Mainship Nantucket 40 with Detroit 8.2 L Diesels

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cantal

Member
Joined
Oct 28, 2018
Messages
9
Location
United States
Vessel Name
Nevermore
Vessel Make
Marine Trader Tradewinds 38
Anyone out there have a 40 with two Detroit Diesel 8.2 L engines. What is the expected fuel usage and cruising speed for these engines?
 
Suggest you visit boatdiesel.com and inquire on these engines. You will get varying viewpoints.
 
I have done the boatdiesel research and what I found is there is a problem with the coolant system air locking at high power levels which results in overheating, head warping, etc. It apparently is easily fixed (before it overheats!) by installing a bypass from the back of the head to vent the air lock.


I used one for a week on a friend's MS34 and it was a smooth and solid engine. We were running at about 7 kts so no stress at about 1,500 rpms.


David
 
This is a four cycle diesel, which I find if you look at fuel usage/load charts they are all somewhat comparable.

This series had a limited lifetime in the marine world, might want to also check around on parts availability as well.
 
Run easy like on a trawler, they can live long. Run hard (near their rated output), they are prone to cracked exhaust manifolds and head gasket trouble.

Second that about checking on parts availability. Especially exhaust manifolds and turbos specific to the marine application. Base engine part should be available.

Also has an annoying "road load" or speed limiting governor. Not a big deal, just different from most marine engines.
 
Like I said above I captained a boat with an 8.2 Detroit for a week and never noticed the different governor. Maybe if I knew in advance I would have picked up on the differences, but they are subtle and no reason to not consider this engine.


I believe that the manifold cracking that Ski mentions is due to the air pocket issue I noted above and I understand that the vent hose solves this problem. But I agree I wouldn't want to run this engine much over 100 hp in any case.



David
 
There are a number of companies that make replacement manifolds for Detroit Diesels and other makes. Surplusman : Home Page sells used marine diesels and parts.
 

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None of those ads cover manifolds for the 8.2.
 
We have a pair of 8.2's in our Atlantic and they run great. 1650rpm / 5.5pgh / 7kts all day long. No problems replacing HE, exhaust elbows, etc so far, but i can see some potential long term concerns with limited service availability (our local DD dealer won't work on them) We want to keep the boat for another 10+ years and do some longer cruising (loop, bahamas, etc.) so could be an issue down the road. Boatdiesel is a great resource.
 
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