454 chev big block broken pushrods,

[Dean J S]

Can anyone tell me, my 454 chev big block has been running rough, since i put it in my boat.<br />Now in no. 4 cylinder there is a broken pushrod, and in no.8 cyl, the push rod went through the rocker. The guy i bought the motor off told me that these 2000 model mark 6 motors run longer spark plugs, my mechanic put in the small plugs, now the importer is saying that by using the small plugs it caused an explosion in the cylinders causing the valves to push up and brake the rods.<br />The motor is full of water in the oil, its a new motor. Is this true?

 

[WillyBWright]

Re: 454 chev big block broken pushrods,

Sounds like a crock to me. Passing the buck no doubt. I can't imagine any possible link to the water in the crankcase let alone the pushrod thing. Did you get a MARINE 454 or just a plain 454? You get what you pay for and if it was a cheaper motor not made for marine use, the results are predictable. Among the differences are heavier pushrods and rockers, and marine head gaskets made of different materials.

 

[Bondo]

Re: 454 chev big block broken pushrods,

I Can't see how a shorter plug would cause Any of your Problems.............<br />This Sounds like B/S........<br /><br />As to What Did, I Don't Know......<br /><br />Tight Valve adjustment ??

 

[trog100]

Re: 454 chev big block broken pushrods,

fitting a long plug where a short one should go might cause problems but not the other way around..<br /><br />thow "explosions" driving valves up does sound good.. he he.. and u do have two seperate failures not just one.. odd..??<br /><br />the head/heads would have to come off to see for real whats happening..<br /><br />course the entire engine might well be a crock of sh-t and the importer will likely wriggle whichever way he can to get of the hook..<br /><br />trog100

 

[rodbolt]

Re: 454 chev big block broken pushrods,

hello<br /> wow<br /> this guy should be helping me shovel shoot,he can already spread it. other than excessive RPM. and odds are you never went much above 8000, about the only thing that breaks pushrods is a stuck valve or a mechanical interferance with the piston and the valve.<br /> tell us if the motor came out of a truck. tell us if you ever saw it run correctly. a bad manifold or riser will allow enough water to cause a valve to stick when sitting. a valve that is open will allow water to be sucked back into the engine.<br /> so now a cyl head removal and damage assesment is in order. remove both heads.

 

[WillyBWright]

Re: 454 chev big block broken pushrods,

A non-marine car or truck cam can also cause water to enter thru the exhaust and do every bit of damage you describe. It's not a Marine 454, is it? And like Rodbolt said there are other components that could cause it. What took out the old motor?

 

[newport dave]

Re: 454 chev big block broken pushrods,

Is it possible that using the shorter plugs allowed the sharp edge of the plughole (in the combustion chamber) to heat up and cause pre-igniton? <br /><br />Dave

 

[rodbolt]

Re: 454 chev big block broken pushrods,

not likely

 

[LubeDude]

Re: 454 chev big block broken pushrods,

This is "Plain and simple" a MECHANICAL FAILURE!<br /><br />I doesnt matter if its a Marine engine, or a truck engine. The only thing that can cause what you are describing is if the piston contacts the valve causing the pushrod to either break, bend,or push through the rocker. Water ingestion will bend connecting rods but not do what you are describing unless the water was in there long enough to rust the valve in closed posision. My bet is that the valves were incorectly adjust from the start. Did you check them before you started it? Who set them, you or the engine builder? The timing chain could have been put in a tooth or two off also. The person that told you what you said is TOTALLY FULL OF EXCRIMENT

 

[Bondo]

Re: 454 chev big block broken pushrods,

I'm Just Guessing here,<br />But, I think there's More to this Story, than we've heard.......

 

[LubeDude]

Re: 454 chev big block broken pushrods,

Originally posted by Bondo:<br /> I'm Just Guessing here,<br />But, I think there's More to this Story, than we've heard.......

YEP!!!

 

[rodbolt]

Re: 454 chev big block broken pushrods,

yep twice

 

[Bt Doctur]

Re: 454 chev big block broken pushrods,

Only way to have the damage you describe is from a stuck valve/piston hitting a valve/ incorrect cam timing/ high lift cam. Water in a cylinder will take out the piston rods but not the pushrods.Definitely more to this than your telling.

 

[jimmythekid]

Re: 454 chev big block broken pushrods,

its either been over revved, has got the wrong valve springs (probably) or the wrong head piston combo. Generally speaking, You need to have matched pistons and heads (closed chamber vs open chamber) also big chevys need the right guide plates because they have two different size pushrods available. I would be barking at the builder for sure. Make sure he put the right cam in it. whatever the reason, sounds like your engine might be toast. No the spark plugs have no bearing on the pushrods whatsoever. his excuse might sound good to someone who has no idea, but I know better, if he had said that to me I would have.....<br /><br />ALL engines have explosions in the cylinders thats what makes the piston move down causing them to make power. Even if using his logic???, that some how the plugs caused an explosion, how many mechanics have worked on thier own car/boat and have put the plug wires on wrong at some point in thier lifetime? Causing the plug to fire at the wrong time while a valve was still open? All of us I am sure. I NEVER had a pushrtod bend/break because of this. At worst, it could blow up a muffler or exhaust hose or an engine fire from a backfire from the carb, but not mechanical damage. He is shmoozing you. MAKE him build you another engine

 

[LubeDude]

Re: 454 chev big block broken pushrods,

Hey, I want to know more!!! <br /><br />Bump!!

 

[DHPMARINE]

Re: 454 chev big block broken pushrods,

How about bad engine,water on top of piston (hydrolock) Crank turns cam.cam pushes rod .rod cant move,and breaks?I think bends.<br /><br />DHP<br /><br />Wrong plugs ? Have you need for a alfaromaguiser? I have a numbered set of one for sale.

 

[Dean J S]

Re: 454 chev big block broken pushrods,

The original motor was pulled out & is in our garage. We opted for new long motor & new manifold & risers & had outdrive service. We think its a truck motor. We first transferred all extras from old motor & it got installed b4 xmas & the marine mechanic who installed said it didn't sound right from the start. Timing was always out only ran at 39 degrees advanced. So we tried new extras. & still it only ran well idling but not under load. Took off knock sensor & it run under load well only did that for 10 mins. cause we did that ourselves. Went back next day & it started, we took off & it laboured again. We turned it off & first thing found rotor button broken, then two rusty spark plugs replaced those & it was running allright but still not ok. Thats when we took rocker cover off & found milk in both sides & Right side Cyl 4 had broken push rod (in half) & cyl 8 push rod went through rocker (made whole).<br />Is there a difference between a MK4 motor and a MK6 engine? All the extra parts came off a 1996 motor. Importer says New Engine is a 2000 to 2001 model Mk6.

 

[jimmythekid]

Re: 454 chev big block broken pushrods,

Originally posted by DHPMARINE:<br /><br />Wrong plugs ? Have you need for a alfaromaguiser? I have a numbered set of one for sale. [/QB]

what is a alfaromaguiser?<br /><br />glad to hear you got it back out, maybe the broken pushrod went through the head, causing water in the oil?? If thats the case you might only need a new head, if your lucky

 

[LubeDude]

Re: 454 chev big block broken pushrods,

Originally posted by jimmythekid:<br />

Originally posted by DHPMARINE:<br /><br />maybe the broken pushrod went through the head, causing water in the oil?? If thats the case you might only need a new head, if your lucky

Went through the head?????? What the #$#%@ How could that happen!! What am I missing here?<br /><br />First we are "Running rough", then we have "broken pushrods", now we have "water in the oil"! Time to tear the whole thing apart and start over with a different mechanic.

 

[Dunaruna]

Re: 454 chev big block broken pushrods,

There is another aspect to this that is possibly being overlooked. It is the responsibility of the FITTER to ensure correct oil pressure, timing blah blah blah. I'm not saying that the builder isn't at fault but unless you can confirm startup oil pressure etc. - well you get the picture. <br /><br />If it was me, the knock sensor/ timing issue would ring alarm bells from the getgo. I think you have gone to far down the track to be able to make a claim on the builder - but I'd be interested on how this story unfolds - good luck.<br /><br />Aldo