cooling and waterpump pulley misalignment problems

PeterCrespin · Post by **PeterCrespin** » Fri Feb 19, 2016 12:56 am

I'll get you a4.2 measure.

The Jaguar advice is a bit misleading David. It was for race-prepped cars (AKA almost permanently flat-out). Street driving is very different in terms of engine temp control. My D will have had no tstat and no bypass - ever - and I may have to resort to blinding part of the rad core for normal driving.

64etype · Post by **64etype** » Fri Feb 19, 2016 1:25 am

PeterCrespin wrote:I'll get you a4.2 measure.

The Jaguar advice is a bit misleading David. It was for race-prepped cars (AKA almost permanently flat-out). Street driving is very different in terms of engine temp control. My D will have had no tstat and no bypass - ever - and I may have to resort to blinding part of the rad core for normal driving.

Dang it....I missed the very first line and went straight to the restrictor bung in the bypass hose. (I would not run a stock E without a thermostat on the street). But I do still have an interest in the restricter. Wonder what the thinking was for the specifically sized hole? Air in the line inducing cavitation?

By the way, David, I couldn't find a bypass blocking plate or sleeve on SNG UK or U.S.

Post by **Heuer** » Fri Feb 19, 2016 11:22 am

Eric

This is a photo Julian sent me of the sleeve they supply:

I will ask him for a part number. This is the information they supply with their C3731/1* Thermostat:

Polse7317 · Post by **Polse7317** » Fri Feb 19, 2016 12:25 pm

That thermostat seems correct for my serie1 : 11mm to 22mm sleeve movement. It's that one i have bought, i'll tell you when i'll fit it .

64etype · Post by **64etype** » Fri Feb 19, 2016 7:55 pm

Thanks for the larger photo. Looks like it wouldn't work for me with the thermostat in place as it mounts in the same groove. If Yves' unit is the correct diameter, perhaps the issue is resolved. If not the sleeve might be the correct diameter to use in a modification. I'll use a restrictor in the bypass hose until the issue is clearly settled. Thanks for doing all the leg work on this subject.

Tony · Post by **Tony** » Fri Feb 19, 2016 11:15 pm

Is Lataud's problem a thermostat problem or have we digressed into a technical discussion on thermostats? I may have missed something but has he solved his his overheating problem?. From my very limited experience on other cars the problem has always been something others than the thermostat after trying it without one.

Post by **mgcjag** » Fri Feb 19, 2016 11:31 pm

Hi Tony....Yves had incorrect stat fitted and is waiting for the sng one to arrive...so watch this space.....fingers crossed it works out good for him.....running without a stat can cause overheating becaus coolant can circulate around the bypass and not go through the rad to get cooled

Tony · Post by **Tony** » Sat Feb 20, 2016 9:06 am

I can see the principle of it circulating down the bypass but by clamping off the by pass for a few minutes when the engine is warm would soon tell if the the bypass was the problem.

Post by **mgcjag** » Sat Feb 20, 2016 9:40 am

Hi Tony....that sounds about right...

Tony · Post by **Tony** » Sat Feb 20, 2016 10:00 am

Hi Steve

I note Ladaud states the engine overheats after Half an hour. Is this half an hour of driving or standing on tick over. If standing on tick over for half an hour, would this not test any e type, in particular if it running on the jaguar standard model aeroplane fan.

Polse7317 · Post by **Polse7317** » Sat Feb 20, 2016 11:21 am

It was a test Inside the garage, bonnet open, with an external fan by the motor .

cactusman · Post by **cactusman** » Sat Feb 20, 2016 11:31 am

For what it is worth I have a coolkat fan on my S1 replacing the original aeroplane fan plus a second kenlowe type on the other side blowing into the rad....been stuck in traffic for well over half an hour....behaved impeccably! Maybe I got lucky but mine seems trustworthy...so far!

Post by **Heuer** » Sat Feb 20, 2016 11:41 am

The second fan is a) unnecessary and b) will most likely increase temperatures by creating turbulence and interference with the Coolcat fan. They spin at different speeds and have different blade designs. The second fan will also reduce airflow when the car is moving.

I have the original fan on my FHC with a replica Marston radiator, have been stuck in traffic several times and the temperature remained stable. I did have a Coolcat fan fitted for a while but found it made no difference so went back to the two blade and Lucas motor. My OTS has a Kenlowe and even stuck in traffic in Biarritz, when temperatures topped 41C, there was no problem; driver and passenger less so!.

Post by **1954Etype** » Sat Feb 20, 2016 12:02 pm

On my 66 original car that spent its life in Cupertino, Calif, it had a replacement fan motor (from square to round so little difference). The car has 98k miles and retained the original 2 bladed fan.

Having said that, l run a coolcat on my car but l bet it would be fine with an original fan.

cactusman · Post by **cactusman** » Sat Feb 20, 2016 4:34 pm

Second one was there when I bought the car. It is not that large but seems to cause no adverse effects. Otter switch turns both on but I can switch the second one on any time from the dash :D

neal herridge · Post by **neal herridge** » Sat Feb 20, 2016 5:19 pm

I have just removed my thermostat housing on my 1965 4.2 to check the dimensions & found I have the wrong stat fitted no sleeve to cover the bypass , the car has never over heated all the time I have had it, when I rebuilt the engine two years ago I just put back the old stat as it had always worked . Should have known better as it is a well known problem on XK120's which I have.
The dimensions for the 4.2 are very different as follows.
Bore 50.1mm slot starts just 5.5mm from front face & is 3mm wide. there is also a 1mm deep c/bore in the front face.
This means the 3.8 stat would cover the slot when cold & leave it open when hot.
So does any one know the correct stat for the S1 4.2's.
Thanks Neal.

Post by **mgcjag** » Sat Feb 20, 2016 5:43 pm

Hi Neal can you post a photo here or to my email will pm it to you ..thanks Steve

neal herridge · Post by **neal herridge** » Sat Feb 20, 2016 5:51 pm

Hi Steve will get a picture in the morning may be a bit tricky though as the inlet manifold is still on the car.
Neal.

MarekH · Post by **MarekH** » Sat Feb 20, 2016 7:08 pm

I think people need to stop getting too upset about "the wrong thermostats".

Clearly when they open the bulk of the water goes around the radiator loop in preference to the smaller bypass slot. Whilst it'd be ideal for all of it to go via the radiator if the 'stat is fully open, clearly enough of it does such that a properly maintained cooling system isn't going to be troubled.

If you don't have a problem, don't bump up SNGB's profits unnecessarily by running around like headless chickens. You'll probably just upset your cooling hoses and get water leaks around your Cheney clamps for all of this trouble. Spend the money on beer instead.

kind regards
Marek

Post by **Heuer** » Sun Feb 21, 2016 12:19 pm

Can't agree Marek! The XK engine was in production for 43 years and at no time did the designers decide to delete the by-pass even in the cost cutting BL days. The lack of a correct thermostat is a well known issue with XK120/XK140/XK150 owners which is why the SNGB part number applies to those cars. They are more susceptible to overheating than the E-Type due to the lack of airflow and confined bonnet and a few degrees can make a big difference when the ambient temperatures are high. The owners lobbied SNGB for a solution and #C3731/1* became available again.
Over-heating worries push E-Type owners into installing more efficient fans, alloy radiators, fan override switches, Water Wetter and even electric pumps when we may have been missing a fundamental solution, and all for ?25. So when you are sitting in traffic with your eyes glued to the temperature gauge as it inexorably rises you will probably think why the hell didn't I fit the correct Thermostat. Even if it only gives you a margin of 2 - 3 degrees it could be the difference between finishing your journey and being stuck on the side of the road.

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