LAC_STS

I have a boat that had a 350 in it. I just put in a new Vortec 350 and have the old one sitting in my garage. What happened to the old one was that is was slowly leaking oil.

I checked the oil before going out and it was fine. I went out and a after a while all of a sudden I saw the oil pressure go to 0. I shut the engine off and checked the oil and it was low so I added some. It only held 1 1/2 qts.

Since I shut the engine down so fast the temp got up to 210 or so. Boat engines usually run at 140 or 160. When I went to start it up it sounded like the battery was dead. It wasn't dead I even tried to use a jump start box on it. It would crank but slowly.

I let it sit for about 30 mins and then it started but there is a knock coming from the bottom of the engine.

At idle (700 RPM) you cant hear it, but any higher RPM and you can def hear it.


I plan on either fixing the engine or doing a complete rebuild depending on whats wrong with it. Im thinking either a main or rod bearing spun. I didnt trouble shoot it before deciding to drop a new crate engine in because I just wanted to get back on the water.

So Im going to pick the engine up at my friends shop in the next couple days. Where do you guys think I should start?

Compression test?
Leak down lest?
Drain oil and look for metal particles?
Drop the pan and check the bearings?
All of the above?

If it is a spun bearing can I just change the bearing and thats it or do I need to completely disassemble the engine and clean everything out?


Any help/suggestions are greatly appreciated. Thanks

JTM

Remove the oil filter first, cut it open and inspect the filter for metal/bearing content. They make a specific tool to aid in cutting the filter open. If you have spun a rod bearing, you'll most likely need to have the crank turned and your rods resized. If you try to just replace the bearing on a spun rod, your going to have more problems and it will be a waste of time. If it is a spun bearing, you need to disassemble the engine, clean the block and all of its oil galleys. I would take it to a reputable machine shop, have the block & crank cleaned and magnafluxed, then start from there.

LAC_STS

Thanks


I will do that as soon as I get the engine back to my house.

F-Body Lover

I had the exact same problem with my old '78 vette it turned out the timing was waaay off

LAC_STS

It only did the starting thing when i was trying to start it after the low PSI and high temp.

After I made it back to the dock and let the engine sit for a while it will start right up.


I think it was a combination of the low oil PSI and how hot the engine was. Im hoping it wasnt a zillion metal particles stuck in the engine from something.

brandoz28

iTrader: (3)

sounds like the timing may have jumped to be advanced. this will cause it to crank really hard when its warm, and you may have been hearing detonation

F-Body Lover

yes that can do it also

1 FMF

iTrader: (1)

regarding the old motor...
-what year is it?
-how many hours on it?
-is it also a vortec motor, what's the cylinder head casting #'s ?

since you already bought a new crate vortec, what are you going to do with the old one if you rebuild it? I guess it would depend on how much cash you plan on throwing at it, you could build a 383 out of it and then drop that in if you're in to that sort of thing. Or are you going to rebuild it then put it aside in your garage and have a spare boat motor just in case ? There are people that carry an extra set of points if they have a points ignition, some people carry an extra electronic ignition pickup ($$) just in case, you could brag you have an entire spare engine. But to be realistic, if you want to tear into it for the experience then go for it, but don't get your hopes up to much thinking you'll make money back by being able to sell it in this economy. You may get lucky, 350's are common boat motors and somebody might want it, but you may have better luck parting it out depending on the year of the motor.

take the plugs out of the old motor, get the motor on an engine stand if possible but don't need to, rotate it by hand from the flywheel or crank pulley. It'll be heavy but should be smooth. If it grabs or you can't rotate it smoothly then that's a good indication some main and rod bearings are fubar'd and there would be no reason not to pull the pan and inspect.

LAC_STS

Thanks FMF.

All I for sure know about it is that its a 2pc rear main seal.

When I bought the boat the guy gave me $5K or so in receipts from having a rebuilt engine installed. I noticed after a while that the receipts were not clear on exactly if an engine was bought from the marina or where from so I called them and they said that the guy had brought them a long block and they used the old engine parts and installed it. The dates on the receipts were from March and supposedly it only has about 65 hours on it.

After all the bs with the engine (the rebuilt one that came with the boat when I bought it), I bought the Vortec engine and when I did they said that the flywheel and coupler would fit from the old engine. But when I got to installing it it didnt fit and the reason was that the old engine was a 2 pc seal which takes a 3 1/2" bolt pattern flywheel and the new Vortec was a 1 pc seal which took the 3" bolt patter flywheel.


The engine is still at my friends shop. I should have time to get it this week. Then I will get the numbers off of it.


If I were to sell it I just meant if I could fix it and sell it. Then I could recoup some of the money I spent on the new engine. If I open it up and its a spun bearing maybe I can just fix it and then put it back together and sell it. It would be a complete engine if I did sell it whole. Complete as in, manifolds, risers, carb, IGN, flywheel, etc. I even have the coupler to it.

If I have to do a rebuild then thats where I will have to make a decision on whether I should rebuild it and sell it or if I should part it out.

I see used complete to semi complete 5.7's on CL and ebay all the time for about 2K. A fresh rebuilt one maybe more.


Oh yea. I'm 90% sure its not a Vortec engine.


I was also thiking about keeping it as a spare or something. Or maybe finding a small boat about a 20 footer and putting it in there with a new SEI drive.

1 FMF

iTrader: (1)

i forgot to mention that you may have better luck selling it as is and letting the buyer rebuild it. My opinion on something like this is i wouldn't trust a private seller selling a rebuilt engine. I'd rather pay less and pick it up busted and then be in control of the rebuild, so i think you would have better luck going that way versus having it rebuilt then trying to sell it. After all, your previous owner had receipts of a rebuilt engine and look how far it went. And unfortunately the pre-vortec low compression 350's are not that sought after, especially the heads and intake. The block, if you were to advertise short block pre-vortec 2-piece rear main, you might have good luck with, that would be in demand by people who have the older motor and maybe had freeze damage or something and are looking for a cheap fix. Then you could negotiate if buyer wants you to have it rebuilt or whatever. Those who have the money, if they're smart, just get a crate vortec like you did. And the heads on the pre-vortec I think you would have better luck selling separate because like before someone may just be looking for a cheap replacement fix.
you can price out marine 350's at basicpower.com, jasper, and rapido to see where you would have to price yours.

and if you pull the pan, look at the big end of all the rods around the bearing, for bluing on the rods. If it ran dry and ate the bearing, there's probably evidence of the rod overheating in which case those blued rods would need to be replaced. If it was a quick loss of oil pressure and the motor never seized then the damage was probably minimal and you could get away with just replacing the damaged main & rod bearings and doing an easy internal cleaning and inspection.

LAC_STS

Thanks,

I run into people around me (im in S FLA) all the time looking for engines.

Everyone wants the cheap way out. People want to get on the water with minimal money out. They dont think about the best thing to do like I did (just buying new Vortec engine).

Jasper, USEngine, etc all run about 5K for a complete Vortec engine at least. Yea you can buy a long block but most people dont know how to do stuff like that and would end up having to pay a marina $$$ to build it up.

There is probably 1 person a week on iboats talking about replacing theyre 5.7.

Not arguing just saying.

If I have to rebuild it I may consider selling it as is but Ill probably just rebuild it. Like I said, even if I can rebuild it and almost break even Ill be happy for the learning experience.

The engine never seized. It still ran when taken out it would just knock at over 1500 or so RPM. It still started up great and sounded great at idle. Hoping for the best I guess. lol


If I end up not being able to sell it I will find a project boat and put it in there with a new SEI drive.


Thanks again for the help