Detroits 8v71's

[gbmacca]

Hi Chris

No - sadly not!

Was using a mix of Acetone and hydraulic fluid, which I poured down through injector holes but, 4 out of 8 cylinders, the pistons were below the flutes in bore sleeves, so fluid went straight to sump!

We then reckon, metal rings then rusted to metal liners and hence no luck.

in the end I rigged a block and tackle on long pole, but could see I was about to snap main pulley bolt - so gave up ---

Just about to pull them out and rebuild - with hopefully - an older mechanic who knows what a Detroit motor is. Young mechanics, can't believe 2 stroke diesels ---- existed!!

See how you go with pouring mix down cylinders and hopefully, if motor rotation has stopped half way - you may have better luck than me.

Good luck.

Gbmacca

[Lepke]

Since the engines sat for a long time with salt water residue, the sleeves and rings are shot. There may be damage to the cam, lifters, gears and so on. The pistons will come out with the sleeves if you take the heads and pan off and rotate the crank. Half the pistons are going up and half down. Disconnect the ones going down, move to the side, rotate, pull the sleeves and pistons and then do the other half. It's better to do an engine kit in a motor that's been flooded. Especially in salt water. And you want to pull everything, cam, lifters, blower and flush with fresh water.

Write down the numbers on each sleeve and the cylinder it came out of. There will be shims on the bottom of the sleeve. They're probably shot, too. But with the numbers, your engine kit can be made to be exactly like new. If they're clean enough, you can mic the shims and that will be close to what you need to reinstall new sleeves. (The top of the sleeve needs to be within the ability of the head gasket to seal the cylinder - the shims make that happen.)
What I usually do with a flooded engine is remove the pan and heads, make a catch pan under the engine and fresh water or solvent flush. Then the gear train.
Detroits were designed and made to be overhauled in the field, including their accessories. With a shop manual, a good non-Detroit mechanic can do it. It's a PIA to do it in an engineroom like most yachts have, but it's doable. If you're in a place where pulling the engines is affordable, it's a lot easier out of the boat.
I was in your place about 50 years ago. I was trained on aircraft engines and I had 2 Detroits that needed rebuilding and a shop manual.
I did my current boats 671 Detroits a few years ago. I sent the heads out, but did everything else, including the blowers. Cost was about $5G.

[gbmacca]

LEPKE
May I say thanks for your reply.
Sensible, knowledgeable and as I am not a rocket scientist - easy to read.
I have found a guy, older, who has worked on Detroits and from watching him crawl around in the boat and the questions he asks, seems to know what he is doing.
Younger guys, say they will 'pull them out and then get hold of someone' which of course, costs more.
The engines had done less than 3000 hrs, so we are in the process of ordering a standard rebuild kit, as hopefully, crank not worn.
I will pass your remarks onto my mechanic as there was some specifics in there that I think I will reiterate to him.
Again, many thanks for your knowledgeable reply.

Cheers

Gbmacca

[Lepke]

The numbers on the cylinders are important. They make up for small machining differences between cylinders. Sleeves come in different lengths and widths. If a block was ever damaged, got too hot, the cylinder wall may have raised spots that were honed/bored out. So an oversize sleeve is put in that cylinder. Brand new from the factory engines could have some different sleeves. Generally the bore stays the same, but the sleeve could be thicker to make up for boring or longer to make up for machining the deck lower. That way all the engines have the same hp per cylinder.
Your crank and other bearings are probably standard unless there was some accident. It's marked on the bearing back. My 1947 DD cranks are standard.


I don't order the engine kit until the sleeves are out.

[CaptMinnis]

Where would the red wire connect to?