very slight leak t-stat housing 5.0 mpi

A

aerobat77

Active Member
Aug 12, 2014
816
germany
Boat Info
Boatless
Engines
Boatless
hey gents ! i replaced the tstat with a new gasket and have a very minor leak on the housing , port side of the bolt . i haven loosen the bolts again , moved the housing a bit but still have a droplet or two with engine running . bolts a torqued to specs , any idea what to do ?

best regards !
 
If the gasket surface is above the water or if not,plug the large feed hose.
 
You may not have removed all of the original gasket from one surface or the other. It doesn't take much to cause a little leak.

If you decide to use gasket sealant (typically not necessary), be careful around the brass contacts area.
 
i wish i have never touched the tstat - it worked ;-)

i,ll have to find out a way to remove , resurface and regasket the housing maybe without to haul the boat .

never touch a running system ...
 
It's really not a big deal - you can remove the thermostat while the boat is in the water, a little water might leak out but not much. Just remove the top housing and gasket - being careful not to damage the gasket. Then clean up the surfaces, use a scraper, sandpaper or a scotch pad. You probably have old gasket material on there not letting the new gasket seal properly. Also, make sure the two brass brads are able to make contact with the metal housing, otherise your sender will not work right and the gauge will be off. No need to use gasket sealer.
 
great info , thanks !

so assuming undamaged you say reusing the gasket ( only few days old but installed ) is ok ?
 
aerobat77 said:
great info , thanks !

so assuming undamaged you say reusing the gasket ( only few days old but installed ) is ok ?
Click to expand...

I would just replace the gasket if you’re going through the trouble of removing it.
 
Either way, if undamaged you can re-use the gasket. If you replace it, you have to get the specific gasket for this - it has two brass brads in it, this makes a connection between the top/bottom of the thermostat housing, if you just use a plain gasket your temperature sender and gauge will not work. A little trick for gaskets like this that you might want to remove/replace periodically - ie some people remove the thermostat housing to winterize - spray the gasket with silicone and it will come off later without sticking and tearing.
 
Additionally, clean the mounting bolt threads with a wire brush, preferably with a wire wheel on a bench grinder, then put sealant on the threads.
 
Another point of view, you don't need the fancy expensive gasket with the brass grommets, the 2 3/8" mounting bolts provide plenty of continuity between the t-stat housing and the manifold
 
i pulled the tstat housing and the gasket teared in several places , so new gasket ordered.

i have another gasket from the kit but it does not have the grommets - scoflaw makes a very interesting point about this - common sense dictates the bolts should provide enough continuity !
on the other hand i do not want to make the work only to see the sender is off because they most probably had an idea producing a gasket with grommets .

what is the idea in putting sealant on the bolt threads ?

One hint : i drained the block maybe half a gallon in a pan and that is enough the tstat housing falls dry and you can remove it on the water without messing with your bilge - i hate ANY water in the bilge ;-)
 
Order a felpro gasket 35062 at any autozone for $2. Buy two actually. Go to your boat and you'll see that the center section of the gasket needs to be marked and cut out slightly. Use a sharp razor blade. It's 10x better than the crappy grommeted gasket and it won't leak.
 
The reason for sealant on the threads is as I recall the threads holes extend in to a water jacket and I have seen water deep past the threads in very small amounts.
 
Use Perfect Seal on the threads. I've started using it on all bolts. It doesn't harden so won't be a problem coming off, but stays tacky enough to help seal small areas.

BTW I just saw Sierra sells a stainless thermostat housing. I'll prob replace mine with this as mine is also in bad shape.
 
ok i resurfaced carefully the gasket surfaces , put a new gasket in and sealant on the threads and everything is bone dry now !!!

thank you very much for your help - it did the job !
 
You must log in or register to reply here.

Forum statistics

Threads
113,172
Messages
1,427,860
Members
61,086
Latest member
MrWebster
Back
Top