Well I have done 3 water outlet/gasket replacements

1st one was crappy gasket blue felpro gasket.(new housing)

2nd one leaked due to warped housing

3rd another crap gasket with factory adhesive backing which had not sealed -the housing fell of when i took the bolts out !

So i installed another new housing (diff manufacturer) with a nice thin gasket -
Dry and clean head mounting surface a light touch of emery cloth so the RTV grabs better for both surfaces.
I always THINLY spread black RTV on both the head surface and housing surface let it set a bit and apply gasket to the housing.
Make sure T stat is set flush in its mount flange.
Bolt it up tighten 15 ft lbs or so.

Now after a few days driving I see a couple tiny beads of greenish goop at the gasket edge that is peeking out of the seam

Is this the gasket material oozing when engine get up to temp ?

btw: Engine is running smooth, temps are perfect. Coolant good 'n green. Oil clean, exhaust clean.

 

If your coolant is green, then it sounds like coolant is seeping. U say 15 ft/lbs or so. Could the "or so" possibly mean over tightening, as in excessively squeezing the RTV out? Mounting surfaces must be perfectly flat, sterile clean, no cracks and the bolts just snug.

 

Definitely not over tightened
Fisrt tightened to spec then noticed a tiny goo bit on the gasket edge.
The upper bolt had loosened slightly so i gave it another 1/4 turn.
No extra RTV spooged out of the seam, I had put a thin layer on so it was a very neat fit.
Yes I do use green colored Coolant.

 

Then I'd say revisit mounting surfaces that aren't perfectly flat or sterile clean or maybe a hairline crack is going unnoticed.

 

While going thru the repair docs whenever the XJ went the pro shop for something I see I went thru the same thing back a few years Good thing those guys keep good notes on all their repair history . Notes said I changed it twice still leaked then they did it and sealed tight.

I think I am gonna go without RTV and just clean surfaces and apply gasket by itself. Since thats what they do as well as a different shop mechanic I spoke with.

 

Good luck, hope it works. I've never heard of RTV preventing a gasket from sealing. RTV fills/shapes itself into small mounting surface imperfections that a gasket won't fill/shape to. RTV will not seal warped/cracked/dirty surfaces....neither will a gasket.

 

Maybe try permatex ultra grey and let it set up for 12-24 hours before use. Some of the cheap rtvs are not that great.

Miles

 

this works for me every time.

 

I've replaced numerous stat housings and other such parts over the years including 2 stats on the currnet XJ never using RTV (gasket sealer), a gasket is exactly that, a gasket and should be the sealing point. If it doesn't something else is wrong.

However, did you put thread sealer on the longer bolt (left facing the engine from standing in front)?

 

The long bolt is actually upper right on housing ('92 -4.0 )
The seepage is occurring below along the seam (on the drivers side of housing).
i did put some sealer on the threads even I think both these bolt holes are dead ended though, i know the bottom was is.
Gonna have at it again, today and use just some Permatex tack stuff that 'prcherokee' posted about or similar.
Since the two shops i inquired of how they do their housings said just the gasket and NO RTV etc.