IMCO manifolds discoloring
 

Just had my engine builder complete my engines and he also suggested installing some Imco manifolds (4 hrs total) on both of the 502 mag n/a. They Don't look as trick as my CMI'S on my old ride, but they do look clean and have heard perform resonably well under 550hp and my builder recommends them.
Well, took the boat out for a good blast at sunset at our lake and noticed some discoloring on one of the risers at the connection to the manifold assy. The black area is starting to bubble up. It all happened within a 15 minute blast. And now the engine runs rough. So i shut it down and limped in on one engine.
Thoughts?

Re: IMCO manifolds discoloring
 

From looks you've got a leak around the gasket. How did you prep the mating surfaces?

I lost two engines because the "mechanic" used an air-driven wire brush to remove the paint from those surfaces. Needless to say they leaked like a sieve and I got water in all the cylinders and hydrolock--on one test run.

Of course the shop said the manifolds were defective and since I provided parts they had no liability.

Re: IMCO manifolds discoloring
 

I am not sure how the shop prepped the surfaces. He said he installs many of these and assume he is qualified to follow product procedures.
He sold me the manifolds and installed, turn key at the same time he rebuilt my other engine. Very reputable shop, message is on their answering machine waiting for a response.

Re: IMCO manifolds discoloring
 

Start keeping a "blog" of all conversations and start organizing reciepts. Hopefully they have some sort of errors/ommission insurance but you'll have to sue to get and resolution.

Re: IMCO manifolds discoloring
 

Can you post a full view of the engine. It looks like they installled dry joint elbows with old stlye manifolds that don't have a provision for a jumper hose. The damage shown in that picture is from heat not a leak. soemthing is wrong with the water flow and that manifold got smokin hot.

Re: IMCO manifolds discoloring
 

Hillbilly,
Here is another shot. Hope this helps
Thanks

Re: IMCO manifolds discoloring
 

From what I can see in the picture I don't see a water outlet for the manifolds, he water somes in the botom but has no way to get out. Those elbows have no water ports they get their water through the hoses that hook to them. Like I said it looks like they used dry joint elbows with wet joint manifolds and no jumper. It got hot and puked the gasket and from what you described it sounds like you have water in the clyinders now. I'd see what the builder wants to do from here.

Re: IMCO manifolds discoloring
 

Mine are hooked up exactly like you have shown. My water exits thru the tail pipes. After three years the chrome looks like new. It definetly looks like it got hot, at least that one. How come the others are not discolored?

Re: IMCO manifolds discoloring
 

yes, it looks like only one is discolors...you would think that if they are hooked up wrong all would discolor ....looks like maybe a sealing issue as discribed...

gociggie
...I guess you will see how reputable your engine guy really is. :eek: ..best of luck and keep us posted.

If it turns out good let us know who he is ....and also if it is bad, I would like to know who to stay away from when I dump my money in another gofast later this fall.

again, best of luck

Re: IMCO manifolds discoloring
 

It looks to me like the hoses are hooked up wrong. The hoses that feed the manifolds should come off the aft hose connections (closest to the intake manifold) and the hoses that feed the risers should come off the forward hose connections (they have the checkballs). The one manifold may have overheated due to the checkball sticking.

Dave

Re: IMCO manifolds discoloring
 

I agree, it looks like the hoses are hooked up wrong.

Water exits the manifolds into the riser the same way as stock merc iron manifolds with holes between them.

Here's a pic of my old engine with Imco exhaust. My hoses are the reverse of yours.

BTW, those manifolds are not very new that he sold you. I would say at least 5-6 years. They changed the letering on the sides about that long ago.

Re: IMCO manifolds discoloring
 

mod image so you can see the hoses

Re: IMCO manifolds discoloring
 

uh oh.. Time to make another call. Sounds like a free rebuild...... :evilb:

Re: IMCO manifolds discoloring
 

Dave N,
thank you for the diagram. It looks like the hoses are switched. Dropped off boat at the shop today. Odd thing is that both sides are hooked up the same and only one side appeared cooked. Maybe the other side was on its way. I did notice a little more of a restriction kink in the bend of the hose on the side the manifold that fried.

Coin, . He built one motor and installed these new manifolds on both engines that I purchased from him, plus he does allot of go-fast stuff out here. . .yes gotta believe the repair shop will do the right thing I got faith in this guy :drink: keep ya all posted good or bad-wish me luck :eek:

Re: IMCO manifolds discoloring
 

Just wanted to close this thread out and keep ya all updated on what happened.

Manifold gasket burnt due to restricted flow(sticking thermo or check ball I think). So replaced manifold/gasket, pulled all the spark plugs, cranked out all the fresh water in the cylinders, douched with wd40, performed compression check, replace plugs and VAROOM, it started with no funny noises and idles as it did before along with pulling up to +5100 RPM... whew...boy do I feel lucky I did not bend a rod or ?. Just call me LUCKY.

Attached find the IMCO water hose routing recommendation FYI which recommends to remove the check valve(also different hose routing w/ IMCO applications vs Merc)

As always many thanks to you guys on OSO and Fred at Imco on the gaskets ++ and SUPPORT :D

:D :D :D