Used Tolly with GM Diesel

A friend is over on the west side of WA looking at a used Tolly 40' that had a GM diesel in it. I know Tolly builds a nice, stout boat, but I have questions about the GM 8.2L turbo diesel. It's rated at 600 hp.

Here's the boat.
1985 Tollycraft 40 Sundeck Motor Yacht Power Boat For Sale - www.yachtworld.com

You guys probably have more familiarity with that engine than I do. Should they walk away from the boat or are the GM diesels worth having?

Mike

I had 2 of the 8.2's.
Pros- Great on fuel. GM rightfully named it the "Fuel Pincher"

Cons- specialized knowledge to work on them. Most Detroit Mechanics have very little training on 4 stroke Detroits.
Parts were hard to get in the early 90's, I would bet its a LOT harder now.
Basically obsolete engine designed for buses and small trucks that kept blowing up heads. Resized head bolts from 13mm to 14mm. The engine issues weren't as prevalent in boats (constant speed, constant load).
I would want a big discount on purcase price if it had these motors.

Strongly recommend they ask around the local mechanics and DD dealers. Support will be of utmost importance. Mechanic support but also parts.

I know two people with them and they are happy. The 8.2 seems to have been the better of the two. They are not, though, strong engines and need to be propped right or suffer the consequences. But other wise OK engines if in good shape.

Bob Hale of Waggoner had them in his 37' Tolly, which I think he sold last year, and he was happy. We saw them at Jennis Bay and talked a bit so we were aware of their plans.

I also strongly suggest that your friend join Boatdiesel. There are several people there that have them and are knowledgeable. Peruse the threads for the 8.2. Not a lot of them but they are there.

I owned one with the head upgrade that still went bad. Perhaps this is one of the worse engines ever made and widely distributed.

I am helping a friend fit out a Mainship 34 with one of those engines and have done a bit of research on them.

First it is 300 hp per engine and on the OP's boat they are twins.

Two things need to be done to that engine to keep it from overheating and/or blowing the head gasket:

Standard head bolts were 15 mm and GM later upgraded them to 16 mm. Check one of the exposed bolts and it should show a 15 or 16.

Air builds up in the coolant side of the front of the exhaust manifold which causes overheating of the forward cylinders. The fix is a vent line from the exhaust manifold.

Both are fairly low cost fixes and will allow the engine to operate in the 200+ hp range with no problems.

Parts are difficult. One owner is trying out Chinese replacement turbos with little success and the DD guro at Marine Diesel Services is working with Garrett on a dry turbo replacement. I think that other than the turbo and exhaust manifold most other non marine parts are available.

I would prefer Cat 3208Ts which are of similar vintage, and I would pay a little less for a boat with DD 8.2s in it. But I wouldn't say it was the worst diesel ever made.

David

Good looking, clean Tolly. Low engine hrs. Gotta luv Tollycraft. Don't gotta luv DD's.

Best luck!!

Thanks for the feedback. I'm sending him a link to this thread so he can read it.


Please continue with the posts if you have some pertinent feedback.

I like Tolly's but hate the tiny engine room. If your friend is under 60, good boat!

Old deckhand said:

I owned one with the head upgrade that still went bad. Perhaps this is one of the worse engines ever made and widely distributed.

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My results were like old deckhands. sold in 1991 and was having a hard time sourcing parts. Power Products (a big DD dealer at the time) was close by. Mine were the 250 HP versions. Caveat emptor. From a diehard DD fan....just not a 4 stroke DD fan.

ask your DD mechanic if he owns the tool to set the injector timing.

Xsbank said:

I like Tolly's but hate the tiny engine room. If your friend is under 60, good boat!

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"Tiny engine room" becomes an easily accessible to most things and full-headroom engine compartment when large floor hatches are employed. Nearly all sundeck Tolly can have the salon sole made into piano hinged hatches.

That includes the 48 Tolly which are not known as a "sundeck" design.

I will not purchase a boat that forces me to crawl around under floor for servicing engines and equipment. No stand up engine compartment/room with good overall accessibility to engines and other equipment on board boat = No Purchase by Me!

This is our 34' Tolly engine compartment = EZ Pizie for Servicing by standing upright on center teak gtating!

The 8.2's are probably comparable in size to your gassers, Art

GFC

Unless your friend is a gear head and has experience and tools for working on engines, I'd recommend a pass. In the hands of the right guys, these engines are beloved, kind of like a BSA bike motor. The Tolly folks I know that have the 8.2s are very hands on, expert parts chasers or replaced them with JDs or Cummins 5.9s.

sunchaser said:

GFC

Unless your friend is a gear head and has experience and tools for working on engines, I'd recommend a pass. In the hands of the right guys, these engines are beloved, kind of like a BSA bike motor. The Tolly folks I know that have the 8.2s are very hands on, expert parts chasers or replaced them with JDs or Cummins 5.9s.

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Twin screw diesel replacement with different brand engines can surpass $50K in blink of an eye...

I love Detroit Diesels, but the 8.2 is nowhere near as reliable as the 71 series 2 cycle. They are way better than gas engines. Parts are available.
Detroit Diesel 8.2 L Parts

GFC said:

A friend is over on the west side of WA looking at a used Tolly 40' that had a GM diesel in it. I know Tolly builds a nice, stout boat, but I have questions about the GM 8.2L turbo diesel. It's rated at 600 hp.

Click to expand...

We had an '87 Mainship III with a single four-stroke DD 8.2T marinized by Johnson & Towers... and it was rated at 220-hp (IIRC).

We had no issues with it, and it seemed to work fine for that application... but then again there was that pesky headbolt recall that should be checked.

Not a recommendation, just an observation...

-Chris

Art said:

Twin screw diesel replacement with different brand engines can surpass $50K in blink of an eye...

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You are absolutely correct. But, there is an ever increasing number of Tollys in the PNW that have had gas engines or older diesels replaced with new diesels. The improved ER access by removing a V8 and dropping in a straight 6 is dramatic. Likewise getting rid of a 6-71 and dropping in a Cummins 5.9 knocks off a lot of weight, improves range and yields a cleaner ER.

Tollys were made very well and updating systems and mechanicals is attractive for some. Good bones and economical planing hulls remain a draw. Kinda like 57 Chevies, always an audience. Like car rebuilders, boaters are not totally bottom line oriented.

sunchaser said:

You are absolutely correct. But, there is an ever increasing number of Tollys in the PNW that have had gas engines or older diesels replaced with new diesels. The improved ER access by removing a V8 and dropping in a straight 6 is dramatic. Likewise getting rid of a 6-71 and dropping in a Cummins 5.9 knocks off a lot of weight, improves range and yields a cleaner ER.

Tollys were made very well and updating systems and mechanicals is attractive for some. Good bones and economical planing hulls remain a draw. Kinda like 57 Chevies, always an audience. Like car rebuilders, boaters are not totally bottom line oriented.

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What you say is true!

Would be great to locate a Tolly with good brand, well installed, low hour, replacement twin diesels already correctly broken in. Our 34' self contained Tolly tri cabin, although a gasser, came with interior 90% in great original condition, port engine fully rebuilt, starboard with new top end and rebuilt port trany too. She's been a great boat for 9 years of ownership. Everything still tests-out well. Quality of the build-out is exceptional that Tollycraft production line accomplished for all portions of the craft.

Unless our boating needs change we can see her as our "Girl" into our 90's [we're mid 60's now]. 92 +/- was age of the original owner who simply had to leave boating soon before we purchased.

I sent a link to this thread to the friend who was on his way to look at that Tolly.


I got an email back from him this afternoon. A short one liner that said they were passing on that boat. When they get back here I'm sure he'll tell me more about it.


Thanks to all of you for your honest input. I'm sure he appreciated it. And no, he's not a mechanical kind of guy.

What he will save in fuel, repairs and headaches over the next decade by replacing the DDs with Cummins 6BTs will more than pay for the engine swaps.

Both are SAE#1 bellhousings so the gears should mate right up. Custom engine mounts to work with the current beds are easy enough to have made. If he likes the boat, I'd say he should get it but use the 8.2s as a lever to drive the price way down, then use what he saves toward an engine swap.

Fleetmate said:

What he will save in fuel, repairs and headaches over the next decade by replacing the DDs with Cummins 6BTs will more than pay for the engine swaps.

Both are SAE#1 bellhousings so the gears should mate right up. Custom engine mounts to work with the current beds are easy enough to have made. If he likes the boat, I'd say he should get it but use the 8.2s as a lever to drive the price way down, then use what he saves toward an engine swap.

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As much as I despise 8.2s, they are VERY fuel efficient. I think you are confusing them with the 2 stroke Detroits.No comparison. I bet the fuel consumption was within 5-10% of like era Cummins or Cats. The modern versions of these engines would be even more fuel efficient but doubt it would come anywhere near the replacement costs. Especiallt on 200 hours a year typical recreational users.

"I'd say he should get it but use the 8.2s as a lever to drive the price way down, then use what he saves toward an engine swap."

"Especiallt on 200 hours a year typical recreational users."

For many recreational boaters any savings might not be till the next century.

If the engine has no problems another 2,000 hours (a decade) there would be no reason to change anything , only do PM.

If extra long range on installed tanks is not required a modern gas engine might be best choice for only a decade or two if the 8.2 finally dies..

Marine gas engines are a joy when used in correct parameters. Inexpensive at all levels, quiet at most rpm, relatively fuel efficient [especially at low to mid range rpm], easy to maintain, powerful [dependent on size and design] and light weight. It's not rocket science to learn/know how to be careful with container enclosed explosive fuel and exhaust fumes.


Additionally... low cost quick to attain parts and relatively low cost [compared to diesel mechanics] knowledgeable gas engine mechanics abound - nearly everywhere!

Ditto!

Especially with the Air Police demanding almost impossible standards , Diesels are for the folks that really need them .

4 ,6, 8, $5.00 spark plugs or rebuilt injectors for $600-$1200 each plus installation?

At 2000+ hours a year , every year Diesel makes sense , for a coastal recreational boat , hardly ever.