I'm considering DIY overhauling both 8v71Ti's in our 58' YF!!

[MarioG]

So I'm faced with several decisions on which direction to go with overhauling in frame or engine swap for our 1972 58' Yachtfisherman.
Yes, I am well aware of the size and scope of the project. No I will not hire a "professional" to do the job as I have no need since I can do most of the work myself while having access to many friends in the overhaul industry for technical guidance .

My main discussion questions are mainly to those that have done "in frame" overhauls and to those that have done engine out swaps. This experience is very valuable to me. Any thoughts, tips and ideas would be greatly appreciated!

Not to be overlooked, I have contemplated the idea of perhaps going to a newer engine (cummins/CAT) but obviously the costs are vastly different and perhaps prohibitive.

So let's here the pros and cons, the experiences and the do's and don'ts.

Mario

 

[dottieshusband]

So I'm faced with several decisions on which direction to go with overhauling in frame or engine swap for our 1972 58' Yachtfisherman.
Yes, I am well aware of the size and scope of the project. No I will not hire a "professional" to do the job as I have no need since I can do most of the work myself while having access to many friends in the overhaul industry for technical guidance .

My main discussion questions are mainly to those that have done "in frame" overhauls and to those that have done engine out swaps. This experience is very valuable to me. Any thoughts, tips and ideas would be greatly appreciated!

Not to be overlooked, I have contemplated the idea of perhaps going to a newer engine (cummins/CAT) but obviously the costs are vastly different and perhaps prohibitive.

So let's here the pros and cons, the experiences and the do's and don'ts.

Mario

From a cost perspective, plan on about 13-14k per engine. About 5k for new turbos and blowers. 3k to get the heads reworked. 4k for the basic overhaul kit (pistons, rings, bearings, liners), 1k for injectors, 1k for gaskets and consumables. I've built many engines, so in many respects, it wasn't my 1st rodeo... fitting the liners is a tough job, and the sheer weight of the components makes it hard. The ER on my 63 is huge, so I was able to pull the upper oil pan (130lbs), without lifting the engine. If you can't do that, I'd advise against it. Access to the underside of my engine was easy. Without that access, farm it out.

 

[jim rosenthal]

It seems to me that the biggest problem is that you all live on your boat. Living on your boat whilst you are overhauling the engines sounds like a very unpleasant situation to me. Do they need it that badly?I would think that your most efficient and cost effective way to do this is to contract for two rebuilt 8-71 long blocks, and swap them into your boat. Send your engines back as cores.

 

[MarioG]

It seems to me that the biggest problem is that you all live on your boat. Living on your boat whilst you are overhauling the engines sounds like a very unpleasant situation to me. Do they need it that badly?I would think that your most efficient and cost effective way to do this is to contract for two rebuilt 8-71 long blocks, and swap them into your boat. Send your engines back as cores.

Yeah, no way we'll stay on the boat. Probably stay at our house or somewhere.

The long block idea sounds interesting.

 

[MarioG]

From a cost perspective, plan on about 13-14k per engine. About 5k for new turbos and blowers. 3k to get the heads reworked. 4k for the basic overhaul kit (pistons, rings, bearings, liners), 1k for injectors, 1k for gaskets and consumables. I've built many engines, so in many respects, it wasn't my 1st rodeo... fitting the liners is a tough job, and the sheer weight of the components makes it hard. The ER on my 63 is huge, so I was able to pull the upper oil pan (130lbs), without lifting the engine. If you can't do that, I'd advise against it. Access to the underside of my engine was easy. Without that access, farm it out.

Yeah, by the looks of it, there is poor access under the engine . Engine will have to be lifted somehow.

 

[johnjen50]

Mario, I’m finishing up this exact project now on my port engine. You can’t pull the oil pan without lifting the engine, which means unhooking it from the transmission, or lifting both somehow. At 3200 or 3500 pounds that task alone is tough. I didn’t want to do all of the piston and internal work myself so bought a long block from MTU. Yep, they have a long block program where they will give you about 2k back for your block. Once this was factored in the long block cost me 16k. Now yes the turbos and blower, intercooler and anything else you want to change will be on top of that, but I figured if I got it from MTU I stood a better chance of getting it done right than farming out to someone I didn’t know. Also, up here in NE there are simply not a whole lot of shops that will do this. You can find their long block program if you google it. Take LOTS of pics with the camera because it greatly improves your confidence when putting the accessories back on to the new engine. The little things take an inordinate amount of time to figure out if you don’t take pics....... and from several angles helps too.

 

[Boatsb]

Why bother doing all that work if its not your regular job. I'd suggest working some extra time and having it done..

1) if you get hurt and cant work your screwed.
2) I'd not buy a boat with a DIY overhaul as a reliable rebuild.
3) I can make asmuch or something more money doing things I do well for work than it cost to hire a good mechanic to do what he does best.

And most importantly that's a lot of work. A repower is probably easier than an inframe.

 

[MarioG]

Mario, I’m finishing up this exact project now on my port engine. You can’t pull the oil pan without lifting the engine, which means unhooking it from the transmission, or lifting both somehow. At 3200 or 3500 pounds that task alone is tough. I didn’t want to do all of the piston and internal work myself so bought a long block from MTU. Yep, they have a long block program where they will give you about 2k back for your block. Once this was factored in the long block cost me 16k. Now yes the turbos and blower, intercooler and anything else you want to change will be on top of that, but I figured if I got it from MTU I stood a better chance of getting it done right than farming out to someone I didn’t know. Also, up here in NE there are simply not a whole lot of shops that will do this. You can find their long block program if you google it. Take LOTS of pics with the camera because it greatly improves your confidence when putting the accessories back on to the new engine. The little things take an inordinate amount of time to figure out if you don’t take pics....... and from several angles helps too.

A quick search found me this:

https://www.mtu-online.com/mtu-northamerica/partsservice/detroit-diesel-2-cycle/long-blocks/

 

[jim rosenthal]

Unless you REALLY enjoy this kind of work and you are good at it.. I'd hire it done.

You might also be able to hire a good DD mechanic who would agree to have you be the second pair of hands, but he would be in charge. I've done that a few times and it's worked out well. I'm the helper- I learn a lot, and save a few dollars in the bargain.

MTU guaranteed long blocks are a good idea. You still have to have rebuilt turbos, blowers, heat exchangers, etc.

I don't envy you. Are your present engines THAT tired? Really?

 

[MarioG]

Unless you REALLY enjoy this kind of work and you are good at it.. I'd hire it done.

You might also be able to hire a good DD mechanic who would agree to have you be the second pair of hands, but he would be in charge. I've done that a few times and it's worked out well. I'm the helper- I learn a lot, and save a few dollars in the bargain.

MTU guaranteed long blocks are a good idea. You still have to have rebuilt turbos, blowers, heat exchangers, etc.

I don't envy you. Are your present engines THAT tired? Really?

If I did go with MTU long blocks I would think most of the technical overhauling is done leaving only the accessories to install (turbos, blowers ect)

I'm not worried about the work involved. I can handle big projects myself no problem. I do have lots of friends though.

Yes, the current engines are very tired now. All the symptoms of low compression are there.

 

[dsharp]

I’m not trying to talk you out of doing the work yourself I can only this information from growing up in boatyard hell and my observations from watching the diy process. If you are going to do it make sure to clean up as you go. The heads are heavy, have very sharp edges and things get slick with oil and diesel in a hurry. I had a customer drop a 6-71 head on his hand and it mangled it. There’s also times that I saw owners pull an engine apart 3 times and it still would spin a cam bearing after about 3 minutes of run time. The only way my Dad would do it for a customer was pull the engine, send it to a dealer and let them rebuild it and test run it. If you do decide to press on you are going to need a set of a-frames with a stout cross bar and a pair of quality come-alongs. We used a length of 2” shaft material. You also need to shore up the floor. You can cut 2x4’s and brace from the stringers. Once you have the engine lifted it’s not much more work to set the engine on a cradle and roll it out the door on pipe rollers. We had our old hoist set up with a pair of I-beams where the straps go and a long I-beam with a counterweight to reach in and lift the engine out. It was an Algonquin that was on rails that was electric so it was very controllable and quiet so you could hear the spotter. Check around and see if something’s available to get the engines out. That’s a lot of heavy iron.

 

[nautibake]

A quick search found me this:

https://www.mtu-online.com/mtu-northamerica/partsservice/detroit-diesel-2-cycle/long-blocks/

I really enjoy learning from these threads. I used to dream of QSM’s or Cats if we win the lottery, but see that this MTU option probably makes vastly more sense. One question, why the “long block” distinction? I read the MTU web site description, and did some searches which lead me to a great David Pascoe article on Detroit’s vs all the 4-strokes, but didn’t find anything else specific about “long block”. I assume the MTU has to fit in the same 8V71 engine space and mounts?

 

[SeaEric]

Why bother doing all that work if its not your regular job. I'd suggest working some extra time and having it done..

1) if you get hurt and cant work your screwed.
2) I'd not buy a boat with a DIY overhaul as a reliable rebuild.
3) I can make asmuch or something more money doing things I do well for work than it cost to hire a good mechanic to do what he does best.

And most importantly that's a lot of work. A repower is probably easier than an inframe.

What Scott said. I'm a firm believer that everyone should do what they do best. Fly some extra trips and hire a mechanic to do the boat work.

 

[Pascal]

If I did go with MTU long blocks I would think most of the technical overhauling is done leaving only the accessories to install (turbos, blowers ect)

I'm not worried about the work involved. I can handle big projects myself no problem. I do have lots of friends though.

Yes, the current engines are very tired now. All the symptoms of low compression are there.

Looks like they re called MTU long blocks because Detroit belongs to MTU but they have to be identical to the older Detroits. It is a better option than rebuilding as you know they will be done right. Plus in our boats there is really no access underneath so they d have to be raised or taken out anyway. florida Detroit Allison, up on the river, is probably the local dealer for these long blocks.

Personally i dont think you want to rebuild your engines yourself. Just one mistake is all it takes to be back to square one. This is why i repowered but the long blocks are a good alternative

 

[dsharp]

I really enjoy learning from these threads. I used to dream of QSM’s or Cats if we win the lottery, but see that this MTU option probably makes vastly more sense. One question, why the “long block” distinction? I read the MTU web site description, and did some searches which lead me to a great David Pascoe article on Detroit’s vs all the 4-strokes, but didn’t find anything else specific about “long block”. I assume the MTU has to fit in the same 8V71 engine space and mounts?

A long block is the block assembly (short block) plus the cylinder heads. Same engine just comes with the liners and crank installed and the heads with valve job already torqued to the block.

 

[Briankinley2004]

I have assisted in some engine swaps where we used a sky track lift to remove the engines. We secured an I beam of the proper length to one of the forks. Then the I beam is sent through the salon door or wherever the access point is and attached to the engine. Old engine out and new one back in place in one sitting. No need for jacks, shoring up, etc. Just make sure everything is loose and ready to come out before you call the rental company if you are doing a one day rental.

 

[Photolomy]

Do any of the newer engines use sleeves like the older DDs did?

 

[MarioG]

Looks like they re called MTU long blocks because Detroit belongs to MTU but they have to be identical to the older Detroits. It is a better option than rebuilding as you know they will be done right. Plus in our boats there is really no access underneath so they d have to be raised or taken out anyway. florida Detroit Allison, up on the river, is probably the local dealer for these long blocks.

Personally i dont think you want to rebuild your engines yourself. Just one mistake is all it takes to be back to square one. This is why i repowered but the long blocks are a good alternative

Clearly, as of now, an MTU long block makes obvious sense.

 

[oscarvan]

Yes, the current engines are very tired now. All the symptoms of low compression are there.

You mean you checked the valve adjustments and then did a dry compression check followed by a wet one in any suspect cylinders and ALL of it is bad on the lower end?

You may find you're lucky and just have to R&R head(s).... or rebuild one or two jugs and get a whole bunch more hours out of them.

There's a lot you can do before you condemn the whole motor.

 

[MarioG]

I have very hard cold starts, smoke like a volcano when cold. Bluish smoke, the smell of unburned fuel in the exhaust is nauseating. High oil consumption.