Smoke on 8V71TI-425HP's

[SportFishCruising]

I am seeking opinions on 8V71TI - 425HP's in a 1979 HATT 46C with Allison Transmissions and 1500 watt block heaters, all with 1150 hrs.
Current owner always uses the block heaters 4hrs prior to start-up and reports no smoke. When asked about a cold start to test smoke and oil pressures, he is reluctant or refusing stating that "it will smoke out the whole marina and will continue all the way down the river".
I have throughly read this forum and the many posts on engine smoke, and most of you report no smoke, to little smoke, or too much smoke but that it generally clears up after 5 minutes.
So, cold start vs warm start smoking conditions; what should I be concerned about here? Should some alarm bells be ringing in my evaluation?
This is a preliminary investigation prior to any offer conditional upon surveys and sea trails.

 

[mobilemn1]

heaters are not going to make a good engine bad or a bad engine good. This guy may be a tree hugger, or someone sold him on the idea that engines are better with heaters,,,,I had a boss like that,,,,he wasn't a tree hugger,,,just an idiot

 

[SportFishCruising]

Thanks Daryl for responding;
I realize the block heaters don't make a bad engine good, what I am concerned about is what the warm start with bock heaters might be hiding, especially since he is refusing to perform a cold start for my evaluation.

 

[Canuck Dennis]

If he says they are that bad I would suspect a rebuild is in order, not surprising at 1150 hrs if ran hard or ran too slow. Get an engine survey. If bad allow 3K per cylinder for rebuild minimum.

 

[Boatsb]

Even in winter (ok 45 degrees in Florida) My engines do not smoke on start up unless I loaded them up with fuel somehow. If he wont start them in 60 degree weather without the block heaters I think he is hiding something.

 

[mobilemn1]

Thanks Daryl for responding;
I realize the block heaters don't make a bad engine good, what I am concerned about is what the warm start with bock heaters might be hiding, especially since he is refusing to perform a cold start for my evaluation.

If this guy is of the nerd variaty, vs. mechanically inclined, would hold more weight as to any problems. Now if they smoke while being on heaters for four hours is when I would really have a problem. Just explain to the guy why you want a cold start, and see where his jiberish takes you then,

 

[doc g]

Smoke on cold start up is low compression ..........................Pat

 

[Genesis]

Tell him that's fine: No Cold Start test (e.g. my "30 second compression test") means your offer will reflect rebuilds for both motors.

 

[SportFishCruising]

If he says they are that bad I would suspect a rebuild is in order, not surprising at 1150 hrs if ran hard or ran too slow. Get an engine survey. If bad allow 3K per cylinder for rebuild minimum.

I am surprised that you say, not surprising at 1150hrs. I thought that was rather low for this engine at that spec. I was hoping/expecting them to be good to 3000hrs. An engine survey will be a difinite with any purchase, this is preliminary to save expense and my main goal is to get good engines and avoid having to do them myself. Any boat I get must also be suitable immediately for a 2-6 week trip, just to get it home to Lake Ontario.
Owner runs 20kts@2000rpm on plane with this boat.

 

[SportFishCruising]

Tell him that's fine: No Cold Start test (e.g. my "30 second compression test") means your offer will reflect rebuilds for both motors.

Thank you... I am going to quote that!
I read your 30 second compression test sometime ago, but I would leave that for the engine surveyor; I just wanted a layman's cold start to hear the engines, see the smoke, check pressures from cold start, stuff like that; mainly to see if the boat warrants an offer with the expense of hull & engine surveys.

 

[Boatsb]

I am surprised that you say, not surprising at 1150hrs. I thought that was rather low for this engine at that spec. I was hoping/expecting them to be good to 3000hrs. An engine survey will be a difinite with any purchase, this is preliminary to save expense and my main goal is to get good engines and avoid having to do them myself. Any boat I get must also be suitable immediately for a 2-6 week trip, just to get it home to Lake Ontario.
Owner runs 20kts@2000rpm on plane with this boat.

The 20 Kts at 2000 RPMs sounds a bit overpropped to me but I am not an expert on the 46. If it is over propped (engines will not run up to rated RPM) it is probably time for majors and the idea that he runs it too hard makes me wonder about the rest of it.

 

[SportFishCruising]

Even in winter (ok 45 degrees in Florida) My engines do not smoke on start up unless I loaded them up with fuel somehow. If he wont start them in 60 degree weather without the block heaters I think he is hiding something.

I've read about you guys comparing smoke levels on different engines and stuff and it related to what doc g says...

Smoke on cold start up is low compression ..........................Pat

This brings us back to the 30 second compression check...ummm Genesis, where is the 30 second test?
But, I think I must stick to your quote Genesis, because he doesn't want to start the engines for me because he won't do the 4hr warm up as he lives away from the boat. When I use your quote on-site, he'd be smart to do the cold start or we just wasted everyones time.

 

[SportFishCruising]

The 20 Kts at 2000 RPMs sounds a bit overpropped to me but I am not an expert on the 46. If it is over propped (engines will not run up to rated RPM) it is probably time for majors and the idea that he runs it too hard makes me wonder about the rest of it.

The boat runs 28 x 34 4 blade bronze props. 23kts is tops, don't have the rpms but it's all within original spec. If these engines are due for a major, rebuild or repower.... then it's crossed off my list.
hmmmm... Don't ask if ya don't wanna know tha answer! lol
Thanks to prior research on this site, I kinda knew the answer but needed validation.
If I don't get the cold start...I'll just walk away.
(All I want is these engine to live out 3000hrs; isn't that within expectations for this engine givin these specs?)

 

[saltshaker]

He could have someone else turn on the heaters or he may just leave them on. Insist on a cold start. Verify that the engines are cold before you start them. touch the pan and some of the cooling pipes to see if they are warm. If they are, you won't get a fair cold start evaluation. I have 6V92's and they will smoke for about 10 seconds on a cold start. Smoke clears completely well before they warm up. I used to have 8V71's and they started the same way.

I have the same boat. 20kts@2000rpm is a bit fast for those engines even if the bottom is perfect and the boat is not fully loaded. it typically will take 2100-2150 to hit 20kts and about 23kts WOT. 2000rpm is an OK cruises speed provided she turns up at least 2300RPM with full fuel and water. 3000hrs is reasonable provided they have been cared for. If not, forget it. I've heard that 8V71's cost a bit more per hole to major because they are harder to work on.

Check the motor mounts. Most of these boats had engine mounts that have a thick piece of rubber sandwiched between 2 steel plates. The mounts can be repaired. Replacing them we cost several thousand just for the parts. They most likely are sagging if not replaced or repaired. Also make sure the gears, particularly the port gear, don't have play at the output shaft.

 

[SportFishCruising]

Thanks Jack, this is the same boat we communicated about before, I'm still at it. The boat is run with minimal loads of fuel/water/etc.
I'll check all the items you mentioned and it's good to hear I am not off the mark expecting 3000hrs on particularly the 8V71TI-425hps.
Quite a few members here are running these engines and I haven't really read any poor remarks about them. I'll push for the cold start.. I need it to justify the cost of an engine survey.

 

[Genesis]

At that power calibration IF NOT ABUSED those are ~3,000 hour motors, maybe more.

However... note the "if not abused."

The "30 second compression test" (cold start guide) is here:

http://www.samsmarine.com/forums/showthread.php?t=1499

 

[MikeP]

IMHO, if you expect 8V71Tis to start cold and quit smoking in a few seconds, you are expecting something that is unrealistic. As I have stated before here - there are a bunch of 53ft Hatts w 8v71TIs at our marina. NONE of them (including ours) will pass that test and none of them will be smoke-free at idle, regardless of how long they idle.

To me the critical thing is how quickly they will start cold. For example, our engines will start virtually instantly down to temps in the low 40's. They will hunt for 10-15 seconds at those temps but they will start immediately. At normal temps without block heaters they will smoke a LOT at startup (Mosquitos beware) and will NEVER stop smoking at idle. However, while running at cruise, they will not smoke at all. However, when reduced to idle, they will again smoke a bit. As noted, all the 53 hatts here exhibit the same behavior.

 

[mike]

FWIW, have twin 8v71N's with 3K+ hours, no smoke on cold starts even after 6+ months of storage. Granted N's are less apt to smoke due to higher static compression, but still a reference point. Bottom line Genesis is spot on, adjust offer price if no test, or fails cold start test. Don’t be rushed, it’s likely to remain a buyers market for now on into the foreseeable future. There are lots of boats out there, some of which can't be given away, let alone sold.

 

[Canuck Dennis]

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

 

[SportFishCruising]

Thank you Genesis for the link, the search function didn't find it for me looking back 5 pages of results and then I looked through your 20 pages of posts but now see it was posted by Pascal. I'm pretty sure this boat has not been run hard so will follow this procedure as best I can as a guide before booking the expense of an engine survey.
And I also recall reading the original thread you refer to MikeP and will pay particular attention to the start-up items you refer to and try to get a comfort level on what is acceptable smoke.