Smoke on 8V71TI-425HP's

[mike]

N's are different, can have 6000 hrs and still not smoke,, totally different engine.

Yep, agree as already stated major difference being N vs TI compression ratio, turbos are 2nd order effect at start-up, however still a reference point none the less.

 

[newinlet]

I would not walk away from a deal or make some low ball offer just because he will not cold start it. Maybe if you reason with him and explain the cold start is just one part of your evaluation of the boat and not a deal breaker if there is smoke at start up. You really got to take the whole survey and sea trial into consideration before you reject a boat or worse start spouting off low ball numbers, when in fact after some smoke at start up it clears away and the boat performs well in all other areas.
FWIW I got 671Ns in my boat and I use heaters also to keep the E/R warm and oil and coolant In my opinion it is a great way to reduce wear and tear and moisture in the E/R. When cold with no heaters my boat will smoke and then clear up and not smoke further much at all. the man I hired to R&R my Cyl head offered to buy my engines if I decide to upgrade. and my motors run very well And I bet the ones you are looking at do also.
I see some much newer boats with cats/cummings/volvo do the smoke thing on start up some more than the old detroit's in my boat at times.
Sorry for the long post I just think smoke from a two stroke Detroit is and should be expected ... The boat is a 78 come on

 

[Canuck Dennis]

Regardless of what anyone says, an engine survey with the bores scoped is a major insurance policy. Plus, a good surveyor will find many small but very very important items that will need attention.

 

[Brian Degulis]

I would not go forward with a possible purchase without a cold start. Maybe the seller needs to better understand that the cold start is essential for evaluating the condition of the engines it's basic. From there you decide how you want to proceed. If they're smoking a lot on start up and you still want to proceed with a possible purchase your going to have determine if the smoke is a compression problem or a fuel problem. It's important to know that because the expense to correct the problem will vary greatly depending on what it is.

At 70 degrees or higher a turbo DD should start quickly. within a minute it should be running steady on all cylinders a little hunting is ok but all cylinders should be firing. It may smoke moderately at start up it should be light smoke within 2 minutes and if you drop it in gear there should be just about no smoke. The above assumes the engine has 1000 or so hours and is in typical condition for that amount of use. The turbo engine will smoke more on start up and in the lower light load RPM ranges because the compression is around 95 lbs lower than the naturals.

Some of the confusing comments you see on here regarding smoke may just be a persons interpretation as to what is smoke. All DDs smoke even brand new in perfect condition just start one in a building and it's obvious. So IMHO when someone says no smoke it's relative to what we're talking about.

Brian

 

[SportFishCruising]

This is what we found out during our pre-inspection of the boat. Considering that the boat is 30 years old, we found it to make a very good dockside presentation. Original paint looks good as does the chrome hardware and most canvas work.The inside is nice and clean with the usual wear and tear on cabinet corners etc, but not bad at all.There was only one real issue with the interior, and that being a stained headliner above the TV console. The original headliner is nice, but this stain indicates a small leak from the flybridge, most likely a handrail or such.

The engine room is very clean and orderly. The engines themselves were very clean, no grease or oil leaks, spin on filters, heat exchanger recently serviced and the turbo chargers looked good. Hotwater block heaters were turned on at 0400 and started by us at 0900 in the engine room. We witnessed minimal smoke out the back, and ER gages showed 35-38 psi on the oil which I expected to see around the 50 psi mark. The heaters are WATER TYPE and not pan mounted; therefor the oil was "cold". Started after 2 seconds of cranking with almost zero hunting. We started it up 3 times and everything sounded really good. Last time they were timed and tuned was 1999, with yearly oil and filter changes. Oil looked new in transmissions and engines. There are Allison M model gears at 2:1 instead of the MH models. 15kw Onan and the rest of the AC and DC systems looks very presentable, new battery charger, newer big truck type batteries, all connections looked good and with 1200 original operating hours. Overall, the boat looks very well cared for and no signs of abuse or neglect.

This boat rates very high on my list for consideration of Offer to Purchase subject to Sea Trial, Hull & Engine Survey once I find myself ready to committ to a 46C. Your comments on these findings would be appreciated and I would like to express sincere appreciation to the forum members. It is from this forum and the members that I have been able to progress this far and I am feeling more comfortable and becoming more knowledgeable about proceeding properly in evaluating a HATT purchase.

 

[MikeP]

A start with 5 hours of block heater time is not much of a test - it's starting a warmed up engine. Our block heaters - same kind, water heaters - will easily have the engine at around 140 degrees in 5 hours which means there is plenty of heat in the combustion chambers which is where it matters to get an "easy" start. Under those conditions the start should be virtually instantly when you hit the button with no hunting at all. I'd really suggest you do a completely cold start and see how quickly the engine starts. It should still start within a second or two though it might hunt for a few seconds if the temp is down in the 50s or lower.

 

[Brian Degulis]

I guess from your reply that the owner simply would not allow a cold start? Basicaly he's telling you that you can only do limited inspections. If you decide to proceed you would be wise to do a very complete engine survey. Oil analysis compression on all cylinders bore scope everything. I would make sure the owner will permitt that make sure he knows that every injector will be removed and a basic tune up will have to be preformed. If he won't allow that then factor majors into your offer.


Brian

 

[SportFishCruising]

I guess from your reply that the owner simply would not allow a cold start? Basicaly he's telling you that you can only do limited inspections. If you decide to proceed you would be wise to do a very complete engine survey. Oil analysis compression on all cylinders bore scope everything. I would make sure the owner will permitt that make sure he knows that every injector will be removed and a basic tune up will have to be preformed. If he won't allow that then factor majors into your offer.Brian

Yes, a rather limited inspection and no Sea Trial until I put some money down with an offer. Can anyone recommend a really good engine surveyor in or around Dalton, IL? And also a Hull Surveyor?

 

[Genesis]

No cold start = full engine inspection including boroscope and compression test. That's going to cost; make sure you factor it into your efforts, and I would do that FIRST before you pay for a hull survey. After 3-4 hours of preheat on the blocks I would have EXPECTED an instant start and no misbehavior of ANY sort, even if the engines are well below minimums on compression or have other internal issues. Oil pressure you observed is normal for a preheated start; "middling-warm" idle oil pressure (which is where you wind up on a block heater) is usually around 30-40psi, so you're right up the middle. Hot (185F water, full operating temperature after being run under load for an hour or more) oil pressure at idle minimum spec is 7psi (alarm setting) but more typical normal at 550 RPM is in the neighborhood of 15-20psi. This all assumes the proper (40wt straight grade) oil.

My order of proceeding would be:

1. Reduce offer by cost of FULL engine survey.

2. Offer contingent on engine compression + boroscope (first), hull survey and sea trial with engine inspection during running, in that order (that is, engine compression and boroscope are done BEFORE the rest.)

Realize that if the engines meter out near minimums you're going to eat the inspection cost. I would try to negotiate a clause that if they meter on compression BELOW minimums or show clear evidence of a necessary rebuild on boroscope (e.g. broken rings) that the SELLER eats it, since he doesn't want to do a cold start. This negotiation may fail; if it does, then reduce the offer by the inspection cost that he's forcing you spend on, and decide if you want the gamble (sounds like the answer is probably yes)

Note that the flybridge leak can be bad news as it MAY indicate compromised core in the overhead (floor for the bridge); if so the surveyor will (if he's any good) find it. That sort of problem is a big deal if present as it will cost many thousands (and perhaps 10 large) to fix, and it HAS TO be fixed as it will only get worse. You won't know until you do the survey (assuming you didn't percussion-test the bridge floor yourself.)

 

[REBrueckner]

My own experience over 11 years, just completed,about 1100 hours or so run time, with 1972 8V71TI's at 425 SHP mirrors post #17 and I did a little better than post #24 suggests. I had the advantage of a cylinder kit overhaul on my port engine at the beginning and so was able to compare with the largely original stbd engine. Both always smoked moderately at 70 degree ambient without preheating for maybe five minutes, usually no hunting, but they'd hunt a lot at say a 60 degree start with more smoke. The overhauled engine always started a bit cleaner than the original, but I'm not sure the average person looking would have noticed a difference. The overhauled engine would start at 70 degrees ambient in maybe 2-3 seconds, the other maybe 3-5 seconds. I would typically have light smoke for maybe five minutes until the engines warmed and combustion improved OR if I put the engines in gear (one fwd one rvse) dockside and bumped up RPM from maybe 550 RPM idle to 600 or 700 RPM smoke would almost entirely disappear.

I got in the habit of always using block heaters dockside for about 45 minutes before start, while when at anchor genny warmth in the engine room would be more than enough for a typical 3 second or so start. I never observed smoke under load at cruise nor at idle after cruise.

The only time I had some miss/smoke underway was due to a clogged fuel filter..even though vacuum pressure was only slightly elevated...never did figure that one out...
I changed filters and decided not to worry....and after five weeks in Nantucket my return trip was normal.

When I had the same mechanic who did the overhaul give me a tune up at about 600 hours, both engines ended up smoking a bare amount MORE. It was a waste of time...the mechanic is the only person I let touch my engines and he even came back to double check the N 90 injector settings and confirmed they were correct. I did get to razz him a bit but his boss got to keep my money!

So why will the seller not allow an ambient temperature start? I don't get it.

 

[SportFishCruising]

Thank you everyone, I learned alot through this thread and my first experience with a pre-offer inspection. From your responses I've also learned how to proceed, which is to have an engine surveyor do a pre-full survey doing engine inspection, compression test and with boroscope, etc. (pass/fail); then sea trial with full running engine survey completition (pass/fail) followed by hull survey. 1,2,3... sounds easy...lol. I'll be sure to always get a general consesus here too, you guys help alot to educate me.

 

[Brian Degulis]

You'll want to make your offer make sure it's acepted and put down a deposit to secure your first right of refusal before you spend the $ on the engine survey.


Brian