200tdi overheating after thermostat change.

I changed my thermostat tonight in the hope that my engine would finally get up to temperature within a reasonable amout of time (I suspect the old one was a bit dodgy). When tightening one of the thermostat housing bolts it sheared off. The other two bolts tightened fine so I took it out for a drive to see how it did.

It heated up well. A bit too well actually, and it wasn't long before it was in the red. Pulled over and there was a lot of steam and no coolant left in the expansion tank. Drove back home and bled the system incase of any airlocks. Went out a drive and it did it again however this time there was coolant still there. Tried bleeding the system again and this time got a few bubbles from it. It's still overheating quite a bit though.

The rad is cold all over and is being cooled fine, the coolant in the expansion tank is cold. But the thermostat housing and the top pipe to the rad are boiling hot whilst the rad bottom pipe is cold. Is it possible that where the bolt has sheared off this is drawing in air and causing an airlock in the thermostat housing? It's the only thing I could think of. Unless the new thermostat (****part unfortunately) is faulty.

Did you test the stat before putting it in? I put a brand new one in my vw a few weeks ago and it was worse than the one I took out! Check the pipes both sides of the stat after a few minutes running, if they are not a similar temp then it's a dodgey stat. Bolts only need to be
Nipped up enough to seal the gasket. Rtv will seal round where you have snapped the bolt till you get a chance to drill and tap a new one

With the thermostat open the top part of the rad should be hot and the bottom of the rad warm - if its cold all over then i would say that the thermostat isn't opening and you aren't getting cooling!!

Buy another thermostat (genuine 1 if you can) replace it and sort out the sheared bolt at the same time

Daz

I'll stick the old thermostat in and see if that makes any difference. It wasn't as if it was the thermostat though, it was heating up very quickly which it only did once before when the fan belt snapped and there want any coolant being pumped around, hence why I thought it may be an air lock

easay check is to feel top hose hot it opens cold it doesnt

The top hose was hot and bottom hose cold'ish

id be looking at rad or water pump in that case

Both were working perfectly before the thermostat was changed, to the extent that it was ridiculously overcooled. Problem only seemed to start after I sheared the bolt on the thermostat housing

unless housing is leaking i wouldnt think its cause though does want fixing ,in that case you will need to look a thermostat probably not opening fully

No problem. Cheers for the replys, ill sort the bolt and replace the thermostat and see how it goes

Bolt was easy to fix, thankfully there was enough left out to grab with some pliers.

Turns out the brand new ****part thermostat was indeed faulty. Knew I should have checked it before I put it in

Glad you got it sorted mate!

Daz

Cheers daz, I should have known better when I saw the britpart box

Back to my old thread and I'm still totally confused about this. I contacted the well known land rover parts suppliers whom I bought my first thermostat from and explain to them its faulty etc... So they sent out another one. Bearmach this time so happy days thought I, its not ****part. Tested it this time before I put it in and it didn't open whatsoever. Rather miffed I contacted them again to let them know it was faulty but this time they were having none of it. They said that they had none whatsoever returned faulty this year and that it must be my engine. I explained that it was fine with the old thermostat, overcooled but definitely not overheating, and that I wasn't keen on sticking this second, non functioning thermostat in if it wasn't opening on testing. The guy put me on hold and came back to explain that apparently this new type don't open in boiling water (confused the funk out of me, when the hell is it supposed to open). Well he said to basically put it in and see what happens. I was getting quite annoyed by this time, for the sake of 3.50 and they couldn't send me out a decent thermostat that works.

Well tonight I put it in and took it for a drive. Lo and behold the first time I took it on a dual carriageway the temp gauge shoots up and will sit just on the bottom end of the red marking. However it doesn't seem to go past this, which is better I suppose. Is it at all possible, bearing in mind that with my old original thermostat the temp would barely make it to the first white mark, that the temperature sender hasn't been changed to work with the gauge (disco 200tdi into what was originally a 2.5td) and if that is indeed the case would this be causing the problems?

The thermostat won't open the instant its in boiling water - it does take a few mins.
Anyway - i'd change the temp sender for a 200tdi defender one - it might be starting to go on the blink. Just make sure that when the top rad hose is hot that the radiator is hot at the top and warm at the bottom/bottom hose.

Daz

Yeah i think its probably worth trying. Any idea on a part number as ive seen about three different ones mentioned on t'interweb. The predominant one that keeps coming up is PRC6663 but ive read a couple of posts on various sites saying this didnt work for them. Also i know theres a difference between coarse and fine threads, how could i identify mine?

Cheers

You would need to remove it and have a look at it - as its a disco engine the sender might not match your gauge??

I fitted an adaptor into my top radiator hose and fitted a 52mm water temp gauge (pic in my gallery - the 1 on the left in the 3 gauge pod) it doesn't work accurately until the thermostat opens BUT it indicates that the thermostat is working correctly and that the water from the engine isn't getting too hot due to a cooling system/radiator fault - it should give me an early indication of over heating

Daz

Pic here: Land Rover Zone - DISCOVERY1-DAZ's Album: My defender 90 - Picture

Daz

Have a read of this : http://www.landyzone.co.uk/lz/f7/how-land-rover-90-td-discovery-200tdi-engine-conversion-90679.html

He mentions about the temp sender/gauge problem

QUOTE " Fit a new temperature sensor to match the TD gauge. Depending on your old TD engine the sensor from that may fit but there are two different types so not always. Mine didn't so the temperature gauge reads just under red when it should actually be in the centre"

Daz

Cheers Daz, helpful as always.

Yeah id read that about the temp sender on a number of forums. Found the following site particularly helpful if anyone wants a look -

200TDi into Defender - some useful info - by Glencoyne Engineering

Some other cracking info on there too.

But i think the cheapest and easiest solution will be to buy a new temp sender that matches the gauge (again if anyone knows a part number it would be appreciated) and see if thats all the problem is.