Hey all, I'm in the middle replacing the radiator and water pump in the 4.0, I've got an OEM pump and gasket, and was curious if anyone knows if these gaskets need gasket sealer or not? And does the same go for the thermostat gasket? It seems to vary from vehicle to vehicle. :cheers:
No RTV, just go with the gasket that came with the water pump. RTV is not used anywhere in the cooling system.
To show just how easily sealed the cooling system is, I had to do an emergency trail repair one day when my thermostat stuck shut. The gasket got torn up in the process so a replacement gasket was cut out of a piece of the cardboard box holding some MRE meals. That MRE cardboard gasket was leak free until I finally got around to replacing it with a real gasket maybe 6 weeks later. No RTV was used even for that makeshift gasket.
One last hint.... use a scraper then a fine wire brush to insure the gasket seating surface on the block is absolutely 100% clean and pristine. Make sure that ALL of the old gasket material is gone before installing the new gasket and water pump. Any shards or even a spec of old gasket material will cause it to leak. Ask me how I know... and it was on a day that was over 100 degrees.
FWIW i've had a different experience with some of the gaskets in the cooling system. Earlier this spring i replaced the water pump, thermostat, thermostat housing, and gaskets with new. The problem i had was with the thermostat housing. Did the pristine clean thing on the surface of the head, new dry gasket ... it leaked. Tried several new gaskets with and without gasket sealant ... it leaked. Yes i checked both sealing surfaces with a precision straight edge, made sure they were both shiny clean and smooth, properly torqued, and it still leaked. It seemed the gaskets were absorbing coolant and becoming mushy, go figure. My solution was to clean it all again, apply a very thin layer of black RTV sealant to both clean surfaces and bolt it all together at the correct torque sans gasket. It has lasted all summer and through several wheeling trips and not a drop.
I say use RTV. It doesn't hurt anything and is just a little extra precaution. I always used RTV on water pump/Tstats until reading a thread on here convinced me I was not cleaning the surface enough. I used a Dremel with brush attachment to get the Tstat mating surface shiny new and baby butt smooth and just used a gasket on the Tstat housing. It leaked almost immediately. I have never had a mating surface leak in the cooling system of any vehicle using a gasket with a little RTV. Including the Tstat and water pump of which I changed both recently with no leaks using RTV.
How does the factory get away without needing RTV for any part of the cooling system? The only time I've ever had a leak between cooling system components (did my first cooling system repair probably 45 years ago) was when the gasket surface wasn't clean or if the thermostat housing had warped and was no longer flat enough to seal.
How does the factory get away without needing RTV for any part of the cooling system? The only time I've ever had a leak between cooling system components (did my first cooling system repair probably 45 years ago) was when the gasket surface wasn't clean or if the thermostat housing had warped and was no longer flat enough to seal.
I think this is the key statement. Many times you are dealing with an irregular surface not due to lack of cleaning but due to heat and age. RTV can compensate for these irregularities. Personally I've not used RTV in any coolant system component on either of my jeeps over the 16 years or so I've been driving them. The one time I had an issue it was on the thermostat housing and I opted to replace it rather than "band-aid" the issue with RTV. The new housing sealed without the need for RTV. Of course, we aren't always that lucky.
I have always used a little rtv on them to hold the paper gasket in place when mounting everything up and I have always figured that it wouldn't hurt anything to use a little.
When I replaced my cooling system last year I spent probably an hour scraping away the old gasket. No RTV used and I havent had a leak yet it. I agree with Jerry on this, dont use RTV and just take your time making sure the surfaces are clean as can be.
Just did my rad and T-stat a few weeks back. Jerry is 100% correct... no RTV needed when the surfaces are super clean. My 1st go around I THOUGHT it was clean, to only have it start dribbling once filled. Drained it, took the T-Stat body apart, and REALLY cleaned it. I used extra fine emery cloth to get it good and clean, installed another new gasket, and no leaks.
I would say that and only that unless they go full retard and use way too much.
Sometimes I will wipe a very light skim coat on with my finger.
Mostly to help hold the gasket in place while I'm assembling everything, but also somtimes if the metal looks like it has some imperfections.
It just depends on the situation and sometimes my mood.
When I do water pumps I use a gasket and sort of an rtv. I use permatex aviation form a gasket. You paint it one with the supplied brush and it creates a nice even thin layer, sealing up everything nice and tight.
I don't think that means what you think it means. RTV stands for Room Temperature Vulcanizing and it is used in the context of common silicon rubber based adhesives and sealants, most of which have an acetic acid curing agent. I doubt very seriously that there is anything whatsoever in stuff you used that is either silicone based or that vulcanizes at room temperature. You used a solvent based gasket sealer and there is nothing sorta RTV about it.
Well I got the old lady all stitched back up and I went to drop in the new radiator I got, an all aluminum 2 row from Northern Radiator and the brackets do not line up with the factory mounting holes, and I don't feel like taking the time to fix it so its getting sent back. Anyone got recommendations on a good radiator? I'd like something decent for the 115* summers here in Phx
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