Collapsed lifter, bent pushrod
 

1989 gen IV 454 mervruiser

Hey guys i have an issue on my motor...i opened it up and discovered om the number 4 cylinder that the lifter collapsed on the exhaust side...im hoping that as i was running 3000rpms the side effect was that pushrod bent (on intake same cylinder)as it couldnt open valve becuase of first issue....just looking for some insite on the issue. I will be replacing both pieces...
Thanks,Harry

Just curious, how do you know it's a collapsed lifter ? any chance you lost a lobe or 2 off of the cam

I pulled it apart. Intake is off. Hydraulic lifter is hollow..

Sounds more like you had a stuck valve and the pushrod got bent because the valve was either froze in the guide or there was water in the cylinder when you 1st went to crank it up.

Redid a 2 - 454s last year in a cruiser that had this issue. Collapsed lifter could be a after result of the problem also.

Sometimes they just fail. Had one swell inside the liter bore this spring. Nothing like that has happened before.
fyi, it's a Mark IV. When you say "Gen" anything people naturally think its a newer motor.

No water in cylinder. Just checked it out...also the valves are not stuck...i just moved other parts over to this cylinder. And turned motor over.

And the result of a cam lobe inspection?

. Everything worked...cam was ok...any ideas what could of caused it? Or is this just something that could happen

So, your thinking intake pushrod bent because of trying to open against the pressure of a non-evacuated cylinder due to the innards coming out of exhaust lifter ?

I would put a scope in that cylinder and inspect it a little closer.Home Depot sells a Ryobi scope that has proved invaluable for multiple uses since i bought it for a 100 bucks.

I know you know better than that.

I have had motors run with with a bent pushrod on one side not allowing the cylinder to evacuare and did not experience any damage to the other valves pushrod.

Still sounds like A. water on a startup that had bled down there and filled the cylinder and hydrolocked but more than likely it was a corrosion that temporarily stuck both valves.

How soon after starting was a miss or problem noticed? How long was the boat sitting before it was started and noticed?
Is it a saltwater boat? How old are the risers?

Check the rocker arm really well for any signs of pushrod contact outside of the cup. Maybe the lifter plunger collapsed and that eliminated all of the preload on it. That could leave enough room for the pushrod to come out of the rocker arm cup. I've seen them do that and push off center on the rocker or come out of the guide plate and bend the pushrod. The rocker arm will have some evidence of the pushrod hitting it somewhere other than the cup.
Eddie

I was asking him what his thinking is, Note the ? LOl.

Anyhow, without further evidence, bending pushrods and gutting a lifter in the same cylinder would have me looking for something more tramatic as you are saying.

I've never gutted a lifter - I have only seen this on lifters with wire retainers not running enough preload.

I have, however, bent pantloads (yes, that's a number...LOL) of pushrods. Typically due to over rev.....that used to be my trademark. Double LOL.

Eddy. The exhaust lifter bit the farm. The intake pushrod bent.

Oh crap. Never mind then. Disregard everything that I said. Guess I should have read more carefully.lol

Eddy: That's why I pointed it out. Would be very easy to miss that and thus not give the OP valid info. I could see many others missing it to.

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Just dug my grey matter and do remember a cust's motor that gutted an exhaust lifter. Was a 502. Freakin thing sounded like a bunch of firecrackers. Intake psuhrod/rocker/etc/etc was fine. Exhaust pushrod wasn't, but it was lying in the head. It may have had a broken exhaust valve spring too...that part I don't really remember.

The guy limped it back approx 10 miles.

Is the intake lifter in good shape? I assume it didn't collapse?

The motor had only sat for 1 day prior to this event. Also .this happened after running for about 45 minutes...no water in cylinder. It is a saltwater boat. The exhaust is nee this year. All clean and dry inside. im still baffled...i will try to do more inspection...didnt want to pull the head.

Just as suspected. Engine shop says one caused the other. Collapsed lifter not allowing gases to escape
..caused pushrod failure on intake....said it's prettu common

So you are saying exhaust lifter collapsed and because exhaust wasn't fully opening ,intake pushrod bent ...I gotta cry BS

Yep me too.

Unless you are running some incredible unheard of cylinder pressures that is creating air so dense it can not be measured on earth there is no way that a intake pushrod will bend trying to open a valve in a non evacuated cylinder.

Think about this Once the cylinder has built up 150 lbs of pressure after it has taken a gulp of air from the intake stroke and compressed it why doesn't the exhaust valve pushrod bend trying to open the exhaust valve against that 150 lbs of pressure? They are all one and the same pushrods.

After the second stroke of the exhaust valve not opening the intake would be able to take in very little more air so at best the pressure may build anothee 10 or 20 lbs .

Every other stroke as the pressure would build from the exhaust valve not opening the pressure would relieve itself through the intake valve and pop out the carb causing a backfire.

Just for some history my dad had one of the old soft cam problematic sbc in a brand new 1978 305 Chevrolet that ground the exhaust lobes off 2 cylinders of the cam.

He ran it a couple thousand miles back from a trip with it backfiring thru the carb the whole way and no bent exhaust pushrods,

back when I was working on a Trans Am series Corvette we qualified in Detroit with and broke an exhaust rocker. motor still turned 7k during qualifying and never bent the intake pushrod. even with 200 psi in the cylinder the intake would only need to move a few thousands and the pressure would push out the intake and all the load on the pushrod would go away. unless you have some cheap pushrods the only time I have seen them bend is when a moving object meets an unmovable object. just my 2 cents.

Motor will reassembled this weekend...will keep you all informed...lots of good information here

after cyl fires, piston goes down and exh valve opens. i betcha that on a 8;1 4cyl with 1/4 inch pushrods the exh valve is being pushed open into more than 200 psi. engine builder will tell you ANYTHING...except "yup, it is my fault and we will cover it." pull heads. check valves.

back when we were running Class One in APBA and blew up a lot of motors our engine builder said the same thing with everything we broke. "never seen that break before!" they were still happy to sell us another engine each time.