I have now bought 3 thermostat housings after trying just to change the gasket and thermostat upon retourqing (no where near the spec) and evenly results in the crappy diecast metal snapping into two peices.

Have spent roughly £50 on buying loads of thermostat housing and have just snapped my 3rd one.

Any ideas anyone before I loose it.

 

Are you using the same brand/source for the 3 housings? Can you please let us know which one you've been using?

 

Do you have the correct thermostat? This happened to me on my V6 passat the thermostat came from Nappa and was listed as the correct replacement, but when I put it on it would hit on the housing which was plastic and made a hole. Check to see if is hitting the housing? I had to buy a OEM from the dealer to it work. Paul

 

Used the correct thermostat and gasket I even tried using another old one with the same parts which I took apart and tried to refit.

Just seems like the diecast metal falls apart after not even getting close to torque spec.

 

Something must be stopping it from seating correctly, you should be able to fit the housing almost flush without torquing. Correct torque? foot pounds - inch pounds.

 

I am going out on a limb AGAIN, cut the limb if what I say is not useful.

The thermostat sits into a groove in the cylinder head. This groove must be CLEAN, so the stat sits down correctly.

The stat sits vertical, spring bit inside the cylinder head, now this is where gravity reeks havoc. As you fit the cover that bloody stat slips out of that grrove, and drops down over the gasket face, you cant see it, the cover is NOT see through, and when the housing is firmed up, "crack", V12 people know all about this for the LH stat.

Clean that groove, make sure it is DRY, apply a match head size of RTV at 3 or 4 places around the circumference of that groove, sit the stat in the groove, spring bit INSIDE the cylinder head, and the RTV will hold it there whilst you slide the cover on and firm it up.

Apart from that scenario, I have no idea, other than you got one angry car paying you back for something you did, mmmm.

 

I would ask would the housing fit with no pronlems without the thermostat in place. If it will then it's the thermostat, not fitting correct. I changed one two weeks ago and had no problems at all. Very strange that it will not fit. I'd try the housing on it's own and see..

 

I took the entire housing off on the last attempt it sits flush with the thermostat and no rubber ring installed around the thermostat, as soon as a I put the rubber ring on and gaskets it sits about 1/2cm from flush waiting to be seated.

I get no where near the required tightening and the gap is still 1/4 of a cm then it cracks.

It just seems like the diecast metal is not up for the job of resealing the only option I have left which is what im doing tomorrow is just buying another second hand housing and fitting it without changing the thermostat.

 

I see your problem.

Take the o/ring, give it to the dog as a toy, YOUR groove is one of the "no o/ring" style, same as mine.

Sit the stat in the groove in the cylinder head, WITHOUT THE O/RING, apply some sealant to your gasket, fit the housing, firm it up, no need for TIGHT, just nice and firm. JOB DONE.

I have NEVER seen the o/ring on our engines, and being Ex Jaguar Spare Parts I have never understood the listing for the o/ring, it is bloody confusing.

The groove in the cylinder head for the "o/ring" style is MUCH deeper, and slightly larger in diameter to allow for the larger stat assembly to sit flush PRIOR to the cover being installed.

 

Grant is exactly right...

My first fix after purchasing my X300 and driving it across a few states to get it home was to install a new thermostat. The new one came supplied with an o-ring...cracked the housing with barely any force at all while attempting to install it.

Tossed the o-ring before putting my newly purchased housing on using permatex this time. A much better outcome. I'll remember that one!

Bob

 

+1 on tossing the O-Ring.

I just did mine and the O-ring just didn't look right. Thankfully, I found this thread and along with the EPC photos was able to determine that the O-Ring that comes with the thermostat I bought (at O'Reilly's, but with the exact markings of the original one that came off of the car) didn't belong.

I used Hylomar to seal the gap without a gasket, but I am going to order the correct gasket and re-install (even though I have no problems with leaks at all with only the Hyomar). The Hylomar can be purchased at O'Reilly's as well, but it is hard to find a store with it in stock. "Permatex - Gasket Dressing & Flange Sealant" with "Universal Blue Racing Formula" on the package.

The correct gasket for my car (and I suspect yours as well if it is a 1995-1997) is Part Number NBB 2217AC .

This is my first post, so gentlemen please be kind if you find that the information in this post is useless. Best regards,
Hugh