re using large marine diesel motor

Salt water has a unique ability to profoundly damage engines but it's worth a shot flush it out with fresh water and give it a try .Obvously if you need it to be guarenteed you have an exspensive dilema .Most likely it's junk bearings quickly corrode and fail but I suspect it's free .Otherwise the rebuid is still risky I would flush it and run it but anyone will tell you you can't .

Do you know for a fact whether or not the engine was running at the time it sank?

No, motor was switched off and not running when boat went down,

We see outboard motors frequently when they have been a few days in salt water. The priority is to IMMERSE them as quickly as possible in clean fresh water.

Then rinse off thoroughly.

As the engine was stopped, you have a chance that the mechanicals will be ok, but you will probably need to replace some electronics and some wiring.

We have jsut completed a 4 cylinder diesel, and we replaced the Electronic Control Unit but still had to repair several sites of corroded copper in the wiring harness caused by cathodic corrosion as the 12 volt power was still on until the battery was completely flattened.

Check out the economics, the project could be a real winner, but it could cost more to repair than a secondhand unit would cost in good running order.

Good luck

www.explorermarine.co.uk

Along with what Genome1 is asking, if the engine was running when it sank and stopped due to hydraulic lock, you'll have some bent rods in the engine. You can't compress a liquid so something has to give.

Corrosion will soon be a problem so it must be cleaned very soon.

Good luck

Float planes routinely drown their engines, and that requires a major overhaul, ie new engine.

A have drowned 2 outboard motor boat engines, both while running. One blew the head gasket out and never ran very well afterwards. The other the ignition took a huge hit, but was mechanically OK.

If it is free, or cost of replacement = rebuild, or your cost / benefit / reliabilty guarantee will probably make your decision.

If you have any hope at all it will need to be rinsed and dryed and oiled ASAP. Salt water is nasty.

Whether running or not when submerged, you will need to do a full overhaul, your safety is paramount.

Whether a 6, V8 or V12 cylinder engine, at least one cylinder will remain with inlet and exhaust valves open giving a through path for air and sea water. Depending on which way up she is sitting, tidal coverage, sea water - air(oxygen), sea water - air, is the worst environment for corrosion, your engine won't look too good either, so check everything. Throw the oil away, flush all the oilways. Water in oil is no good for cylinders, bearings, gears. Exchange the turbocharger, all filters. Decide or get professional help as you go along, safety is reliability.

Maybe your insurance company will require certification that you have carried out a full rebuild

We intend doing a complete strip-down, replace all gaskets, bearings, and filters etc. Motor is a 6 cylinder MTU unit used in the long line fishing industry, I believe the motor was made in Germany.

In addition to all the above technical concerns - I assume that you've checked local maritime law regarding salvage rights etc. I'm ignorant but curious

thats all sorted thanks

Hello: I have worked with (drowned ) engines befor; completely flush the engine out with OIL, not water; you can even use recycled oil, to spare some expense; ensure that all the elctronics are dry and in order, and fire it up. The nice thing about marine diesel engines, is that they can take a lot of abuse, and be reused, after cleaning them.

Good luck.

The biggest problem you have right now is the change in tide; every time there is a tide change you are exposing much of the engine to oxygen, hence oxidation as well as salt corrosion. You may have some electrolysis going on as well, especially if the batteries are still hooked up.

I would suggest that once you have got the engine off and on a stand, remove the injectors, injection pump and turbo and drain the crank case. Hand crank the motor over to clear the cylinders of water. Add a good volume of something that will displace the water and or mix with it and still has some lubricity, to the crank case, (in the past, I have used Pine-Sol), and crank the motor over with the starter. This will help clean out the oil galleries and passages prior to disassembly. Also, immerse all parts in mineral spirits or diesel as you remove them from the engine and you'll probably salvage just about everything.

Prior to taking on this project, check out the cost of parts for a MTU. It may stop you in your tracks!

tidal exposure will greatly increase damage. I suggest you remove a rocker box and check for rust/corrosion before removing the entire engine. If OK good,no guarantees on anything else. If bad--you saved a lot of work.

Please let us know the outcome!

Hi there

Suppose engine's model is a 186. 186 is basically a Mercedes' engine (very common use on Mercedes' trucks, and spare parts are easily available).

Anyway, after removing from sea, a complete overhaul is necessary (a W5 maintenence work). To remove the salt from the engine you should do the following:

wash engine with water, just to remove dirt from outside

completely dissassemble the engine, until smallest screw is off

wash individual parts with water and blow dry with compressed air, and immediatly

immerse parts in anti-corrosion oil.

(now starts the heavy job)

parts should be taken from anti-corrosion oil bath, and hand-cleaned as:

case of machined surfaces, moving and alluminium parts:

clean using anti-corrosion oil and soft brush (I used scotch brit, a green brush used to clean dishes), then

dry with thiner blowned by compressed air and store.

case of non-machined parts (engine block, cyinder heads)

removal of anticorrosion oil with thiner,

cleaning with rotating metal brush until it's metallic clean and then

wash with thiner blowned with compressed air. Store.

small screws M5, M6,M8, M10 and M12 consider replacing by new ones ( cleaning them is a hard job). If not, clean each one of them with rotating metal brush.

Replace all gaskets, o-rings and seals, replace the bearings and rinse crankshaft oil channels and main oil channel by recirculating new anti-corrosion oil (dry with thiner).

Then assemble according to MTU's specifications and paint.

It should take about 3 weeks to have the job done and it's not a easy+cheap job, but the engine is so good (and expensive) it's worth the work.