Detroit Engines

[kemosabe421]

I recently sold my 42' boat that had 3208 Cats. When I bought the boat, I replaced all the injectors and had the valves adjusted. I put over 2000 hours on the engins with absolutely no problems. None. The only thing I did to the engines was regular oil and filter changes. Wonderful engines!

The reason for selling my boat was to move up to a 53 classic. I love the 53! I have been looking at them for the last 2 years on YachtWorld. I have also been reading the posts on this forum to learn as much as possible about the Hatts. My biggest concern is the Detroit engines. I have seen post after post on this forum about problems with this or that on the engines. I don't want engines that require a lot of routine maintainance (intercoolers, aftercoolers, air boxes......). Am I being overly concerned? Have I read too much into the posts I have read on this forum? Also, given your choice of Detroits, would you prefer the 71's or 92's and why? Any advice would be greatly appreciated.

Kemosabe

 

[Genesis]

Inter or aftercoolers should be checked annually and pulled and cleaned every 2-3 years - no matter WHAT engine they're on.

Detroits should have the tune checked annually. This does not take more than an hour or so if everything is ok. A full tune-up can be done on a pair of engines by one man in a day.

Nothing particularly complicated about any of it. You CAN let the tune go, but it doesn't hurt to check it.

I don't consider Detroits to need any more maintenance of substance than any other engine. You may get away with neglecting things like cleaning the heat exchangers on any enigne for a while - or you may not.

 

[Boatsb]

Most of the maintenance you mentioned is required for all engines.

If you do not clean the SW side of the cooling system it will clog up with sea life and junk.

Injectors need adjustment on detroits and fuel pumps need tweeking on cats as they are pressure timed.

If you ran 1500 hours on only oil changes you were very lucky. Turbos, Oil lines, Water hoses all need checking and replacement at times. If not thay fail at bad times.

 

[Passages]

The weak link on Detroits are the turbos, inter/aftercoolers and a propensity for oil leaks.

If you want a reliable Detroit, try to stay with the "Naturals". They are pretty much bullet proof unless you do something silly like have it overheat or run it without oil.

 

[mopester]

i ran 6-53's for a long time. i have had them side ways and still run with only loosing a gallon while on its side. they were ""OLD RELIABLE"" i have run a 6-92 wound up, it was not so reliable, but nothng major that i can remember. of course even in a gas engine the more you squeeze and wind it the more likely it will break. I have 8-71ti in my boat i had run the boat for five years before pulling it with only doing what i consider minimal maintenance.==oil/filter, coolant check/additive, tune ups, fuel filters, impellers/cleaning sea strainers.
I have also heard that cats (some?) are throw away engines?? I can't say for sure ive only run one cat and it was finicky!!!!


Something to consider is what you might be seeing here. It might only be when people break or need repair or have a problem, but think of all the people who dont post about all the reliable nothing happened or no problems boating that they are expieriancing all the time. With good old drippy detroits!!


Mike.

 

[SKYCHENEY]

It also depends on how you run the boat. On a 53MY you may find that you would prefer to run near hull speed. This will get the engines up to temp without really pushing them. Naturals will do this job just fine, but if you want to be able to get up on plane at times, you need to get one with the 8v71TI's or the 6v92TA's.

The performance is almost identical with the 71's or 92's. I would argue, however, that the 6v92's will cost less to maintain over the long run. For one, you have only 6 cylinders per engine instead of 8. This means less parts and lower overhaul and tune-up costs. The 92's also have a much simpler raw water path since they do no have intercoolers and the wet liners are easier to replace in an overhaul than the dry liner 71's.

With that said, I still would find the boat that you like first. I would not let the selection of 71 vs 92 influence the decision either way. FWIW, if you don't like Detroits, there were a few 53MY's built in the early 70's with Cummins.

 

[captddis]

Here is one example of the " high amount of maintenance" Detroits need.
I have a 1983 46 C HP. It has 650 HP 8V92s. At the time they were the highest output 8V92s available.
Covington did updates to the engines in March 1984. Other than routine maintenance the engines were not touched until 2004. No tune ups no injector replacements NADA!! The valve covers were not off in 20 years and 3000+ hours.
When I did the overhaul on the port in 06, I put the dial gauge on the injectors all were within .005 of 1.460. The valves were also within a couple thousandths of .016. Do I reccomend running this long without a tune up ?
NO. But it shows how reliable these engines can be. Oh I forgot to mention,
NO LEAKS either. I wish some of these myths would go away. I would prefer a Detroit to most new engines, period. Nothing can compare to the proven reliability of the old 2 strokes.

 

[motoryacht lover]

I just sold a boat with 6V71's 375hp TAs and I liked them and would definetly own them again. However, it was my experience that Detroits are very sensitive to temperature creep. I was very diligent about removing the heat exchangers every other year and having them dipped and maintaining my cooling system. It did kind of drive me nuts because I did not want to get them over 190. I ran the boat at 2000 RPMs and if the temp started creeping up I would back off a couple of turns and it would stabilize. I would not have problems with the creep in the intracoastal with all the slowing down and it would take about an hour of steady running for the creep to start. I think others will tell you that they didn't have sufficient cooling capacity so everything must be just so. Other than injectors and the cooling system I never had any problems in 8 years of ownership. I would not hesitate to recommend them but it does bother me that they are no longer in production and you hear about 6 week waits for some parts.

 

[DavidK]

There's a good write up by David Pascoe on comparing 2 cycle and 4 cycle diesel engines.

http://www.yachtsurvey.com/comparing_diesel_types.htm

FWIW

 

[Boss Lady]

Detroit rates their engines for intermitten and continuous duty rpms. To my knowledge the big iron continuous duty rpm is 1900 rpm, so when you exceed this rpm with a full load, you can exceed the cooling capacity of the system if the raw water temperatures get high enough. You can also heat them by running at max rpm past the heat saturation point. You can run them all day at 1900 rpm. Beyond that rpm you must act like the captain of the boat and use good judgement. You can exceed 1900 rpm for continuous load only when raw water temps permit. The never exceed temp is 185 degrees. You want to know why the commercial guys get 10,000 hours out of the same engines? they run them everyday, and they don't run them past the continous duty rpm.