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Old 08-07-2020, 11:52 PM   #1
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Questions about Detroit 8.2L engines

I am new to the trawler forum. A year ago we sold our sailboat and have/are making the switch to what some have called “The Dark Side” . (We are thinking simply enlighten ) While I have a bunch of experience with a variety of sailboats I’m just learning about trawlers. My wife and I are actively shopping for a trawler in the 40 - 45’ range. Some of the boats we are interested in have Detroit 8.2L diesels. My research indicates they tend to have significant problems. On the other hand, some on this forum report having them for years, requiring little more than routine maintenance and TLC. Are there any key indicators a good engine survey would discover that could give me a thumbs up or down on the Detroit 8.2L engines in a boat we’re interested in? My wife and I are used to sailboat speeds and not interested in going fast. Seeing a consistent 8 - 10 knots would be wonderful. Obviously boat weight and configuration are determining factors on how much power it takes to make that speed. Again, the Detroit 8.2L is the issue. Thanks in advance for any and all thoughts and reported experience.
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Old 08-08-2020, 02:17 AM   #2
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whether you think they are a good engine or not, parts availability is problematic.

I had 2 , never again
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Old 08-08-2020, 06:54 AM   #3
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I helped a friend move a boat with an 8.2 and lived with it for a week. Before the trip I researched this forum, boatdiesel, etc. I discovered that head bolts were a weak point and if you planned to run the least bit hard then upgrade them. The other weakness was the cooling system and there was a straightforward fix that consisted of a vent from the rear cylinder.

But if you ran them easy, say 100 hp each they would be fine with no upgrades and were as solid as any engine.

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Old 08-08-2020, 07:14 AM   #4
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I personally know of two owners who swapped out their pair of 8.2s. One went with JD 6068s and the other with Cummins 5.9TAs. In both cases the 8.2s had less than 1,500 hours.

Someone can correct me on this but I don't recall the DD 8.2s had much more than a 6 year build life. DD's 6-71 is generally regarded as a much better choice if you want a DD.
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Old 08-08-2020, 10:36 AM   #5
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Much has been written on 8.2 Detroits at boatdiesel.com. You'll get lots of options there. In their defense, I have two friends who have them and like them.
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Old 08-08-2020, 03:40 PM   #6
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8.2s are nowhere near as reliable as the previous 2 cycle Detroits. I never owned one but worked on a couple. They tend to blow head gaskets when under near full power and had overheat problems. They also had a head bolt problem getting proper torque. If run easy they last about as good as most yacht engines and are more fuel efficient than older Detroits. You can get parts and rebuilt engines.

I'd rather burn more fuel and have a reliable engine.
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Old 08-08-2020, 04:28 PM   #7
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I have two low hour engines in our OA for Fifteen years and counting. Zero issues...ever. The head bolt issue was addressed by the factory years ago...mid-80’s. I run them vey conservatively...mostly hull speed. No doubt they have thousands of hours left in them. Some posters here speak from experience with trucks where the engines demanded more than normal maintenance time and tended to be in light duty trucks with poor access. Hence they were abused and ran poorly. In a boat the injector racks get set at an rpm and are not in constant motion as for a truck with an accelerator pedal. They are well known to be very fuel efficient. Parts are comon on e-bay. Good used engines show up on wrecking yard sites all the time. Water pump rebuild kits are available. Even new turbos. The only item that might be scarce are marine exhaust manifolds, but I believe Mesa has them (expensive). While I haven’t had to replace anything, I do keep an eye out for spares. I just don’t get the comments about parts being difficult. Are these current owners making these remarks??

There are quite a few of these engines in boats and you simply don’t see owners posting about issues on this forum for sure Certainly nothing close to posts associated with Lehman’s, Cats, Volvo’s, 2-stroke Detroit’s, and even Cummins from the same era. That’s the real world test. Those of us who have them, like them. Just don’t run them hard for extended periods. Treat them like the vaunted Lehman’s get run and they’ll run longer at lower fuel consumption. The only engine From that era that I consider to be in the same league might be the single non-intercooled turbo Cummins. Whenever this comes up the same detractors (who have never personally owned and run them in a boat chime in about engines they worked on long ago or someone they knew who had them. Take that anecdotal “stuff” with a large helping of salt.
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Old 08-08-2020, 05:46 PM   #8
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Old 08-08-2020, 05:56 PM   #9
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Relative to DD 2 strokes, parts are in deed scarce and expensive. The same can be said for the Cummins 555 engine. There are many engines that fall into this category. You won’t find DD 8.2 engines in any go fast boats, they died long ago. You will still find them and the 555 in low demand applications.

The head gasket issue is never going away on an 8.2. It only has 10 head bolts while the other engines have 18. Upsizing the bolts helped the issue but did not completely solve the issue. Running the engines moderately does seem to solve the issue.

Not knowing the application and intended use of the engine one has to give an opinion on how an engine performs across the board. 8.2’s earned their reputation and you see that reflected in this forum.

I would try to avoid this engine but if it’s your dream boat then you need to know it’s limitations.
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Old 08-08-2020, 06:13 PM   #10
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I have no experience with them but they do seem to have a bad reputation. So take that into account if you ever want to sell it, it probably will make it more difficult to sell. Oh, BTW welcome aboard.
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Old 08-08-2020, 10:07 PM   #11
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I truly appreciate the feedback. My wife and I are actively shopping for a trawler, and us really liking a couple of OAs we’ve seen, but me being spooked by the engine’s reputation prompted my questions to the wisdom of this forum. I’ve not yet had a survey done, but we’re coming very close. I’ve also considered the cost of repowering with smaller engines as we go back to our live-aboard life-style. With any luck and lots of TLC, I’ll never need to worry about repowering. Thanks again for everyone’s input.

John
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Old 08-08-2020, 10:37 PM   #12
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Repowering is fine to do as long as you realise that when you eventually sell you will get low return on the dollars you spend doing it. But fine if you are keeping the boat for 10-15 years to get the benefit of new engines.

As noted in another thread recently, old Taiwanese boats have some or all of well known issues: deck cores deteriorated from screwed-in teak, leaking windows, rusted fuel tanks and poor quality plywood delaminating. The time to consider a repower is if you pull the engines to replace fuel tanks, which is what I did. You will get a bit of money back from selling running take-outs.
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Old 08-08-2020, 10:44 PM   #13
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Very good point about the return on the dollar for repowering. Good engines make the boat sell faster, not for more money. Also your comments about Taiwanese boats of earlier vintage is well noted. There are some things even the best, most thorough surveys don’t catch. They only become evident with fuel in the bilge or some other nasty surprise.
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Old 08-09-2020, 11:13 AM   #14
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Very helpful information. Thank you so much. What prompted this question is interest in an OA 42
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Old 08-09-2020, 12:34 PM   #15
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.....a few more thoughts. Our OA has a very loud audio alarm that goes off at 205 degrees F engine temperature. I had a raw water pump throw a belt some years ago while I was driving from the fly bridge. A glance it the temperature gauges showed the starboard engine at guess what....205 degrees. A press of the red shutdown button cut off the fuel and I fixed the problem enroute. Had I let it overheat a head gasket issue might have ensued. You want to be sure that alarm is functional on both engines and keep an eye on water temperature. How dang difficult is that?

But even if the engine had blown a head gasket, odds are that the fix would have been as simple as replacing it. I don’t get the “replace” the engine or re-engine talk. Why?
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Old 08-09-2020, 01:14 PM   #16
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205 F is pretty typical for an alarm set point. If the cooling system is filled with 50/50 antifreeze you have until at least 230 deg F before the system starts boiling dry and then time to react before it goes dry and ruins the head gasket and possibly the head.

But a Borel alarm is always a good idea on a marine engine. It alarms when the exhaust gas below the mixer exceeds 165 F which gives you even more time to react.

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Old 08-10-2020, 06:49 AM   #17
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Quote:
Originally Posted by Alaska JD View Post
On the other hand, some on this forum report having them for years, requiring little more than routine maintenance and TLC. Are there any key indicators a good engine survey would discover that could give me a thumbs up or down on the Detroit 8.2L engines in a boat we’re interested in? My wife and I are used to sailboat speeds and not interested in going fast. Seeing a consistent 8 - 10 knots would be wonderful. Obviously boat weight and configuration are determining factors on how much power it takes to make that speed. Again, the Detroit 8.2L is the issue. Thanks in advance for any and all thoughts and reported experience.

We had a single 8.2T in the '87 34' Mainship we had back in the early '90s. Johnson & Towers did a "recall" (service bulletin) to upsize the headbolts. Did that, all good, we never had issues and as far as I know that engine is still in service with the new owner.

It wasn't uncommon back then to see twin 8.2Ts in 34-40' boats with planing hulls.

Depending on how those engines have been maintained, and depending on your intended method of operation, I don't think I'd be scared away. There was another thread sometime not too far back where Fred (FF) was musing about a boat with 8.2T power, and I think the end theory is that in his case it'd be OK to get the boat, run it, worry about it down the pike if problems arise. Read that thread, if you haven't already...

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Old 08-11-2020, 06:20 AM   #18
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"It wasn't uncommon back then to see twin 8.2Ts in 34-40' boats with planing hulls.

Depending on how those engines have been maintained, and depending on your intended method of operation, I don't think I'd be scared away. There was another thread sometime not too far back where Fred (FF) was musing about a boat with 8.2T power, and I think the end theory is that in his case it'd be OK to get the boat, run it, worry about it down the pike if problems arise. Read that thread, if you haven't already..."

The boat I was after was a Tom Fexas 44ft Midnight Lace, a fine inshore boat for a couple. I love the fwd cockpit , and decided , if not now , when?

The hassle is the boat was seldom used , so came up for sale.Asking $80K

MY GUESS was the seller or broker decided to run on the pin for too long and overheated one engine. The engine was removed and sent to a truck repair shop , when returned it still did not work , so was sent back again.

That's when I lost interest.

Another Lace in TEXAS lost its engines and 2 Volvos with new V drives was installed.

About $40K worth of engines plus the install. The engines are under the cockpit sole so it shouldn't have been too bad.

The price was asking $135k.Not a bad deal but I am not a Volvo fan., I cold have been OK with the Volvos but other hassles arose.

The builder uses GRP fuel and water tanks , my favorite , but for some reason they were removed. The concept of living with metal tanks was enough to be a big turnoff.

I have made an offer (a low ball) for the Texas boat , thinking if its accepted any tank work or engine repair will be contracted out with the money saved.

Who knows , fingers crossed , still waiting.
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Old 08-11-2020, 06:53 AM   #19
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I had 2 in a boat I had in the late 80's, early 90's with 8.2's. Mine had the headbolt upgrade as well. Great on fuel, hard to find parts for,hard to find people who are familiar with them and willing to work on them. Local Detroit dealer only had 2 techs trained on them. I would think its a much harder task chasing parts today. Not "Dock talk", truck talk or other talk. Real world owner who put hours on mine. My DD tech told me parts situation would be getting worse as engines had been discontinued years before. And that was 30 years ago..
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Old 08-11-2020, 08:24 AM   #20
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I had 2 in a boat I had in the late 80's, early 90's with 8.2's. Mine had the headbolt upgrade as well. Great on fuel, hard to find parts for,hard to find people who are familiar with them and willing to work on them. Local Detroit dealer only had 2 techs trained on them. I would think its a much harder task chasing parts today. Not "Dock talk", truck talk or other talk. Real world owner who put hours on mine. My DD tech told me parts situation would be getting worse as engines had been discontinued years before. And that was 30 years ago..
So what parts failed on your engines that were difficult to find in the late 80s and early 90s? Complete engines are still easy to come by. I have one pickled in my garage, along with a new in the box: set of turbo pistons/rings, new cam, head gasket sets, fuel pumps, fuel shutoff solenoids, bearing set, water pump rebuild kit, and a complete set of tools for setting injectors. Then there’s the spare water pump, starter, and governor set up. No there isn’t a dealer parts network, but parts are around. By the way, I bought all these things along the way because I mistakenly bought into the dock talk and thirty year old conjecture. I haven’t touched a single one of those spares in fifteen years.

There’s no rocket science in the design. The only thing that’s arguably unique is the cam actuated injection carry over from the 2-strokes. When I read about injection pump/system issues on Lehman’s and Cats, parts supply/cost issues with Volvo’s, the recent thread regarding #6 cylinder meltdown issues on Lehman’s, I conclude that the design of the 8.2 (head sealing aside) was a stroke of genius for a small marine engine. Respect the well known head gasket issue and the engine will keep on keepin’ on.

Of course dealers were reducing support for the engine by the mid-90s. Your engine tech’s remarks were no doubt speculation based on what was happening with Detroit Diesel. The internet took up the slack. I found a diesel shop in remote northern Michigan that has a mechanic who is knowledgeable with the 2-stroke injection set up if I have a need. But I also have the excellent shop manual and adjustment tools. It ain’t rocket science.
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