of the thermostat housing anyway because I don't like the idea of not being able to change the thermostat due to the corroded bolts, even if it turns out that the thermostat is not the problem.

[Retrohowla]

I have not long done a 2lt pinto to 2.5 di on my mk2, i owned the mk4 that the 2.5 di came from so know it was running perfect and at the correct temp/stap operating correctly
When i put the di in the mk2 the temp gauge read very low, so i put the pinto temp sender into the di stat housing, reads a tad higher now but still reads only just warm when it is actually at full operating temp.
I struggled to work this out and in the end gave up and just have a mental note of whats norm and what would be hot on the gauge.
dont know if that made sense but basically my di is running fine but dont read on the gauge right still

[Smooth Hound]

heat exchanger, not really necessary to run a 2.5 di on veg oil, but each to his own, could be the problem though, its simply just not allowing the engine to get hot enough, i run on about 85% veg oil, no problems as it is, have also ran it on 100% no problems, i would however fit another thermostat just to make sure it is ok,

[sam l]

I'd be concerned about long term damage running a lucas pump with more than 50% veg oil. Wish I had a Bosch.

The heat exchanger is not a factor as the gauge reads the same as before it was fitted. I have lagged it too! Also if the coolant thermostat is working properly it should regulate the engine temp regardless of the heat exchanger which can never lose as much heat as the radiator.

I think there is a similar thing happening to what Retrohowla is experiencing cos the thermostat on the heat exchanger is lighting it's lamp after a few miles, which suggests that the engine is heating up OK. I will do the same as Retrohowla and stop worrying!

Ta.

[Inline Boarding Portugal]

It's always run with the temp needle at the lowest end of the normal scale. The temp gauge works, and the thermostat is not stuck open, although it may be operating too soon.

It happens exactly the same with our '85 DI MK2. (although, we really don't know if the thermostat is stuck or not...)
We can see slight variations on the gauge, from "seems to be dead" to "just the start of the scale"...

It's weird, because on our's '81 (not-DI) MK2, after a while with the engine running, the gauge indicates half scale.. And when running, if you pull it on a hill, the temp will rise almost to the high end of the scale...

WEIRD..

Anyone knows what is this all about?

[sam l]

I'm going to stick a new thermostat in next week, will let you know if this has any effect.

[FredTransit]

It's always run with the temp needle at the lowest end of the normal scale. The temp gauge works, and the thermostat is not stuck open, although it may be operating too soon.

It happens exactly the same with our '85 DI MK2. (although, we really don't know if the thermostat is stuck or not...)
We can see slight variations on the gauge, from "seems to be dead" to "just the start of the scale"...

It's weird, because on our's '81 (not-DI) MK2, after a while with the engine running, the gauge indicates half scale.. And when running, if you pull it on a hill, the temp will rise almost to the high end of the scale...

WEIRD..

Anyone knows what is this all about?

That sounds like the normal operating range, but for a petrol! Is yours a conversion?

[Inline Boarding Portugal]

No conversion!
Both our vans ('(81 & 85) are straight standard.

[Inline Boarding Portugal]

I'm going to stick a new thermostat in next week, will let you know if this has any effect.

Do you already put the new thermostat? Any difference?

[sam l]

Haven't got round to the thermostat yet cos I have to take the housing off and drill out the bolts and re cut the threads. But I'm pretty sure it's opening too soon cos my 60degC light comes on fine in town but not at all on a fast road or motorway.

Also a bit back I said I'd post a pic of my engine cos I've no idea what year it is, so here it is - please help! I think it might be an 86? The alternator has the pump thingy (for the brakes?) bolted to the back of it if that helps.

[Inline Boarding Portugal]

And the fuel pump it's an Lucas-CAV...

I can't tell you the year of your engine..
But despite of the air cleaner a bit different, everything it's pretty much like ours.. And our it's an '85.

Please post any news about the thermo when finished.

[sam l]

OK so I finally got round to drilling the bolts out and fitting a new thermostat. Which has made bugger all difference, except that I can now replace the thermostat without having to put the housing in a big vice and bash it with a hammer.

Can anyone else enlighten me as to the year of the engine from the photos in the post above?

I think the cooling system is just too efficient for the engine maybe? Or maybe I've got too much water in it. Either way I've definitely got the wrong temp sender.

[Luke]

have a look at the head under the top hose there are some numbers cast in the date should be there!
but a vac pump on the alt is later than 86 i think