replacing thermostat

[daz]

A little bit further along with my problems, today I've removed every pipe & flushed the system through, there were no obvious blockages everything flowed properly.

Is this the heater jiggle valve? I can blow & suck it with no resistance, could this cause the problems?

I also removed the stat while I was in there, is this fitted correctly?

Anyway, after a 30 minute drive through traffic without the stat fitted & the heater set to cold the gauge stayed 1 mark below half without moving, but after a motorway blast the temp gauge dropped to just above the quarter mark, so it seems I'm getting somewhere, hopefully. I'm assuming the gauge dropped because the stat wasn't there to control the flow, both underfloor pipes are now heating up nicely.

Got home & rebled the system & there was a tiny amount of air in the heater, I'll test it again tomorrow night & see if it's still the same.

I'll be testing the stat in a pan as soon as Mrs Daz isn't around & hopefully be fitting a PRT.

[RobboMC]

My understanding is that air is meant to go thru the jiggle valve but not coolant.

So being able to blow through it is a good thing, I think.
Testing it under pressure will not be easy.

If you believe the problem is with the thermostat just fit a new one, they aren't that expensive
compared to the problems they cause.

[daz]

If you believe the problem is with the thermostat just fit a new one, they aren't that expensive
compared to the problems they cause.

It's a brand new thermostat, I fitted it around a month ago in a failed attempt to fix the overheating

I tested the stat last night & it seems to be opening & closing correctly, I'm at a loss now & not sure where to go next.

[radddogg]

Fit the prt and see how it goes

[daz]

A quick follow up. I went out for another good blast yesterday in the scorching heat, again with the heater set to cold & without a stat fitted. I did a mixture of long, fast country lanes & sitting in a lot of stop/start traffic & again the needle didn't move once it had settled at just under halfway.

It seems a bit odd that removing the stat has cured the overheating when the stat is brand new & worked as it should when tested in a pan of hot water. Anyone have any ideas? I'm stuck now

[radddogg]

Yet a different stat?

[RobboMC]

Perhaps you are getting a 'cold spot' due to the circulation of the coolant behind the water pump.

I wouldn't know why or how, but that's the only explanation for the stat not opening in the car and working fine in the pan.

[daz]

I think I'll fit a 82 degree stat & give that a go, any recommendations?

[Martin_Bmth]

Ive not read all of the entries in the post but are you sure the thermostat is the right way round when you fit it? It is possible apparently to get it the wrong way round.

Ive recently had a similar problem with a metro and after several attemps at getting it to run cool it got sold on to someone with more patience.

[daz]

Yes it's definitely the right way round.

[daz]

Just in case anyone is still interested Today I've replaced the thermostat again, while I was in there I took the heater bypass jiggle valve apart & there is nothing in there, just a washer type thing with 3 holes, is there supposed to be anything in there to block the coolant flow? I've just bled the system & am waiting for it to cool down.

I've used a cable tie to restrict the flow from the jiggle valve as a bit of an experiment, my thinking is that the coolant can simply bypass the coolant pipes & return to the header tank through this valve rather than travel around the system & open the stat. Don't know if that's right or wrong, just my thoughts on it.

[daz]

That was a bad idea, it made no difference at all, with a stat fitted it overheats when the heater is set to cold, but without it it'll happily sit in traffic Without the gauge moving at all. I'm really struggling now. It's almost time to call it a day I think.

[daz]

I think this is sorted now, this morning I replaced the 4 way connector, expansion tank & removed the stat, then fitted a PRT up front by the rad. A very spirited drive this afternoon around 50 miles & the temperature was rock solid, staying between 85 - 90 degrees if the heater was set to hot or cold. Using torque I could actually see the temps dropping slightly when the stat in the PRT opened at 88 degrees, then stabilise again.

So a mix of town, fast country lanes & fast, long dual carriageways today & all is good in the Daz household

[ArntyR]

Hi daz I followed this with interest being a kseal victim and an inlet manifold widow...
My TF 115 already has a PRT but a d-I-y new gasket and rad vastly improved the bleed flow from all three points when cold.
Torque is giving me 92 - 94C overall and less hotness and heating smell.
A bit higher than your readings, tho'. You've seen a PRT: In your opinion can they get blocked up by kseal too?
It's good to experience your solution and problem closure. More posters should consider this...we can all learn + prosper, as you've shown. Thanks.

[daz]

I only had a quick look at the PRT, from memory it just looked like a normal thermostat, so I'd imagine it could get blocked up. I don't think 92 - 94 is to bad, after all it's a 88 degree stat.

[ArntyR]

Hmm...thanks for that insight daz. Perhaps my 'stat is a little sticky from the kseal but my temps only need watching for the present.
It might be useful if other Torque App-type owners could list their 'temp-range-when-warm' readings, again so that we can all profit from the info (if only to cure a little of the paranoia we need to curb as part of running these K series monsters)