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2021 383 stroker mercruzier, are the bearings smoked?

C

Cracker32

New member
Customer repowered in 2021. Has had problems off and on ever since. Think I was the fourth mechanic to look at the boat. When I got to the boat I found the lipstick broke off in the tube, and the distributor housing cracked where the cap screwed down. boat ran fine for about two months.

He said that the engine bogged down and after letting it sit for about 30 mins it ran fine back home. I found some oil in the bilge couldn't locate the source. So went on a sea trial and after 20 mins seen oil coming out of the dip stick and strb valve cover. Limped home and the strb valve train started making a lot of noise and never stopped. Went to pull the head and found a sheet of folded plastic under the intake, over the push rod seats.

now I'm worried that the crankcase had so much pressure it could have smoked cam or crank bearings..... has anyone seen anything like this in a crate engine before. How concerned should I be about the bearings? The noise while running sounded like it was all in the valve train. No oil I can imagine it sounding rough like that.

https://yourimageshare.com/ib/zNBIOn6NWU

https://yourimageshare.com/ib/VsxtkwIDvV

All thoughts welcomed.
 
The plastic slide between the push rods and the seats in valley. Doesn't the oil flow through the push rods? If the plastic is in-between the rod and the seat, it would make sense that I could hear the rockers. My main concern is the build up of pressure that caused the oil to pump out of the dipstick tube. That much pressure in the crank case could hurt the bearings I would think. But this is a one off for me.
 
The oil pressuregot high enough to push past the rings, or the intake valve seal in #4 the plug was coated and electrode melted off.
 
the potential pressure buildup inside of the crankcase will never get anywhere close to the pressure in the oil galley....there's no way it would get 'pushed' past the rings in any significant quantity....the lack of lubrication very likely enabled a temperature rise which crippled the valve seals - and probably exhaust much faster than the intake...

I didn't see anything on the plastic film in the video to indicate it had lodged between a lifter and a pushrod...that said, you have the first hand account.

If you a spark plug meltdown, I'd pull both heads at a minimum...and check the pistons for damage...If the bottom end still rotates freely, I'd use it...If you want to be thorough, the time to plasti-gauge the bearings would be a good investment...
 
All bets are off since this is obviously some kind of who knows what engine. Maybe I don't know anything but I don't think Mercruiser put purple roller rockers in any of their engines. It's prolly a regular automotive engine that some brilliant bloke thought would be more powerful.
With that said, my guess is that it was assembled wrong. It would be best to do as Mark suggests and check the bearings.
 
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