Detroits 8v71's

[gbmacca]

Boat sunk in February and managed to get the motors turning. 'Don't touch or you will get less back from the insurance!'

So after a week - left sit. Now - with a minimal 'Go take a jump' payout from Insurance company am trying to get motors to turn.

'People' have suggested pouring diesel down the bores - rust removers and a mix of 50/50 acetone and hydraulic fluid.

Any 'knowledgeable' persons out there with previous experience?

Cheers

Gbmacca

[a64pilot]

Yes, do what people suggest although I lean towards Marvel Mystery oil myself, get it in there as soon as possible

[gbmacca]

Hi

Am in Australia so not all your products are available here.

Watched quite a few blogs and the general consensus is that Auto fluid and acetone 50/50 seems to be the best for ridding rust - although remember ---
'rust never sleeps!'

HAve been trying for 3 weeks now - but still no movement.

MAnaged to save batteries - 32v - and starters seem to be fine - so will try to crank on crown wheel as this may give better leverage.

If we get them going - then have to tackle electrics ---- joy!

Cheers

Gbmacca

[Lepke]

If the motors turn the bores aren't bad. Diesel, if anything down the bore. The big issue is getting all the water out. You don't want even a little hydrolic lock.
I"ve salvaged several engines in my life and been running DDs since about 1960. In fresh water and the engine was cold going in, almost zero damage occurs in short immersion. In salt water the big issue is getting the salt out. I'd pull the injectors and turn it over to see what water comes out. Then with a tubing that fits the injector hole, remove any water with a syringe or small pump. Also compressed air down the injector hole while rotating the engine and blasting the loose water out the ports. The fuel system is closed so should be water free. Use some tubing to catch fuel coming out the open inlector tubes.
Fresh water sunk engines, I make sure there's no water in the cylinders, the injectors operate freely, and no water in the pan. Often all the water is from the intake and airbox into some of the cylinders. Depends on the seals, valve covers, etc. Drain the airbox.
Once I'm convinced all the big water is out, and change the oil if there is water in the pan, (the filter is part of a sealed system) so leave it for now, replace the injectors, set the rack, circulate fuel and start it up. Warm to normal and change oil, filters and maybe coolant. I put an electric fuel pump in line to circulate fuel for 30 minutes prior to start. Have a plan for emergency shutdown. I've never had a runaway. My father had 1 in a 40 year career. Not as common as the stories.
Saltwater engine similar, but probably several oil changes, analyze oil until no salt is apparent.
If you have to take off the heads, then I'd pull it apart and usually put in an engine kit.
I have overhauled several of these salvaged engines, thousands of hours later. Usually finding no internal differences. A couple I didn't remember until informed by the owner.
Several times I have been called to diesels where the owner was excessively cranking a cold engine in winter and left the sw seacock open putting water up the exhaust and into the airbox. A little water is ok if the engine hand cranks completely over. Little water meaning drops of water.
I know this sounds half assed, but Detroits are durable. I ran one in Vietnam with a 6" hole thru the airbox for 30 minutes. It didn't run good but it ran.

[Bill Seal]

Like the suggestions, just pull the injectors and pour some Marvel Mystery Oil or PB Blaster into the cylinders and let it soak. Unfortunately, since they're V8s, you're going to have to heel the boat over 45 degrees to get the oil to the top of the piston. , or pour enough oil in to fill the cylinder.

[gbmacca]

Hi Lepke
MAny thanks for your response. Most informative and unlike a few people I have spoken to, you seem to know your business!
Motors went under in salt river, had them turning then a week later - I had to go away - they wouldn't turn. Socket and bar - thought one was turning but was just the pulley bolt so stopped that quickly. Saved batteries so tried to crank with them - clunk clunk - so stopped that!
Told to leave them as insurance would pay - but now - 9 months later and after a lot of legal hasselling - paid me a 'ef off amount' which is no where near enough to rebuild motors.
So, am trying again to turn. HAve removed injectors and pouring a mix of acetone and hydraulic fluid down which I ahve been told can take a month or two before things start to free.

Put camera down bores and they look good with a little surface rust.

First dick told me to take off side plates so fluid pours down side of motor. Will replace these.

Another said, drain sump and reuse (originally drained sumps and gearboxes) what in there as the sulphate in the oil, plus diesel, acetone and hydraulic fluid a good mix - so will try that.

Blowers look to be ok but of course can't rotate to see if stuck.

The vessel is a 55' Chris Craft Constellation with twin Detoit 8v71's so a little hard to turn on a 45 degree angle as suggested, but any advice is greatfully appreciated.

All the best to you all for the coming festive season. 41 centigrade here yesterday - how you guys going?

Cheers

Graeme

Perth Australia

[Bill Seal]

The 45 degree was sort of a joke, but it might actually work on a monohull sailboat. you might dream up some way to spray the oil or PB blaster or whatever up to the high part of the piston so as to get the oil coating the entire cylinder.
I freed up a rust stuck Volvo Penta once by making up a bar with a couple of bolts welded to it so they could get between the spokes on the crank pulley so I could wiggle the crank back and forth.

[toddedger]

I had an instance with a old Chris that sank this summer in freshwater. Both 8-71s were hydrolocked. Waited about a week for insurance to sort out and diesel company to show up. Mechanic removed air box covers and was able to slowly turn engines over by hand. He used an electronic scope to look inside engines and was amazed at the condition. All the leaky Detroit oil seems to have floated on top of the water and put a nice preserving coating on everything as the water level went up and down. Changed the oil, added new airbox cover gaskets, and started them up. Three more oil changes to get all the water out and back in business. There was no pulling injectors or pouring anything in cylinders.

[jimbunyard]

No-ones suggested it yet but take off all the air box covers and have a look.


(oops, I see someone has suggested it, ^^, but it's still a good idea...)

Some of the tops of the pistons will be visible, and may give you an indication of what's in store.

The good thing is that parts are ubiquitous and inexpensive if it comes to that...

[gbmacca]

Thanks guys.

All good sound advice.

Wish my engines were as clean and as accessible as the photo shows but will see if I can get to the air box covers and remove.

If I do, will all lubricant poured down through injector hole, just piss out into the drip tray?

Will also look on pulley to see if any threaded holes which I can put a couple of bolts into. Much better than breaking off the pulley bolt.

HAve been quoted A$15.000 each to rebuild, plus removal, plus slipping, plus reinstall - looking at $50.000 odd grand - which as a non paid pensioner - I don't have. Bugger!!

Another option is to get two motors and boxes I have found - but they are turbo's and I think from their red colour were marinised up in Canada so would ahve to change exhausts, fittings etc and take the risk of buying unknown motors with no past history!

Cheers

Gbmacca

[jimbunyard]

If your air box drains are clear, what you've put in the cylinders will have already drained. If not, it will come out when you remove the air box covers.


Though you've probably done this if you have the injectors out, full loosen or remove the rocker arm brackets too. Stuck valves can lock up an engine just as tight as stuck pistons. So can a frozen blower, so take out the blower drive shaft or remove the blower drive coupling as well.

[Lepke]

If you're buying used engines, a leak down or compression test will give some indication of the cylinder/ring life left.
Since the engines were loose and now stuck again, probably things are not too bad. If you're going to pour something down the injector hole, use diesel. WD-40, popular here is made for Water Displacement in electrical equipment, and has almost NO lub qualities. It became well known after a Texas hurricane. Remember you have dished pistons with a dimple under the injector. The best way is with a syringe and a tube you can point to the uphill side of the piston so all of the rings are coated.
If you don't have a service manual, by joining boatdiesel.com, you can download a pdf there. Ebay is another place to look to buy one. With a service manual, great care, and some tools, a person will some mechanical ability can rebuild those engines. That how I learned about 1969. The only help I had was a guy on a radio and a WWII manual.
Detroit Diesels under their original name of Gray Marine, was designed to be rebuilt in the field, along with the engine accessories. If you go that route, the sleeves are the only unique part. Each sleeve has to be a height that the head gasket can seal the cylinder. Service manual will explain. Each existing one should have a part number. You need to write that down so the same new sleeve goes in the right hole.
If you can't get it started or decide to overhaul, I did my IL671s for about $2500 US each. That's sending the head out, engine kit, rebuilding the blower myself and leaving recent accessories and governor as they were. I did it in place because the main cabin was built without a hatch. It's a PIA, but doable. You shouldn't need a complete overhaul, just cylinders, an engine kit, if the heads are low hours.
By the way if you have a stuck valve, usually a slight hammer tap and some diesel on the stem fixes it.
You can contact me if you like.

[gbmacca]

Hi guys,

Many thanks - yet again. Your advice is very much appreciated.

I will check out air boxes and also see if I have any stuck valves today when I go down to the boat.

HAve been reflushing engine after draining the sump - which was full - but didn't mind as it would be lubricating crank, bearings etc. The mix is now diesel, acetone and hydraulic fluid so feel a good combination.

May block dip stick and fill with diesel so it covers the lowest pistons.

One motor went right under (see photos) so will take off the blower to see if that is stuck. Other looks as good as gold and only got water in dip stick and up exhaust. Still not sure if it made it all the way up to the motor.

A lot of rusty looking water came out of exhaust when refloating and moving in the Tammy lift - so must have got to some metal parts????

Will continue pouring down fluid as one Detroit specialist here said it could take a month or two - then suddenly free itself.

Will also get oil can with flexible nozzle so I can try to pour on top of pistons.

Wish me luck and have a very Merry Xmas and happy new year.

Think our weather will be about 35C tomorrow.

Cheers

GB

[gbmacca]

Hi guys

Were they photos of 8v71's?

Climbed down and checked out - but except for side plates, which are already removed, so I can see part of the bore/piston - no other covers.

Will give it another couple of weeks with the mix down the bore before pulling engine apart as to remove blower - looks to be a big job!

Checked a couple of valves that I could get to and they seemed to be free so will give the rest a go.

Took belts off alternators as they were locked - so a little less resistance.

Apart from blower, valves, piston rings and possibly bearings and crank, what else could be locked/rusted?

Many thanks yet again and hope your Xmas day goes well.

Amazing - just done xmas with the kids and the ''ex and now they all have jobs - the quality and quantity of presents rises substantially - much to my surprise.

Only a few more years - then I will have grown to be fully independent!!!

Cheers

GB

[candapifer]

Just inquiring if you ever got your 8v71s to free up.
I have a similar problem. It's been 3 months since they would turn.

Thanks, Chris