Bent 350 Chevy Mercruiser Snout?

[tank1949]

I recently took a 350 Marine Chevy engine to a local shop for a complete overhaul. I have used this shop before and experienced good results. Upon installing motor, after rebuilding transom (too) , my neighbor and I adjusted Mercruiser motor mounts as I have done in the past on several other 350 Mercruiser I/os, since 1976. We put a small bottle jack under Harmonic balance since there was no lifting tab on thermostat housing. The rear mounts were semi tightened, no extra exhaust manifold weight, and we carefully raised and lowered jack (outdrive out of course) and inserted and reinserted MC alignment tool until it would easily go into MC coupler. It took several tries to get it perfect. We tightened all mounts and reinserted alignment shaft. OK!!!! But, after cranking motor we noticed that the harmonic balance appeared to wobbled. So, we swapped balancer with my other motor's balancer to determine if jack had caused problems. The overhauled motor with the other balancer still produced wobble. The older motor with overhauled motor's balancer installed didn't wobble. Hum? Overhauled motor produces 70 psi oil pressure (cold). So, I don't believe crank is bent internally, or perhaps snout is bent? I also don't believe that the bottle jack asserted (stripped motor) more than 300 lbs of force on a 1 1/4" shaft and would have caused a bend in snout. WE didn't drop motor!!! We are going to try to affix a dial indicator on snout and determine run out. If jack bent snout, then it appears to me that I could use the dial indicator to determine high spot and amount of run out. If jack cause bend, I should be able to reassert jack and hopefully take most of wobble out? If anyone has an opinion, please share. I suspect someone at shop dropped motor on end and didn't tell owner/mgr. I can't see 300+ vertical lbs on snout would have been enough pressure to bend 1 1/4" steel? This has been a boat ride from hell!!!!!!!!! Another observation is that the key on crank cannot be moved. Perhapes it is wedged and prohibiting me from installing ballancer to correct seating depth? Help!!!!!!

 

[Grub54891]

Re: Bent 350 Chevy Mercruiser Snout?

Wow,never jacked any from there,didn't want to damage it or the pulley. However,I did see 2 others break off the snout of the crank,one went down and hit the road and away,never found it,friends car. Another went up and left through the radiator,found that one wedged by the headlight bucket. Can you fix it,mabe but
I wouldn't trust it!
Grub

 

[alldodge]

Re: Bent 350 Chevy Mercruiser Snout?

Never ajusted an engine that way my self but I also don't see how it would bend the snout. If the center bolt and washer is removed from the balancer, how much distance is their from the surface of the balancer to the face of the end of the crank?

 

[achris]

Re: Bent 350 Chevy Mercruiser Snout?

As already mentioned, NEVER jack the crankshaft, that's just asking for trouble. Do the job properly, make/find/steal/buy a lifting eye for the thermostat housing. Merc put it there for a reason....

Pull the spark plugs out, get a nice strong battery and crank the engine while watching the end of the crankshaft. If you see a wobble, then you know you have a bent crankshaft. As far as fixing it... Little chance. You'll be needing a new crankshaft. If the shop had dropped it, then the balancer will have a ding mark on it, or the sump will have a bend....

Chris.......

 

[tank1949]

Re: Bent 350 Chevy Mercruiser Snout?

As already mentioned, NEVER jack the crankshaft, that's just asking for trouble. Do the job properly, make/find/steal/buy a lifting eye for the thermostat housing. Merc put it there for a reason....

Pull the spark plugs out, get a nice strong battery and crank the engine while watching the end of the crankshaft. If you see a wobble, then you know you have a bent crankshaft. As far as fixing it... Little chance. You'll be needing a new crankshaft. If the shop had dropped it, then the balancer will have a ding mark on it, or the sump will have a bend....

Chris.......

Thx for responding, but we took motor parts (torn down) to shop. We never supplied HB or pan to them. We didn't notice scratches to assembled long block, indicating it had hit concrete floor, etc. Shop stated that they only polished crank because it didn't need turning. With the pressure of belts and chain constantly asserting pressure on sprocket and HB, what little weight I may asserted via jacks seems moot. However, if crank was that week, it may have been a accident waiting to happen 100 miles offshore. I am wondering if crank key is wedged in a way that prohibits HB from fully seating on snount? Thus, this would cause a wobble. I have to jury rig a dial indicator to determine true run out on snout. Then I will pull plugs or hand trun motor to determine any warpage.

 

[tank1949]

Re: Bent 350 Chevy Mercruiser Snout?

I borrowed a dial indicator from shop who built motor. Magnetic base and all... We adjusted dial on Snout about the middle of key and rotated crank with wrench. It was .030 out of round. We perfpormed the same process several times and got .030 difference each time.

We also positioned high side of snout at the bottom and raised engine with bottle jack pressing against bottom of snout and my friend stood on motor. Snout would not bend!!!! Still .030 out. So, either crank came like this from begining, or somehow it was damaged or swapped at shop. Raising motor via HB didn't bend snout. We couldn't bend back with an additional 200 + lbs on it. Or, this .030 out of round can be acceptable.

 

[alldodge]

Re: Bent 350 Chevy Mercruiser Snout?

Sorry to hear but looks like another disassembly is coming. I think the shop should help even if they it was not their fault. They had the crank and checked it and said it only needed polishing. With it being 030 out someone missed something or as you said something happened before you got it back.

 

[tank1949]

Re: Bent 350 Chevy Mercruiser Snout?

Shope warrenteed their work, but it took almost two days to pull, install and realign coupler/mounts. They also updated date of purchase to guarentee their work. 60-70 oli pressure at idle and motor really runs good.

 

[alldodge]

Re: Bent 350 Chevy Mercruiser Snout?

Sounds great and it looks like you found a reputable shop. Happy boating