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John T
RO# 195
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 Posted - Nov 21 2009 : 15:27:20
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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?
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Homeport: Seaside Park, NJ; Barnegat Bay
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Kellyg
RO# 19800
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Posted - Nov 21 2009 : 15:33:34
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Collapsed lifter?
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Gary
Mt. Sinai, NY
2001 Regal 3780
2002 Striper 2101DC
Smooth seas never made a skillful mariner. |
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Homeport: Patchogue,NY
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John T
RO# 195
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Posted - Nov 21 2009 : 15:36:15
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Don't know. Just wondering if anybody has ever experienced this. It will be a spring repair but I'm starting taking notes now.
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Homeport: Seaside Park, NJ; Barnegat Bay
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pdecat
RO# 842
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Posted - Nov 21 2009 : 15:50:31
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probably because of a stuck valve. more investigation is needed.Look for rust on valve stem.
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Bruce
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Edited by - pdecat on Nov 21 2009 16:15:00 |
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Homeport: Gulf Coast FL
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Chief Alen
RO# 31229
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Posted - Nov 21 2009 : 19:23:45
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stud pull up a bit. Spring broke?
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| Be good, be happy for tomorrow is promised to no man. |
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Homeport: Manalapan, NJ
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jtybt15
RO# 3300
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Posted - Nov 21 2009 : 22:38:19
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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.
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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
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Homeport: Ca
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diver dave
RO# 2890
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Posted - Nov 22 2009 : 08:05:03
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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.
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Homeport: Lantana, FL
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happyhour
RO# 4143
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Posted - Nov 22 2009 : 10:29:14
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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.
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Homeport: Newport Beach, Ca
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littlebookworm
RO# 27413
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Posted - Dec 06 2009 : 21:05:15
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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
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Homeport: Eastport, NY
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Cpt. Harold
RO# 29184
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Posted - Dec 06 2009 : 21:11:17
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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....
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Homeport: Boqueron, Puerto Rico
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jtybt15
RO# 3300
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Posted - Dec 07 2009 : 05:53:19
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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.
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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
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Homeport: Ca
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John T
RO# 195
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Posted - Dec 23 2009 : 17:15:55
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Thanks to everybody for your advice. Happy Holidays and Seasons Greetings to all!
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Homeport: Seaside Park, NJ; Barnegat Bay
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dollelliott
RO# 11160
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Posted - Dec 29 2009 : 17:09:16
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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.
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Homeport: North Palm Beach
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John T
RO# 195
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Posted - Apr 30 2010 : 14:36:20
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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.
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Edited by - John T on Apr 30 2010 14:37:30 |
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Homeport: Seaside Park, NJ; Barnegat Bay
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Stephen
RO# 14
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Posted - May 02 2010 : 09:50:58
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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.
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Homeport: Matts Landing, NJ
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pdecat
RO# 842
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Posted - May 02 2010 : 10:01:51
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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. That’s why some folks like to rotate the engine a bit now and then and stuff rags into the exhaust ports.
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Bruce
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Homeport: Gulf Coast FL
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jtybt15
RO# 3300
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Posted - May 02 2010 : 10:09:05
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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.
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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
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Homeport: Ca
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John T
RO# 195
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Posted - May 25 2010 : 14:51:34
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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?
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Homeport: Seaside Park, NJ; Barnegat Bay
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Chief Alen
RO# 31229
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Posted - May 26 2010 : 06:00:18
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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
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| Be good, be happy for tomorrow is promised to no man. |
Edited by - Chief Alen on May 26 2010 06:02:15 |
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Homeport: Manalapan, NJ
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John T
RO# 195
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Posted - May 26 2010 : 13:11:12
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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.
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Homeport: Seaside Park, NJ; Barnegat Bay
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