I have a 2005 V70 2.4 5-cyl Non-turbo, 204K miles with the "Vertical Thermostat" setup. i have an intermittent leak where the thermostat housing meets the cylinder head, I replaced the gasket according to the book,I cleaned the mating surfaces with a scotch bright pad before re-assembly, torqued the bolts down to 13 ft-lb and it leaks even worse than before. The gasket is metal with a thin coating of something black on it, it does not say to apply any sealant or gunk to the gasket before use.

Does anybody have any ideal what is going on. I forgot to check the housing for flatness before reinstalling. I even tried re-torquing the bolts again, this time to 15 ft-lb but it still leaks. as far as i know the engine has never overheated.

 

I had a similar problem with my S40 and wound up replacing the thermostat and its rubber gasket (even though it was a new part) to fix the problem... I was thinking I may have been given an incorrect part.

 

I have the thermostat housing without the rubber gasket, i have the newer vertical thermostat housing where the actual thermostat is not serviceable and you have to buy an entire pre-assembled housing in order to replace the thermostat, but the cover seal is not leaking it is the gasket where the housing mates to the head.

 

i have the same car with the same leak, i took it to my local european shop and they advised replacing the entire assembly, which, you already know, costs around $140 for a genuine Volvo replacement. would have had it done then but they didn't have it in stock.

 

Follow up.

I ultimately had to purchase a new thermostat and housing combination (because it only comes that way??). and when i went to put it on i found out that the bottom hole had been cross threaded by a previous repair job done by someone else. Therefore I needed to HeliCoil the hole which required me to remove all of the accessories and the accessorie bracket (lots of scraped knuckles). I also chose the thermostat housing gasket by FelPro because i believe it makes a better seal than the standard Volvo gasket.

One more thing. I was fooling around with the old housing before my new one arrived and i determined that the holes in the old housing did not perfectly align with the bolt holes in the cylinder head. (this might have been why the last mechanic cross threaded the hole). after running a drill bit threw the hole and cleaning it up a bit, it had an acceptable fit.