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Thermostat Housing Leaking Oil

2373 Views 15 Replies 4 Participants Last post by  starchild
I am having an absolute nightmare with my ZR TD at the moment, bought it a couple of months ago and noticed the temp gauge rarely hit halfway and on normal driving hardly warmed up at all, guessed there was a problem with the thermostat, and I guessed right, there was no Thermostat! Fitted a new thermostat a couple of weeks ago but it started leaking almost immediately, took apart again and upon closer inspection noticed there was some sort of black sealant around the oil cooler, removed this and tried again without it, still leaking, took apart again and tried using some sealant, this didn't work either as it was still leaking coolant, but another problem had occured, now there was oil coming out from somewhere too. I'm guessing it's coming from the housing. So took apart again re-did the sealant and now the coolant has finally stopped leaking but the Oil is still coming out, what the hell is going on?? Please help me as i've had enough.
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The thermostat housing also houses the oil cooler inside the same alloy unit. I would check that the seals on the oil pipes leading to it are intact to start with.
Not coming from the pipes, it appears it's coming from between the oil cooler and the plastic housing.
I think you will need to remove the entire unit and inspect it carefully, if the oil pipe joints are not leaking, and it's not dripping down from above the area from another part of the engine.
Any idea how long that will take? Really need to get this sorted ASAP. Need it for work and also dying to find out what difference my SDi Injectors and new MAF sensor have made.
If you have already had the end cap off to put the stat in, it is not a lot more work to remove the entire unit. From memory it's a couple more pipes to remove, and a few fixings holding the assembly on.

With any luck the fixings will come off easily enough. If there is a fault with the unit then I would search around for a second hand one, you can always swap the 'stat over. New ones are a lot of money.
Thanks for that, got one from for £50 and a couple of "O" rings from Rimmer Bros. Gonna tackle it on Thursday.
I have the same problem with my oil cooler unit, it leaks between the alloy and plastic housing, i thought you could not seal these and had to get a new unit? I got a second hand one from a guy on these forums, and gonna have to fit it soon. I have read in the Haynes bible that you have to take the radiator off to get access to remove the oil cooler unit, and looking undernieth the ZR i think this is the case.

Let us know how you got on? how long it took you? and any hits/tips/problems you encountered, would be greatly appreciated.

good luck
Well I have just finished replacing my oil cooler and it was a bit tricky, tried to remove the radiator fan but the nuts just kept turning round so in the end I just undid every hose I could see and managed to remove the old one by pulling it downwards and the wiggled the replacement down from above, took me nearly 3 hours but if it was wasn't for the p***ing rain i'd have been finished sooner. So I didn't need to remove the rad but would have been easier if i'd been able to remove the fan.
Took it for a test drive with no problems and felt the improved acceleration from the SDi injectors and new MAF sensor too. Happy Days!!
Happy Days!!
Quick reality check!! MOT on Monday!
mine is the same, i replaced the O-rings on the oil lines that feed the cooler and PTFE'd the threads but it does appear now that ive cleaned all the mess up that it's the same plastic-metal joint thats weeping...

i guess the housing must have a hairline crack that only opens up when the unit gets hot.

can the Rover 200/400/600 oil cooler be fitted instead? i dont see any issues with those weeping oil.

or a front mounted oil cooler?
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Good luck for the MOT starchild

Geoff, you won't need to remove the radiator to take the oil cooler off, well I didn't anyway.
Good luck for the MOT starchild
It PASSED!!! Happy days! Just a couple of advisory points, the main one being the rear fuel pipes are badly corroded, i'm sure Rimmer Bros do these so no problem there, but I also got a "Low Ride Height", it is on lowered spax springs (30mm) but i've never had that before with other cars i've lowered.

Did you remove your oil cooler while the car was on jacks, lying on your back trying to do it? did you have to remove all/most of the radiatr pipes etc to get better access?

I put mine on ramps, removed virtually all the hoses and also the electrics for the alternator, not much room but it is possible.
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