The 'E' Type Forum

Hello….i changed the thermostat on my car with a brand bought from a major Etype parts supplier. Now the car is running very hot. There is a lot of confusion on which Thermostat is a good choice for an Etype V12. Any suggestions will be greatly appreciated.
Sandy

I'm not sure what you are confused about.

The manual states 82'c thermostats. This sets the minimum operating temperature of the engine. (The thermostat won't send any water to the radiator below this temperature.)

You want a thermostat which opens out far enough to let it's bottom perch to block off the bypass. (This makes sure all of the water goes to the radiator once the thermostat has fully opened, which is typically about 12'c higher than the opening temperature.)

If you meet those requirements and are still "hot", then this isn't a thermostat problem.

kind regards
Marek

If both inlet and outlet hoses to the radiator are hot it means water is flowing through th radiator, are you sure the fans are coming on when they should?

Also check whether your thermo switch is operating if the fans are not working C45086.

I did add VW fans, change the thermostats and Otto Switch…it was after this work the car runs hotter than before, Have you seen this link on Etype series 3 thermostats… https://www.coolcatcorp.com/thermostats ... -Type.html

I can hear the fan, and assumed it was a defective thermostat. How does one pinpoint if thermostat is the issue?

As I said if both hoses on the radiator are hot then the thermostat is open, on some cars one can try running without the thermostat to see whether there is a difference in running temp. Are you sure the fans are blowing air in the right direction (cold air in), I assume the water pump is working OK.

Greensand73 wrote: ↑

Sun Jun 18, 2023 6:49 pm

I did add VW fans, change the thermostats and Otto Switch…it was after this work the car runs hotter than before, Have you seen this link on Etype series 3 thermostats… https://www.coolcatcorp.com/thermostats ... -Type.html

Are the fans blowing the correct direction? It wouldn't be the first time someone as fitted fans that blow towards the front of the car.

MarekH wrote: ↑

Sun Jun 18, 2023 7:21 am

The manual states 82'c thermostats.

You want a thermostat which opens out far enough to let it's bottom perch to block off the bypass.

Marek

Adding to what Marek says, the thermostats MUST have that extra little circular plate, which is actually a valve that closes the radiator bypass circuit, IF (as Marek says), the thermostat moves far enough to actually block that bypass route. From memory, it has to move at least 42mm to close the bypass port. I always test,even new thermostats, in a kettle to be sure the open and do so far enough If this plate is absent or does not close, a significant amount of coolant does not flow through the radiator.

Use C28067 (74C) or C280671 (82C).

Greensand73 wrote: ↑

Sun Jun 18, 2023 6:49 pm

How does one pinpoint if thermostat is the issue?

One is systematic in one's approach and one discloses all the appropriate information.

Your second post reveals you've actually done four separate things, rather than just ask for a thermostat recommendation.

1/ You have changed the fans
2/ You have changed the Otter switch
3/ You've changed thermostats
4/ You've moved some of the wiring and connectors about.

For 1/, I would check the fans run when the black/red wire is earthed. This can be done by bypassing the Otter switch at the Otter switch. As noted, the fans should pull air through the radiator.

I would then drain the coolant.

For 2/ I would check in a pan of water that the Otter switch connects and disconnects at the same temperatures as the previous one fitted. If you think about it, the Otter switch on/off cycling has to be linked to the thermostat spec. It's no use having the fans come on much later (hotter) than if the new switch works differently to the old one. Not all Otter switches are spec'd the same way. That should be apparent from Mike Frank's site.

For 3/ I would pop all four thermostats into a pan of water and do the same check as for 2/. Whilst there, check the overall height they open to so you can gauge whether the bottom "foot" (which is spring loaded) blocks off the bypass when hot. Clearly, it was designed spring loaded for a reason. I would also have labelled the parts as soon they were taken off of the car. It is possible the left side is totally different to the right side and knowing "which side" is better than simply knowing one side "is different".

4/ 50 year old wiring and connectors can be brittle. Adapting new looms to old isn't necessarily straightforward. Your fans might work on the bench but not in situ.

Once the coolant is back in, any air pockets need to be bled out before concluding anything about circulation. To do that, you'll need to run the engine and cycle the heater matrix in and out of the circuit. It is a high point and there will be pockets of air there which need to work their way back to the header tank.

There may be reasons other than the above. For example, a more retarded ignition wastes more energy through heat. We only have a few paragraphs of information to go on here.

kind regards
Marek

Fabulous and thank you! I will get back to you..i am working with a mechanic.will let you know
Thanks
sandy