Which Thermostat?

[ukkid35]

I'm hoping my thermostat is stuffed, if not I'm in serious trouble. Having poured boiling water over it, it doesn't seem to open much, perhaps 3 or 4mm, and closes fairly quickly when removing it from the water. I don't have a thermometer to check the water temperature though. My existing stat is branded Wahler, which I consider a quality make.

I have found the following on eBay for £20 inc p&p

Quinton Hazell QTH221 85C
Gates TH11987 87C
FirstLine FTS137.85 88C

On a German mailorder site rexbo.eu there's a Valeo 819837 79C for €40 + p&p

Then there's the unknown stat sold by RG for £40 + p&p (CleverTrevor price)

Also there's the unknown 85C stat sold by RaceTech for a whopping £84 + p&p

Strangely Powers are showing an unknown right angle (rather than approx 135deg) stat for £43 + p&p

Any thoughts on which to go for?

[Tirus]

gerradiuk said:

Thermostat from a Quetin Hazel QTH134

Fits:
Fiat

131 1.3, 1.4, 1.6 1975-84

132 1.6 1974-77

132 1.8 1972-77

132 2.0 1972-76

Argenta 1.6, 2.0 1982-84

Ritmo 125TC 1.6 1984 -

Strada 125TC 1.6 1984-88

Morgan

4/4 1.6 1982 -

Plus 4 1.6 1982 -

Seat

124 1.6 Sport Coupe 1970-74

131 1.6 1976-81

132 1.6, 1.8 1972-75

132 2.0 1977-82

I have just been lucky enough to buy a new one but unboxed for a Morgan for £10!

[ukkid35]

The QTH134 is 90deg angle, I want to stick with the original 135deg angle which is why I've listed the QTH221.

[MoonMonkey]

I've had 2 QTH221's both made by Wahler, both failed and caused overheating. Also tried the Clevor Trevor one which didn't work straight out of the box(they refunded no problem)

I'm using the Gates TH11987 from Ebay, which works fine but I think it's rated at 78oC not 87. Means the temp never gets much above 80oC in the winter unless stuck in traffic,which always has me worrying about oil temp.

Thinking of changing to the race tech one but £84 is a bit steep

[ukkid35]

Original Wahler courtesy of MoonMonkey


FTS137.85 eBay doctor_car


QTH221K eBay Redlinecarparts


Unknown eBay Redlinecarparts


Clever Trevor / Racing Green


Gates


Racetech Direct



Looking at these there appear to be two different designs, assuming I have oriented them all the same way, with the 135deg angle between top hose and bypass.

At the moment I'm erring towards the QTH221K.

Here's one more pic showing mine after pouring boiling water through it, I'm sure it should open more than this. It was fine before my rad sprang a leak and I ran out of coolant without realising it. I'm not really sure how one could have caused the other, perhaps the stat failed first.

[ukkid35]

I've just found MoonMonkey's thread where he comes to the same conclusion about the two different designs.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

[MoonMonkey]

The 90 degree type will fit ok, but I think the QTH 134 has an opening temperature of 78oC.

From what I've seen I think the QTH221 made by Wahler was the OE part on an AJP Cerbera. I think they were originally fitted to a 1.6 Lancia Delta in the 1980's

The Wahler ones definitely look to have a bigger more robust opening mechanism than the Gates ones, just never found one that works!

[ukkid35]

MoonMonkey said:

The 90 degree type will fit ok, but I think the QTH 134 has an opening temperature of 78oC.

From what I've seen I think the QTH221 made by Wahler was the OE part on an AJP Cerbera. I think they were originally fitted to a 1.6 Lancia Delta in the 1980's

The Wahler ones definitely look to have a bigger more robust opening mechanism than the Gates ones, just never found one that works!

I have silicon hoses that are perfectly configured for 135deg angle, trying to force them to 90deg would not be good, especially since it's unnecessary.

My stat is marked Wahler 85c, and date stamped 03/98, so that suggests it definitely was the original part.

Any idea what the difference is between the QTH221 and QTH221K?

[sonnylad]

ukkid35 said:

I have silicon hoses that are perfectly configured for 135deg angle, trying to force them to 90deg would not be good, especially since it's unnecessary.

My stat is marked Wahler 85c, and date stamped 03/98, so that suggests it definitely was the original part.

Any idea what the difference is between the QTH221 and QTH221K?

Should be Temperature from memory when i originally started getting them in K is 85° without K is 82° or somewhere near that

[MoonMonkey]

Hi I've no idea what the difference is between the QTH 221 and QTH 221k. Looking at the description they seem to be the same in terms of opening temperature.

I see Amazon has some from a marketplace seller

[Luckyone]

My thermostat has always been & still is fine.

But as a few people mentioned on the linked thread I too noticed with the laptop connected both that & the gauge read 75deg on the motorway, with it warming up as soon as I slowed.

I don't think the gauge used to drop quite so much before I rebuild the car but I was careful routing the capillary tube this time, the heater output used to drop by the same amount before.

It's just due a coolant change now & a 85deg stat sounds perfect, but I don't want to remove a perfectly good stat to fit one that's going to fail & cause the car to overheat! I can't see any gates stats anywhere at the moment. The official TVR parts people show one with an angle of 90, that I don't want. Racetech actually say the one they have is rubbish....

Should I leave it well alone?

It's only the oil temps that bother me really.

I fitted an oil stat many years ago but I put the oil temp sender in the sump plug when I fitted that so I'm as much reading the temp of the sump its self as the oil, that doesn't go much over 50deg in the cold weather. According to the Four-Stroke performance tuning book the ideal oil temp is 95-110degC so it can effectively burn off all the nasty stuff that builds up in it (stuff left on the liners after combustion on every power stroke). So I think my oil temp gauge is under reading a bit, but not enough. Worryingly it says an engine should never be driven hard till the oil is over 70. With the water at 75 I imagine the oil is going to struggle to get to 70 & certainly never going to get to 95.

Mind you that is just theory, I guess all Cerbs are much the same. You just need to make sure you give it a good thrashing once you have slowed down enough for it to warm up, but then you'll likely be going fast again....

[FarmyardPants]

Ever considered covering up the oil cooler in winter? I have, but have never actually done it.

My car never reads less than 82 on the dash gauge once warmed up.

[Luckyone]

FarmyardPants said:

Ever considered covering up the oil cooler in winter? I have, but have never actually done it.

My car never reads less than 82 on the dash gauge once warmed up.

Funny enough I was going to say I was thinking of the old London cabby trick of cardboard over the front to see if that made any difference.

I'm fairly sure Think Automotive who I got the oil stat from (who I used to live round the corner from) said it would never actually fully close so having it covered could make a difference. Probably having the cooler covered all winter would be fine. It's only really needed for the track. It wants someone who went to the bother of putting the oil temp gauge sender in the pipes to get a proper reading to see what difference it actually makes though.

Have you looked at a read out of the ECUs water temp to see how low that goes, I think my dash didn't used to read much below 80 before I re-rooted the capillary tube. Or were you talking about your oil temp there?