What is this noise?

[FreeBeeTony]

Re: What is this noise?

This was the end result of what I believe was a hung-up lifter.

Fought this problem for about a year......thought I fixed it after I loosened the rockers......then 1 day while cruising at 3600RPM.....bam...........came to a sudden stop! Basically took out the entire engine.

Here's a pic of the plug from that cylinder.

And of the piston.......found pcs of the valve through out the engine.

 

[kwoolard]

Re: What is this noise?

Verdict is in, at least it's what it appears to be, will have to remove the engine and drop the oil pan to know exactly:

Broken Connecting Rod or Rod Bearing Cap Dropped Off

Took the intake off, everything good, nice and clean, lifters looked good. Pulled the head and the valves looked good other than some slight rust in a couple locations, then I looked at the piston and noticed it had some hammering marks from the valves. It also was rotated slightly, which explains why it was hitting the valves. I then tapped the piston with my fist and it dropped about 1/4", , must not be connected.

Not sure why the rod would break suddenly, other than a hydrolock. The head gasket and intake gaskets and surfaces are perfect, no signs of water intrusion from those areas. That only leads either somehow water got into the exhaust port while running it on the muffs, or excessive condensation in the exhaust manifold or intake manifold and when I started it, hydrolock. I did notice some surface rust, as if water had been in the #8 intake port, you'll see that in the photos.

Can condensation be that excessive to cause a hydrolock? My boats sits in my driveway and i have the boat tilted up so water will drain from the bilge, but the driveway also leans to the starboard side. Looking at the intake runners, if water was to condense in the intake manifold it would run to the #8 cylinder. Likewise if it was to condense in the exhaust manifold. I dunno, just know i'm in for major repair.

I can't think of any other causes, other than a freak of nature. What do you guys think?

Photos are here.

You'll also see in the photos, the number 2 intake lifter has been hitting the lifter retaining bracket. Not sure if that was making some noise.

 

[Bondo]

Re: What is this noise?

Can condensation be that excessive to cause a hydrolock?

Nope,.... No way in 'ell....
Now, rain water could do it...

 

[fishinpa]

Re: What is this noise?

Ouch !

Not good news , hopefully it didnt damage all the goodies down below also..

Sorry to hear the news.

fish

 

[FreeBeeTony]

Re: What is this noise?

WOW, wasn't expecting that! The rod is broken or not connected to the crank??

 

[kwoolard]

Re: What is this noise?

Can't tell if the rod is not connected to the crank or to the piston, but the piston moves freely inside the bore, at least 1/2" when I pushed on it. Could have broken at the wrist pin. I know spinning it over by hand and with the starter I couldn't hear or feel anything unusual.

I know rain water didn't get in there. Only thing I can think of then is that water was pushed into the exhaust somehow when I cut the engine off last time it ran good, while I was walking to the water shut off valve.

Not good either way, just would like to know what happened. Hopefully the block is in good shape and just needs a head job, new piston and rod and rod bearing.

 

[Grumman59]

Re: What is this noise?

Too bad but expected, I guess. Can you pull the remains of the piston out through the top, then at least yo will be able to see what is actually broken in there.

Maybe with luck, you can get away with a new rod and piston if the crank hasn't suffered.

 

[Gary H NC]

Re: What is this noise?

From your posts about the compression on the other cylinders i would have it rebuilt or get another long block for it.
You came this far and the numbers from those other cylinders sounds like the engine is pretty worn out and tired...They were not very even numbers.

 

[wire2]

Re: What is this noise?

With a few ABS plumbing fittings, you can probably pull the piston out the top right now, for a look.
A 3" coupling should fit into the cylinder and sit on the piston nicely. Slip in a very short piece of pipe, then reduce it to 1?" and connect it to a shop or central vacuum.

A central vac at ~140" wc suction is equivalent to 4.6 psi pushing up from below the piston. The inside of the coupling is ~3.5" diameter, so ?D is 11 sq inches x 4.6 = 50.6 lbs of lift.

A small bead of grease will give a tight coupling/piston seal, if required.

If the piston was smooth on top, just the vacuum hose might lift it out, (4.7 lbs pull) but the valve relief in the piston will probably not allow a seal.

 

[Grumman59]

Re: What is this noise?

The piston is not a lot of good. Might as well just drill a hole in the top, put in a large self tapper and yank it out with visegrips. It may hang up on the ring ridge but it should come out (since it already went down without the engine turning).

 

[superpop]

Re: What is this noise?

Time for a new long block, I would pressure check the manifolds while I had it all out.

 

[Alpheus]

Re: What is this noise?

 

[ENSIGN]

Re: What is this noise?

Pull the oil pan,and push the piston out

 

[kwoolard]

Re: What is this noise?

Obviously I'll be pulling the engine next to view the damage, if any, done below. I noticed a little rust, you can also see in the picture as well, in the combustion chamber near the top. It just puzzles me how this could happen after it ran perfect the weekend before.

I have this gut feeling it was hydrolock, but don't know how enough water got in the combustion chamber to do this damage. If water got in there from shutting it down while it was on the muffs, then running on the muffs just isn't worth it.

I do remember before I fired it up I took the flame arrestor off to make a choke adjustment and noticed a fair amount of water that I dumped out of the flame arrestor, and remember thinking to myself, "Hope there wasn't any water that dumped down the carb body".

That was why I asked the question about excessive condnesation, say after shutting down a hot motor on a cool afternoon.

If you look at the photo of the #8 intake and exhaust ports, it looks like water had set in the combustion chamber, by the looks of that rust line that is present

Would starter have enough torque to keep turning the motor over if the engine hydrolocked?

How do you upload the pictures into the text?........nevermind...

 

[Alpheus]

Re: What is this noise?

The starter may crap out first if that piston was next on its compression stroke, but it may have been timed just right that the other pistons fired up and forced that #8 piston up against the water and snapped your rod,piston skirt, or wrist pin. This is just weird to me. It takes allot of force to do the damage that has occurred. Were their any other incidents during this season that may have weakened any components in that cylinder??? I don't see how just idleing can cause that damage, especially just being ran 1 week before.

 

[Jeepster04]

Re: What is this noise?

If you turned the engine off before turning the water off then theres a good possibility it forced just enough water into the engine to hydrolock that cylinder. Doesnt take much at all to do what has been described. It must of been just enough to let the engine turn over and just enough to break what ever its broke below the piston. If too much water would of gotten in there it wouldnt of been able to turn at all.

 

[Grumman59]

Re: What is this noise?

... but it may have been timed just right that the other pistons fired up and forced that #8 piston up against the water and snapped your rod,piston skirt, or wrist pin.

Yes, if it was hydrolock, the damage would be caused by another piston firing rather than by the starter.

I never had it on a V-8 but I did have it on a two cylinder two cycle engine and it was due to gas rather than water. What happened was that the other piston immediately fired once and the engine seized solid.

In that case, it bent the rod in an S-shape. I was able to straighten it out and the engine lasted for years afterwards. But a GM V-8 rod is a whole lot thicker and stronger..

If it was me, I'd still try to save that engine if the crank is OK. I don't think the compressions were that bad.

 

[kwoolard]

Re: What is this noise?

I wanted to give an update on this motor since its been a while.

I have to say Bondo was correct about rain water entering the motor, never would have thought it, but that is what happened. The previous owner of the boat drilled a bolt pattern for a seat to mount on the engine box, and I've never mounted the seat and just left the bolts in place. I removed the black plastic flame aressotor cover so that I could make some tune up adjustments and have left it off since the summer. I always noticed a little water on top of the engine after a rain, but didn't think anything of it. Apparently with the heavy rain we had here right before I fired this motor up the bolts holes leaked and allowed some water to leak by and drain water directly on the carburetor. The way the boat sits in the driveway it allowed all the water to drain to the #8 cylinder, and the rest is history.

Anyway, I thought before I would remove the motor I would give the insurance agent a call and see if my policy covered anything like this.......he said more than likely not, but would file a claim anyway...........good thing I did, cause they are mailing me a check to cover the replacement with a new long block!!

Now, the question is can I repower with a higher horsepower long block motor (low grade 383, 360hp) without having to change ignition module? I know I will probably need a 4 barrel carb and manifold. But can the Alpha handle this or am I better off going back with the 350, 2 barrel mercarb set up?

The reason I wanted to do this was to get more bottem end performance. The 350 I had topped out at 4400 rpm with a 15" pitch prop and just seemed like the boat was a little underpowered.

 

[Don S]

Re: What is this noise?

Now, the question is can I repower with a higher horsepower long block motor

My suggestion would be to start a new thread with that question, or it will be lost at the end of a 2 page post.

 

[kwoolard]

Re: What is this noise?

Taking Don's advice, new thread will be started.

Visit here: Upgrade or NOT?

Thanks!