Hi - I had a leak from thermostat housing due to the rubber seal around the thermostat cracking (old type thermostat?) . Have had to buy a new thermostat with housing with rubber seal - thermostat held in place in new housing by spring clip (new type thermostat). 

 

All ok except that the engine now runs cold - only getting a bit above 70 degrees - previously the temp guage would quickly get up to the halfway mark - 90 degrees I think. I assume the new thermostat is opening early.  Now it takes quite a while (a few miles) to respond at all.

 

The shop wont exchange it but insist they send it back for testing and I can buy a new one -if later deemed faulty I would get a refund.

 

The car does get to 90 degrees and beyond if just idling - I have done this with the coolant filler top off - and let it bubble for a while - to try and ensure no air locks, but this hasnt cured the problem - it drops to a low temp in normal driving.

 

Is there any other reason why the car could run cold? - After arguing with the shop I am loathe to buy another thermostat (£20) from same shop and run the risk that it 'tests ok' and I wouldnt get a refund.

 

Note I have recently put on a new cylinder head gasket, and so I have had to drain and refill the coolant - but the car initially ran at ok temps - Ive only had to change it due to the rubber thermostat seal leaking - any advice?

 

Thanks

The only reason I can see is that the new thermostat is sticking open, if true you should be able to see this by removing it and inspecting it, if it is stuck open then you can simply take it back and swap it for a new one since the fault is clearly visible.

I've Got exact same problem, with exact same type of thermostat/thermostat housing. Takes a long time to warm up especially when cold or with heater on full blast.

At first I thought that I had the 80 degree stat, but when inspected it was clealy stamped 88 degree.

The Mark 2 thermostats are clearly faulty. Either that or there is some sort of compatability problem. There are plenty of other posts with complaints about these thermostats.

It's a shame you had to buy a whole new thermostst, because I have a spare seal from when I changed mine.

Did yours come with a new coolent temp sensor?

Here is a picture of where my car's temp gauge runs at during normal operating conditions.

 

To be clear, you've removed the old thermostat (in the metal housing) and fitted the new style (in the plastic housing)? 

 

There is a fault because it should sit at 90c. Have you tried removing the theromstat and checking that you haven't left any debris in the housing? 

You don't have an air lock in the system do you?

Sent from my Galaxy S5

Drop it in a bowl of hot water and watch what happens

Drop it in a bowl of hot water and watch what happens

 

I need a accurate thermometer to see when the stat starts to open, and then close.

Thanks all for your replies - I have tested the new thermostat (which is the new type - held in place in plastic housing by metal clip) on a stove with large  saucepan and thermometer, and it starts to open about 75 degrees. I have put old thermostat back in (not held in place by plastic clip, but held in place by the 2 halves of the housing) and it works fine.  Still have very slow drip which needs sorting - but a plastic pot catches the drips as temporary measure.

Pretty sure no air lock - have also run engine hot with filler cap off so it bubbles. 

New thermostat returned to shop as faulty (though they insist supplier / manufacturer test it before refunding).

Finally I have worked out what is wrong with the, non skoda genuine, new type thermostats. It's that the thermostat doesn't form a watertight seal in the thermostat housing, so the effect is that the thermostat is permantly open. Any way it is an easy fix, using some instant gasket around the edge of the thermostat, then clip it back in place. Problem solved.

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