4 replies to this topic

[Knuckles]

Hello all ,
I've tried everything known possible to stop this leaking. I've tried new gaskets , gaskets coated in instant gasket , instant gasket on its own. Coating the threads of the bolts in sealant. New housing and stat.
As shown in the pic it keeps coming through the bolts.



I've even recently replaced the head gasket and the cylinder head & it still leaks.
Any tricks or tips to stop this leak ?
Many thanks
Clark

[FlyingScot]

Your pic shows bolts holding the housing on (with your steady).
If it's the SPi quoted in your profile these originally had threaded studs and nuts and the thread on each was different.
Not sure what thread your bolts are? Do they protrude into the head? Could be the thread is incorrect and the water is being forced up from the thermostat hollow in the head.

Edit size is the same at 5/16 but one end is unf and the other unc

FS

Edited by FlyingScot, 07 May 2014 - 08:55 AM.

[Knuckles]

I bought the relavent parts from mini spares.
They sold me what my head had on it already which was the housing and 3 bolts to hold it all down with gaskets.
The threads on the bolts do match the head as they wind in nicely.

Is it better to use studs ?

[dklawson]

I had the same thought as FlyingScot.  The problem may be that the tapped holes in the head go down into the water jacket.  If they do, then no amount of gasket or gasket sealant on the housing will seal the leak because the leak path is up around the threads and up through the clearance holes.

 

As a test you could remove the wet bolt shown in your picture and wrap the end of the bolt with a few layers of Teflon (PTFE) tape. Run the bolt back in as normal and drive the car for a few days to see if the leak is still present. If it is gone or reduced, that says the leakage is/was along the fastener threads.

 

If it is leakage along the threads then the studs may be a better choice but only if you take some additional steps.  To create an effective seal you would need to remove the t-stat housing and drain enough of the coolant so the tapped holes can be flushed with clean water and allowed to dry.  Once dry, apply a big drop of (blue) Loctite to the female threads in the head and a smaller amount of Loctite to the studs.  Run the studs in finger tight, then wait an hour or two for the Loctite to cure.  The Loctite should both secure the stud and seal its threads.  So you don't have problems with the studs and t-stat housing in the future, coat the shanks of the studs and the corresponding holes in the t-stat housing with a layer of anti-seize compound.  That will reduce the chances that the studs and housing corrode to each other over time.

[Knuckles]

Thank you very much for the replies.
I will go mini spares and see if I can get the studs & relavant nuts.

Hopefully that advise will cure this once as for all.

Thank you !