the best gasket sealant?
 

i need to know what you guys use on your gaskets. im replacing a few and i dont want any leaks.

First off, it depends on the gaskets. You just hit another pet peeve of mine, so get ready...:)

First off, exhaust gaskets need NO sealant. Zero. If you put RTV on exhaust gaskets, I'll come over and whup you. :) RTV can't take the heat and pressure, and becomes the failure point on exhaust gaskets.

Water and oil gaskets need a light coat of RTV. I prefer the grey RTV - it has a VERY high level of adhesion, and is resilient to movement. Use it and I guarantee you won't have any leaks, and you'll need a hammer to separate the flanges next time you take it apart - this stuff works GREAT.

For air gaskets, you need nothing. Sometimes you can use a gasket cement on one side to "glue" it onto the manifold so it stays in place - this is how Mazda does it. Gasket cement comes in little jars with a brush - brush it on the one side you want to stick (usually on the lower half of something) and then assemble.

O-rings just need a coating of oil on them, such as the oil pedastal o-rings and the oil metering pump o-ring.

Banjo bolts need NO RTV. These are the water lines to the turbo (where they connect to the turbo), the rear oil cooler line, the oil metering injecors, etc. Banjo bolts use copper crush washers. RTV again makes a point of failure - BAD BAD BAD.

OK, that's my tirade for now :). Hope this answered your question - let me know exactly what you're replacing and I can give more specifics.

Dale

Well I say go get the correct gaskets from Mazda. And for exhaust gaskets, go to the local auto parts store and buy some, get copper if you want the best.

first off im replacing to for now. the first being the thermostat gasket. the second being the VDI manifold lower gasket.

The '89-91 cars don't use a gasket for the thermostat - it's a rubber ring that goes around the thermostat. Again, use NO RTV here - it's basically an o-ring type seal. And, make sure to get a Mazda thermostat - parts store thermostats are JUNK.

For the VDI gasket, just a little gasket cement on one side to stick it to the lower manifold and you're good to go there.

Dale

its an 88 gtu, with a 87 gxl engine so what do i use on the thermostat gasket. the engine was rebuilt about 25,000 miles ago and the person used some sort of blue goo crap which burnt away in the fire i recently had surrounding the primary injectors.

Whoops, when you said VDI I assumed it was an '89-91.

Anyhow, yes, the '86-88 cars have a thermostat gasket - a paper gasket. Use the grey RTV on both sides, a nice even coat, not gloppy. Again, get the stock Mazda thermostat.

I also put anti-sieze on the bolts that hold the water neck on - they frequently rust, and break when you go to remove them. A little anti-sieze will make life a lot better next time you take the water neck off.

Good luck,
Dale

thanks for the help

I use the red shit on almost everything. Ends of housings (endges I use Hylomar obviuosly), oil pan gasket, water pump, thermostat housing, ... Oil & solovents can't phase the red shit at all .. plus its High temp, so that helps. I use gasket sealant on my Air gaskets also. ... hlyomar or Vasoline on O rings. I just like that added protection on air gaskets (I put it on Very thin) .. i know its not entirely neccisary .. I don't use anything but metal exhaust gaskets. No sealant.

Get The Right Stuff Gasket maker. When I bought my rx7 the oil pan gasket was fucked, i tried looking for the correct gasket but no one had em. my mechanic tol me about Right Stuff and it works great on it. it says on the bottle that it works better than factory gaskets, you can use it for anything, and it's ready in like 5 mins, not 24 hours like some other shit. u need a special caulking gun thingy to get the shit out.

I used to use red RTV, but I was SOLD when I switched to the grey stuff. It's a LOT more hardy than the red RTV - try it sometime.

Dale

I will give the grey a shot when I rebuild my N/A Eventually (knock on wood, 201k and counting)

Grey Stuff? WTF, BUY RIGHT STUFF NOW!!!