Detroit Diesel 12 V 92 DDEC Rebuild timing and est. cost

[northshoreone]

I just had Florida Detroit Diesel on the boat to correct a block heater issue. The Tech. told me that these engines 1996 12 V 92 DDEC are 1,500 hour engines and its time to rebuild. My first question is do you Detroit experts out there agree with that statement? He said he's seen them go longer but not much past 2,000 hrs. I asked if running hull speed vs on plane made a diff. in engine life? He said that the biggest factor was engine load. If the boats not propped correctly to make or exceed top engine RPM's at WOT its taking hours off engine life no matter what speed or RPM you run...per him. My final question is do any of you know what a in frame rebuild of this engine should cost today...EST.?
Thanks much for your time and knowledge...

 

[nor'easter]

Many here will have more complete info, but what a bad reason to rebuild....cause someone says most only get 1500 hours. Do your some at start....how hong? Do they struggle with a cold start? Do they make 2300 rpms full load? If they start ok and make rated rpms, they might be fine for a long time. I think even when they start to get tired they will go for a while if you take care of them and dont run it like you stole it.

 

[Avenger]

Engineers will tell you engine life is measured by fuel burn. An engine has X number of gallons of life, do it 1,000 hours or do it in 5000 hours, and yes, that is mostly related to horsepower and load. Also yes, over propping will shorten engine life, however I would never consider a rebuild based on hours alone. At the very least a compression check is in order before even considering a rebuild.

 

[Artzco]

Be cautious and check all the things suggested by experienced forum members. I used FL Detroit Diesel once to work on my DDEC controls and they eventually fixed the problem, but kept driving up the hours and travel time to "evaluate"

 

[workingonadream]

ive heard that the high horsepower 6v92s are ready for rebuilds around 2000-2500 hrs but never heard anything about the 12v92. I agree with the above posts horsepower is an indicator roughly about when you should start considering an overhaul, but before I did an overhaul I would survey the engines ie compression checks oil samples cold starts etc. and I wouldn't call the guy who did your heaters.this guy is probably trying to sell a job.i believe those engines will tell when they are getting tired, and what is true for one 12v92 may not be true for yours, a lot of it comes down to maintenance and how hard you run them. please get a second opinion before you spend a ton of money that is unnecessary and I mean a ton, like upwards of 20,000 per side ,not including pumps blowers or turbos. good luck

 

[saltshaker]

Sounds like bad info and advice. Yes they can be shot at 1500hrs, but not typically in a MY run at hull speed. Many get 3K-4K hours out of them when run light. If they are over propped that will certainly shorten their life but only when the engines are over or heavily loaded. Scrod nailed it, it's not about hours it's about gallons of fuel burned. If you're running them slow, your using less Hp and they should last much longer provided they are making temp and are maintained properly. There is a 65 Hatt SF out there with 16V92 DDEC which are much more problematic than your 12V92DDECs. That boat is run hard all the time. She fishes tournaments and is rarely run slow except when trolling. Engines had been tired for a long time but they still ran them up to almost 5K hours. I heard this from a few brokers and another HOFer who knows the boat and the mechanics who maintained and eventually rebuilt them.

As for cost of overhaul, I'd expect around 40-50K per engine from a Detroit dealer. I was looking at a boat with questionable 12V92 DDECs and all the big outfits were quoting high. Lowest was 90K and highest was 140K not including yard fees or bad cores. You can do better with a good independent but the DDECs are a bit more expensive to rebuild and you need a DDEC mechanic to do them right. They are a bit different than your standard Detroit mechanical engines.

 

[northshoreone]

Thanks for the impute so far...I will add that the engines where rebuilt about 1,200 hrs ago and that was with a previous owner at about 1,100 hrs...I can't tell you why. The starboard engine at cold will start a bit harder than port...after sitting for over a month it took about five try's to fire the starboard engine but it was a cool south FL morning. When you start each motor they smoke for just about 10 or 15 seconds and then are smoke free. You can run all day and find no black soot on the transom. Fuel burn at 2,000 rpm is about 83 gallons an hour and less than 20 gph at 1,000 rpms. I posted here about six months ago about a engine high load issue on the port engine and the answer ended up being that Detroit Diesel in RI replaced all the engine wiring harness's on both engines chasing a firing miss....I believe just overcharging the previous owner as he didn't drive it let alone understand anything mechanical!!....They ended up placing the wrong wiring harness on one bank of cylinders on the port engine so two cylinders never fired!!...I had that head pulled and all is well none the less on those cylinders .....Thankfully! They really don't leak much oil...which was another sign that the Tech. said was an indicator of heading for a rebuild...Does anyone know the correct compression that the engine should have and also the compression that would indicate that its time to reach for the wallet!!
Thanks for your help!

 

[rwappleton]

I would not walk from that guy I would run!!!

Scroddy must have taken his professional pills just prior to responding because he usually leads with his sense of humor (and he may do business with the firm you mentioned).

His answer is the one I would use. And my answer is if it aint broke dont fix it!!!

 

[rwappleton]

Scroddy,

Have they developed a leakdown cylinder test for diesels yet rather than straight compression?

 

[Genesis]

If they clean up like that on a cold start and their oil consumption is reasonable I'd run 'em until one of those things changes or something goes wrong that's real obvious.

I concur with the others who have said this guy's looking to make work for him at your (sizable) expense. I don't have the DDEC specs for compression but Detroits have to be checked with them RUNNNING, which means you need the specific gear to do it (it's not like a car engine!) I wouldn't spend the money to pull a compression test unless you have symptoms that are consistent with low compression or some other cause to get into the engines, and it doesn't sound like you do.

 

[jim rosenthal]

If it ain't broke, don't fix it.

I concur with the folks who think the block heater guy is trying to sack your wallet. I'd dismiss him and just run your engines, keep up the maintenance, and enjoy your boat. I don't even think I'd get an engine survey at this point. I'd think I'd just keep the block heaters on when it's cold.

 

[captddis]

They do have a habit of of spinning bearings after the 2500 hour mark. That may be what he is thinking.

 

[northshoreone]

I should have also noted that while chasing the issue of load on the port engine, a compression check of that cylinder bank indicated great compression. My previous Tech. (who was killed in a freak accident this spring) at first thought it was a injector issue and replaced cylinder #4&6 injectors. When that didn't solve the issue...it led us to the analysis of the electrical components revealing the incorrect wiring harness on that cylinder bank.
The boat is based in south Florida in the Fort Myers area. If anyone here has a name of someone that has the skills to work on DDEC's close to this market, that information would be greatly appreciated!! I would also like suggestions on individuals or company's that you would recommend to rebuild the engines when the time comes!.....Hopefully a long way off yet!!

Thanks again members for your years of knowledge and willingness to share the same!

 

[Avenger]

I wouldn't necessarily jump on the mechanic bashing bandwagon. He may have just been relating his experience or some knowledge like captddis just did. We weren't privy to the conversation. And no, I've never done any business with them.

Scroddy,

Have they developed a leakdown cylinder test for diesels yet rather than straight compression?

You can do leakdown on diesels, but IMHO a compression test is more definitive. i.e. a leakdown test only tells you the condition of the rings/bore at TDC which could hide a problem lower in the stroke.

 

[capttonyf]

I have a friend that's been working on my boat along with my clients and friends boats for many years. He has worked for a Detroit Dealer for 30 years and works on his friends/clients boats in the evenings and on the weekends. He's very, very good and reasonable, so that means he's also busy but if you need Major work completed and are willing to bring the boat to Ft. Lauderdale it will save you atleast 1/3 to maybe as much as 1/2 of what it would cost you to go through a dealer directly. Not to mention it's his name on it and he makes sure it's done right.

We had a major problem recently and when checking on why it happened he noticed on one of our 92 Series motors that the guy who did the rebuild before we bought the boat mismatched two of the rod caps where they bolt to the crank and the tolerances were off and and caused it to fail at 500 hours, he said he was surprised it went that long because each cap is machined and matched per rod and it can effect oil flow causing those two cylinders to run hotter and wear prematurely. We ended up dropping the pan on the other motor than also to check and make sure they didn't mess up on that one also. What are you going to do?

Anyway, I don't see him travelling over to west coast often but I know he does occasionally if need be. If you were to ever do a major overhaul and you dont have anyone there you can trust it would be well worth your time, money and peace of mind that it's done right to bring the boat to Fort Lauderdale, rent a private dock for a month or so and have any other work done at the same time.

I don't want to put his information on the thread but if you feel you may need a good guy and want to reach out to him contact me privately and I'll get you his information. He really is great, and I trust his skills and opinion with out question. Hope everything works out there for you.

 

[Threestiks]

I am Located in Miami, long time Detroit Diesel 12v92ta (1989) need a good mechanic. Mine is retiring.

Henry

 

[JLR]

I have these engines on my boat. One thing I was told is that because they are DDEC's, they are slightly lower compression engines that should always be started with the block heaters having been used. It is easier on these engines that way.

 

[saltshaker]

Interesting to re-read this thread given the original poster had a failure and is now rebuilding one of the engines.

 

[nor'easter]

I think my 692 DDECs had 15 to 1 compression. Lower than I expected for sure.

 

[ddctech]

There really is no difference and need for special training when dealing with the ddec engine. The difference is no racks or governors. The cylinder kits on the ones I've seen have been 15:1, but as long as you order parts by engine serial number, and match the old to the new, it should be easy. That should be done with any engine! I never throw away old parts or turn in cores until the job is complete and turned back over to the customer. The two cycle Detroit engine is something different and special. Unlike other marine engines out there, these are cheaper to work on, and don't have a real set maintenance schedule. Just make sure the temps are right and you change the oil. The rest pretty much takes care of itself. Unlike what most will say, if built properly, they can be oil leak free. I've done it, not easy, but it can be done. I'm independent, based out of savannah. If you would be willing to travel, I can do the job at a very reasonable price. From what I'm reading though, I see no reason to overhaul unless you just feel like doing so. But if you would like, I can at least write up an estimate for you, if you can pm over your engine serial numbers.