bent push rods!! AGAIN!!!

I just picked up a 1962 Cadillac 390 engine. I did a huge "once over" on the whole drive train. I drove it around over the weekend and it ran sweet. I let it sit for about a week and then started it and I heard a huge ticking noise in the engine. I pulled off the valve covers and I saw that I had a few bent push rods (8 of them). I pulled off the rocker train and removed all the push rods and about 8 of them were bent. I replaced them with new once and then started the car again. The engine ran sweet again. real smooth. I then waited till the next day and started it again. and again!!!! its making that ticking noise. Im pretty sure they are bent again. The lifters looked okay when I inspected them. Could it be my oil pump???

Thanks.

 

Valve springs coil bind ?

 

Hydraulic lifters may be pumped up and sticking or valve stems scored causing binding in guides.

 

i know i had the same trouble with an engine in a friends car, he had the motor built 3 years before he brought it to me to start for the first time, it fired right up and we broke in the cam, let it cool down then fired it up again, ran nice and slowly it started ticking, louder and louder, so i pulled the vavle cover and one of the push rods is bent, i had another and we put that in, ran fine and then it starts ticking again same as before, i pull the valve cover and the same push rod is bent, so we pulled the head, he took it to the guy who built the engine and he pulled the valve and had a look, i guess hed did file a little bump off the valve stem and put it back togather and it never bent another push rod, i think the valve guild was a little tight and when the motor heated up it got tight and the rod bent, couple people said it might be the lifter but how can a lifter bend a puch rod? maybe you have sticky valves?

 

i know nothing about 390 cads , are the rocker arms adjustable? if so , are they adjusted correctly?

 

are you running to thick of oil? to thick of oil will keep the lifters pumped up

 

if the lifters are sticking or stuck down then it would just be a loud tapping noise??? right??? It cant fall out of place and bend.... right??? humm...

But I have bent push rods on both sides of the engine.... I dont think both heads or valves will go bad at the same time???

damn.........................
I wanted to drive my dang car!!

Thanks again.

 

im running 10w-30. new oil..

the 390 cad rockers are not adjustable.

 

When lifters are pumped up they hold the valves open piston hits valve head and push rod bends.

 

Were the bent push rods all intake? exhaust or a combo?

 

when you say "once over" the drive train , does that mean the motor is rebuilt? does it have a stock cam , or a bigger one? without adjustable rockers , how do you adjust the valves on a cad 390? you say you replaced some pushrods , are they the correct length pushrods? as i said , i know nothing about those motors , just thinking of possible reasons for the valve train to bind

 

well then its probably not the oil. might be the lifters. has the motor been running good until this or is this a motor you don't have history on?

 

I, too, have had this. The problem was BAD OLD GAS! It causes gumming on the valve stems. Use an upper valve train cleaner, like Gumout, and drain old fuel, replace with fresh.

 

Also make sure your Rocker Shaft is not bent... and also that the rocker assembly part where the bolts go through and bolt onto the head are on the right way.

I had 2 bent push rods on my 331 cause the guy that rebuilt it put them on backwards
it bent the rocker shaft as well...

 

A machinist who posts regularly on the y-blocksforever forum has been cautioning people to put gas stabilizer in the gas tank if you're going to let a car sit for more than a couple of weeks. Evidently, today's gas will gum up valve stems if it's allowed to get 'old'.

Do a search on the y-blocksforever forum. The machinist's name is Ted. He sounds like a real sharp cookie.

 

YES, bad gas.. Our older cars let gas evaporate and distill down very rapidly.
Modern (off topic ) cars have sealed fuel systems that keep vapors captured onboard.
You will find a red/brown residue on the valve stems.
If you are going to run this car you need to clean or replace the gas tank.
Todays gas formulation will not last even in a sealed gas can for very long without a fuel stabiliser. I use STA-BIL in everything.. BTW ..In the last 18 months I have fixed at least 9 cars and several gas powered pieces of equipment with this problem..
The first time i encountered this was back in 84.. My bud left his car with his sister while he was working out of the country. She never drove it.. 5 years... Parked with full tank.. We went to start it, refilled the tank (bad idea, we know now !! ) put in a fresh battery and started it up . NO problem.. Next morning ..8 bent pushrods..
Fast forward, 3 sets pushrods and heads off twice ! The varnish would stick the valves hard and fast in the guides overnight..
Clean or replace that tank !
Now I will not attempt to start anything that sits for more than 1 year without thoroughly cleaning the tank,lines,pump and carb..
I have a 60 cad waiting to get in the shop right now with 3 bent pushrods..Customer started it up 4 years after his Dad passed. Ran great until the next day !! Here we go again !!
Dave

 

I bought a 70 bronco once with a brand new rebuilt 302 ford engine installed. I drove it 3 miles and it started making all kinds of noise. Ran excellent at first. All the push rods were bent and the rocker posts were pulled out on most of them. Apparently, the machinist that redid the valves and guides went to tight on the clearance. Once the engine warmed up the stems froze up in the guides. Have your heads been redone??

 

oh man.. I guess Im not alone with this.

The "once over" was chainging new fluids, spark plugs, wires, point set, cap and rotor, adjust the timing, just a full tune up.

The engine was running good in tell the first bending of the push rods happen. Then I replaced the bent ones. it ran good on the drive way for about 10 mins. then I turned if off for the day. then the next morning I started it and the same ticking sound came back again. im guessing its not the oil pump because the "dummy oil light" did not turn on. ( I know not to trust that light) and the engine was running fine for 10 mins and did not burn up. So im guessing the oil pump is okay. what ever is wrong is common with both sides of the engine. since both sides had bent push rods.

The gas is new. I put in about 3 gallons in on an empty tank.

Thanks again for all the replys

 

No they have not.

 

humm... I was thinking... If both cylinder banks left and right had bent push rods. It has to be common with both sides. could my cam timing chain set have too much slop or skipped a tooth??

 

Most likely the tank has a bunch of sour gas left in it from sitting. All you did with fresh gas is desolve some of the gum and it keeps sticking the valves. Was the car sitting for how long before you got it running?

 

1 night

 

DOREEN, John is correct ! By adding 3 gallons of gas all you did is begin the cleaning process.. Only problem is that it will take a few thousand gallons of gas to cut the varnish completly !
SO, change the pusrods and never shut the engine off for more than 5 minutes ??
Or , take the advice from the poeple here that deal with this every day.
If you are lucky so far you have not bent any valves.
I have had to get creative a few times because you cannot always get the tank into a boil out facility..Or , in one case ,I could not get the tank off of the vehicle.( some Moron welded the gas tank into a motorhome !!)
Good luck
Dave

 

new gas sucks!!

 

I just ordered a set of new push rods. Im going to install the new push rods, drop the gas tank, clean it out, do an engine flush with some ATF. start the thing and go from there. I guess that will be this weeks project..

 

Draining old gas can be a pain in the rear. Do all factory gas tanks even have a drain plug? Im' pretty sure that some I've seen do not have.

 

Some idiot put bronze guide liners in your heads when they redid them. Remove the heads and have them change at least the Exhaust to iron and the problem will go away. See it all the time but the shops alway insist it is something else but this repair awas cures it without fail. Why they like bronze liners is because they can be bench installed instead of machine installed. They neeed only a hand neld electric drill and a air chisel with a ball driver. However during heat soak on bigger stemmed valves and even on SBCs they will gro and snag the hot exhaust valve and usually if your lucky the pushrods sags instead of breaking something. In a race engine it is usually kis it goodby time.
Now you can argue and fuss all you want but IF you did have the heads done and if they did do the guides then THAT IS what is wrong. 40+ years of experience says so.
Don

 

It isn't sticking valves, in the sense of binding that would also prevent the valves from closing, in that case When one valve sticks open, the motor misses. If 8 stick open the motor won't run.

It might be lack of oil getting to the valve stem or incorrect angle of the rocker against the valve where the valve stem is binding/resisting opening, but closes freely.

It could be sticking lifters. If the lifters are clogged with gunk there isn't a fix for that either, except new ones.

Also.............don't discount the possibility that the pushrods were bent and now they are bending again just from force and the problem that caused them to bend in the first place has disappeared. New pushrods would be my first attempt to fix it. At the same time as somebody has already pointed out make sure the rocker arms and springs are correct.

 

Yes, Don , you are right ! Bronze guides DO need more clearance than iron..
Been there before, no fun at all. LOL !
However , DOREEN did not have anything done to this engine. Car was started after sitting for a long time.
Bad , stinky gas is the culprit here.
Dave
Please keep us posted on progress DOREEN, OK ?

 

it has to be sticky valves, valve guides,or something above the pushrod, rocker shafts maybe, a jumped timeing chain, a lifter can not bend a pushrod on its own, something has to create the resistance so when force is applied to the bottm of the pushrod it bends if it has no place to go.