6bta 5.9 turbo

Low hour engines
Would black soot and small amount of oil be an issue
I'm looking at why my 3788 only pulls 2200 rpm at wot
I've looked at all the other possible issues

2,200 rpm at wot vs 2,600, 2,800 rpm or 3,000 rpm rated (depending on model) is way over propped and you are damaging your engine. Not enough information in your post to comment further. I suspect that you need a complete servicing of the raw water and air cooler system before going further.


David

The crank case breather has a check valve. sometimes they stick open and then you get extra oil into the air intake, and you may even see oil dripping out of the air sep.

There was a lot of information and ideas thrown around on your last recent post on this issue and I think the better question is this...


What is the possibility that both turbo's have the exact same problem at the exact same time?


"Would black soot and small amount of oil be an issue"
To answer this question with the information posted and just this one picture I would say these look very typical of many turbo's I have seen in various Bayliners and Sea Rays. Can you get a boost reading even with a temporary gage?

tadhana said:

The crank case breather has a check valve. sometimes they stick open and then you get extra oil into the air intake, and you may even see oil dripping out of the air sep.

Click to expand...

I added the pictures and did have another post with more info on the low power
I was told that $1700 was the cost to rebuild the one turbo
So don't want to make the mistake
Props are clean

When was the last time the engines made their rated rpm?

What has changed since then?

I hate to say this but many times this is a mental issue. We chase problems down the wrong rabbit hole while totally ignoring advice given. I see it over and over and over. People keep trying to bang you over the head with the most likely solution but you are too far down the wrong path to listen. YOU ARE LIKELY OVERPROPPED!!!! I know of a person that chased every possible solution expect the one that was causing the problem....right up until the point where holes were burned into the pistons. Listen up!!!!! When people like Ski say something....it should be like EF Hutton!!!!!

"I hate to say this but many times this is a mental issue. We chase problems down the wrong rabbit hole while totally ignoring advice given. I see it over and over and over. People keep trying to bang you over the head with the most likely solution but you are too far down the wrong path to listen. YOU ARE LIKELY OVERPROPPED!!!! I know of a person that chased every possible solution expect the one that was causing the problem....right up until the point where holes were burned into the pistons. Listen up!!!!! When people like Ski say something....it should be like EF Hutton!!!!!"


Baker has a great summary posted.
If you want to hear a different suggestion here I would suggest that you somehow secure some additional information so that folks are not attempting to diagnose an issue from one picture.
Things like this....
- What is the boost readings at various rpm from 1800 to max?
- Do your trim tabs full work? (that boat needs max tabs to reach planning angles)
- What are your curremt prop specs? D X P X number of blades and material)
- What are your trans ratios?
- When was the last time your boat achieved planning speeds and correct rpm?
- Over how long of a time period did this problem happen?
- What other symptoms do you have? (soot, temps, high idle rpm readings, etc)

Nobody mentioned a fouled prop!! Dramatic impact on WOT!!
Assuming (not clear from posting) that engine did reach WOT in the past and prop has not been changed, then how could engine be overpropped??

"Nobody mentioned a fouled prop!! Dramatic impact on WOT!!
Assuming (not clear from posting) that engine did reach WOT in the past and prop has not been changed, then how could engine be overpropped??"


You would have had to read the other post from a couple of days ago. If you so desire the link is right here.....


http://www.trawlerforum.com/forums/s6/bayliner-3788-low-rpm-26830.html

Chrisjs said:

Nobody mentioned a fouled prop!! Dramatic impact on WOT!!
Assuming (not clear from posting) that engine did reach WOT in the past and prop has not been changed, then how could engine be overpropped??

Click to expand...

I guess the proper term here would be overloaded. We still do not know if it used to reach WOT and now it does not. But you can overload a boat that was previously perform well by a fouled bottom or fouled props.

Another thing not discussed is while it may appear both engines are suffering the same problem, could there be an engine that is malfunctioning(ie turbo) and causing the other engine to be overloaded??? I think I read a case on boat diesel where the HEALTHY engine was belching smoke because it turns out, it was the only one trying to do work while the other engine had a slipping transmission or something like that. Bottom line, a fault of one engine made it appear that the good engine was faulty.

"Assuming (not clear from posting) that engine did reach WOT in the past and prop has not been changed, then how could engine be overpropped??""


The OP - Yoeman is posting on the BOC as well as the trawler forum.
I just saw a few posts over there that indicates he has bought at least 2 maybe more boats very recently through an auction with no background on the boats and no sea trails.
Based upon that and the previous posts here I would guess that we have all the information he has so far on this new to him boat.
When and if any additional data become available I am sure folks here could narrow this down quickly - until then it is just a wild ass guess.

not again?????

Not enough info. 2200 WOT is so far below rated WOT that it's hard to know where to start.

Read David's and Ski's post again, they are both experts and will save you much time and money if you listen.

And read Bakers post again. I could be and probably am the guy Baker refereed to as chasing the rat down the wrong hole. I was overpropped and got the reman to prove it.
It probably is the obvious problem even if you don't want to believe it.

Perhaps the PO installed a set of cruising props and WOT cruising is no longer contemplated?

Black soot is the usual sign of a prop being run at an RPM too great for it.

Try 1800RPM or so to see if she runs well there as that probably was the goal.

Even 15-1600 might be a great cruise.

Not every owner wants to tow water skiers.

I concur with FF, however if overpropped is going to be considered normal, and the engine run at reduced rpm, the throttle should be limited to eliminate the possibility of overstressing the engine.
The seller should also disclose such information upfront.
I'm curious as to what max rpm is out of gear?
Envirovent is an aftermarket blowby separator system from Seaboard Marine that works well for the Cummins B's and C's, worth looking into.

What is the EGT.......was mentioned about over proped or fouled if EGT's are higher 1000 1300 I agree with proper symptom

yoeman said:

I added the pictures and did have another post with more info on the low power
I was told that $1700 was the cost to rebuild the one turbo
So don't want to make the mistake
Props are clean

Click to expand...

So put a link into your post so we can read it without a great pia search. I tried a search but no dice.
Help us help you. Or repost all the other info.
I agree, no where enough info to hazard any kind of reasonable suggestions.

I suspect this a dead issue since the O.P. hasn,t replied but

SOOT

Yes soot, if it is indeed soot, is an issue. That is most likley an exhaust leak. Soot from that will quickly plug air filters. Engines are excellent vacuum cleaners. A plugged air filter can cause poor performance and often heavy black smoke at the transom.

Soot will also make a big mess. You may have to watch while the boat is run to locate exactly where it is coming from. Soot often leaves telltale blackening where it leaks from so you may find the leak with a close examination of the entire exhaust .

Edit. Sooting in the engine compartment is what I was referring to.

If he's not coming back, I don't feel bad about a sidebar...what are "spooling" and "droop."?

H.W.

Spooling. At least with engines usually refers to the turbocharger acceleration

Droop. With diesel engine usually is part of the fuel delivery by the injection pump governor where the engine has reached its Rated rpm but not the final absolute max. Rpm set by the mfgr. The few hundred revs difference between the Rated and the final max. (High idle) is often called the droop. It can be called by other terms but droop is often used.

I hope I haven,t blathers about the wrong issue.

C lectric said:

H.W.

Spooling. At least with engines usually refers to the turbocharger acceleration

Droop. With diesel engine usually is part of the fuel delivery by the injection pump governor where the engine has reached its Rated rpm but not the final absolute max. Rpm set by the mfgr. The few hundred revs difference between the Rated and the final max. (High idle) is often called the droop. It can be called by other terms but droop is often used.

I hope I haven,t blathers about the wrong issue.

Click to expand...

Got it. Those two terms were used earlier in this discussion so you defined the right droop.
Thanks.

HW,

Droop I realized I left a wee bit out. The rev difference between Rated and Hi Idle is the speed where the governor starts to defuel the engine as it backs off feeding to not overshoot the high idle. The mechanical injected engines need that spread so they don,t abruptly
defuel.

The electronic ones do the same but the control can be done smoothly in a much tighter spread to the point that dialing in a prop needs some different techniques.

Turbos

I'm guessing I'm not the only guy that has purchased a bank repo with no sea trial so not sure why that's coming up
The Bayliner37 with 250 hp 6bta was slightly under powered from what I read so I was looking for info on prop pitch and performance numbers like cruising rpm and speed
I have had a ton of good info on this site that helps me trouble shoot
Yes I have had 2 bayliners that are not great performers but I still enjoy boating and love the 3788
Thanks for all the help
I'm going to look at the props then post back with real numbers

The 38 Bayliner, 3788 I believe, was a lobster boat hull copy. Those boats had a good turn of speed but we're not fast boats. Usually designed to be a seaworthy hull in usually rough waters that could also carry a good load without fuel use breaking the bank.

The later real pleasure boat need for greater speed was not intended so original, early 3788, were according to later standards slow and underpowered.
For original intentions and market at the time they filled a niche.

2016 Powerboat Guide says 19 to 20 knots cruise and 24 knots wide open. One clue to whether you are over propped or not is how close to the 24 knot top speed you are getting at wide open throttle. If you are near the 24 knots with low rpms then you are probably over propped. If 2200 rpms gives you closer to the advertised cruise speed then you more likely have an engine problem.

In the circumstance you are over propped the engine is overloaded. In the other circumstance the engine is just not making the power. It has been my experience over the years dialing the props in for the last couple 100 rpms doesn't drastically change top speed. It just matches the load better to the engines capability.

FYI those engines should turn 2,600 rpms according to boatdiesel.com

yoeman said:

I'm guessing I'm not the only guy that has purchased a bank repo with no sea trial so not sure why that's coming up
The Bayliner37 with 250 hp 6bta was slightly under powered from what I read so I was looking for info on prop pitch and performance numbers like cruising rpm and speed
I have had a ton of good info on this site that helps me trouble shoot
Yes I have had 2 bayliners that are not great performers but I still enjoy boating and love the 3788
Thanks for all the help
I'm going to look at the props then post back with real numbers

Click to expand...