So, my thermostat housing went causing my polo to over heat. Got a new housing and fitted it with the new thermostat.

Then found that my engine wasn’t getting to temp properly. Stationary it would heat up and then stay at 90 Degrees no problem, but as soon as the car was moving it would drop to cold ( as if engine turned off). Then warm up when stationary

Though it my be the thermostat as it was a factors one, so swapped it back for the VW one on Friday.

Been driving all weekend over 150 miles, still same problem.

Any ideas?

Cheers

Chris

not had the over heating issue before mate...however mine does the exact same thing as yours is doing now mate :(

Mine did the same after I changed my thermostat, and loads of people seem to get the same thing.

I carried on driving mine as normal, under the basis that as long as it isn't overheating, it's fine.

Went back to normal after a couple of weeks, needle upto halfway and stays there

your thermostat is allways open, so its always cooling

mine done it aswell

The day I passed my test my 6n overheated. Finally got it home and the next day set about finding the issue. My neighbour said to me to cheack the thermostate so I took it out and started the engine. Got to temperature fine then when I drove it the needle dropped as if the engine was cold (like above). So I bought a new thermostate, fitted it, started the engine up and it over heated again! So now I am driving my car without the thermostate because I really don't know what the problem is. I have even changed the temp sender but still no luck!

Anyone know the solution?

There will be additional cooling air flow over the radiator when the car is moving - what is typical outside air temperature at this time of year - close to freezing?

regards,

engineerthomson

Why is my car still overheating when I put a brand new VW thermostate in?

Danny-dub

There is a small plastic bridge inside the thermostat housing. This bridge is fragile and breaks. The thermostat pin pushes against this bridge to open. If the bridge breaks the thermostat stays shut. I have had 2 fail. If the overheat problem goes when the thermostat is removed and if you have replaced the thermostat this is most likely the fault.

Regards,

engineerthomson

My Polo 6N2 did overheat last month, it turn out to be a broken housing,

As the picture shown, there is a hole in the center which supposed to be solid.

I have pickup the broken pieces carefully from the coolant hose, then change coolant,

I have my thermostat changed also, now it's working fine.

But as for the thermostat stays open, then that can be a either a bad one,

or it doesn't line up properly to the housing.

Try to boil the thermostat , the pin will pop out when heated to 100 degree.

if the pin not moving, then it's bad.

Edited 12 December, 200718 yr by smokeGTI

mine done the same the other day! car overheated!

fixed it though.. one trip to GSF later for a new housing, stat and some coolant and i got it all sorted

OK the houseing breaking is what happened to me. I fitted a new housing, lined up the factors and the VW thermostat fine. but it still drops when the cars moving. Dont think its the time of year as when it went original in the summer it would still drop down to just under 70, no cos its so bloodly cold out its not even heating.

I'm wonderin whether its my body kit as it allows a loot of air through it.

Look in the gallery under P10 GOT to see what i mean.

Chris

nah it isnt that p10got...mine is a standard 1L with no kit and mine does the same thing...someone must know why surley?

the thermostat is part of a plastic housing which has a rubber o-ring at one end

this allows it to seal againt the part shown in the pictures above...

check that its still there...your problem is almost certainly within the thermostat housing area

I had this. Turned out there is to different thermosats. Changed it for the other one and it was fine.

Test richie - I've tried botht the factors and the vw thermostat, and bout do the same

16vTej - I'll have a look for that seal, is that between the main bodie of the housing and housing in the above picture? or in the housing around the thermostat ( witht eh spring in it?)

where is the thermostat and how do i get to it? I'm doing a service today so will have a LOOK? CHEERS

where is the thermostat and how do i get to it? I'm doing a service today so will have a LOOK? CHEERS

Coolant hose from the radiator attaches to a stub plastic pipe near the distributor. This pipe is about 2 inches long and has a flange plate with 2 bolts attaching it. This pipe is the thermostat housing.

smokeGTI has posted a photo of the thermostat housing - see above.

Check the small bridge inside the housing - also visible in photo.

This often breaks. The thermostat has a pin which extends when the thermostat heats. This pin pushes against the bridge to allow the thermostat to open and thus coolant to flow.

When the bridge breaks the thermostat stays shut and the engine will quicky overheat

regards

engineerthomson

vw dont refer the photo above as the thermostat housing, it is the thermostat "cover".

the thermostat housing is the big unit on the side of the block which the temp sender, coolant hoses and thermostat cover sits in.

Test richie - I've tried botht the factors and the vw thermostat, and bout do the same

16vTej - I'll have a look for that seal, is that between the main bodie of the housing and housing in the above picture? or in the housing around the thermostat ( witht eh spring in it?)

the one i mean is on the end of the bit with the spring inside it...

when mine was over-cooling i found that the end of that piece had lost a few chunks of plastic as well as the o-ring so wasn't sealing properly when the thermostat tried to stay shut

vw dont refer the photo above as the thermostat housing, it is the thermostat "cover".

the thermostat housing is the big unit on the side of the block which the temp sender, coolant hoses and thermostat cover sits in.

Irrespective of the name the component in the photo has to be removed to access the thermostat.

I've had to abandon the polo (6n) coz of ova heating yesterday and now the proud driver of my mothers puma. I've been told that my over heating could be caused by the water pump failing, yet I've lost no water, the car drives fine bar over heating and the heating within the car works.

Do you guys feel this will be my stat also? I feel this is what has failed not the pump.

Thanks all.

Ash

I've had the same problem , changed the thermostat twice the temp sender and the thermostat housing and it still wont get to half way when I'm driving . This is really anoying me now . Could i have done something wrong?

Fitted my new housing tonight and the problem is solved. The broken one had a whole in like in the pic above. Temperature drops off when I drive but I gess thats because its sooooo cold. Cheers guys!!

Fitted my new housing tonight and the problem is solved. The broken one had a whole in like in the pic above. Temperature drops off when I drive but I gess thats because its sooooo cold. Cheers guys!!

When you say it drops off, do you mean back to 0?

yer, usally stays just off 0 like near 70