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[ Active Members: 14 | Guests: 123 ]  [ Total: 137 ]  [ Newest Member: mark h bischoff ]
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 Rocker arm
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Author Previous Topic: What is this? Topic Next Topic: 1996 Raytheon 108 - 112 GPS Sensor  

John T

RO# 195

Posted - Nov 21 2009 :  15:27:20  Show Profile  Reply with Quote
I went to winterize my 1988 454 Mercruiser and when I started the engine after sitting for 3 weeks or a month it sputtered and backfired (small backfires, not like a cannon) through the carb few times before it ran. And then it ran rough. Turns out a rocker arm popped off under the port valve cover. Any ideas why this would happen?

Homeport: Seaside Park, NJ; Barnegat Bay

Kellyg

RO# 19800

Posted - Nov 21 2009 :  15:33:34  Show Profile  Reply with Quote
Collapsed lifter?

Gary
Mt. Sinai, NY
2001 Regal 3780
2002 Striper 2101DC

Smooth seas never made a skillful mariner.

Homeport: Patchogue,NY Go to Top of Page

John T

RO# 195

Posted - Nov 21 2009 :  15:36:15  Show Profile  Reply with Quote
Don't know. Just wondering if anybody has ever experienced this. It will be a spring repair but I'm starting taking notes now.


Homeport: Seaside Park, NJ; Barnegat Bay Go to Top of Page

pdecat

RO# 842



Posted - Nov 21 2009 :  15:50:31  Show Profile  Reply with Quote
probably because of a stuck valve. more investigation is needed.Look for rust on valve stem.


Bruce



Edited by - pdecat on Nov 21 2009 16:15:00

Homeport: Gulf Coast FL Go to Top of Page

Chief Alen

RO# 31229

Posted - Nov 21 2009 :  19:23:45  Show Profile  Reply with Quote
stud pull up a bit. Spring broke?

Be good, be happy for tomorrow is promised to no man.

Homeport: Manalapan, NJ Go to Top of Page

jtybt15

RO# 3300

Posted - Nov 21 2009 :  22:38:19  Show Profile  Reply with Quote
Do a comp test on that cylinder,too.

There's always a possibility of bent pushrod from stuck lifter or hydrolock...may have damaged/holed the piston.





Charlie

There is much to be said, in a world like ours, for taking the world as you find it and fishing with a worm.-Bliss Perry, 1904



Homeport: Ca Go to Top of Page

diver dave

RO# 2890

Posted - Nov 22 2009 :  08:05:03  Show Profile  Reply with Quote
I'd only add it could be as simple as a backed off stud nut. Replace it. I've also seen a worn cam lobe contribute to this. I agree with the rust on the valve stem, collapsed lifter, etc. Whatever the cause, roll the push rod on a flat surface to check it.


Homeport: Lantana, FL Go to Top of Page

happyhour

RO# 4143

Posted - Nov 22 2009 :  10:29:14  Show Profile  Reply with Quote
Popping thru the carb was probably a stuck valve, which in turned allowed the rocker to lift off. I suspect the valve freed up so the popping stopped but now that cylinder is not working hence the rough idle.

You probably have a damaged lifter or pushrod as a minimum. Possibly valve and piston damage. Time to pull the head.



Homeport: Newport Beach, Ca Go to Top of Page

littlebookworm

RO# 27413

Posted - Dec 06 2009 :  21:05:15  Show Profile  Reply with Quote
Over the years, I've seen that happen with small and big block GMs in cars. Usual causes: stuck valve (carbon build-up), pulled rocket stud, collapsed lifter, bad cam (rarely), loosened adjustment nut, overtightened adjustment which cause wear at rocker pivot point, or poor oil flow through that lifter or push rod (dirty oil)causing wear at rocker pivot point. As was suggested, a pulled head and check-up is in order. I would also suggest you check all the valves and lifters on both heads. You'll have the upper part of the engine pretty much apart anyway. If one valve/rocker/lifter/stud has gone bad, others might not be far behind. Better safe than sorry. Hy


Homeport: Eastport, NY Go to Top of Page

Cpt. Harold

RO# 29184

Posted - Dec 06 2009 :  21:11:17  Show Profile  Reply with Quote
While you are at it, if you have to change rocker arms go to the modern roller fulcrum type. Much less friction and more HP....


Homeport: Boqueron, Puerto Rico Go to Top of Page

jtybt15

RO# 3300

Posted - Dec 07 2009 :  05:53:19  Show Profile  Reply with Quote
I wouldn't bother with replacing 20 y/o rockers with roller rockers. 454 had issues with cam lobes wearing flat.

Doing a rebuild, roller rockers would be appropriate.

Pull the intake and pull each lifter to check em and check for straight pushrods and pulled rocker studs while you're at it.

You can check each cam lobe /wear with a dial indicator at each rocker.

No need to pull heads just yet.





Charlie

There is much to be said, in a world like ours, for taking the world as you find it and fishing with a worm.-Bliss Perry, 1904



Homeport: Ca Go to Top of Page

John T

RO# 195

Posted - Dec 23 2009 :  17:15:55  Show Profile  Reply with Quote
Thanks to everybody for your advice. Happy Holidays and Seasons Greetings to all!


Homeport: Seaside Park, NJ; Barnegat Bay Go to Top of Page

dollelliott

RO# 11160

Posted - Dec 29 2009 :  17:09:16  Show Profile  Reply with Quote
And one more shot - I had the same thing, twice as a matter of fact, on my GM 427 which is a destroked 454. The knowledgeable mechanic (who builds Nascar type engines) said that it was common on big blocks. I then installed roller rocker arms and the engine has been trouble free and run smoother than ever. Apparently the weak link in big blocks is the valve train. The last of the Mercruiser 454's all had roller rocker arms.


Homeport: North Palm Beach Go to Top of Page

John T

RO# 195

Posted - Apr 30 2010 :  14:36:20  Show Profile  Reply with Quote
well i have found that I have 2 stuck valves on the port bank. stuck in the open position (valve springs compressed) any ideas how to unstick them? any old mechanic's trick will do - without removing the head. thanks in advance.


Edited by - John T on Apr 30 2010 14:37:30

Homeport: Seaside Park, NJ; Barnegat Bay Go to Top of Page

Stephen

RO# 14

Posted - May 02 2010 :  09:50:58  Show Profile  Reply with Quote
Put penetrating oil on the valve and wait several minutes. Grab it by the end with small vice-grips and rotate it slowly. Do not remove the keepers or you risk it falling into the cylinder. Once it's free, lube it with oil as you don't want to run it with the penetrating oil. Even if you release it, chances are high it will stick again. You should plan on getting the heads rebuilt if it happens again.


Homeport: Matts Landing, NJ Go to Top of Page

pdecat

RO# 842



Posted - May 02 2010 :  10:01:51  Show Profile  Reply with Quote
Yes for the oil but then just tap them with a hammer assuming there is some uncompressed spring. Rust from sitting is common on boats stored for winter. The open valves are exposed to the atmosphere via the exhaust. Thatís why some folks like to rotate the engine a bit now and then and stuff rags into the exhaust ports.


Bruce



Homeport: Gulf Coast FL Go to Top of Page

jtybt15

RO# 3300

Posted - May 02 2010 :  10:09:05  Show Profile  Reply with Quote
The bad thing, if the valves are open very far, there's a chance the pistons could have been damaged or valves bent.

Happens mostly on center exhaust valves from water. Have to get the piston at BDC of that cylinder and tap the valve with a small hammer to loosen. You may need valves and guides installed but ya gotta go thru this step by step to determine the extent of the damage

First thing is free valve(s)...them comp test to see if those cylinders are holding comp.





Charlie

There is much to be said, in a world like ours, for taking the world as you find it and fishing with a worm.-Bliss Perry, 1904



Homeport: Ca Go to Top of Page

John T

RO# 195

Posted - May 25 2010 :  14:51:34  Show Profile  Reply with Quote
well i was unable to free up those valves and i had to throw in the towel and take it to a mechanic. they pulled the heads and discovered rust in 3 of the cylinders, bad enough to not recommend heads replacement. so the motor is essentially toast. any good leads for a long block or complete?


Homeport: Seaside Park, NJ; Barnegat Bay Go to Top of Page

Chief Alen

RO# 31229

Posted - May 26 2010 :  06:00:18  Show Profile  Reply with Quote
They had it apart and didn't recommend over boring it 30 thou why ?

Anything you buy rebuilt will be over bored anyway .

Chit your right by me here i'm in manalapan. BT is in spotswood. Why not have him rebuild it for you.

Email me

Chiefalen "at" symbol above the 2 aol.com


Be good, be happy for tomorrow is promised to no man.

Edited by - Chief Alen on May 26 2010 06:02:15

Homeport: Manalapan, NJ Go to Top of Page

John T

RO# 195

Posted - May 26 2010 :  13:11:12  Show Profile  Reply with Quote
quote:
Originally posted by Chief Alen

They had it apart and didn't recommend over boring it 30 thou why ?

Anything you buy rebuilt will be over bored anyway .

Chit your right by me here i'm in manalapan. BT is in spotswood. Why not have him rebuild it for you.

Email me

Chiefalen "at" symbol above the 2 aol.com



Chief Alen thanks for your reply. They are working on quotes for a rebuild of the existing, assuming the block is good, to a reman long block to a reman full to a new drop in complete. First thing I asked is if they could hone the cylinders. No matter what, the motor has to come out. Right now i have a lot of other stuff going on with a home under renovation and this just adds to that agita. I'll keep you posted and thanks for the email - check your inbox.



Homeport: Seaside Park, NJ; Barnegat Bay Go to Top of Page
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