school me on freeing a stuck valve 73 155 f engine (1 Viewer)

[richardsc]

hi guys/gals

I recently acquired a 73 model fj 40 in exchange for a 2nd hand hj60 5 speed I had sitting around,origionally for use of parts on my 66 model as its pretty rough,as you do though my thoughts changed and I have a hankering to get the 73 running and back into shape

I got the f engine running,but its a bit tappety,but idles pretty good when warm,so ripped rockercover off for a look inside,one of the valve springs is stuck down,the pushrod to the rocker is getting no where near the rocker assembly but pushrod is moving up and down,that push rod is also very wobbly from side to side

at the advice of a mate I ripped side cover off to inspect fot a bent pushrod buty iots as straight as all the others and not wobbly when grabbed from inside side cover area

any tips would be great as im new to this sort of thing

also is there a downloadable section for a 73 fj40 covering this

poor old f was full of crusty old oil ,so have added an oil flush then dumped the oil,hoping I can salvage the engine

 

[whitey45]

In the past i have freed stuck valves by tapping on them or just using a prybar to lift it back up. Last one i did was a few years ago and it has never stuck again! Unless the valve is bent? Which i doubt in an f engine.

 

[Heirloom]

A quick compression check will help you determine if that valve might be open. If the cylinder has good compression numbers, have you checked the valve lash adjusters yet?

 

[alberta mac]

fill the motor with deisel fuel and hand crank the motor numerous turns, let sit for a few days turning each day then drain off the oil and replace.
That freed up a motor I had and may work for you.

 

[shipmag]

If it runs poor some auto transmission fuel down the carb start slow letting it run then increase the flow until you put so much in it dies. Let it sit for 20 minutes or so letting the transmission fluid soak in around the valve stem. So when I say put it in till it dies it has to be alot to coat the valve stems. Then start it with the garage door open it will smoke like crazy until it burns all the fluid out. Do this a couple times. Should unstick the valves. Done this for 40 years and it works for me.

 

[Howard705]

Penetrating oil down the valve stem. Let soak. tap-pry. once it starts to return with spring pressure keep tapping until it returns fully.

 

[Tancruiser]

I took the rocker off and the spring ( with air pressure in the cylinder ) sprayed down with some pb blaster the hooked my cordless drill up to the valve stem and slowly spun it backwards and forwards and freed it up . It was alot of work but it did work for me.

 

[richardsc]

thanks guys

a few options for me to try

just out of curiosity,what causes them to lock up

this 73 has been sitting for a while,judging by the condition of oil in it poor old things been neglected

 

[shawnfj40]

One trick is to soak the valve stem with penetrating oil. Remove the spark plug and get that piston on the rise. once that you have the piston about half way up stop and feed small rope or line (clothes line works good)until the cylinder is as full as you can get it. raise the piston to put upward pressure on the valve then start tapping the valve stem with something like a brass or aluminum punch.it wont tae long and the spring will get it moving again for you. The extra pressure from the rope should get er done. They sometimes stick after long periods of sitting in one place and corrosion combined with the hardening/swelling of the valve seals.

 

[Howard705]

The only thing that it returns it is the spring. couple hundred pounds pressure. air can go through the intake and carb-with the humidity and rust the nice bare shiny stem. It's probably the good tight/unworn stems that stick the easiest as the tolerances are tightest.

 

[richardsc]

ok managed to free the valve with some tapping and prying but accidently stuffed the top of push rod so will need to replace that

another thing i found was a leaking welch plug the one closest to firewall so that will need tending to as well and explains the moisture and gunk i found when i first removed rocker

speaking of rockers.whats the best rocker cover to use in place of the steel number of the 155 f