Info on Detroit Allison 8.2 turbo engine

Hello- Does anyone have any experience with these engines? Im looking at a 1986 Mainship 40 ft Aft Cabin with two of these motors. Supposedly only 700+ hrs. Thanks!
Theo

yes, I had 2 of them in the late 80's,early 90's. They had stop making them a few years before and parts were getting hard to source back then. Be very careful. I wouldn't own them again unless I got a boat with them that was priced below repower level.
They were Detroits mistake,problem child.

Lots written on this engine at boatdiesel.com. Some advocates but many nay sayers.

I've run and rebuilt 2 cycle DDs all my life, but stayed away from that engine. I know people that bought them based on the reliability of the 2 cycles. But they're not reliable or long lasting. Because the engine was no where near the popularity of previous DD engines, there aren't other companies making aftermarket parts. So parts have to come from Detroit if they are even available. This engine is probably why Detroit Diesel is now owned by Daimler.

Those engines could get you backwards real fast on that boat. The boat doesn’t carry enough value to Repower and you may just have to do that.
Did you ever see what has to happen to Repower an aft cabin boat? I suggest you don’t watch.

Arc said:

Those engines could get you backwards real fast on that boat. The boat doesn’t carry enough value to Repower and you may just have to do that.
Did you ever see what has to happen to Repower an aft cabin boat? I suggest you don’t watch.

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You need to get access to the ER through the side doors, not through the big sliding aft door on a sedan style. Not difficult at all, though a big V8 will require the door to be wider than for a straight 6.
My 6 cyl swap took about 4 hours of Truck with HIAB time to get 2 oldies out and 2 newer engines in. In the process of a repower, that was one of the very minor parts.

It all depends on the boat and how much you can strip the engines down to make them fit through an opening. In my case, my engines are under the salon. With manifolds, etc. removed there's just enough space to lift them in / out with a crane through the available openings.

Theo said:

Hello- Does anyone have any experience with these engines? Im looking at a 1986 Mainship 40 ft Aft Cabin with two of these motors. Supposedly only 700+ hrs. Thanks!
Theo

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4-stroke engines, not the typical DD 2-cycles...

We had a single in our '87 Mainship Mk III, 220-hp I think it was, and it worked fine. It had been marinized by Johnson & Towers, so you might call them to have a chat. I remember ours had a recall at one time, increasing the size of the head bolts or something like that... Anyway, it wasn't a problem.

These don't have a great rep on the web, but in the grand scheme of things I suspect there are quite a few out there functioning fine.

I never heard the name "Allison" associated with ours; only DD. And I think our gear was Velvet Drive... but it's been a lot of years since then...

-Chris

Fifteen ears ago I spoke with the lead J&T engineer for the 8.2 marinization project. His first comment was that the 250 HP version of the engine is a "gem" in a marine application...the best engine they ever certified... primarily because the injector rack is moved very little in a boat (unlike an accelerator pedal in a truck or bus for example). Wear in the rack components is virtually non-existent and the requirement for recurring adjustment is virtually nil. This maintenance issue in road going applications, along with the early head gasket problem led to a bad rep on the street, and sadly, it stayed with the engine. It's mostly unsubstantiated "dock talk"...urban legend today. (By the way, the 8.2 was always envisioned as an interim engine while the Series 60 four strokes were under development).

The J&T engineer advised that the 220 and 250 HP engines were the best of the lot, with the 180 NA version being underpowered (for the displacement), and the 300/350 intercooled versions (typically used in small sport fish boats) being short lived.

If you look at Boat Diesel (or even on this site), compare apples to apples. You'll find that the Lehman, Perkins, Volvo, and even Cummins offerings have far more issues than the 8.2...including parts availability. The engine is indeed a gem in my experience. Zero parts failures in 15 years....NONE! Belts and hoses...that's it. Simple, efficient, leak free, and absolutely reliable. Further, they have that reassuring big boy V8 rumble...worth a premium by itself.

There are still plenty of 8.2 engines in wrecking yards. Yes, marinized components are expensive, but the exhaust manifolds are available as are the riser elbows. Like an idiot, I purchased a spare engine, a set of pistons, rings, bearings, gaskets, injection governor, fuel pump, etc,, and put them in storage for a rainy day. It never happened. The dock talk is urban legend, BS. If the engines in the boat you're looking at are 220/250s and have been cared for, they will outlast you and the next few buyers.

PM me if you have questions or wish to discuss the engine.

There is more to the 8.2 engine issues than "dock talk". They can be OK in trawler operation at low loads but do not last at higher loads. One of the reasons is the open deck design of the 8.2 block. The cylinders are free standing and fret against the head under higher loads. In addition, only 10 head bolts provide insufficient clamping force even after they were upgraded to 15mm. Compare that to a 3208NA block with a closed deck and 18 head bolts per head. And the 3208 is not known for head gasket longevity at higher outputs either.

gsholz said:

There is more to the 8.2 engine issues than "dock talk". They can be OK in trawler operation at low loads but do not last at higher loads. One of the reasons is the open deck design of the 8.2 block. The cylinders are free standing and fret against the head under higher loads. In addition, only 10 head bolts provide insufficient clamping force even after they were upgraded to 15mm. Compare that to a 3208NA block with a closed deck and 18 head bolts per head. And the 3208 is not known for head gasket longevity at higher outputs either.

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I agree! He may have had zero issues but thats not the norm... If they were so bullet proof, why did they stop making them? Short run of around 10 years or so. Even the factory trained mechanics badmouthed them.

1. The head bolt issue and deck design is common knowledge. I specifically stated that the higher horsepower versions had longevity issues. If anyone has documented evidence that the 220/250 horsepower engines have a persistent associated issue, please provide it.

2. Mechanics didn't like them because the rack was a pain in the neck in road vehicles (a non-event in a boat application). That and the early head bolt problem took care of the rest. That doesn't mean the mid-horsepower engines were/are junk. It means that urban legend is a powerful thing.

3. I specifically said the 8.2 was intended as a stop-gap engine until the Series 60 came on line. It was expensive to produce and was never intended to compete with their own new product line. Add the lingering early rep from gasket failures and it was a no brainer to stop production. Again, that doesn't mean the mid range power versions were junk.

The 220/250 engines are reliable and economical in the pleasure cruiser/trawler application...period. That's from someone with first hand experience and interface with other owners....not dock talk. This subject has come up before. The people who run them like them. The arm chair experts who have never owned and operated them come out of the wood work to badmouth them. I don't do it to other brand engines etc...but I sure could. Not nice.

They had a bad rap 20 years ago and they were old then, with an aft cabin boat I'd walk away if it was me.

Rufus said:

1. The head bolt issue and deck design is common knowledge. I specifically stated that the higher horsepower versions had longevity issues. If anyone has documented evidence that the 220/250 horsepower engines have a persistent associated issue, please provide it.

2. Mechanics didn't like them because the rack was a pain in the neck in road vehicles (a non-event in a boat application). That and the early head bolt problem took care of the rest. That doesn't mean the mid-horsepower engines were/are junk. It means that urban legend is a powerful thing.

3. I specifically said the 8.2 was intended as a stop-gap engine until the Series 60 came on line. It was expensive to produce and was never intended to compete with their own new product line. Add the lingering early rep from gasket failures and it was a no brainer to stop production. Again, that doesn't mean the mid range power versions were junk.

The 220/250 engines are reliable and economical in the pleasure cruiser/trawler application...period. That's from someone with first hand experience and interface with other owners....not dock talk. This subject has come up before. The people who run them like them. The arm chair experts who have never owned and operated them come out of the wood work to badmouth them. I don't do it to other brand engines etc...but I sure could. Not nice.

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I owned 2 of them....Not dock talk. Mine had the larger headbolt upgrade done while I owned it. I used Power Products, the local Detroit dealer. They didn't even like to talk about these engines. They had 1 guy who was the specialist even though others were trained on them. Those techs hated those engines. My "dock talk comes right from the mechanics mouth, not the marina. I put more hours on them than most pleasure boaters did.

I knew a few peeps that had good luck with them but any boat with them will be a hard sell and will suffer in the marketplace. Expect to discount.
There are so many reliable engines around without stigma,why would anyone chance it without a large discount?
By the way, it was a Power Product tech who told me (1991) that parts were becoming problematic

@Marlinspike

The original poster asked for comments from members with experience with the engines. Are you saying you had a boat with these engines and that you had serious mechanical problems? If so, please describe exactly what went wrong. Again, there's a lot of conjecture and hearsay out there, but not any detailed descriptions of actual experiences.

Me thinks the incessant negative dock talk keeps current owners from speaking their piece. The engines will run trouble free for many thousands of hours in that hull, in part because they likely won't be run on the pins all the time, and in large part because there are no fuel injection pumps to overhaul. The fuel system is bullet proof. Fifteen years with not a single issue, folks. Look at the forum threads for other engines....fuel injection pumps, head gaskets, valve problems, parts availability. If I was interested in a Mainship, I'd buy one with 700 hour 8.2s in a New York minute.

As an aside, a V8 would come out of our aft cabin boat in pieces. Remove the heads, remove the oil pan. Rotate the short block 90 degrees on it's longitudinal axis and it will go out through the side door beside the lower helm. Alternatively, the short block will fit (level) though the large starboard side window in the salon. Easier than a six by a long shot.

Sailor of Fortune said:

I owned 2 of them....Not dock talk. Mine had the larger headbolt upgrade done while I owned it. I used Power Products, the local Detroit dealer. They didn't even like to talk about these engines. They had 1 guy who was the specialist even though others were trained on them. Those techs hated those engines. My "dock talk comes right from the mechanics mouth, not the marina. I put more hours on them than most pleasure boaters did.

I knew a few peeps that had good luck with them but any boat with them will be a hard sell and will suffer in the marketplace. Expect to discount.
There are so many reliable engines around without stigma,why would anyone chance it without a large discount?
By the way, it was a Power Product tech who told me (1991) that parts were becoming problematic

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So did you actually experience a head gasket failure?

By the way, I have a complete spare engine and twin Disk 502, along with every part (new) needed to rebuild an 8.2. They show up routinely on Ebay. There's even an Air Research turbo repro for the engine available. Last year I ran across a 300 hour 250 HP engine from a fire department pumper trailer for $700 (being sold by a small town fire department). Maybe Detroit stopped stocking parts, but they're still out there. Certainly better than old Volvos, and many Perkins, and Lehmans.

Yes, boats with these engines are discounted. You buy it at a discount and you sell it at a discount with thousands of trouble free hours in between. So what. Volvos or Detroits were the only factory offering in our boat. I am hugely relieved that I chose low hour 8.2s. Beats the hell out of buying a boat with high hour engines of another brand with the certainty that high time components are going to fail.

I have a pair im my Canoe Cove 42. After 3 years of ownership they have been trouble free. Both are at the 4000 hour mark. I'm pleased at the economy. We are experiencing 3.4 gallons per hour all up running at 1600 rpm. This includes some furnace and generator use.

They start instantly and seem to run clean. I will do some maintenace this winter servicing the cooling system and checking valve clearances. If the valves are close I will forego adjusting the injectors.

I do keep my fingers crossed with these as the need for major work could make repowering a better but more expensive answer.

If you go with the purchase the advice I would give is get service lined up first if you don't do your own and don't run them hard. Overheating these can quickly lead to shortened life.

Antares,

Good advice. But I'd add that a serious overheat would likely just result in a blown head gasket....an inconvenience for sure, but certainly not catastrophic. I find it interesting that the forum has a standing "sticky" for changing the head gasket on the Lehman, the beloved engine of the trawler community. What a joke. Try running a 120(or turbo'd) Lehman or Perkins (even a Cummins) for extended time near the maximum rating and see how long they last....BOOM!

Our boat has a sensor that trips an obnoxious audio alarm when the coolant temperature reaches 195 degrees F. It's happened to me once when a misaligned raw water pump pully caused the drive belt to jump off when I pushed the power lever up. The alarm gave me plenty of time to snatch the power lever back before the temperature even reached boil over. I've thought about adding those clamp-on temp sensors on the exhaust hoses, but it seems it would be redundant as the existing sensor would probably trip first. Anyway, there's no way I'd contemplate an engine change for a blown head gasket. Keep an eye on the cooling system, including the raw water pumps and be sure the warning system functions, and I'm convinced they'll outlive their contemporaries by a large margin. The fat torque curve on these big displacement gems tells a story. The 220/250 engines are not stressed.

I typically operate the engines at 15-1600 rpm (hull speed plus a knot or so), but always run the engines up to 2500 (14-15 knots) for about 10 minutes each hours. Max is 2800. They never, ever show signs of overheating. Temperatures stay rock solid at 170. That said, I've removed and rodded the engine and transmission oil coolers to insure that the cooling systems is functioning at max efficiency....and that's something I'd make a periodic maintenance task....especially in salt water. I suppose if the engines were run at maximum rpm all the time, there would eventually be issues (as there were with the 300/350s in sport boats). But so too would there be problems with other brands in this power range. These engines give me super efficient slow cruise, and the option of (semi) planning at 14-15 when I need it on occasion. (The boat will reach 17 knots at 2800 rpm).

Treat them with respect, and they keep on keepin' on. The urban legend is nonsense.

Thanks to all for your comments both pro and con. I have no doubt that many negative comments are "arm chair quarterbacks" just repeating things they've "heard" but have no direct experience. In re-reading all of the comments I guess I'm still on the fence about these engines. I realize there are NO sure fire guarantees with ANY engine and exceptions to the rule do exist. I guess I'll mull it over some more and then flip a coin.

Theo said:

Thanks to all for your comments both pro and con. I have no doubt that many negative comments are "arm chair quarterbacks" just repeating things they've "heard" but have no direct experience. In re-reading all of the comments I guess I'm still on the fence about these engines. I realize there are NO sure fire guarantees with ANY engine and exceptions to the rule do exist. I guess I'll mull it over some more and then flip a coin.

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Theo, three things:

1. Suggest you find a reputable diesel mechanic in your cruising locale who realistically assures you he loves these engines, has worked on them for years and can guarantee a spare parts source.
2. Recommend you don't plan any long distance cruises where tow boat and cell phones don't exist.
3. Many of us do have first hand 8.2 experience but gave up the fight decades ago.

BTW, for a river boat, they may be just fine since so much time is spent enjoying life at the dock. I did it for years with gassers in a big boat. Speaking of which, why not gasser?

Sunchaser,

I believe we've had this discussion previously. Same old snarky remarks, especially the towboat/cell phone jab....as if both engines quit at the same time.

If I remember correctly, most of your experience with the engine had to do with a truck fleet back in the day. If you had them in a boat, perhaps you could tell us what kind of boat, and the exact nature of your issues. Presumably you had a simultaneous dual engine failure??? Tell us what boat, which power rating on the engine, how was the boat operated, and how it left you stranded. Without supporting information, this is just mean spirited mudslinging. Thanks.

Theo, there are related threads in the archives were current users have piped up to say they're having no problems. Suggest you search around.

8.2 v8

Rufus
Could you please tell me how to identify the Detroit 8.2 v8 turbo 250 hp engines
I just bought a 3607 aft cabin carver with twin Detroit 8.2 turbo engines
Labels read 4082-8300 and 4082-8301

Most of the bad reports come from early engines and most of those were used in trucks and buses. Over time Detroit fixed most of the issues.

Here's a link to some info and pictures (includes serial number guide):
https://everythingaboutboats.org/detroit-diesel-8-2/

Chacon said:

Rufus
Could you please tell me how to identify the Detroit 8.2 v8 turbo 250 hp engines
I just bought a 3607 aft cabin carver with twin Detroit 8.2 turbo engines
Labels read 4082-8300 and 4082-8301

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4082-8300 is starboard
4082-8301 is port

Rated power output, maximum: with 4T80 injectors, 250bhp gross, 240shp net, 3200 rpm

Rated power output, intermittent maximum: with 4A70 injectors, 220bhp gross, 211shp net, 3200 rpm

Source: Detroit Diesel datasheet 4SA300 8902

Sorry I missed your post from a couple days ago. Congrats on the new boat.
Feel free to contact me if you have further questions about the engines. We've had our current boat since 2005 with no problems. The only thing I've done besides regular maintenance is clean all four heat exchangers (vinegar immersion for a few days each), add K&N air filters, and changed impellers on raw water pumps. Our transmissions are Twin Disk.