Freeing Sticky valves

[anglosax]

Hi all
I have a mercruiser 454 with 2 stuck valves and 2 bent broken pushrods damaged on startup . I have the rocker cover & rockers off and would like to free the valves up without lifting the head . I have tapped the stems and can get them to go down but they are too stiff to return. Currently they are marinading in MMO to try to free up the carbon deposits. Anyone had success without lifting the head ? heat ? chemicals ? prayer ? :facepalm:

 

[90stingray]

Re: Freeing Sticky valves

The marvel mystery oil should do it! Problem is the carbon build up is going to be on the stem by the valve itself. Had a stuck down valve on an old car once... had to pull the head and clean up the crud. Lapped the valves and reassembled. I know it sucks... but you will sleep better at night, knowing its nice and clean and shouldn't let you down on the water.

 

[Don S]

Re: Freeing Sticky valves

They may be bent. Time to take it apart and check.

 

[Pete104]

Re: Freeing Sticky valves

how are you getting mmo to the stems with them stuck? Break down & show it a little love!

 

[anglosax]

Re: Freeing Sticky valves

They may be bent. Time to take it apart and check.

Yeah I know guys - but I always hope for the magic cure - FYI I built dams around the valve springs with moddelling clay to get the mmo to stay on a 30 deg slope

 

[anglosax]

Re: Freeing Sticky valves

So If I have to lift this head- Is it just 8 bolts and a couple thru the exhaust manifold- Ive done other heads but not this one- any advice appreiciated
Thanks

 

[dan t.]

Re: Freeing Sticky valves

Pull the intake and exhaust manifolds then off with its head.

 

[FreeBeeTony]

Re: Freeing Sticky valves

I would definitely remove the head and do it correctly........last thing you want to do is have the valve stuck open when the piston is coming up..........

 

[John_S]

Re: Freeing Sticky valves

And the other head should probably be done as well. If the lower end is solid, have both heads redone since you have them off.

 

[Bondo]

Re: Freeing Sticky valves

So If I have to lift this head- Is it just 8 bolts and a couple thru the exhaust manifold- Ive done other heads but not this one- any advice appreiciated
Thanks

Ayuh,... There's really no If about it....

There's a few more than 8 bolts,... look outside the valve covers,...

 

[Volphin]

Re: Freeing Sticky valves

And the other head should probably be done as well. If the lower end is solid, have both heads redone since you have them off.

I second that. Nothing like having to do a job twice.

V

 

[RogersJetboat454]

Re: Freeing Sticky valves

So If I have to lift this head- Is it just 8 bolts and a couple thru the exhaust manifold- Ive done other heads but not this one- any advice appreiciated
Thanks

Pull the heads. Valve guides could be junk-ola. Dropping a valve could cost you the whole engine.
Pull your 8 head bolts, then pull the other 8 head bolts out and you will have the ONE head off (GM didn't trust just 4 bolts per cylinder with either the mouse or the rat), repeat with the other head...

 

[Don S]

Re: Freeing Sticky valves

If you don't have a proper service manual, don't even touch it.

 

[anglosax]

Re: Freeing Sticky valves

I have to agree, time to pull the heads.

Okay I get the message >>>..
I have the 8 bolts inside the rocker cover, and 6 or 8 outside the cover down by the spark plugs , the alternator bracket and the HX bracket are all removed but the head is still fast - Do I have to remove the rocker arm studs to get the head apart from the block or what have I missed ....where do I have to whack this thing..
Oh yeah - all you wise guys talking about find out why you have sticky valves in the first place - the exhaust manifold port on that cylinder is major rust past the gasket - manifold holed? engine shot ??? Ho BOY !!!!

 

[spdracr39]

Re: Freeing Sticky valves

Might have to tap on it with a rubber mallet to loosen it up.

 

[Don S]

Re: Freeing Sticky valves

Might have to tap on it with a rubber mallet to loosen it up.

That might work for a day or two, but it just gets the engine running, doesn't cure the underlying problem.

Oh yeah - all you wise guys talking about find out why you have sticky valves in the first place - the exhaust manifold port on that cylinder is major rust past the gasket - manifold holed?

See. not even knowing it, you found the problem. The rust is probably from bad manifold/elbow gasket surfases due to corrosion.

Post pictures of the manifold and elbows. Also need the year, or better yet the serial number of your engine.

 

[anglosax]

Re: Freeing Sticky valves

That might work for a day or two, but it just gets the engine running, doesn't cure the underlying problem.




See. not even knowing it, you found the problem. The rust is probably from bad manifold/elbow gasket surfases due to corrosion.

Post pictures of the manifold and elbows. Also need the year, or better yet the serial number of your engine.

Don
Will post pics
Do I need to remove the rocker studs to release the head from the block - I dont want to get this wrong.......

 

[RogersJetboat454]

Re: Freeing Sticky valves

Don
Will post pics
Do I need to remove the rocker studs to release the head from the block - I dont want to get this wrong.......

Nope. Rocker arm studs have nothing to do with holding the heads on. Make sure you count all 16 head bolts (per side) are out. As long as they are out, it may take some persuasion to remove the heads. As a tip, put a couple of head bolts back in each side (3-5 turns in) loose, to keep the heads from falling on the floor when you break them free. Then use blocks of wood W/ regular hammers, or rubber hammers to give the head some wacks in about the area where the intake manifolds bolt too. You can also do some prying with the intake port's. A wooden/plastic/fiberglass hammer handle would work for this.

 

[FreeBeeTony]

Re: Freeing Sticky valves

I assume you removed the intake..............