Thermostat

[The Nige]

Hi
Looking for some guidance. Just put every thing back together, runs fine until the engine coolant temp gets to 80 ish the left fan kicks in but within a split second the gauge jumps to 100, the thermostat was replaced and wondered if this sounds like a faulty thermostat. Any thoughts?

Cheers Nigel

[Jhonno]

Have you checked the temperatures by plugging it in? Could be a faulty gauge..

[The Nige]

Hi Jhono

Just checked and they are not far off each other. Left it run briefly with the laptop showing 104 with both fans running, a little too high perhaps.

cheers

[notaping]

The thermostat, fans, and gauge are all independent of each other. The thermostat is just a mechanical valve which diverts flow through the radiator at a given temperature. This operates purely on the temperature of the water. The fans are controlled by an electrical sensor (connector with twisted blue/black wire in pic). The gauge works off a capillary sensor (Rusty connector with wound coil protector in pic)

I think the fan switching on and the temperature jump are a bit of a coincidence. The thermostat should open about 85-ish, which is about the same as the fan. It's more likely that this is effecting the increase at the gauge.

I suspect you might have an air lock and when the thermostat opens there is a sudden surge of hot water from the water manifolds at the top of the engine, OR - check the thermostat is fitted in the correct orientation.

[FarmyardPants]

Sounds like air in the system.

[gruffalo]

FarmyardPants said:

Sounds like air in the system.

Yep sounds like it needs bleeding.

[The Nige]

well couldn't work it out so drained down and removed the stat. Stat on the left is the old stat pretty much in orientation as it was on the car, with the new stat in the orientation that I put it on the car.


New stat as I now have it on the car and working fine.


F@#k me talk about spinning me out.
Oh that must have been why I mentiond bleading instead of bleeding on the other thread.

Cheers for all the input.


Nigel

[An Marcach]

Compare the flow direction etc of the old thermostat to the new one as, even though the housings may look almost identical, the internal ports can be set up differently.

I got caught out by this a good few years ago so I know it can happen.

[ukkid35]

notaping said:

Probably worth getting yourself one of these

https://www.ebay.co.uk/itm/162824073625

I doubt that connection to the temp sensor is very reliable, and will be feeding false info to the ECU, messing up the fueling