PDA

View Full Version : Exhaust Risers Lt-r330


Chief
08-16-2006, 08:00 AM
Second attempt: I replaced riser gaskets and had small leakage when running wide open. Further investigation showed that there may have leakage on the internal side of exhaust but no motor intrusion (WHEW!).

I removed and cleaned surfaces and bolted back together without gasket and there is a .025 gap between riser and manifold. I have filed and flattened the surfaces to get withing .012 between the surfaces and .003 to .005 on riser and manifold and estimate the new gaskets to be .040. I guess the question to be asked is: To use gasket sealant or not to use gasket sealant. It's about a 50/50 school of thought on this subject.

If anyone knows of a sealant that will work: (since I know that the permatex ultra copper high temp sealant didn't work too well the last time, but may be due me running a bead instead of smearing on with my finger to ensure proper coverage.) I will be forever grateful since this is my second stab at this and I really really do not want to ruin the engine.

Thrall
08-16-2006, 12:58 PM
I have yet to pull the risers off my boat (and hope I don't need to), but I see no reason that the Ultra copper, black or red hi temp sealants wouldn't work. There are no sensors or anything to screw up w/ the sealant on the exhaust and it's not hi temp due to te water running through. Yes, smear the entire surface, rather thin coat so that it just squeeezez out around the edges. Shouldn't be any different than using it on a thermostat housing, water pump, etc.
You are planning on using it on bothsides of the gasket, correct?

TMCNo1
08-16-2006, 01:55 PM
4 years ago I replaced the riser gaskets on our 351 and the BLUE gaskets that came from MC required no sealant, because they were self sealing according to MC. FWIW

Chief
08-16-2006, 04:21 PM
I think I'm going to use the Loctite 510 on gaskets, from what I have read its good up to 400 degrees and will help seal any imperfections on the surface (up to .020) and hopefully put this puppy to bed. Thanks for the replies.

Ryan
08-16-2006, 06:16 PM
I think I'm going to use the Loctite 510 on gaskets, from what I have read its good up to 400 degrees and will help seal any imperfections on the surface (up to .020) and hopefully put this puppy to bed. Thanks for the replies.

This sounds like a better option than the goop in my opinion.

I just replaced the manifolds and risers on my boat and went through the same dilema. Since I run my boat in salt I was hoping to avoid salt getting into the fibers of the gasket and speeding corrosion. I even called Indmar to get their official opinion. They use gasket sealant on almost everything on their new engines (sounds like a cost saver to me) and said go for the sealant, but gaskets work great too. Not much help, but for your sake Indmar says your good to go with high heat gasket sealant.

In the end, I used a small amount of high heat engine paint to seal the edges of the gaskets and used them -similar to your solution to prevent leaks from imperfections. I wasn't sure the sealant would be even and consistent enough as I bolted everything on, and I didn't want it seeping into the exhaust flow.