bent pusher rods loose rocker arms

frankieland692 · Aug 16, 2009

Hi need help 1985 chris craft alpa drive rebuilt took boat out
3rd run rocker arms loosend up after a hr was backfiring headed to shore
tool compression test no vac on port side removed rocker arm cover found
loose rocker arms on two push rods bent one almost z shape should i just
replace with new rods and re set rocker arms on springs or pull head and look for more damage could the rocker arms loosing up cause that or is something else wrong wondering if i rest with new rods and check compression what ill find gm 350 moter that was sitting for 2 seasons
out of the water please help Frank

Bt Doctur · Aug 16, 2009

Re: bent pusher rods loose rocker arms

push rods do not bend or break unless the valves got knicked by a piston or the valves were stuck in the guides and not moving.

cr2k · Aug 16, 2009

Re: bent pusher rods loose rocker arms

Or the lifters pump up for some reason.

frankieland692 · Aug 16, 2009

Re: bent pusher rods loose rocker arms

do you think there is more damage from the rods should i pull the head

futz · Aug 17, 2009

Re: bent pusher rods loose rocker arms

bring the heads to a shop and let them rework them.

xltier · Aug 17, 2009

Re: bent pusher rods loose rocker arms

i would put the new pushrods in and turn it over and watch the rockers to see if it all moves.then take a compression test and see.then u could start it and let it idle and watch.you will need something for the oil squrting.either some rags os a set of rocker stoppers at the parts store.they r a cheap tool.more than likely it was the valve guides sticking from sitting.happened to me once on a 350 rebuilt that sat it my shop 2 seasons before installing.they did free up after a while.now it runs great.good luck

futz · Aug 17, 2009

Re: bent pusher rods loose rocker arms

xltier...
And this motor that sat for 2 years did it bend pushrods also? Your motor was not in the same condition!

Rob_NC · Aug 17, 2009

Re: bent pusher rods loose rocker arms

..thing is this can get expensive quick..busted pistons..wear off a cam lobe...a quick check of whats going on is something I would do..yeah maybe it is a tight guide..but what if it`s not....

THERE'S NEVER ENOUGH TIME TO DO IT RIGHT BUT THERE'S ALWAYS ENOUGH TIME TO DO IT OVER

...and the do over is $$$$$$ that could have been saved...for gas these days...

diehard · Aug 17, 2009

Re: bent pusher rods loose rocker arms

who ever rebuilt your engine mess up your valve guides when your engine heats up and the metals exspand the valve does not have enough clearence and gets stuck and you bend a push rod .. once they get bent your rocker arms will be loose ....I WOULD BRING THEM BACK ! ! !

mkast · Aug 17, 2009

Re: bent pusher rods loose rocker arms

diehard said:
who ever rebuilt your engine mess up your valve guides when your engine heats up and the metals exspand the valve does not have enough clearence and gets stuck and you bend a push rod .. once they get bent your rocker arms will be loose ....I WOULD BRING THEM BACK ! ! !

Are you serious? After running for one hour, must be slow to heat up.

diehard · Aug 18, 2009

Re: bent pusher rods loose rocker arms

mkast said:
Are you serious? After running for one hour, must be slow to heat up.

i had rebuilt my heads on my 454 in my truck ran it for 2 months then started to bend push rods ..took them to a different machine shop was told me the guides were to tight when the moter heats up ..he instaled new valve's and guides and 200,000 miles later never happened again

mkast · Aug 18, 2009

Re: bent pusher rods loose rocker arms

diehard said:
took them to a different machine shop was told me the guides were to tight when the moter heats up ..he instaled new valve's and guides and 200,000 miles later never happened again

What you were told and what was the truth can differ.
If your guides were too "tight", why didn't the machine shop just ream the guides? Why install new guides.
Pushrods can bend because the nut holding the rocker down will no longer maintain torque. Factory nuts can't be used over and over again. That's one reason Poly Loc's were invented.
In the installation of guides, cylinder head is drilled to outside diameter of the new guide. Installed guide is reamed with standard size ream for that sized valve. It isn't a question of ,"What size drill or ream will I use today." I have run into a tight guide after installing with an air hammer. Doesn't matter, the ream will size the guide to original specs.
Anyway, most shops don't install new guides anymore. They install liners. Faster and cheaper.

Silvertip · Aug 18, 2009

Re: bent pusher rods loose rocker arms

The big question here is did you do the rebuild and if so, what procedure did you use to adjust the lifters? If they were adjusted too tight, it is possible the press-fitted studs were pulled from the head thus loosening the adjustment and the would also be the cause for bent push rods. Too tight could also cause the piston/valve collision previously mentioned.

bent pusher rods loose rocker arms

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