ljsmith1

Just as I thought everything was good to go for this summer.... ..Stock Merc 330HP BBC (1987). Recond heads 2 seasons ago (purchased from guy that put DART heads on his BBC - only 10 hours). Everything ran great for 2 seasons...I fogged the crap out of the motor for the winter as I always do.

Now..Today I commissioned the boat for summer..started motor up..running real rough Did not get any better as hyd. lifters pumped up. Plenty of oil and good cooling. I put new plugs in...still no better. It sounds like a miss.

Did compression check...120# in all cyl except #3 - NOTHING! WTF! Was able to pull valve cover w/o removing manifold. Found #3 Exhaust valve stuck down with the rocker arm popped off the side. Spring looks ok from the angle I see.
It may be stuck from a little rust on the stem

Questions: Is there any way that I can pop this valve back up without removing the head or exhaust manifold? Do you guys think the valve is already bent from hitting the piston? Why would this happen?

P.S. Stock type manifolds are new 2 seasons ago with no problems.

ARRRGGGHHHHH!!!! My boating season is not going to go very well this year!!!

Any help would be greatly appreciated!

-Larry

GOODT

you can try putting compressed air in cyl remove keepers and valve springs then try working the valve very carfully with a pair of vice grips spray some pb blaser on stem, be carful not to scar the stem


may or may not work....when engine warms up it may stick again or stem may be bent

MOP

What works some times is to take a brass punch and a small hammer tap lightly on the stem straight down I have had pretty good luck. Air will not work on an open valve, tap it and pray!

Phil

stevesxm

and make sure piston is down when you do it

ljsmith1

Thanks guys for your suggestions.

Update.....I ended up taking the riser off and the exhaust manifold. It looks like there was a slight riser leak right into the #3 exhaust port. I was able to just pry up the spring and valve enough to be able to use my on-the-head spring remover. Once I popped off the valve spring, I used the old keepers and a vise grip attached to a slide hammer. While I ruined the keepers, I was able to free up the valve until I could move it up and down with my hand (barely). I used plenty of PB blaster and soaked it good. I'll let it sit overnight and take a look in the AM. I did close the valve by hand and turn over the engine. It gave me 130# compression w/o the spring. I guess that means the valve is OK.

So....It looks like I need two keepers, pushrod, rocker arm, manifold gaskets, and a riser gasket set. This should hopefully get me an engine that runs well. It would be great if AutoZone had the pushrod and keepers. This way I can at least pop the engine over w/o the manifold and see if she sounds good now.What p/n's would I look for to see if they have it?

Thanks again for your help!


-Larry

Do you guys recommend using permatex #1 or silicone for the OEM riser gaskets? I used Quicksilver gaskets with the steel shim last time. Also, I made sure both surfaces were flat by running a machine file across the surfaces. They were flat when I bolted them together 2 seasons ago.

jmherbert

I was told by more than one seasoned merc mechanics to use nothing if they are the steel/graphite ones.

I had so many problems with that joint and those manifolds leaking I went to Revolutions, the #1 reason being there is no wet flange. They transfer water thru a small hose between the riser and manifold.

I don't think I'd ever put those stock setups back on any boat of mine again.

GOODT

this is correct, if using a barr or osco gasket you can use some aviation permatex

MOP

I would be checking that cylinder for rust water runs down hill!

ljsmith1

Like I said, 130# compression after I was able to get the valve up. I would assume that the cylinder and valve seals are ok. I wonder if all the problems with the leaks on this OEM riser design have to do with the long 5" bolts stretching while running and the massive cast iron heat sinks expanding and contracting...

Well...off to the parts store tomorrow afternoon!

Thanks guys!

-Larry

BillK

Larry,
The pushrod should be the same as a 1987 454 truck engine, but you need to see which diameter you have. SOme of the MC engines used the small 5/16" pushrod, others used the larger 3/8" diameter. As far as the keeper goes, see if there is a machine shop near you, they should have them in stock. Matter of fact, might be easier to take the pushrod with you and have someone at the machine shop look at it for you and match it up.
Hope this helps,

Bill Koustenis
Advanced Automotive Machine
Waldorf Md