Leaking Flange on CMI's
 

Hey guys , I am having an issue that I want to stop before it turns into a major one. I have a leaking exhaust flange that I am having trouble sealing.

I have a pretty fresh 502 with CMI E tops . At the V band clamp that connects the header to the tailpipe, I am getting an external drip and also some water draining back towards the exhaust valve after shutdown.

I removed the gasket and noticed carbon on the V band clamp as well as water marks on the gasket where it has been leaking.

After replcing the gasket, I still have the same issue. I dont want to run it like this to prevent any engine damage.

Does anyone have any insight on how to get this to seal. Should I use a copper RTV or other sealer in conjunction with the gasket? Could this cause hydrolock if left unattended?

Thanks.

I had the same issue with my E-tops and CMI said to use double gaskets or sealant if needed.I was concerned about the water also and they said once its sealed water would not be an issue getting into the motor,So far two years later and no issues.I used two gaskets and sealant.

Nordic95

Thanks for the quick reply, thats very reassuring. I thought of doubling up, but was unsure until now.

Thanks again.

Use 2 gaskets. No sealant.
Works like a charm.

Also - it would be a REALLY good idea to send your tail pipes off to CMI. They can weld in some reversion rings. That will stop the water from traveling up the tailpipe past the joint.
What is happening is: When you install those the std (1 gasket) way, there is sometimes a small leak. That leak interrupts the exhaust pulse - which in turn pulls water up the tail pipe. If it is leaking at the joint, you can bet that water is getting into your motor somewhat. 2 gaskets will seal that leak for awhile. But the best remedy is for CMI to weld in the rings.

I agree with Billl R. Those headers and tails have a dry joint, thats why there is a bypass hose. Water should not be there at all. You engine is sucking it back up. Is the engine stock? What are the cam specs?

For stock motors, it is not an issue of cam sucking it back up. It is a case of the exhaust pulse being disrupted by a minor leak. THAT is what brings water back up. Reversion rings in tailpipe will stop this 100%.

Where do you guys purchase those gaskets and the v-clamps? I used to get them from Trick marine and will no longer do that.

We have the parts in stock at Ateco (847)623-2737.

This may sound crazy, but most of the time this is condensate at the hot flange joint, with the cold water being pumped around it. I thought I had the same isse and it was condensate. Highly unlikely that your engine has enough cam to draw water up the pipe.

I doubled up the gasket and it appears to have stopped the leak at the joint. Before, I could visibly see water dripping from the joint . It would take about 5 mins for the drip to start , but after that it was constant.

Hopefully the issue with the leaking joint holds until I can get some rings welded in. I was definately getting some water into the motor, because I found some "shake" when I drained the oil. I replaced the oil / filter, ran it, replaced the oil / filter again and ran it . seems ok so far.

The motor does have a crane cam, but it isnt anything crazy. I am looking for the cam card for the exact specs.

Thanks again Guys.

UH OH...

After fixing the exhaust gasket I ran the boat for about an hour under all different rpms and everything seemed perfect. Oil and water temps were great, and all seemed well with the boat. I changed the oil again and there was still some "shake" present.

I assumed it was oil that was in the cooler or left over from this experience.

I went to take the boat out the very next day and bang..! Hydrolock. Pulled the plugs and about a half a quart came out of cylinder #6. Plugs 4 and 8 show signs of droplets.

Now I'm thinking head gasket but i have to do a leakdown test tomorrow..

Any rec's on gaskets (Cometic?) or what else may need to be addressed before I pull the motor apart?

This motor has 40 hours on it...WTF

Man that sucks... what motors due you have. Did you just have work completed on them recently? Cannot be new and have 4o hrs or it would be under warranty? I would go back to who did the work on them. Just my $.02

I just put back together my port motor exhaust (header & Y pipe) after having carbon exhaust leaking from the flange. I used two gaskets and perma gasket and I hope this does the trick, I have yet to put the boat in the water to test it, hoepfully tomorow.

Headers have likely sprung a leak.
Older (merc) Etops are famous for that. Probably leaking right @ the flange that bolts to the head.
If so - DON'T fix them. Buy the new cool collar Etops. Then you will not have this issue again.

SAME thing happend to mine.

well, I went to do the leakdown test and my tester was F'in up so I didnt get too. I pulled the header on that side and the primary tube for #6 was FULL of water. That primary has the orange water spots all over it and didnt look very good. 4 and 8 had some water in the primaries as well but still looked good.

Also, It appears that the flange is still leaking internally even though i couldnt see external signs while it was running.

Why would the primary have that much water in it. I am starting to think its my header now but I still have to do the leakdown tomorrow.

Thanks for the replies

You can hook a garden hose to the header - remove the rubber crossover and cap it- then hook the hose to inlet and turn on. Your leak should present itself.

Thanks man, gonna do that right now. You guys have been a big help.

I know its been a few weeks , but heres an update. It was a very small breach in the head gasket. Replaced and no more issues. Everything else checked out great.. At least its fixed and the headers are still good.. lol

Enjoy whats left of the summer.

Thanks again guys.

Excellent... Glad to hear you are back out having fun. :ernaehrung004:


I am in the process of taking off my manifold and tail pipe on the Stbd side of the stbd engine to add a second gasket and some permatex to stop a leak that came about last weekend.
Had to do another one earlier in the season, they are a pain in the Azz.