Exhaust elbow popping off

"Hello:

We are in the proce

"Hello:

We are in the process of surveying a Tollycraft with twin Crusader 454 CID 350 HPs.

When the survey started, it was determined that the lower 90 degree elbow on the outer side of port engine was disconnected. This is the part of the system which leads directly to the waterlift muffler and the exhaust thruhull.

The surveyor was able to jack up the elbow so that the vertical section of hose could be reclamped to the upper 90 degree elbow. There was no hanger so the hose and elbow were supported only by the hose clamps. This seems like a lot of weight especially since the inner side of the exhaust system was also attached with a t fitting.

At the dock, the engine started fine. However, on the sea trial, the lower elbow and hose popped off the upper elbow again.

Any ideas about what may be causing this? Is there suppose to be a hanger or could it be a restriction in the exhaust system?

Thanks."

"This is more boat specific th

"This is more boat specific than engine so this might not be the best forum.

For reference, the only "hangers" on my Trojan are attached to the exhaust "Y" connecting both rubber exhaust hoses to the muffler. From your description, it sounds like you're missing this hanger.

How does it compare to the other engine?

Bob"

Without a picture we don't

Without a picture we don't have much to go by but the hose should definitively be supported. It sounds like you may need to replace the hose as the old one may have gotten hard with age and use. I would make sure you are using good quality HD clamps and that the hose is supported properly. Also look for any type of obstruction in the exhaust system which may be causing excessive backpressure and aiding in the failure.

"I'm with Rick; that old h

"I'm with Rick; that old hose must be really hard not to fall off like that. Frankly, it's HELL trying to get them off most of the time!

Tollycraft are nice boats with great performance. I hope you like it.

Jeff"

"When I recently disassembled

"When I recently disassembled the exhaust on my twin 270hp 350's we had to jump up and down on the main exhaust tube (lower elbow to muffler) to get the lower elbows to separate from the upper ones. It sounds like that short section of tubing connecting the two is stretched out too much. Were they double clamped on both ends? Also, on my rig the tubing in this area was not that heavy reinforced stuff used elsewhere in the exhaust system. Mine was fairly thick rubber tubing but it was much softer. I don't think this is a significant problem unless the muffler is somehow clogged up which I suppose could cause it to blow that connection."

Exactly my point! I had to cu

Exactly my point! I had to cut the old ones off mine.

Jeff

"When these hoses are "fre

"When these hoses are "fresh" they will have a higher tendancy to fall off, vs. when they really become bonded to the metal over a period of time. I'd put more emphasis on the clamping/supporting arguments. There is marginal room there for double clamps, so the single clamp should be picked with care and made TITE. A t bolt clamp works, but I'm getting away with single AWAB clamps, using a small wrench to tighten."

"Those T-bolt clamps are the w

"Those T-bolt clamps are the way to go, especially if the 'downstream' elbows are cast iron and there is any 'weight' on the hose.

Ideally, the exhaust system should have enough support so its components' weight is not carried by the neighboring components. sounds untrue in this case, so I'd expect to spend some money getting this issue fixed if you decide on that boat."

"A stiff, hard exhaust hose ca

"A stiff, hard exhaust hose can not be securely clamped. Period.

I challenge anyone to pull off a new, properly tightened exhaust hose!

Jeff"

"The mechanic put the hose bac

"The mechanic put the hose back on and said the engine was ready to go. On the next sea trial, at 3000 rpms, it popped back off.

When the mechanic came the second time, he thought that the problem was due to backpressure from the sightly deformed end fitting on the opposite side of the Y as the side that popped off. The deformity was caused by an overheat.

I have heard that an overheat hot enough to deform a fiberglass Y can also delaminate and reduce the cross section of the hose.

The resulting backpressure could be causing this problem?

I believe it is a model 350 454 CID.

Any other ideas?"

"if it was hot enough to defor

"if it was hot enough to deform a fiberglass fitting, the fitting should have been replaced.

I'd expect the hose to part or burn thru before any fiberglass transition. If you can see the fitting is deformed, it would be prudent to replace it and the hoses connecting it as well. The rest of the exhaust system should be checked and any suspect items replaced. Ditto for the exhaust system on the other side.

If the mechanic suspects a backpressure issue, he should pull out his hose adapters and his manometer and measure it. If he gives you the "DUH" look, maybe its time to get another one?"