Remote thermostat problems?

[whaleys]

Hi guys,

Was wondering if i could pick some brains about the new thermostat (eliseparts PRT) that Ali fitted for me. Before I had it if I was on the motorway the temp would sit at around 85-86 with only slight movements every now and then. Now with the PRT fitted, when driving back to Dundee from Ali's when its up to temperature its at around 84 then over the next 30 seconds works it's way up to 89 then drops back down to 84 then goes through the whole process again and again continuosly. This was travelling at a fairly constant 60mph.

Is this normal? I thought that it was the temperature fluctuations that could damage the engine and what this was supposed to alleviate?

When driving with a heavy foot, it does the same but goes more 83-90. Any ideas?

Graeme

[roadboy]

Sounds like there is still air in the system. They are a PITA to bleed properly.

HTH

Dan@JPS

[robin]

Are you sure it's a PRT and not a remote thermostat? I didn't think Eliseparts sold a PRT but they do sell a remote stat.

The remote stat if fitted at the radiator end should provide a nice blending action (at the expense of slower heating up in the first place - the chassis rails become part of the bypass circuit). This slows down the response of the cooling system but reduces the "shock" on the engine because there is always hot coolant circulating in the chassis rails, and when the stat allows flow through the radiator, that freezing cold water blends with the already hot water in the chassis rail so the engine sees less violent changes.

The remote stat if fitted at the engine outlet (i.e. down by the oil filter, in a line behind the drivers seat) suffers from basically the same problems that normal stat does - when engine speed is low and the engine is hot, the stat opens to increase flow through the rad to cool down the engine; when engine speed and/or road speed rises suddenly, flow through the rad and/or effective cooling is much higher and the engine will cool down below target operating temperature until the stat can react and shut off the flow. Hence most elises if you get them to normal operating temperature and then cruise on the motorway, drop a few cogs and floor it, the temperature will drop quite suddenly, then creep back up to the correct temp as the stat adjusts to the new rate of cooling.

However, at steady road and engine speed, all the stat systems should settle to a sensible opening and provide a constant engine temperature. The fact that you aren't sounds like the flow rate is variable (perhaps due to air lock as Dan suggested) or the sensor itself is on the way out (not uncommon, apparently, though it hasn't happened to me).

Best get on the blower to Ali and see what he suggests?

Cheers,
Robin

[whaleys]

Thanks Robin and Dan, will speak to Ali, but thought I'd ask you guys before I bothered him again, just in case it was me being paranoid.

cheers

oh and its not a PRT you're right Robin its just a remote thermostat (I got it with the car I didnt buy it... honest)

[whaleys]

I have an update...

I spoke to a few people then decided I was getting way too paranoid and decided to give it a few weeks but keep an eye on it. The results are now that the elise is most definately fully blead and I am still getting those slight fluctuations in temp. I spoke to ali, and he was very sure that the system had been fully blead when he did the service, and suggested I contact eliseparts.

I spoke to Geary and he has said that this is fine? He mentioned that lots of Elises' do this and even some standard ones and there is nothing to be worried about. I know that he knows his stuff, but I am still a little sceptical, just wondering what you guys think?

Cheers

[Shug]

I wouldn't worry about a 5 degree fluctuation. In all honesty, it'd never show on a normal damped temp gauge and it's not really the sort of fluctuation to cause damage. The thing about the digital gauge in the Elise is that it makes you even more paranoid...

[steve_weegie]

Not wanting to cause any panic, but I've just finished testing 3 eliseparts thermostats, all with the wrong spring rate. If the temp is dropping when your revs increase, my guess is you've got one of the dodgy ones.

[Rich H]

As Shug says, if its generally ok and doesn't drop sharply or rocket then live with it.

Mine is all over the place depending on driving conditions, ambient temp and the amount of electrics I haev switched on. Somewhere between 80 and 95 is ok. Probably.

[fd]

As an example of how a 'true' temp gauge can cause paranioa . . . audi temp gauges are rigged in software (inside the dash) to read 90C regardless of coolant temp as long as it is between 80C and 100C actual . . . this ensures people don't 'worry' about the temp gauge going up and down as the engine produces vastly different amounts of heat and the thermostat loop lags behind in controlling it . . .

The dash (and engine) know the real temp of course . . . it's just the dummy driving it that isn't told exactly what is going on . . .

However . . . in steady state, say 70 along a flat motorway, the actual temp should stabilise to a constant value and stay there . . . if it's changing under those conditions then you do have a problem . . .

Fd

[whaleys]

Ok the plot thickens...

After Steve's reply I spoke to Geary again and he's offered a replacement stat, which I've said I would like to take up the offer of.

Now it seems though, that I am loosing coolant (this seems to be a common problem of a few eliser's of late). I'm not sure if this is suspicious, but on occasion I have been getting steam coming from the radiator, on perfectly dry days. I've got a pro alloy radiator so wont have the plastic end cap issue. Just curoius if this is screaming out anything or just normal.

Any comments or ideas, or abuse welcome

[Shug]

Ok the plot thickens...

After Steve's reply I spoke to Geary again and he's offered a replacement stat, which I've said I would like to take up the offer of.

Now it seems though, that I am loosing coolant (this seems to be a common problem of a few eliser's of late). I'm not sure if this is suspicious, but on occasion I have been getting steam coming from the radiator, on perfectly dry days. I've got a pro alloy radiator so wont have the plastic end cap issue. Just curoius if this is screaming out anything or just normal.

Any comments or ideas, or abuse welcome

If you're sure there could be no moisture in the rad, then it's possible it's leaking. Also possible that the expansion tank cap has just failed. I know which one I'd change first!

[whaleys]

I pretty sure there could be no moisture in the radiator but what are the chances of it being dead, it was only fitted July last year?

I also noticed that when the coolant was at the min level when it heated up it would go to the max level. Now when at the min and it heats up its only going around half way between min and max. Am I just getting uptight now?

[Shug]

I pretty sure there could be no moisture in the radiator but what are the chances of it being dead, it was only fitted July last year?

I also noticed that when the coolant was at the min level when it heated up it would go to the max level. Now when at the min and it heats up its only going around half way between min and max. Am I just getting uptight now?

Manufacturing faults happen - you have any warranty with it?

First, change the expansion bottle cap (or swap it for a known working one for a bit) - there's a valve in it that can fail regularly, but they're a few quid from a Land Rover dealer.

Take a close look at as much of the rad as you can see - in good light (although I'm not sure how much you can see on the S2) and look for watermarks in the corners and moisture.

[whaleys]

Manufacturing faults happen - you have any warranty with it?

It was on the car when I bought it. Its from eliseparts and I have all the receipts, would that cover it? Good thing is the guy I bought it from gave me the original too because there was nothing wrong with it.

I just had the remote thermostat fitted, is there a chance there could be a leak in the pipes/fixings that is getting onto the radiator or is the stat well away from it? (I havent seen it fitted so dont know quite where it is )

Oh and will see about picking up a new cap.

[Shug]

Manufacturing faults happen - you have any warranty with it?

It was on the car when I bought it. Its from eliseparts and I have all the receipts, would that cover it? Good thing is the guy I bought it from gave me the original too because there was nothing wrong with it.

I just had the remote thermostat fitted, is there a chance there could be a leak in the pipes/fixings that is getting onto the radiator or is the stat well away from it? (I havent seen it fitted so dont know quite where it is )

Oh and will see about picking up a new cap.

Dunno where Geary's remote stat is located - I'd assume up the front end somewhere, but I'll leave someone who knows to advise you on that...