Probably have a bent push rod on my IN/OB mercruiser. Anyone have any idea how much a rebuild costs? How long it takes to get it done if the dealership isn't swamped?? Thanks guys.

Not a good time of year for that. I would guess 8 - 10 weeks and 12,000 on a 502 or 3,500 on a 2.5 4 cylinder. Is motor ticking or missing? Check to be shure thats what you have, may be a broken valve spring. Easy fix for push rod or valve spring.

Motor was knocking only under a load. It sounds fine in nuetural when you idle it up. It just starts clattering when you get past about 2k rpms. So are you saying that if its a bent push rod I don't need a complete overhaul? Thanks for the reply.

BTW, I thought for sure it was a timeing issue. The motor isn't ticking. I would have to say it is missing on at least one.

On the pushrods, you can actually bend a pushrod or spit one out and the motor be just fine. Been there, done that. If you over rev the engine, the hydraulic lifters can't keep up and the pushrod escapes. Pop the valve cover(s) off and take a look.

It sounds to me like your timing may be advanced way too far if it's clattering/detonating. Try turning the distributor housing clockwise a few degrees. it would be best to have a timing light, but you can get close by ear/feel. Adjust until it quits detonating.

Could be some sorry fuel too.

Thanks for the replies. I am going to have them pull the intake and go from there.

Have them check the drive coupling bolts.

They don't need to pull the intake to find a pushrod issue. The rocker arms are likely adjustable, and can be done from the valve covers (much less involved). if a pushrod is found out of it's hole, and intact, it can be checked for straightness and reinstalled without pulling the intake. If all this is the case, and the engine wasn't over-reved, then checking the valve lash on all the cylinders is in order. Again, all this can be done under the valve cover(s). Not necessary to pull the intake unless bigger problems are found.

But if its clattering under a load, then timing is the most likely culprit, typically a much easier fix.

Pysco- If it is a bent push rod from over reving, do you think I am looking at repowering? Or could I get lucky and not have any piston damage or anything like that?

Pull the plugs,they can tell a story.Also compression test engine. Also what year,size,and fuel injected?

The push rod opens the valve. If the valve won't open, then it won't get hurt or hurt anything else. What you're worried about in this case is damage to the lifter, the pushrod, or the rocker arm. More specifically, and metal shaving that got loose and circulated through the oil system. A rocker arm and push rod can be replaced easily. A lifter? Depends on the engine that's in it, how it's damaged, and how bad it's damaged. You said something about removing the intake, so i assume it's a V-6 or 8. So yeah, if the lifter is damaged it's a little more in depth. Inline engines can be much more simple to service the lifters.

I'm not scared of engines. So if it were me, and I had reason to suspect the valve train, I'd pop the valve cover off and see.

Easy way to see which cylinder is missing.....Crank the engine on a water hose at home, or in the water at the lake, and pull a plug wire. If the engine changes it's idle condition, then that's not the missing cylinder, replace the wire and try the next one. When you find a missing/dead cylinder, the idle condition will not change when you pull the plug wire. Oh, and wear some mondo insulated gloves to do this. Getting zapped by 30,000+ volts will wake you up the first time. After that it just pisses you off.

Now you know where to look. First I'd pull the plug and see what it looks like. If it's not fouled, I'd check the wire for spark. If that checks out, I'd compression check the cylinder, and the ones to each side of it. THEN, I'd pull the valve cover and inspect the valve train.

No offense meant what so ever. But if any of this is intimidating to you, I suggest having a mechanic look at it. There are also a huge amount of variables depending on what engine it is, and what the symptoms are. I tend to think in Small Block Chevy language.

Yep, the first thing I'd do is pull the plugs and take a look at them. They can tell you a LOT about how that motor is running.

If a valve is not opening, a compression check will not typically show it. But it is great info have.

And yes, by all means. Year, make, displacement, more info on what we're talking about here?

I didn't think about that Psycho, your very right(compression test and the other stuff).
Sometimes you just need a major tune up.How many people only change spark plugs? Me too unless there's a problem.

Thanks guys. I took it in and am just going to hope for the best. I priced a new 350 V8 while I was there and it was about $6000 installed.

Remanufactured- Not new