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Exhaust Riser gasket change
Saw a drip.
Figure if they are leaking in....they are leaking out. So... gonna change all 4. Any cautions? Keep old gasket material out of block? Do you guys use a sealer to keep em in place? They are OMC... but are the square kind like a merc alpha. 4 slots around the outside. Thanks. |
Re: Exhaust Riser gasket change
Fund razor,
All the manuals I have read say no sealant but I have been tempted to look into something. A leak cost me 1 of my engines last fall through the riser / manifold gasket. I bought new aluminum moore manifolds off ebay and am switching to fresh water cooling on my new engines. The new gasket is stainless and the manifold / risers are aluminum. I need to find something that will not destroy that combo and last. Will let you know if I find anything worth while. |
Re: Exhaust Riser gasket change
Mine are doing the same thing with the stock merc risers on a 454. i put new gaskets in during the summer last year, and now i still have rust stains going down the sides on both sides. I didn't use any sealant, and i'm wondering if i should have.
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Re: Exhaust Riser gasket change
If they are the "blue" type, I've been told to use blue hylomar or copper coat on both sides of gasket.
I've also been told not to use anything... I'd use copper coat OR blue hylomar. Copper coat is better suited to high temps. I've used it to help seal up copper headgaskets, and it works excellent on those. PS; I am done with that F$c&ing wet joint, I've ordered Revolution exhaust for my boat. Now all it can leak is exhaust. |
Re: Exhaust Riser gasket change
I know the gaskets i had were just a metal crush gasket.........i was also pondering using the high temp orange sealant
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Re: Exhaust Riser gasket change
Originally Posted by cloudmaster_321
I know the gaskets i had were just a metal crush gasket.........i was also pondering using the high temp orange sealant
For the blue gaskets, I was told not to use any hardening sillycone, like the red stuff. I would check to see if the mating surfaces are flat. I think mine were warped. It would not leak under a garden hose test, but on the motor (read; when @ operating temps) the floodgates opened. |
Re: Exhaust Riser gasket change
I haven't been able to see mine leaking.
But early last year I touched up the manifolds and risers with fresh paint and I could see a small stain that is light in color where some moisture obviously came out. Must have been on a really long run last fall. I have no water collecting or anything. I was kind of going for prevention, rather than fixing a major leak. Again... OMC Cobras, very similar to mercs. |
Re: Exhaust Riser gasket change
OK...
so we have 1 "no sealant" 1 "maybe sealant" 1 "yes and no" 1 "maybe" So.... that's 2 maybes, 2 nos, and one yes. looks like no sealant is winning by a small margin. |
Re: Exhaust Riser gasket change
Definitely good prevention to change those gaskets, I'm in the process of doing a valve job on an OMC that had leaking gaskets sat all winter and destroyed the valve seats...
I to have heard the use/don't use stories of sealant on the risers, whether right or I wrong I always use a small coating of silicone on the gaskets unless there the metal crush kind. If there metal they usually are already coated so no need. |
Re: Exhaust Riser gasket change
Originally Posted by FOUNTAINATLAST
Definitely good prevention to change those gaskets, I'm in the process of doing a valve job on an OMC that had leaking gaskets sat all winter and destroyed the valve seats...
I to have heard the use/don't use stories of sealant on the risers, whether right or I wrong I always use a small coating of silicone on the gaskets unless there the metal crush kind. If there metal they usually are already coated so no need. I think that I will wait and see what they look like when I get them off. Just did the exhaust manifold gaskets and they were really brittle and crusty. I am guessing that the risers are the same way... just not really leaking yet. I was thinking that a light coat might help keep them in place since the tolerances on the passages are so close. |
Re: Exhaust Riser gasket change
Fund Razor,
I am leaning toward some sealer also. When I seperated my old manifolds/risers, it looked like there was no seal at all. My main concern is isolating the center gasket between the manifold and the riser. Major potential for electrolysis. If I could get a ground wire on the gasket, problem solved. |
Re: Exhaust Riser gasket change
Mcollinstn says to use "Perma Tex Copper Spray A Gasket."
So that's what I'm a gonna do. :D |
Re: Exhaust Riser gasket change
I Have Aluminum Manifolds And Risers And Use A High Heat Silicon. It Is A Copper Color, I'll See If I Can Find The Name It Works Great.
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Re: Exhaust Riser gasket change
I have cast iron manifolds and risers, and I'm gonna use Perma Tex Copper Spray a Gasket, just like Mcollinstn said to use.
He said that it was "magic." How can you beat Magic? I have the can sitting on the counter at home. :D |
Re: Exhaust Riser gasket change
On the blue gaskets, I've used sealer (usually OMC gasket compound). On the gray gaskets no.
No matter which one I've used, I always cleaned the gasket surfaces with a scotchbrite roloc pad on an angle die grinder. Then I use a straight edge to check the flatness of the gasket surface. |
Re: Exhaust Riser gasket change
Originally Posted by Liberator21
On the blue gaskets, I've used sealer (usually OMC gasket compound). On the gray gaskets no.
No matter which one I've used, I always cleaned the gasket surfaces with a scotchbrite roloc pad on an angle die grinder. Then I use a straight edge to check the flatness of the gasket surface. Sounds like I will be extra safe. The stuff that I mentioned is designed for high heat and even heat distribution, also... helps fill microscopic voids. Do you mean that you cleaned the manifold and riser mating surfaces with a scotchbrite pad? Or do you really mean the gasket? Then you use a straightedge on the elbow and manifold surfaces? Or on the gasket? |
Re: Exhaust Riser gasket change
Took them off the boat this weekend and opened them up.
Nasty. Maybe 45% blocked and rust city. Looking into replacing the manifolds and the risers x 4 each. |
Re: Exhaust Riser gasket change
And I believe the winner is Dennis Moore reproductions.
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Re: Exhaust Riser gasket change
I clean the manifold, and riser gasket surfaces. Not the gasket.
I'm considering replacing my manifolds and risers as well. I'm looking into the GLM parts. It looks like Dennis Moore is selling them on Ebay. I've heard good things, and bad about them. Have you heard anything? |
Re: Exhaust Riser gasket change
I hadn't heard anything bad yet.
I was thinking brand new repros would be better than 21 year old rusticles. What I like about Dennis is that you call him and he picks up. Hard to find human beings who answer the phone. I think I am gonna pull the trigger on two sets right now. Genuine OMC is 1216.00 an engine. Napa is 1100.00 an engine. Osco is 608.00 an engine. GLM is 369.00 an engine. Will they last 21 years like my OMCs did? probably not. Will they last the rest of the time I own the boat? Probably. |
Re: Exhaust Riser gasket change
The GLM website says that their manifolds take 6 seconds off of the planing time of a 21 foot bayliner.
http://www.glmmarine.com/manifolds/testresults.html |
Re: Exhaust Riser gasket change
Wait... it's a 22 inch bayliner. :D
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Re: Exhaust Riser gasket change
Hey Lib... what did you hear bad?
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Re: Exhaust Riser gasket change
fund, use blue hylomar, it does not harden, it will reduce further corrosion. I have used it on all water surface gaskets and blower gaskets for several years. It was made for Rolls Royce jet engines, aluminium safe, and if you do disassemble, the gaskets just peel off.
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Re: Exhaust Riser gasket change
never mind, I see you are considering headers, I would recommend revolution, do a search here, most everyone is happy with price and performance
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Re: Exhaust Riser gasket change
The only bad thing I've heard was someone complaining about the quality of the casting. They said there was a lot of casting flash inside the exhaust runners. It was a posting on another website. Judging from the guy's other posts, he seems to have an opinion about many things. Everything else I've heard has been good. FPB magazine did a test of the manifolds, and picked up 3mph on a 21' sport boat with a 350 Chevy and Merc drive.
They changed the manifolds right at the ramp. |
Re: Exhaust Riser gasket change
I have also looked into getting a set for my 7.4L, but i would like to see some dyno results for something, he has no info other than "increased performance".
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Re: Exhaust Riser gasket change
Fund razor,
I just bought the Aluminum version from him for my rebuild project. There was some white stuff in 2 of them but I wouldn't really complain about it. Just rinsed them out. They look better then stock Mercruiser and came w / all mounting hardware, plugs, etc. I went w / Aluminum to save the weight. My Mercruiser manifolds gave out in ~ 2.5 years and took both engines with them...Figured I try these out and check them every year. I also liked the fact he actually answers his phone. He did not make any HP increase claim but said his customers had noticed an improvement. I will never really know as I am building 2 new engines and changing everything else. |
Re: Exhaust Riser gasket change
I went ahead and pulled the trigger.
Two complete set ups for less than 750.00 was hard to pass up from a guy with a good reputation who answers his phone. |
Re: Exhaust Riser gasket change
Originally Posted by Island Time
Fund razor,
I just bought the Aluminum version from him for my rebuild project. There was some white stuff in 2 of them but I wouldn't really complain about it. Just rinsed them out. They look better then stock Mercruiser and came w / all mounting hardware, plugs, etc. I went w / Aluminum to save the weight. My Mercruiser manifolds gave out in ~ 2.5 years and took both engines with them...Figured I try these out and check them every year. I also liked the fact he actually answers his phone. He did not make any HP increase claim but said his customers had noticed an improvement. I will never really know as I am building 2 new engines and changing everything else. Did your mercs go out so fast because you are in salt water? |
Re: Exhaust Riser gasket change
1 Attachment(s)
For sale: Slightly used, gently worn 21 year old log style manifolds and risers. They do not leak (in). Still have more than 50% flow capacity on the water side and nearly 90% (accounting for rust) on the exhaust side.
Fits SBC to Cobra. Very common perf boat combo. Extra weight from rust makes ride much better. Don't pass up these rare, original OMC parts. (The pic only shows one, but trust me... they are all as nice as that one.) |
Re: Exhaust Riser gasket change
Hard to tell from the pic... but one each of the long water slots is completely filled in with some kind of a rust/steel organic alloy.
Like growing metal in a petri dish. :D I should weigh them and compare to the new ones. |
Re: Exhaust Riser gasket change
I see rust on the manifold side.
Scary. Wonder how much water was flirting with my combustion chambers and when? I haven't done a compression check... but engine ran, idled and had good oil pressure. Maybe I caught them just in time? |
Re: Exhaust Riser gasket change
Fund Razor,
Only do a compression check if you are ready for the results. Mine were both running too, started, idled, good oil pressure, etc. I blew a water drain plug on my port engine. Decided to pull them both last winter. Turns out the block was rusted beyond repair along with the manifolds. So far I needed 1 new engine. Then I figured I would go thru the GOOD one. The compression was all over the place. Blown head gasket on 1 side and water from the manifold in 1 cylinder on the other side. I'm sure alot of the rust was from the salt water, but I have never seen a worse engine torn down that actually ran pretty good. There wasn't much water moving thru the heads. Most of the water jackets were plugged. Probably could have salvaged the 1 block and built 2 new ones myself but would have lost whats left of the summer. Ended up with 2 long blocks. I powder coated all the tin with a triple coat epoxy, used stainless bolts and added freshwater cooling for the engines and manifolds. I would be interested if you pick up any top end with your new manifolds if you don't change anything else. |
Re: Exhaust Riser gasket change
Originally Posted by Island Time
Fund Razor,
Only do a compression check if you are ready for the results. Mine were both running too, started, idled, good oil pressure, etc. I blew a water drain plug on my port engine. Decided to pull them both last winter. Turns out the block was rusted beyond repair along with the manifolds. So far I needed 1 new engine. Then I figured I would go thru the GOOD one. The compression was all over the place. Blown head gasket on 1 side and water from the manifold in 1 cylinder on the other side. I'm sure alot of the rust was from the salt water, but I have never seen a worse engine torn down that actually ran pretty good. There wasn't much water moving thru the heads. Most of the water jackets were plugged. Probably could have salvaged the 1 block and built 2 new ones myself but would have lost whats left of the summer. Ended up with 2 long blocks. I powder coated all the tin with a triple coat epoxy, used stainless bolts and added freshwater cooling for the engines and manifolds. I would be interested if you pick up any top end with your new manifolds if you don't change anything else. I do like small block work.... so maybe if I keep this boat I will re-block it next winter. I can afford new power much more than new boat. :) And I would swap them myself in the garage over the winter. Anyway... I am curious about top end, too. My top speed with a clean bottom and half a tank is about 52 gps so far. All stock. Thru hub exhaust. It's a heavy boat... as you know. If the manifolds get here Friday I will do them over the weekend. |
Re: Exhaust Riser gasket change
I won't be able to tell a difference in planing time, I don't think.
My boat planes quickly. Freaks people out. Don't even have to do a hole shot. Rpms are not that high to get on plane. Bet yours planes quickly too. |
Re: Exhaust Riser gasket change
Ya, Mine got on plane pretty quick too but lost some top end last year. I should have known something was up but kept putting off dealing w / it. The engine w / the blown head gasket started knocking at high speed so I just backed off figuring it was timing.
You should be OK if you have no rusted plugs and no H2O in the exhaust side of the manifold. Mine had rust droplets all the way to and including the valve. When you replace the manifolds make sure the exhaust valves (If not Stainless valves) and ports do not have rust on them. Good Luck! |
Re: Exhaust Riser gasket change
Originally Posted by Island Time
Ya, Mine got on plane pretty quick too but lost some top end last year. I should have known something was up but kept putting off dealing w / it. The engine w / the blown head gasket started knocking at high speed so I just backed off figuring it was timing.
You should be OK if you have no rusted plugs and no H2O in the exhaust side of the manifold. Mine had rust droplets all the way to and including the valve. When you replace the manifolds make sure the exhaust valves (If not Stainless valves) and ports do not have rust on them. Good Luck! No actual water in the exhaust side. Just corrosion. doesn't continue into the block though. Hoping to get the new manifolds tomorrow. Would like to rebuild them over the weekend. Gonna do new hoses too. |
Re: Exhaust Riser gasket change
New manifold came. (1)
is the cast surface of the new manifold ok for assembly or do I need to work the surface or remove the paint? Not exactly a machined mating surface like you get with machined steel. It's like what you would expect from a casting. Flat but not knife edge. |
Re: Exhaust Riser gasket change
Originally Posted by fund razor
New manifold came. (1)
is the cast surface of the new manifold ok for assembly or do I need to work the surface or remove the paint? Not exactly a machined mating surface like you get with machined steel. It's like what you would expect from a casting. Flat but not knife edge. |
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