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View Full Version : Rust on Exhaust Manifold (Leaking Riser Gaskets)


east tx skier
11-15-2004, 11:48 AM
I winterized on Thursday. When I was changing my spark plugs, I noticed a large amount of surface rust on my exhaust manifolds. Most of it was where the riser gasket has apparently continued to leak despite my changing the riser gaskets earlier this year.

I've heard that surface rust can be more problematic when you do stuff like sand and paint over it. Should I just not worry about it and make sure that the riser gasket is sealed or should I be more proactive.

Diesel
11-15-2004, 11:51 AM
I winterized on Thursday. When I was changing my spark plugs, I noticed a large amount of surface rust on my exhaust manifolds. Most of it was where the riser gasket has apparently continued to leak despite my changing the riser gaskets earlier this year.

I've heard that surface rust can be more problematic when you do stuff like sand and paint over it. Should I just not worry about it and make sure that the riser gasket is sealed or should I be more proactive.

If it is only surface rust I would not worry about it since the manifolds are cast. From your description I believe my manifolds have had the same rust marks since the first year.

east tx skier
11-15-2004, 12:27 PM
I guess it's surface rust. It doesn't appear to have gone all the way through, or be leaking. It's a bit worse on the manifold arm directly beneath the riser gasket leak. I'm having a performer intake manifold put on in the spring and figured that'd be a good time to paint if need be.

east tx skier
11-16-2004, 11:52 AM
Just wanted to put this back near the top. Are Diesel and I the only ones with a little rust?

jimmer2880
11-16-2004, 12:35 PM
nope - mine are rusted also... Just Surface rust though, so I'm not concerned.

east tx skier
11-16-2004, 12:45 PM
I suppose what I should be asking is when do you stop calling it surface rust?

sfitzgerald351
11-16-2004, 01:14 PM
Hmmm... mine appear to be rusted as well, just the lower part where they attach to the heads. They don't seem to leak and this motor is 20 years old (though I think it's been repainted so who knows what the old previous owners did to it). I figure why do anything since it ain't broke. I did replace the exhaust manifold gaskets two years ago when I had the motor out of the boat to replace the leaking oil pan gasket and front and rear seals on the the tranny. The manifolds came right off and looked fine on the inside and bolted back up nicely. That was a great work weekend. My buddy is a Mack truck mechanic and we used a huge forklift in his shop to lift the motor out. It was so easy the work on a motor when you could put it 6' in the air or set it almost on the ground.

east tx skier
11-16-2004, 01:58 PM
I need to redo those gaskets again. They're still leaking even as replaced. I'm going to replace the bolts as well because whatever's on there is a pain to get off.

River Rat
11-16-2004, 02:00 PM
The part of my manifold that is not new has a little surface rust. I was thinking of cleaning it up with scotch bright and painting it with some high temp paint. Anyone tried this???

east tx skier
11-16-2004, 03:22 PM
That's been my question. I have heard it's best just to leave it alone, which appears to be, so far, the consensus.

NeilM
11-16-2004, 03:22 PM
Doug, mine are rusting at the gaskets as well. Since you've just replaced your gaskets, I'd be tempted to do a touch-up (sand and paint) for this season.

east tx skier
11-16-2004, 03:40 PM
Mine aren't rusting at the gaskets. Mine are rusting on the lower parts where the arms go to the heads, but not at any contact points. It's just a little worse where the water is apparently coming out at the riser casket and dripping down the manifold.

Tom Wortham
11-16-2004, 06:14 PM
Doug, There is rust on my '86. Was there when I purchased it in '94 and still a little on it today. Mostly around the drain plugs on the exhausts.

Thrall
11-16-2004, 07:04 PM
I need to redo those gaskets again. They're still leaking even as replaced. I'm going to replace the bolts as well because whatever's on there is a pain to get off.
Doug, use stainless bolts and a little anti-seize on them, will make it easier the next time, if there happens to be a next time.
Also, if the riser gaskets are seeping a little, put a light coat of high temp RTV (gasket sealer) on both sides. There may be a slight warp, pit, or uneven surface that the water is making its way through. Use the high temp stuff, Ultra Coper, or Ultra Black.

ski_500
11-16-2004, 08:16 PM
Three years ago I had the manifolds off to replace the gaskets. They had enough 'suface' rust on 'em that I couldn't stand it. So I sandblasted them clean, and repainted with extreme high temp gloss black. So far...so good.

east tx skier
11-17-2004, 11:11 AM
Thanks, all. I took another look last night and, although a bit rusty, it's not as bad as I initially thought. Good tip on sealing from the side.

The problem with the bolts is that they require allen drivers to remove them and are near stripped. I'm hoping for something I can just take a socket to if need be. I figured stainless was the way to go. Is PB Blaster anti-sieze? Also, any problems with metalurgical reactions b/w the stainless bolts and the iron mainfolds?

JimN
11-17-2004, 11:22 AM
I don't know if you'll find a bolt that lets you get a socket in there. Do you have an Allen wrench with the ball end? That's what I use and it generally works well, unless they're stripped and gouged out.

PB isn't anti-sieze. You can get anti-sieze in small tubes, but it is different. You can attach case iron with stainless.

east tx skier
11-17-2004, 12:24 PM
Thanks, Jim. I don't think the allen drivers have a "ball end" on them.

Thrall
11-17-2004, 03:11 PM
[QUOTE=east tx skier]Thanks, all. I took another look last night and, although a bit rusty, it's not as bad as I initially thought. Good tip on sealing from the side. QUOTE]

Doug, I meant putting the gasket sealer on the gasket surfaces, both sides. Wanted to clarify.

east tx skier
11-17-2004, 03:27 PM
I didn't put it on, but gave the mechanic aviation gasket sealant to apply. Are you saying I can or cannot put gasket sealant along the edges of the gasket surface (visible without removing the riser.

Thrall
11-17-2004, 07:00 PM
You can, but it won't do any good. If It's leaking it's propagating out from the contact surface somewhere. The gasket sealer is nothing more than sticky rubber (for lack of a better description). I does not have great enough adhesive properties to stop a leak w/o being contained between 2 surfaces.

JimN
11-17-2004, 07:58 PM
If the E manifolds are going to be separated from the risers again, maybe it's time to flatten the mating surfaces on a really flat surface and some emery cloth. They may be pitted enough to leak, regardless of what sealant is used now. Once they're flat and smooth, the aviation gasket sealant should do the trick if it's allowed to get tacky before placing the gaskets on the surface.

east tx skier
11-18-2004, 11:17 AM
Good to know. I'll probably wait until spring to mess with this inasmuch as the engine's coming apart then anyway.

lakes Rick
11-18-2004, 10:30 PM
The local muffler guy ( the best one in town) has a giant sanding belt machine to smooth out warped exhaust manifolds and headers. He has done a couple of sets of car exhaust for me.. You might want to call around your place locally and see if any do this....

east tx skier
11-19-2004, 11:21 AM
Cool. Thanks, Rick.

/smooth 'em in; smooth 'em out. :D

JKTX21
02-25-2008, 12:04 AM
Resurrecting this post....

I managed to strip one of my exhaust manifolds when re-installing a plug today. They are 12 years old and generally rusty... You guys think it would be a waste of time to re-tap the hole or should I just replace the manifold?

Right now I have a plug hammered in and leaning towards replacing the manifold, maybe the riser... and if one side, why not both!?

TMCNo1
02-25-2008, 07:38 AM
Resurrecting this post....

I managed to strip one of my exhaust manifolds when re-installing a plug today. They are 12 years old and generally rusty... You guys think it would be a waste of time to re-tap the hole or should I just replace the manifold?

Right now I have a plug hammered in and leaning towards replacing the manifold, maybe the riser... and if one side, why not both!?

You can probably drill it out and install a Heli-Coil and still use it without replacing the manifold, http://www.emhart.com/products/helicoil.asp?gclid=CNHu3pig35ECFQkdPAodywvidw

rkmason
02-25-2008, 10:46 AM
The part of my manifold that is not new has a little surface rust. I was thinking of cleaning it up with scotch bright and painting it with some high temp paint. Anyone tried this???

I have done this on my '98 MariStar. Removed the manifolds and had them sandblasted to remove all paint and surface rust. I repainted them with multiple coats of hi temp rattle can spray paint. I used 1500 deg paint on the ports where they exit the heads (where the manifolds get the hottest) and cheaper 1000 deg paint on the rest of the manifold and riser. I did mine about 5 years ago and the ports are just now showing rust again. The main body of the manifold and riser still looks as it did when I painted it. I used copper-coat on the riser gaskets and have had no joint leakage problems.

WilliM1940
02-25-2008, 10:57 AM
This has been a serious issue over at CCF. If there is noticable evidence of leakage on the outside of the manifold, it could also be leaking inside, causing water to invade the cylinders. Best to remove the riser and flatten the surfaces either by machine shop or other shade tree methods outlined there (emery cloth glued to a stiff flat block for example) and regasketed. Manifolds should be seperated from the block. A pressure test should be done on the manifold to ascertain its integrity if questionable. Bad manifolds, riser connections and water leakage could ruin your engine if not taken care of. Regular enamel paint on the riser sections is all that is needed, they are low temperature. Paint where the manifold attaches to the block is hopeless, unless possibly ceramic coated. Too much heat.

JKTX21
02-25-2008, 02:16 PM
You can probably drill it out and install a Heli-Coil and still use it without replacing the manifold, http://www.emhart.com/products/helicoil.asp?gclid=CNHu3pig35ECFQkdPAodywvidw

Thanks for the idea Harold! I'll have to track down a couple of these.

rob935
02-29-2008, 03:05 PM
my manifolds also have a bit of surface rust and have been like that for past few seasons, nothing to worry about as long as you drain your boat correctly when winterising. i had manifold problems with a previous boat as it had been used in salt water which just eats cast iron and believe me you will know if there are any weak spots as the cast will become porous and leak every where ...just to sum up then leave em be and dont worry about the surface stuff.

Whitfield
06-16-2009, 08:33 PM
http://i9.photobucket.com/albums/a53/whitfimb/Dixie%20Super%20Skier%20299/P6100711.jpg

I just sand blasted my risers and repainted them. Po didn't winterize and cracked the manifolds, my new manifolds and old rusty risers didn't match.

I do remeber reading somthing recently about filing the mating surfaces and cleaning / refiling them every few years. Being an X-Auto mech, hand filing a gasket mating surface sounds sketchy, but if you are just knocking off the rust and scale it probally isn't too bad.

manifolds would be So much easier to mount with (2) guide studs on each side. A Stud and nut on each end would avoid aligning the gasket while one handing the 40lbs assembly and starting the bolts with the other. i stopped by the local shop the other day and picked up a set of (4) of their longest 3/8' Exh studs but the just pass thru the manifold / still too short to get a nut on. But they made aligning the assembly and installing the bolts cake...


**** Is that a Crafty Spammer above me ???

JimN
06-16-2009, 09:17 PM
http://i9.photobucket.com/albums/a53/whitfimb/Dixie%20Super%20Skier%20299/P6100711.jpg

I just sand blasted my risers and repainted them. Po didn't winterize and cracked the manifolds, my new manifolds and old rusty risers didn't match.

I do remeber reading somthing recently about filing the mating surfaces and cleaning / refiling them every few years. Being an X-Auto mech, hand filing a gasket mating surface sounds sketchy, but if you are just knocking off the rust and scale it probally isn't too bad.

manifolds would be So much easier to mount with (2) guide studs on each side. A Stud and nut on each end would avoid aligning the gasket while one handing the 40lbs assembly and starting the bolts with the other. i stopped by the local shop the other day and picked up a set of (4) of their longest 3/8' Exh studs but the just pass thru the manifold / still too short to get a nut on. But they made aligning the assembly and installing the bolts cake...


**** Is that a Crafty Spammer above me ???

With a good, crisp file and good technique (not rushing, basically), filing the surfaces should be OK. Emery cloth glued to a very flat piece of wood, a scrap of granite, marble or Corian isn't a bad way, either.

One thing I found to make reinstalling manifolds easier is to start one of the middle bolts first, That way, it balances better and neither end is so heavy that it will be so hard to handle. I also put the hose on the elbow before mounting it on the manifold.

Dan K
06-16-2009, 10:37 PM
I ceramic coated mine this year so they won't rust anymore.

Dan K
06-16-2009, 10:41 PM
Should show what the engine looked like to start

Whitfield
06-17-2009, 12:03 AM
Man O Man that looks sharp!!!!

I keep thinking Black Chrome Powdercoating ~ But then the reality of time and $$$ keep hitting me over the head. Maybe next winter, I need to get this thing back in the water.

qfjsy
07-01-2009, 12:14 AM
They're still leaking even as replaced. I'm going to replace the bolts as well because whatever's on there is a pain to get off.thread insert (http://www.xhcljx.com/eng) helicoil (http://www.xhcljx.com/eng)

qfjsy
07-09-2009, 12:26 AM
Right now I have a plug hammered in and leaning towards replacing the thread insert (http://www.xhcljx.com/eng) helicoil (http://www.xhcljx.com/eng)

davomaddo
07-09-2009, 02:24 PM
I had rust on my old boat at the same spot. I would always hit it with a wire brush and paint it with high temp paint.

Rust is a reaction between metal and the air. Paint helps seal the metal off from the air and slows down the rusting process.

Overtime, the paint will chip off and the rust will come back - then you paint again.

If it works for the Navy, it should work for us - right?

davomaddo
07-09-2009, 02:26 PM
sorry about the post above.. i think it is irrelevant. I did't read to the end.