Cummins 4BT

[Dan]

I have  pair of 4BTA cummins in a pursuit,apart from the walker airsep’s leaking oil and the cold start pre-heater’s Ive had 1000 hours of virtually trouble free motoring.
I’m aware of the 1000 hour service required,but in doing some research on it I see there was a lot of injector issues with these engines when first installed. One of my injectors has started to weep (externally) and I’m looking at the options to service all eight or buy new,mine are original from new.
I’m down 200 rpm’s at WOT (clean bottom) both originally pulled 3000,can anyone help with the part number or links for the injectors that replaced the faulty units?
Thanks
Dan

Topic

[Dan]

Tony
I pulled one of the aftercoolers on the weekend,and was pleasantly surprised,no corrosion at all! Guess that freshwater flushing system I installed paid off!

On the air side it was better than I was expecting,will get it all cleaned up and refit.

I also installed the seaboard marine envirovent kits,your article on crankcase ventilation perfectly described what I was seeing with my “B” engines fitted with airseps,I’m glad to be rid of them.

Thank you

[Dan]

Tony

Pics from Starb engine, the deck drainage hose behind the valve covers is

Valve cover 1- 90 MM from the center of the valve cover bolt to the OD of the hose.
Valve cover 2- 50 MM from the center of the valve cover bolt to the OD of the hose.

Same height clearances on the Port engine.

Thanks
Dan

[Tony Athens]

Dan,

The height above the valve cover is not “written in stone” as sometimes we make them higher on purpose.

Let’s do this another way–A good picture showing me what you have to work with on the front or #2 valve cover to the underside of the deck about it. But minimum would be about 2″, but higher is always better.

The kits come with everything .

 

Tony

[Dan]

Tony,

Ive read your article here. http://www.sbmar.com/product/envirovent-ccv-kit-4bt-6bt-series/

On your envirovent solution the pickup is either mounted on the timing cover (mine has the tach drives in that location) or the valve cover.As I have very limited space above the valve covers, can you give me some measurements of the valve cover setup?(Top of valve cover to top of fitting that I’m guessing screws into the oil cap hole)

Does the kit come with the cap to block off the breather on the side of the block?

I’m planning on doing the valve adjustment,retro fitting your CCV kit,after cooler service,cooling system clean out,RWP impellers and pulling the leaky injector out.

Once the injector is out and I can see part numbers is there any way to determine if I have the injectors that where causing the issues when these engines came out? I’m spooked about what I have read with tips falling off and total engine failure,I would rather replace them if I am at risk of that.

Thanks
Dan

[Dan]

Tony,

I’m hearing you loud and clear,will investigate further,thanks for the assistance – much appreciated.

Dan

[Tony Athens]

Dan look at the attached screen-shop of your posting.. This says is all..

Your boat has lost performance as your boat is heavier, the windage has increased, the bottom condition is not perfect, or the props themselves have deteriorated someway..

 

Same vessel RPM and less speed-This is not an engine issue. this is a boat issue–Prop down 2-3 inches of pitch and let your engines spin up to OVER 3100 RPM.. Until you do that, you will not improve your performance.

And, get you afterccolers off the engine, on the bench, a fully taken apart while you still can. If one of these fails due to lack of proper maintenance, you will hate life.

Tony

 

[Dan]

Rob,

Thanks for the link, I had not seen it and certainly explains a lot,the fuel solenoid shutoff scenario mentioned is a no brainer and certainly something I overlooked.

Tony mentions in the article that injectors are usually blamed for poor performance but are rarely the culprit,easy to see why after reading the article,my concern was do I have the bad injectors that caused so many failures in the past,and/or where they potentialy damaged by the poor fuel I initially put through them.

“a broken return check valve causing low fuel pressure” was also mentioned – I do have this issue in one engine, It drains fuel out of the pump if not used for a week or so and I have to prime it.

Much to learn,thanks for the assistance!

We will do the aftercoolers,valve adjustment,thermostats,impellers in the next couple of weeks,and I will follow up on the other items mentioned.

Dan

[Rob Schepis]

Aftercoolers should be properly serviced at this point but you say no dark smoke right? so likely the air side is not clogged up…

Have you seen this article? http://www.sbmar.com/articles/understanding-low-power-troubleshooting/

[Dan]

1.
Early Jan 2014
WOT 3000 RPM No speed data
2400 RPM No speed data

Late Jan 2015
WOT 3025 RPM @38.7 MPH
2400 RPM @ 31MPH < this is an average number, not exact as I never measured it at 2400 on the day.

Mid Nov 2016
WOT 2800 RPM @ 34.2 MPH
2400 RPM @28.9 MPH

2. The after coolers where removed in OCT 2015, they where spotless,the cores where not removed from the housing,only a visual inspection of the raw water side.

Thanks
Dan

[Tony Athens]

OK, I am going to try this differently  — I need the answers to these questions  only — Nothing else..

1)  Give me a date 1-2 years ago that you have records of your vessel speed (clean bottom circumstances so I can compare to yesterdays numbers)

approx Date = ??

2) ON THAT DATE———

WOT RPM = ?

WOT Vessel speed =?

2400 RPM speed = ?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 

3) When was the last time your aftercoolers we removed from the boat and serviced on the bench?

You are do for a valve adjustment.

Tony

[Dan]

Tony,
As I said in my reply I couldn’t supply current numbers until today as I was away from the boat,will briefly recap the history,

Purchased boat with 29 hours on it in Jan 2014,the test drive on the lake yielded 3000 per engine,both engines where very responsive (cant remember the speed) the boat was was fully fueIled.I can not supply exact performance numbers at various RPM’s on that date as I did not take them.

Ran the boat until Jan 2015 (aprox 500 hours) with no engine issues, although I did lose approx 150 RPM at WOT towards the end as it had a lot of growth,even though the the bottom had a lot of growth it was still very responsive and performed well.I hauled it cleaned it and had the props tuned.

Put the boat back in the water and the engines spun to to 3025 and 38.7 MPH full fuel.

I drive it at 2250 to 2400 RPM’s and weekly run it to WOT for 30 seconds or so to keep an eye on engine performance.

Both engines have gradually lost RPM’S at WOT and the boat has become a little sluggish in acceleration and is weight sensitive,both engines are not idling as smooth as they used to.

Gradually (in the last year or so) pushing into a strong tide and a bit of weight on board I cant get the engines to spool up past 1800RPM’s, I have to throttle back and let them gradually wind up till they start to get boost,then gradually up the throttles to cruise RPM’s,this never happened before (before or after I had the prop’s tuned) it was virtually unaffected by conditions and weight, I could just gradually increase the throttles and the boat would respond quickly.

I dived on it today, the bottom is clean and yet performance is way down on when the boat had a substantial amount of growth on it,here are the numbers from sea trial today, flat calm running into a very weak tide,half fuel (100 gallons)
RPM            SPEED
2000             20.6
2200             25.1
2400             28.9
2600             32.0
2800 (WOT) 34.2

At WOT the port engine was doing 2800RPM,starboard engine was doing 2790 RPM,for comparison I turned the boat around and ran back down the course running with the tide, the WOT speed and RPM’S where virtually identical.I have checked both throttles are opening the fuel pumps to full fuel.

Rob,
No black smoke,they run very clean,Ive never removed the mixers,I confess I had to google exhaust spill over and an article of Tony’s was the first hit!The exhaust outlet is just above the waterline, distance from the waterline to the center of the turbo is 14” (X marks the spot)

[Tony Athens]

This is all good stuff, but you DID NOT answer what I specific ally asked……….

This is all really  great,  but you DID NOT answer my questions as asked!

Until that is done as asked, and the answers are accurate , I  cannot help properly.

Is not what you came to us for?  A solution as to WHY?

I thought I made it very simple?

 

Tony

 

[Rob Schepis]

Nice and clean and nice proactive approach of ownership you have.

You noted your speed prior to this issue but what is it now?

Is the noticeable rpm drop the same in both engines?  Any black smoke when you’re trying to make those rpm’s?

Do you have any pictures aft of the engines showing the exhaust?  Have you ever removed those OEM mixers and inspected the exhaust side of the turbos?Ever measured the spillover?

[Dan]

Factory specs..

[Dan]

Tony, Thanks for the response.

The boat is a pursuit express, the engines are Family M10TA, 250 HP at 3000,Model name 4BTA 3.9 -M.I purchased the boat with 29 hours on it in Jan 2014,It had been sitting on a freshwater lake and was only obviously barley used!

I trucked it to FL,changed the fluids/filters and impellers and went boating! I drive it at 2250 to 2400 rpm’s (dependent on load) It has always accelerated very quickly and not greatly affected by weight loads.

As the boat sat for so long I had issues with fuel and initially was changing fuel filters every 20 hours or so (primary and secondary) Its running clean now (after 1000 hours) I treat the fuel every fuel up and source the diesel from a very hi volume suppler who supplies to our large fishing fleet here. The after coolers where removed just over a year ago, they where spotless,I installed freshwater flushing on the engines and flush them regularly.

Last year I hauled the boat and replaced all the through hulls and hoses, sent the wheels off for tuning and had them apply prop-speed,the bottom of the boat had only ever been bottom painted once in its life and was in amazing condition,I prepped it and applied new bottom paint and put the boat back in the water.

With half fuel and two people the engines pulled 3025 revs(faria tach’s) and 38.7 mph by gps.

I use the boat a lot,dive on regularly and have it cleaned by a pro diver once a month, the boat has always performed as per the pursuit specs below but performance has fallen away in the last year (its much more weight sensitive,down on rpm and a little lethargic on acceleration) My concern is that the injectors must have been compromised by the fuel. They start instantly with very little smoke that quickly clears up once warm but both are defiantly idling a little rougher. The injector thats leaking appears to be coming from the seat,and its more than a ‘sweat” more like a cupful for a three hour run. I will post current performance numbers after i run it tomorrow.

[Tony Athens]

If you indeed have the 4BTA 3.9 250’s,  then yes, early on there were many injector issues & many upgrades.. But, I have a few of them out there that have never had any .. Until you have an issue, I would not touch them.

An external leak is not a reason to change injectors or have them serviced.. Fixing the leak, if indeed it’s messy and not just a “sweat”,  1st requires to figure out the one of 3 most likely things that could be leaking–Return line, supply line,  or thru the injector seat.. All are very fixable on the boat……… Some really good pictures may help us help you.

Down 200 RPM————-That’s one that needs to be addressed.. Let’s go back to Day 1–Exactly date wise, when was that for you ? Was that zero hours,  or ??

What was the max RPM you could get then,  and what was the vessel speed at WOT.. At that same time, if you cruised at 2500 or 2600 RPM what was your vessel speed–Be very accurate on this

Today ,when you go for a ride, what is your vessel speed at 2500 or 2600 RPM–Be accurate..

When was the last time your aftercoolers we removed for the boat and serviced on the bench? You are do for a valve adjustment.

 

Let’s see some good pictures of the engines as installed showing all from all angles & perspectives

 

Tony

[Author]

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