Mercruiser 5.0 V8 cranking

[dlogvine]

Just got a Larson SEI 200 BR boat. with Mercruiser 5.0 V8 engine. At first thought that the starter does not crank, but when tried to turn the engine manually, realized it was frozen. So I removed the spark plugs, they were pretty rusty, and filled the cylinders with Mystery Marvel Oil. Let it sit for a day and managed to crank the engine, it turned with effort, but it turned. So my question is, is there any chemical compound I can use to unlock and clean the cylinders, would really hate to remove and rebuild the engine. Or should I just keep pouring mystery marvel oil and keep turning the engine until it goes lose?
Second problem is the lower outdrive unit, there is a little part of chipped right where the stabilizer fin is connected so that both holes are missing, the chip is about 5" by 1 and 1/2" size. Should I try to weld a piece of aluminum and put a new stabilizer on it or should I be looking for a replacement of the outdrive lower unit housing? If so where should I look for it? the cheapest one on ebay is about $150-200.
Thx

 

[tpenfield]

It is hard to say if the cylinders will free up and be good enough to hold compression. What does the engine oil look like ?

Post a picture of the 'stabilizer fin' if you can. These things can usually be fixed, but a picture would help with responses.

 

[Scott Danforth]

regarding the engine, depending on how long it sat with water in the cylinders causing the rust, you may need a rebuild. you will definately need to find the source of the water injestation.

regarding the outdrive, you have more than a little bit missing if the little stabilizer annode is missing. post a picture.

 

[dlogvine]

No Title

The oil in the engine is clean, no milky streaks. Tried to turn the engine by hand today wo the spark plugs, turns but with an effort.
The outdrive pics are attached. The anode is not missing it is still there, the chipped part is more like 7" by 2" or even 3"

 

[Scott Danforth]

that is an easy weld repair for most shops. my opinion for the reason it broke was someone bolted a fin to the anti-cav plate.

the fins are not factory. while they work on some outboards, I would keep it off. I would also have the weld shop weld up the other two holes.

 

[Mercruiser420]

Its not simply a matter of getting the engine loose. The problem is that piston rings will rust/freeze in their grooves. They need to be able to move when the motor is running. I'm sure if you try hard enough and with enough marvel you'll get it moving without effort but if the rings are frozen you'll lose compression and possibly further ruin your cylinder walls beyond the maximum 0.060.

When you say your spark plugs are rusted chances are so are your valves/seats. The correct way around this is a teardown and rebuild..considering you just got the boat, who knows what else you might find. I've taken apart plenty of seized engines and believe me, even though some of them werent that badly stuck, theyre usually ugly on the inside. I know I wouldn't take the risk. Good luck.

 

[dlogvine]

There is a fin or at least right half of it in the boat, so could be the fin that broke the plate. I did not know that this could happen, on my other boat I have a fin sitting there without causing any problems, not sure though if it is a factory one or later add-on.

 

[bruceb58]

The cavitation plate breaking off is why you should never put on a Doel Fin or similar device.

Once you get your engine running, do a compression check. I have a bad feeling that it won't be good.

 

[Scott Danforth]

factory NEVER put on a fin

 

[alldodge]

It wouldn't take much to pull the distributer and the intake. Once the intake is off you an look at the intake valves and see if they are rusty. If rusty you need a rebuild or replacement.

 

[dlogvine]

Tried to crank the engine again, no luck. So me and my friend removed the exhaust manifolds and then the covers. Left side was perfect, but on the right side two front cylinders were frozen. There was a lot of gunk in these two cylinders they were just filled with it. So we took apart the engine, removed it from the boat, had to remove the outdrive as well. There was plenty of rust on the outside, likely the previous owner left it under weather without any cover for so e extended periods of time. There is some work to be done to take apart the lower block, and the engine goes to machine shop. Hopefully the cylinders are not too damaged so they could be just honed and would not need reboring.. will put some pictures of the engine tomorrow.

 

[dlogvine]

And another couple questions. First one, i could weld the aluminum plate to the broken part, however i got only a propane torch and some aluminum rods low temp melting point from harbor frieght tools, but im not sure how strong is this type of welding. Should i instead look for a real industrial welder at the shop?
second question, maybe not in place in this forum, but i started working on upholstery and need some advice on where to get some instructions or better some videos. I managed to sew the panel covers from vinyl and they looked semidecent, however could not stretch them well.

 

[bruceb58]

Get a real welder to weld it on there for you. If you bring the drive to him, it won't cost much.

For sewing, there are a few places to go

www.Sailrite.com

http://www.upholster.com/upholstery-forum/

For material, thread and tools www.rochfordsupply.com

For some reason the second link looks weird in my browser. Hopefully, it is only temporary. Excellent resource for people starting out.

Do you have a walking foot machine? If you don't, you are not going to get good results. Main reason is you won't be able to use a large enough thread. You want to be using a polyester V-92 thread.