318 Stuck Valve

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SolomonsDrake
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Joined: Mon Jun 14, 2021 10:36 pm

318 Stuck Valve

Post by SolomonsDrake »

I think I have a stuck valve (number 7 exhaust valve) which caused a bent rod. Any tips for getting the valve unstuck? Is it time for a full head job from a machine shop, or is a stuck valve an easy fix if the heads are off? Any difference between the heads on a marine 318 vs an automotive 318 if looking at remanufactured heads?

Thanks!

Tim
Voyager
1977 32' Sedan Flybridge
Twin Chrysler 318s
Chesapeake Bay
jralbert
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Re: 318 Stuck Valve

Post by jralbert »

I am not a motorhead as my boating pals (Hi Jeff) will tell you. But I have read enough to suggest it is probably a mistake to go with an auto 318 because the marine ones are ..well, marinized. I do not think that is advertising malarkey. I think there are important differences and a call to a couple of reman sellers will explain that to you if no one else comes forward here to do that intelligently. Good luck on getting unstuck.
-joel-
former owner 1988 '32 FB Sedan
Chesapeake Bay
twin 318 / 240 hp
Potomac MD
Fastjeff
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Re: 318 Stuck Valve

Post by Fastjeff »

..."I think I have a stuck valve (number 7 exhaust valve) which caused a bent rod."

Huh? Is the motor apart to see that "bent rod"? And was the piston beat up as well? Please clarify.

Easy to simply get a valve job on the present heads. I'd stick with the ones you have.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
SolomonsDrake
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Joined: Mon Jun 14, 2021 10:36 pm

Re: 318 Stuck Valve

Post by SolomonsDrake »

Jeff - These engines are freshly installed running takeouts that I bought used. I had some popping coming through the carb on the Port engine and my mechanic said he thought it was a stuck valve. Narrowed it down to cylinder 7 and took the valve cover off. Indeed the pushrod is bent on the exhaust side of cylinder 7. Soaked the valve in PB Blaster, but mechanic couldn't get valve to move, so we removed the heads. It looks like there was some water intrusion at some point (likely recently), with a little rust around the valve. Piston looks fine. I think the right answer is to have a machine shop do a valve job on the heads, but was trying to figure out if there is a simpler fix as I'm getting inpatient that the boat has been out of commission since May.
Voyager
1977 32' Sedan Flybridge
Twin Chrysler 318s
Chesapeake Bay
Fastjeff
Site Admin
Posts: 1462
Joined: Sat Jul 12, 2014 5:06 am
Location: Rock Halll, MD

Re: 318 Stuck Valve

Post by Fastjeff »

That's a good plan.

Look for water getting in from the exhaust manifolds. The gasket between the manifold and the riser is the usual culprit. I've learned to silicone that gasket thoroughly since the metal face tends to warp over time.

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
SolomonsDrake
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Re: 318 Stuck Valve

Post by SolomonsDrake »

Jeff - any specific tips for doing the gaskets when putting the heads back on? Head, exhaust manifold, intake, etc.

Tim
Voyager
1977 32' Sedan Flybridge
Twin Chrysler 318s
Chesapeake Bay
Fastjeff
Site Admin
Posts: 1462
Joined: Sat Jul 12, 2014 5:06 am
Location: Rock Halll, MD

Re: 318 Stuck Valve

Post by Fastjeff »

Other than buying only quality gasket material you need to thoroughly clean the surfaces. I recall how long it took for me to get the block cleaned before slapping the head back. Thought I'd never get it cleaned!

On the risers/ manifold joints, ditto on cleaning, and use a really good silicone on both sides of the gasket. And let it cure overnoight before firing the motor up. (If water's getting in, that's where it usually comes from).

Good luck!

Jeff
"We live at the bottom of an ocean of air, not at the top." General Marvage Slatington
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