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Crusader 454 Engine Noise

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major_tom

Regular Contributor
"I have a 1984 Egg Harbor 33&#

"I have a 1984 Egg Harbor 33' with original twin Crusader 454's (1300 hours each). Port engine has what sounds like a diesel knock which has been there since the boat was purchased 3 years ago. Noise seems like its coming from deep inside toward flywheel end, maybe even bottom end, or near distributor gear, but its hard to isolate just exactly where. Noise does not seem to get louder as engine is revved up; in fact, its relatve level seems to diminish with increasing rpms. Its definitely not comming from the lifters or push rods--the rocker covers were removed and its not coming from there. Ignition timing was verified with inductive light at 12 degrees BTDC. Distributor advance is working; ignition system is solid state pertronix and wires look good. Fuel is stabilized 87 octane with water separators and appears good. Same fuel produces no noise from other engine. Belts from all accesories were removed with no change in noise level. Plugs and distributer are new. Engine starts and runs fairly well but I haven't pushed it due to lack of confidence. The noise is apparent in or out of gear. Oil is clean 20W-50. A quart of Lucas Oil treatment had no noticable effect. One local engine guy listened to it and thought it might be piston slap. He did not think it was rod bearings as the noise decreased with engine speed. I haven't noticed much improvement after its fully warmed up, though... Any ideas?"
 
"I have some experience with p

"I have some experience with piston slap and it does sound a little like a diesel and is a heavy noise. Would think you could rule this out with a compression check.

also you can try pulling spark plug wires on and off while running, try to get it to kick back at you , rod bearing, wrist pin , piston slap should talk back to you with this procedure.
If it kicks back at you on every cyl then probable crank bearing or coupler"
 
"Since both Rick and Stephen t

"Since both Rick and Stephen think it could be a "coupler", it raises the following questions?

What is a coupler? I have Borg-Warner gears. Is the coupler a metallic part with a four bolt circle around its perimeter that accepts a splined shaft, i.e. a part suitable for mating a flywheel to the input shaft of a gear box?

How does one diagnose a coupler problem?

Is coupler noise the type of thing that can be ignored or will it lead to bigger problems down the river?

Note that I tried removing one ignition wire at a time last fall but could not identify any particular cylinder as the problem. In good faith I must admit that I did not perform this test systematically, and so that probably bears repeating, along with a compression test as suggested by Stephen."
 
"Your motor may simply be idli

"Your motor may simply be idling rough, which allows the engine to trans coupler to make a lot of noise. Seen this happen numerous times.

Believe it or not, it's very hard to properly adjust the idle mixture on a marine engine (especially if it's hard mounted). Why? The stubborn thing can not rock back and forth on the mounts when the idle mixture is off, and that's what a good mechanic uses to tweak the adjustments.

I've had to resort to a vacuum gage to get the best idle, and you may have to a s well.

Jeff

PS: The about assumes all 8 plugs are firing properly! A plug color check would be the first thing to check."
 
He stated the noise gets quiet

He stated the noise gets quieter when engine is reved up but does not go away. would rule out rough idle as the problem. However in some cases you do hear coupler noise with rough idle. if you carb is dripping at idle then it will cause the noise. carb rebuild takes care of this problem in many cases.
 
"Both Rochester carbs were reb

"Both Rochester carbs were rebuilt last year by a reputable shop. Both engines start, idle smoothly, and run well. But that knocking has got me worried. How hard is it to unbolt the bell housing and take a look at the coupler? Can a problem with it be diagnosed by eye? Is going on its 24th year; maybe its shot."
 
"Tom.

The only way to troub

"Tom.

The only way to troubleshoot a coupler, or damper, as Crusader calls it, is to remove and inspect it. It is not that big a deal to do. You will be looking for a crack in the plate or a broken spring. Crusader flat rate time to change one is 1.0 hrs. but you should leave yourself a little more time than that, especially the first time.

While you have it out, replace it. they are not expensive and yours has exceeded it's life expectancy already.

Damper PN for engines using Hurth gear is 98511 and sells for $182.40

Damper PN for engines using Borg Warner gear is 97334 and sells for $106.00.

Good luck,
Rick"
 
"Looks like I am already well

"Looks like I am already well on my way to replacing a drive damper assembly, as suggested by Rick and others.

I would like to take this opportunity to thank everyone for their help and for all the kind words of advice. I've been following this forum for some time time now and its pretty clear that certain contributors have assisted countless others with troubleshooting and repair advice. Its indicitive of your passion for boating and for helping others and believe me, its no small contribution to the boating world."
 
"BEFORE you go yanking all tho

"BEFORE you go yanking all those parts, make very sure rough idling is not your problem.

Jeff"
 
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