I have a 1973 41’ Commander repowered with 454s. I have water showing up where my manifold bolts to the head, and lots of it. I have determined that’s it’s not from the block, head gasket, or riser gasket, and I cannot get my manifold to riser to leak. The only way I can explain the water, is that it’s backup up in the exhaust and eventually spilling over the top of the riser and into the exhaust passage. Has anyone run into any strange exhaust gremlins on the 41?

Views: 723

Reply to This

Replies to This Discussion

Interesting. I also have a 1973 410 that has been repowered with Crusader 496 big blocks. I have a closed cooling system. Do you have fresh water cooling or closed cooling? 

From  what I know there is no possible way for water to back up out of the exhaust and get loose on top of the engine. Maybe there are some cooling hoses/hard tubes running around on  top of the engine that could leak.

Is it in the water now? If so are you able to run it and look for the leak.?

Good Luck.

John Brock

I'm not completely following you on this one. Are you seeing the water where the intake manifold or exhaust manifold bolts to the head. Some pictures or a video would be a great help. Also any work done to engine lately, manifolds or hoses replaced or repaired? Was the boat winterized and did it see any hard freeze weather?  Is the boat fresh water cooled using a heat exchanger or is it raw water cooled? If it is fresh water cooled is it a 1/2 or a full cooled system.? Sorry to badger you with questions but without more info even a guess as to cause is difficult.

I’ll try to clarify the best I can. I don’t currently have any pictures available. I have water where the exhaust manifold bolts to the heads. I have water ingress into the cylinders so I can’t run it until I find the issue. I replaced the riser gasket on the manifold because I thought that was the source of the leak, it wasn’t. It has not seen any very cold weather(Tennessee has had a very mild winter). The engines are raw water cooled.

I don’t believe the leak is from the block or head because if I had that much water in the cylinder, it would hydrolock or damage a valve and I still have 180psi compression. Everything keeps bringing me back to the raw cooling water somehow getting into the exhaust passage, except my manifolds and and risers have no leaks. 

The only theory I’ve been able to come up with is if somehow my exhaust outlet has a blockage that is allowing the cooling water to back up enough to come back in through the riser. I know it’s a long shot but that’s the only other way I know to get water back into the exhaust manifold. 


It sounds like your exhaust manifold is defective, it may have a bad spot on the inside allowing water to enter and run down to the exhaust port on the head. Manifolds need to be replaced  every 5 years in salt water, and between 5 and ten years in fresh water. 

Dan, that was my first thought as well. But I’ve tested the manifold a dozen times and can’t make it leak. And I’m getting a LOT of water. Not just a drip, I got probably half a quart in maybe 1 minute of engine run time. 

If you have a later 410 (I believe 1979 or 1980 and later) it has waterlift mufflers.    If the outlet tube cracks off inside the muffler it can cause engine flooding.

Warren, I have a Vernatone Muffler. However, that is along the lines of what I have in mind. I had some serious backfiring in the fall, wonder if the fiberglass muffler could be damaged and causing the issues. The “good” engine is louder than the one I’m having issues with. Could a baffle break loose and cause a restriction I wonder? 

Would it be difficult to swap the mufflers and test the bad engine? Or just take out the suspect muffler and run straight hose for a test.

Sam, your seeing water outside the manifolds?  I can see you having water in the cylinders due to a blockage in the exhaust, or a bad manifold. How is the water getting to where you can see it without a bad gasket somewhere?  First thing you need to determine is how is the water getting out of what is supposed to be a gasketed contained environment. 

Kevin, I have PCM 454s which to not have gaskets between the exhaust manifold and the head. I had the bolts loosened so could detect any leaks quickly after initially finding some moisture in the cylinders. 


When you found moisture in the cylinders, was it just one bank or both sides? Did it cause any rust in the cylinders?

Did you resolve the backfire issue or is it still unresolved?

By chance have you inspected the exhaust system on the engine in question for a critter nest in it?

I agree Ron if the boat is out of the water then a nest is certainly a possibility. If no nest I would still lean towards a bad manifold. Had an internal manifold leak in my starboard engine 2 seasons ago and it caused a dropped valve and a boatload of subsequent problems. Curious if the water is entering the engine on the side closest to the exhaust discharge out of the boat(outboard side of engine). Wouldn't make sense if it is a blockage for the water to end up in inboard cylinders without flooding the others first as the path for the water would be longer to get to the inboard side. Do we know how old the manifolds are? Raw water manifolds have a shelf life even when used in fresh water. When you did run the engine what was the flow like out of the exhaust?

Ronald Zick said:


When you found moisture in the cylinders, was it just one bank or both sides? Did it cause any rust in the cylinders?

Did you resolve the backfire issue or is it still unresolved?

By chance have you inspected the exhaust system on the engine in question for a critter nest in it?

Reply to Discussion


Club News

Algonac 2020 Rendezvous - Start making dockage reservations now

If you are planning to attend by boat, please make your well reservation soon. The marina contacted us to say they are ready to take your call.

What: 2020 Chris-Craft Commander Club National Rendezvous

When: July 24 – 26, 2020

Where: Algonac Harbour Club, Algonac, MI Located on the St. Clair River

Algonac Harbour Club

Please call the marina to make a reservation.

Phone 810-794-4448


SuperDisc 15.0 and Resource Collection 5.0 Available Now!

SuperDisc 15.0 is an electronic encyclopedia of every aspect of Commander maintenance and repairs. The information on the disk is retrieved from the discussion forum and e-mail list, but organized in a way that makes information easy to find and use. SuperDisc is available on USB flash drive

Click here for more details https://commanderclub.com/page/superdisk

The SuperDisc 15.0 Complete Edition is for first time buyers of SuperDiscs.

The SuperDisc 15.0 Upgrade Edition is intended for those who wish to upgrade their SuperDisc 1.0 through 14.0. Each year we add over 1,000 posts. Don’t miss out.

Resource Collection 5.0 is great to own too!!!

The Resource Collection 5.0 contents include CC Catalogs and Brochures. CC Service Bulletins, CC Price Lists. Engine & Transmission Manuals. Dick Avery sketches and drawings, a folder for every Commander model, and all kinds of technical and interesting stuff. Over 193 folders and 2,697 Files. A true “Treasure Trove” for the Commander owner!

We thank you for supporting the club with your purchase of SuperDisc15.0 and/or Resource Collection 5.0. We hope you find it to be the value we feel it is, and trust you will enjoy the other benefits your payment will help provide. It’s your payment that helps to support the activities of this dues free organization that has grown from 12 members in 1999 to well over 4400 members in 2020.

To order now click here!


Fall Edition of Styled In Fiberglass Available here!

The Fall 2019 Edition of the Chris-Craft Commander Club's newsletter, Styled In Fiberglass, is now available for your reading pleasure.  Click here to download this and past issues.


2019 Annual Photo Contest Winners

Sixty-Eight photos were submitted for this year's contest.  They were absolutely amazing, making selecting a top 3 an extremely difficult task for your Executive Committee

Thank you to all that submitted a photo to the contest and even if your photo was not in the top 3, it could appear on a cover of Styled In Fiberglass, the club's newsletter due out in November, or the 2020 Wall Calendars, which are now available.

2019 Photo Contest Winners

Past Photo Contest Winners

2019 Photo Contest Entries



© 2020   Created by CCCC Webmaster.   Powered by

Badges  |  Report an Issue  |  Terms of Service