What to do next ? took Volvo apart...

[john232]

I Needed to disassemble My Volvo, 1980, MD7A, 13 HP engine, in order to inspect this engine for salt water dammage since it was under water for a brief period of time when it was being pulled off the rocks by a salvage company. Anyway the boat sat on stands for about a month before it was delivered to me about a month ago. As of right now the engine is broke down to just the engine short block with the transmission drive still bolted on to the engine and the engine is still attached to the engine mounts, the CAV, fuel pump, water pump, thermostat cover, front engine cover plate that is behind the flywheel is off, exaust manifold is off, of course the head is off, fuel tubing and hoses are disconected and put up, ect. ect. ect... All the bolts and nuts came off with no problems (I was worried about stripping some). HERE IS WHAT I OBSERVED, (and I am a rookie when it comes to deisel engines) The raw water channels in the exaust manifold looked surprisingly clean for a 20+ year old engine, all the seals/gaskets on all parts of the engine looked healthy, no blow throughs or dammaged areas of any gaskets or seals what so ever. all the teeth on gears were in great shape, the head looked good, the valves had some carbon on them but nothing major, The injectors had carbon on them also and looks like it will take some muscle to get them out and rebuild them, as far as I can tell the rocker arm looked fine. The top of the pistons had some thin black carbon on them but I think thats normal for an older engine, I did not see any rust or corrosion anywhere that I could see inside the engine. There was alot of salt water in the lower part of the engine (under the piston rods in the oil pan) but I got all the water out now and have sprayed other lubricants in there just in case I can''t see an area that is corroding. Water was in the air filter and surrounding area but I guess there was enough lube in that area to prevent any corrosion to happen. Also when I took the head off I noticed a little water sitting on top of the pistons, but it didn''t seem to start the corrosion process there either. I don''t know if I should take apart the transmission drive and check it for water intrusion, or if there is a easy way to check the tranny for possible water penatration. HERE IS MY QUESTION: Shoud I take the engine out of the boat and have a mechanic go over everything or rebuild the engine and replace bearings and do a valve job ect. ect. or should I just get new gaskets and paint everything and put the engine back together, get new ultranator and re build starter re wire and start it up and go on to somthing else?? Thanks for your replys and opinions. John

[Stede]

John232,

Here is a link that might help you. Good luck!

http://www.marinemechanic.com/site/page108.html

[AJS]

John232,

I''ve been reading along about your boat restoration adventure and wish you the best of luck.
Regarding the engine that was dunked: You have to take the whole thing out of the boat and completely disassemble it. It may look fine at the stage you have it at right now but the crank and rod bearings have to be looked at for pitting or scoring as well as cam bearings and countless other bearings. These are the surfaces that determine whether the engine will continue to run or not. Yes, the outdrive must be disassembled too, for the same reasons. There are lots of dissimilar metals in contact with each other in an engine that may begin to corrode galvanically as soon as salt water is introduced. The fact that it sat for a couple of months afterwards without being flushed out would cause me not to hold out much hope for this engine.
I''m not trying to be discouraging here, just realistic. There are a lot of close tolerances in a diesel engine that won''t accept being pitted. Especially in the injector pump.
So, to reiterate: take it out of the boat and take every piece apart. Make sure you have a shop manual to guide you so you don''t damage anything unwittingly, or have a pro do it. (Maybe talk to a pro first, he might have experience in this area and know just what is and isn''t required.
Good luck and keep us informed.
AJS

[FloridaWriter]

I don''t think you need to disassemble it any farther nor pull if from your boat. Sounds like everything is fine. I would of course have the start (is it a Bosch starter/generator like on the MD2?) Also anything electrical that got wet like the regulator, for example.

Then I would soak down every in Marvel Mystery oil as I reassemble. Change the oil and filter, start and run the engine for 15 minutes or so. Change the oil and filter again. Run it for an hour or so. Change oil and filter a third time. Run it longer. Do a final change of oil and filter and you should be fine. Volvos are tough engines and it doesn''t sound like this one was damaged. Generally speaking the worst damage from being back-filled with sea water, or from a sinking is trying to start it with the cylinders full of water which can break something.

[AJS]

I would normally agree with FloridaWriter. If the engine had only been submerged yesterday you should be able to run it, flush it out and all would be ok. But the sitting for 2 monthes before being cleaned really worries me.
AJS

[Jeff_H]

I strongly agree with AJS. If this engine has been sitting with water in the crankcase for as long as it had, you need to do a lower end rebuild.

Jeff

[john232]

FL Writer: I think you are right about your evaluation. The inside of the engine, like all the head components look great with NO signs of any pitting or rust or corrosion in any way, shape, or form. The piston tops are in excellent condition and after inspecting the rods with a light and magnify glass I didn''t see any problems. I am going to do what you said after a mechanic at the marina looks at the head and gives me a good report and then I will clean and paint everything and start it up. I put 5 quarts of mistery oil in the engine when the boat arrived at my location a month ago and maybe that had a positive effect early on. later.

[RichH]

With MMO in the crankcase, and a few tablespoonsful in the combustion chambers (injectors out) attempt to rotate the crankshaft with a wrench. If the engine crankshaft is difficult to rotate, ADD more MMO to the pistons/cylinders and attempt to rock the crank back and forth until its easy (with injectors removed). Keep rocking and soaking until free - to make sure the piston rings are not stuck/frozen in the piston ring grooves. If the rings are ''frozen'' the engine will be very hard to turn-over by hand ..... and you can easily break them if you force them. If/when the engine turns by hand easily, then spin the engine with the starter in several ''increment'' rotations - then let sit. Sop up or vacuum excess MMO from the combustion chambers and replace the injectors. Open the valve cover and inspect to be sure that the valve stems are not stuck/frozen. If a valve is stuck, soak the stem with MMO and just push/pull it in and out a few times until free - ''whacking'' with a phenolic hammer is OK. Start the engine, run at NO LOAD / IDLE until the engine is at normal operating temp, then shut down - this will distribute the MMO in the oil galllery and begin to polish the valve stems, the piston ring grooves, cylinder walls .... any/most surface rust "bloom" will be removed. Keep a rag handy to jam into the air intake in case the engine starts to "run away" - idle at extreme rpm. The rag will block the air intake and stop the engine. Let the engine sit a day or so between running. Repeat several times. Then change the crankcase oil and run the engine normally. (You might want to consider adding a pint of MMO to the crankcase oil every time you change thereafter.
Sometimes you can take an engine that is totally ''locked'' by internal rust and get it going again with a MMO soak. The whole ''trick'' is to be sure that the rings are **free in their grooves** before attempting to start .... or you can easily break them. Save the MMO from the crankcase and put it back in the crankcase once yearly, run at dile / let sit) then remove - to remove the crud/carbon from the piston ring grooves. This will help to keep your compression at maximum.

Marvel Mystery OIl - a ''funky name'' but great stuff.
I use it mixed in the gasoline of auto engines to ''top oil'' the combustion engines, etc. to prolong life. Great Stuff.

Good luck.

[FloridaWriter]

Actually you can open the compression releases and just turn the engine over for a while before starting to get the MMO circulated.