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To Gasket or not to Gasket: Exhaust Riser Leak Repair


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I ordered some gaskets a couple weeks ago because I have water leaking from both exhaust risers where they meet the manifolds.  There is currently a gasket installed on each side.  Since there are no gaskets between the heads and the exhaust manifold (just black RTV), I'm wondering if maybe I should do the same with the risers.  Just put on a nice bead of Permatex black and reassemble.  I know he doesn't really hang out here much anymore but @Lance B. Johnson swears by this approach.  In another thread, he says "gaskets fail, silicone does not."

Any other opinions before I tear into this tomorrow?

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Turns out I bought the wrong freekin gaskets...  grr...  Plus my exhaust hoses are delaminating pretty bad so I think I'll replace those.  Dang.  Was hoping to have the boat ready to rock this week.  Haven't used it since 3/5 and I'm going crazy.

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After a bit of cleanup, my manifolds are looking OK. Slight pitting between the exhaust and water jackets but solid. I'm going to reassemble with a combination of a very light bead of black RTV and OEM style gaskets. Should fill in any voids nicely. Also redoing exhaust hoses. Mine were really lumpy. 

 

IMG_20200524_121922~2.jpg

Edited by UWSkier
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What did you use to get out the two hard to get to of the four bolts? I’ve tried extended ball end Allen wrenches but a gorilla tightened mine.

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1 hour ago, BlindSquirrel said:

What did you use to get out the two hard to get to of the four bolts? I’ve tried extended ball end Allen wrenches but a gorilla tightened mine.

Regular Allen key with some modifications. Had to shorten it on both ends with a cutting wheel on my angle grinder. A few of those bolts were a pain to get out. I chased the threads with a tap and die set for reassembly, and they'll be getting some anti seize before they go back home. 

I too ordered some ball end keys from Amazon for this job thinking that was the answer. Had to cut its balls off to make it useful. 😂 

Edited by UWSkier
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1 hour ago, oldjeep said:

Black rtv would be weird for exhaust.  Use the copper.

Black RTV is what Indmar specs for the manifold to head union.  Indmar doesn't use any exhaust gaskets on the 5.7 mills.  Figure if it works there, it'll be OK on risers.

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31 minutes ago, UWSkier said:

Black RTV is what Indmar specs for the manifold to head union.  Indmar doesn't use any exhaust gaskets on the 5.7 mills.  Figure if it works there, it'll be OK on risers.

Surprised that the temp spec is high enough.  Black is typically for oil pans and intakes, copper is for exhaust manifolds.

Edited by oldjeep
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dunno.  Maybe because they run these engines so cool and the exhausts are wet.  Indmar has been using black RTV in place of normal exhaust gaskets for ages, and I've heard of very few leaks between manifolds and exhaust ports over the years.  In fact, I think @Bozboat had the only one I've ever seen.

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9 minutes ago, UWSkier said:

dunno.  Maybe because they run these engines so cool and the exhausts are wet.  Indmar has been using black RTV in place of normal exhaust gaskets for ages, and I've heard of very few leaks between manifolds and exhaust ports over the years.  In fact, I think @Bozboat had the only one I've ever seen.

Just because the stuff indmar uses is black doesn't make it the same thing as black permatex.  But good luck.

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12 minutes ago, oldjeep said:

Just because the stuff indmar uses is black doesn't make it the same thing as black permatex.  But good luck.

it's what Larry at Indmar says to use so... lol

Also Bakes.  https://www.bakesonline.com/engine/gaskets/indmar/permatex-gasket-maker-rtv-silicone-black-3-35-oz.html

Edited by UWSkier
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It ended up being a bit more work to get the old gasket stuff off than I thought it'd be.  This was clearly the original gasket and exhaust tubes from 2001.  Removing the risers wasn't very fun either.  One of these tools was what eventually got the job done.  Any guesses which?  :)

IMG_20200528_182405.jpg

Edited by UWSkier
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11 hours ago, UWSkier said:

It ended up being a bit more work to get the old gasket stuff off than I thought it'd be.  This was clearly the original gasket and exhaust tubes from 2001.  Removing the risers wasn't very fun either.  One of these tools was what eventually got the job done.  Any guesses which?  :)

IMG_20200528_182405.jpg

That is precisely why I replaced the socket head screws with hex bolts.

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