RTV and various gaskets...

[Safety Guy]

This may seem like a stupid question, but I'll ask it anyways...

When I did my WP, I put RTV on both sides of the gasket on installation.

I'm about to do my thermostat and I'm thinking the same thing. However, the Chilton's 323 book doesn't say anything about any RTV on the t-stat install.

I also put grey RTV around the large O-ring when I connected the coolant bypass pipes together where they swivel.

When I do my TB gasket tomorrow, I don't plan on using any RTV at all. It's "just air" so I don't think it needs any.

Am I all messed up? What is the "theory" behind using RTV on gaskets, etc? Plus, why all the different colors (black, grey, clear...) of RTV silicone? This is probably "basic mechanics" but I never took the class!

Thanks,

Karl

[Hot_Wheels]

om my b3 i did the gasket like 3 times it was brutal, it keept leaking and left me stranded, theres no lip to the themostat still while trying to line up the bolts, the way i think we got it to finaly seal was siliconed the the gasket to the block and let it set, then applied some to the housing and bolted it down and that finally did it.

[Gforcefd]

Great question, I would love to know the answers to all of the above as well.

[Safety Guy]

Well I've done TB gaskets several times (on my first engine swap) and they worked fine. No RTV needed there.

I didn't do the WP on the first B6 though and I can't recall how much RTV was used by the mechanic. I'm pretty sure he used some.

On this B6, I used it on both sides of the gasket, but I didn't overdo it. We'll see how it does when I get Aqua running.

There should be some "rationale" to using RTV plus gaskets, or in place of them. We know what gaskets "do," but there should be more info on the need for the RTV.

Karl

[Evil D]

I've always used both a gasket and RTV on both sides. Never had a leaking gasket. I've actually used a cut up 12 pack Coke box as an entire gasket kit on a little Suzuki 3 cylinder...from the head gasket to the intake gasket and everything in between, and it worked flawlessly.

[blitzbuggy]

i am pretty sure the color determines the temp rating, as for RTV sealants go, just make sure they are sensor safe, the unsafe stuff tends to make O2 sensors lazy. I just used copper RTV sealant and its works fine, at work i use a purple stuff called gasket maker, and it really works well, is immune to gas and abrasive liquids, ( oil, gas, diesel,) stuff that would normally make silicone cry for mumsy

[getnpsi]

::whistles: I got way lucky on 2 b3's a b6 and a b8-me then. I always had problems with small block fords.

[bhazard]

I use permatex hi tack on my gaskets.

[Safety Guy]

Allow me to make some statements here about Mazda B series engine gaskets. (That's the only engine I've ever really "worked on.")

The following assumes both mating surfaces are in good shape.


Intake and exhaust: steel gaskets; nothing else needed

Throttle body: paper/fiber (regular) gasket; nothing else needed

Water pump; WP outlet; thermostat housing; etc.: use RTV with regular gasket...I put it on both sides of gasket

Coolant bypass pipe connection with O-ring: I used correct O-ring (came in water pump box) and added some RTV around O-ring (not sure I should have done this) First, I smoothed out interior of large pipe where it was rusted so O-ring would seal well.

Head gasket: proper head gasket; upon recommendation of DaveG I used copper spray on the head gasket, both sides

Oil pan: used half-moon rubber gaskets along with black RTV supplied in Felpro kit

Between Main Bearing Support Plate and oil pan: I used "Great Stuff" gasket making black sealant for this (MBSP went on before oil pan--Note: B3 does not have a MBSP.)

Valve cover gasket: Rubber gasket is used after a bead of black RTV is put into groove of VC.

Well folks, the above techniques are what I've done and plan to do.

Comments? Anyone know "theory?"

Karl

[Evil D]

i am pretty sure the color determines the temp rating, as for RTV sealants go, just make sure they are sensor safe, the unsafe stuff tends to make O2 sensors lazy. I just used copper RTV sealant and its works fine, at work i use a purple stuff called gasket maker, and it really works well, is immune to gas and abrasive liquids, ( oil, gas, diesel,) stuff that would normally make silicone cry for mumsy

A good friend of mine went to vocational school at the end of high school and took auto mechanics. He said they had a rep from Permatex come to the school to teach about RTV, and that rep told him the color thing is a gimmick and that they're essentially all the same.

This goes against everything i've ever heard but how can you argue from someone on the inside? FWIW i use black on most gaskets and copper on stuff like headers.

[25Horseplay]

Karl I would do it just like you did in your first post.

[FestYboy]

the other option that i've grown VERY fond of is copper gasket spray, not nearly as messy as RTV and dries much faster.

[JoDan]

I use permatex hi tack on the gaskets that need it to stay on a part like a wp or tstat since it sticks better than RTV and is easily removable so if you mess up squaring off the gasket it isn't a sticky mess to pull it up and try again... other than that everything else goes on dry

[brickdog2000]

I sometimes use silicone to give me a sense of security. I have found it useful when dealing with those gaskets that are hard to keep lined up and sqaured when assembling the part. In other words... its helps to keep the gasket from moving on ya when reassembling to ensure the gasket is lined up properly.