Clanking/banging noise, #5 Zero Compression

I disagree. You don't have to haul the boat to pull the heads. You can pull a set of heads in an hour. Why would you throw away a good engine because it needs some work?
 
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frank2644 said:
To me, it seems highly unlikely that it's worth the expense of removing the heads considering repair shop costs, hauling, etc. given the age of the engine.

I still think removing the pushrods might provide valuable insight and would like to hear more pro's and con's.

Thanks for your input.
Frank
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I’m out.
 
douglee25 said:
I disagree. You don't have to haul the boat to pull the heads. You can pull a set of heads in an hour. Why would you throw away a good engine because it needs some work?
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Given the bore camera, rocker arm inspections, and other tests have not revealed the reason for the banging, I think the overwhelming outcome possibility of removing the heads is:

1. It will not show anything about the banging.
2. It will show a major fault causing the banging.
3. It shows a fault,(e.g., cracked valve etc.) that might or might not cause the banging.

Either way I would not go ahead with the head rebuilding. I don't think you can rebuild the heads and hope that the banging goes away. So it seems to me that it’s more likely that by-itself pulling the heads will not be helpful, and cost money. On a 1995 engine I might as-well just go with an engine replacement.

OTOH, if pulling the pushrods or some other diagnostic proves that detonation or some other minor problem caused the banging then pulling the heads makes more sense.

BTW, I'm not sure I want to do the work myself while in the water.

Thanks,
Frank
 
frank2644 said:
Given the bore camera, rocker arm inspections, and other tests have not revealed the reason for the banging, I think the overwhelming outcome possibility of removing the heads is:

1. It will not show anything about the banging.
2. It will show a major fault causing the banging.
3. It shows a fault,(e.g., cracked valve etc.) that might or might not cause the banging.

Either way I would not go ahead with the head rebuilding. I don't think you can rebuild the heads and hope that the banging goes away. So it seems to me that it’s more likely that by-itself pulling the heads will not be helpful, and cost money. On a 1995 engine I might as-well just go with an engine replacement.

OTOH, if pulling the pushrods or some other diagnostic proves that detonation or some other minor problem caused the banging then pulling the heads makes more sense.

BTW, I'm not sure I want to do the work myself while in the water.

Thanks,
Frank
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Frank - I respect you as a site member, but you're talking in circles and your logic is flawed. Pulling the heads WILL likely direct you to the next course of action. If you have deep pockets and your cash is burning a hole in your pocket, by all means, pull the boat and replace the engine with a new one.

Like the other guy, I'm out.
 
All I'm saying is that pulling the heads is not likely to reveal a fault that you can look at and say, "yes, that's what's making a horrible, clanking, banging noise". It's not impossible, but I think it's a long shot given what we already see with the bore camera, etc.

And if pulling the heads does show a fault that "looks like" it can cause horrible loud banging the fault is probably very severe and I still would likely have to go with a new engine.

Hence, pulling the heads doesn't sound like it will change the prospect that a new engine is needed.

Sorry if my prior notes were confusing.

Just IMHO.
Frank
 
Update: Did some more troubleshooting yesterday. I wanted to check oil pressure and also see if removing the pushrods on the zero cylinder changed anything.

The good news is that oil pressure was good, up to 40 lbs while cranking. The bad news is that removing the pushrods didn't seem to change the horrible, clanking sounds very much.

Rethinking things, I'm wondering if the timing is out of whack. Because it's very hard to start and, when it does start, it runs like crap for the few seconds before I shut it down. Could be the timing if way-off and maybe that's causing detonation and that's the clanking sound.

I'll have to dig out my timing light and start looking in that direction. Perhaps the timing chain has skipped, or something in the distributor has failed.

I'll keep updating.

Frank
 
frank2644 said:
Update: Did some more troubleshooting yesterday. I wanted to check oil pressure and also see if removing the pushrods on the zero cylinder changed anything.

The good news is that oil pressure was good, up to 40 lbs while cranking. The bad news is that removing the pushrods didn't seem to change the horrible, clanking sounds very much.

Rethinking things, I'm wondering if the timing is out of whack. Because it's very hard to start and, when it does start, it runs like crap for the few seconds before I shut it down. Could be the timing if way-off and maybe that's causing detonation and that's the clanking sound.

I'll have to dig out my timing light and start looking in that direction. Perhaps the timing chain has skipped, or something in the distributor has failed.

I'll keep updating.

Frank
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Your dreaming - the damage is done - stop wasting your time
 
Before this problem the boat was for sale, haven't been using it much, I'm looking to downsize.

I really don't want the boat, so I'm not sure if I want to put in a new engine..if I'm halfway convinced it's just a valve problem I'll probably go for a valve job. In the meantime, I've got at-least one person who might buy it at-is, of course at a low price.

Anyway, I'm trying to keep a positive attitude, but it's getting harder here.
 
Sell it.

Discount the cost of a rebuilt engine and you are done.

Most of us would have pulled the heads within 24 hours of the incident.
 
An intake valve that doesn’t seal will wreak havoc, as the fuel mixture burns, it expands back into the intake manifold. Fuel injectors melt, plastic intake manifolds get distorted, and you get a backfire through the throttle Body/carburetor.
 
Actually, I believe it's the exhaust valve that's tuliped. I think my prior mention of intake valve was relative to the "remove the pushrod" test, as I thought it might be good to stop fuel from entering the cylinder during that test. Anyway, there is no backfire through the carb that I hear.

I'm going to check the timing this weekend, although I'm a little perplexed how bad timing could cause the spark plug to break. A wild guess is maybe it caused severe detonation that resulted in pieces of the valve bouncing around.

In the meantime, no reasonable offer refused :>)

Thanks
Frank
 
frank2644 said:
Actually, I believe it's the exhaust valve that's tuliped. I think my prior mention of intake valve was relative to the "remove the pushrod" test, as I thought it might be good to stop fuel from entering the cylinder during that test. Anyway, there is no backfire through the carb that I hear.

I'm going to check the timing this weekend, although I'm a little perplexed how bad timing could cause the spark plug to break. A wild guess is maybe it caused severe detonation that resulted in pieces of the valve bouncing around.

In the meantime, no reasonable offer refused :>)

Thanks
Frank
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With all of the plugs out and the push rods removed with a good cranking battery, wide open throttle, fuel intake eliminated/disabled, engine cranking fast, does it make any noise and does each cylinder suck and blow your finger in and out of the spark hole plug evenly and sound the same?

That's as southern as I can get.
 
Timing chain timing is different than distributor timing. If you timing chain jumped it is possible your piston hit the valve. Could have had broken pieces from that smack the spark plug. Probably not likely but if you are suspecting a jumped timing chain then these are the possibilities.
 
boatman37 said:
Timing chain timing is different than distributor timing. If you timing chain jumped it is possible your piston hit the valve. Could have had broken pieces from that smack the spark plug. Probably not likely but if you are suspecting a jumped timing chain then these are the possibilities.
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Nope, these are non interference engines so jumped timing will not cause noise.
 
techmitch said:
Nope, these are non interference engines so jumped timing will not cause noise.
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Then that answers that. Wasn't sure what the clearances were on these. I know the ones I used to build were very tight tolerances but they were 500+HP spinning up to 8500 RPM...lol
 
Frank,

It’s obvious that you have a thorough understanding of the workings of a gas engine and I admire your tenacity, but you’ve asked for and have gotten good and similar advice from some knowledgeable folks here and continue to ignore the inevitable.

I’d pull the heads, crank the engine for 10 seconds or so to give it a listen. I might then rotate the crank by hand to inspect cylinder wall and piston condition and look for chunks, rust and any other engine killers.

Based on that procedure I’d make a decision about valve job/head replacement.

It’s time to act. Repair or sell, the season is half over and a long winter is just around the bend.

Good luck.
 
+1

And once you have the cylinder head removed, bring each piston to TDC and try to rock it by pressing on the 12 and 6 o’clock positions. A cracked piston skirt will be evident if the piston rocks too much.
 
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