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Hi Guys

I posted this on boatdiesel.com but I know many of you run diesels and may be able to help.

My starboard had 4BT a little pop then power loss and some whitish gray smoke

I am Running twin 4BT 150hp engines. Just took boat on cruise and within minutes I had a small "pop" and immediate loss of power on starboard engine and some whitish / gray smoke. Immediately running very rough.

Engine never stalled but I shut it down and limped home.

Started engine back at dock and have following observations:


*engine still has its usual oil pressure readings and fluctuates normal with increase of throttle.

*engine is running rough and has little power

*now it kind of sounds like its has a knock but I am not sure, hard to tell.

*ran engine with valve covers off and all valves were moving up/down properly

*checked all injectors to see if they had fuel and they did.Cylinder 4 was less pronounced when line cracked open but all 4 injectors are working at some level at idle. 4 was fishy though.

*I want to pull the injectors.

*pulled air filter and looked at compressor fins and spun, no play and seems smooth

*oil level is normal and no water in the oil.

*fuel system is primed and filters pulled and full.

I feel these symtoms are similar to losing the hose on the charged air after the turbo but mine are ok. Just similar symptoms to that. No power and smoking if trying to accelerate.

Maybe broken injector??? This was a "sudden" situation.

These are pretty low hour rebuilds but hey anything could happen. I have run them a few hundred hours since though.

Please any suggestions on what or where to look / test???

Frank V

Check your coolant level!... White smoke usually signals water in the combustion...

coolant level good. The smoke smelled like fuel. that sulphury odor..Def fuel...

I would say that pulling the injectors is your next step...

4bt injectors can have issues. Sounds like the tip is gone.

Bruce gets a cigar

This is my #4 cylinder
Dont know if it caused other damage. Gonna send all 4 out to get reconditioned.

FrankV,
Sounds like a bad injector, fuel smell in exhaust, did you have any water in your Racors or get fuel from a unfamiliar marina.
Just saw Bruce's reply after writing this.
Pete Fallon

Thanks Pete.

Def an injector, they are at the shop now. Just hope no other damage.

I had some priming issues with a fuel system leak that I had a hard time tracking down earlier in the season. Needless to say I bled the injector line on the motor probably a dozen times before I found the air leak on the vacuum side of the fuel system. This may have contributed to this injector taking a crap. Hopefully that is the extent of it.

I went in with a borescope and dont really like what I see. The piston top is a bit beat up. I am gonna do a compression test but just didnt have time.

The broken injector was not showing any signs of melting at all though. I think the piston is showing some signs that it was def getting too hot, I dont know about melting but def beatup (possibly from tip bouncing around b4 it was spit out).

This happened at 2400RPM and I shut it down fast.

I am thinking the piston damage was caused by the injector failing and NOT vice-versa or from something else???

I am just thinking what may have caused this? I had adjusted the valves the previous trip but it ran just fine, I do recall having a very slight whisp of smoke on startup that I didnt recall before though. No smoke while running or idling for that matter.

Looking in the borescope I do not have a trained eye but the piston top is beatup, cylinder wall looks OK as does the outer rim of the piston where it meets the cylinder wall. The top looks crappy though.

If I pass a compression test and a leakdown test than maybe I can install rebuilt injector and test it??? I am going to pull the head and replace the piston regardless during off season but just wondering if I have a chance to salvage another month of the season before tearing into it...

Def not happy with this one...

scenarioL113 wrote:I went in with a borescope and dont really like what I see. The piston top is a bit beat up. I am gonna do a compression test but just didnt have time.

The broken injector was not showing any signs of melting at all though. I think the piston is showing some signs that it was def getting too hot, I dont know about melting but def beatup (possibly from tip bouncing around b4 it was spit out).

This happened at 2400RPM and I shut it down fast.

I am thinking the piston damage was caused by the injector failing and NOT vice-versa or from something else???

I am just thinking what may have caused this? I had adjusted the valves the previous trip but it ran just fine, I do recall having a very slight whisp of smoke on startup that I didnt recall before though. No smoke while running or idling for that matter.

Looking in the borescope I do not have a trained eye but the piston top is beatup, cylinder wall looks OK as does the outer rim of the piston where it meets the cylinder wall. The top looks crappy though.

If I pass a compression test and a leakdown test than maybe I can install rebuilt injector and test it??? I am going to pull the head and replace the piston regardless during off season but just wondering if I have a chance to salvage another month of the season before tearing into it...

Def not happy with this one...

Injectors "loosing" the spray tip is not an unknown phenomenon... And, with the tip "rattling" around on the piston head it's common to see some surface damage to the piston head (as well as matching damage to the cylinder head surface)... USUALLY it's just cosmetic... I don't expect this cylinder to show a drop in compression... And if you find one, I wouldn't rush to blame the dropped tip but I would search for another reason...

Just make sure the broken tip is OUT of the cylinder... And definitely have ALL injectors serviced...

***UPDATE***

cylinder #4 ZERO Compression

Looks like the season is over for me. Piston is probably garbage. Could also be a valve but just wont know for sure until I pull the motor.

Obviously I will pull the head for starters but either way I am changing that piston even if its not the piston.

My gut tells me that the real problem is not that injector unless the injector was causing it to run real hot and cooked the cylinder........

Frank

Sorry to hear that. Keep us posted on what you find.

I spent a little more time looking over this problem and did another inspection and compression test.

The rockers, valves, and valve stems are operating smooth and appear to be working properly. Neither appear to be bent but I did not pull the head.

The push rods are also working properly and smoothly and are not bent. Cam is working good it seems.

This time on compression test I added motor oil to the cylinder ( 2 cap fulls) and I got ZERO again. I added a whole bunch more just for $h!ts and giggles and I got the same result,ZERO, Nothing, Nada... results are shown in this video:

https://www.youtube.com/watch?v=M5QGkOGZubQ


Obviously there is a hole in the piston that I can not see with the borescope or more likely the side wall of the piston is melted away where I cant see it and took a section of the rings with it.

One of the valves could be burned away too.

On the compression test it is a zero, I mean I can not even emphasize how zero I am talking about. Not even tick on the gauge of the compression tester. ZERO>>>>ZERO>>>>ZERO...LOL! I can only humor myself at this point.


Looking back 2 weeks ago,

I had adjusted the valves and soon after (maybe after 5 hours of operation). I dont think the valve adjustment had anything to do with it. I started to notice that when I started the engine I had a little smoke that I never had before that would clear up after a few seconds. I am pretty sure that was the broken injector tip dumping fuel. I think this was going on for a little while (5 hours of operation while) and it burned the piston up and suffered failure.

The rough running was this 4 banger running on 3 cylinders.

I wont have this motor pulled for a while prob december sometime, I need to get setup when I get the boat home. I had a gantry that I gave away so I will have to figure something else out to hoist the motor. Once I get in my garage I will be ggod to go and will updat with pics when I tear her down.

Hopefully this thread can help others in the future.

Frank

scenarioL113 wrote:I am pretty sure that was the broken injector tip dumping fuel. I think this was going on for a little while (5 hours of operation while) and it burned the piston up and suffered failure.

I'm not convinced. Perhaps there was a detonation that cracked the piston, but usually it's a lean condition that runs hot and holes a piston.

Lean = high combustion temps, low smoke
Rich = low combustion temps, high smoke

You didn't see a hole with the borescope. I'm guessing that either the piston dome or the rings are cracked from detonation. That might actually be good. If there's a hole, you have to wonder whether a hunk of piston made its way into the turbo.

You'll know for sure when you lift the head but my money is on a damaged valve... Not uncommon in cases where the injector tip is "lost"...

Ok well here is little progress. I have been busy the last month but have been chipping away at preparing to haul the engine.

I had to suck it up and buy a 16' I-Beam (6"). I have a trolley and chain hoist already and bought some 6x6's and put this together. I welded up some angle brackets that will connect the I-Beam to the 6x6's on each end. I think it should be pretty stable but wont know till I actually use it.....lol.

I should have the engine out sometime next week and will start tearing it down.

The port side post will be about 3 feet off the port side when it is in position with the I-Beam in place.

I still think you should have removed just the head first... You can still do that I suppose... If it turns out it's a valve after all you'll be saving yourself a lot of work...

As for the lifting rig, the I beam will hold the top sides from moving outward but if I were you I'd use some rope or a ratchet type straps to keep the bottom side in its place...

BTW, I understand how you're going to use that rig to lift the engine but once it's up, how do you intend to get the engine on the ground?!... There's no wheels on that lifting rig that I can see...

That was the set up the Cummins dealer used to move my jig around when we re-powered. Only thing is the jig was a stripped out block. To get the engines in and out, he uses a fork lift that has forks about 15 feet long. If you could rent a fork lift and somehow make fork extensions to attach to it temporarily it might work out better for you. Just be sure that you do not have too much weight too far forward otherwise you would tip forward.

The boat is my yard at home next to my pool and pavers so no heavy equipment can get in close enough. (only to the front of the boat). I thought about a crane to rent but by the time I add up the costs doing it this was is only about $400. If I was renting something I would have to rent again to put back in which would be more $$$

@navatech......I agree that the prob may be in the head but no matter what I need to remove the crank shaft and send it out to get miked up. I had low oil pressure @ idle that I never was too fond of...like single digits. Sometimes 5ish. Removing the crank would be all but impossible for me to do with motor still in the boat. Just no room under the engine and its too heavy obviously.

If it wasnt for the low oil pressure I would def not be pulling the engine.

I am laughing as I am typing but I intend to use my driving lawn tractor with its load hog trailer (has 600LB capacity) to lower it into. I will just drive it right under the gantry, I will have about 3 to 4 ft of room to park it. If I remove the exhaust manifold and heat exchanger, turbo and elbow and housing it should lighten it up just enough, GULP,.... The dimensions of the trailer are actually perfect to fit the engine, LOL

I should video tape that part just for entertainment of the faithful.

Progress......

Progress

It worked, you should Pat yourself on the back.

Surprised the neighbors did not come over to lend advice.

Heck, the tires aren't even squatting on the trailer! How many PSI did you put in them?

Rawleigh, they might be rigid. I see no valve.

Yes they are harbor freight solid rubber tires. The trailer was MAXED out though. LOL

Here is the deal!
Not too great. There is mild scoring on the cylinder wall in 2 places.
The cumbustion area on the head is beat up, will need to have machine shop look at it to see if it can be used.
Piston is obviously garbage.

I think both the block and the head will need to be inspected at the machine shop. Block may need to be bored possibly? Maybe honing will be ok but I dont think so. Looks like a valve let go but I just dont know what caused this. That cylinder was the one that had the broken injector tip and was slightly smoking at idle. When this happened though it was sudden, like boom and then instantly no power.

That valve probably broke when the piston slammed a hunk of injector into it.

mike ohlstein wrote:That valve probably broke when the piston slammed a hunk of injector into it.

Sounds like the most likely explanation.... Going back to your initial description of the timeline: "a little pop then power loss"...

The "little pop" was the injector tip, "then power loss" was the result of losing the valve...

Navatech wrote:You'll know for sure when you lift the head but my money is on a damaged valve... Not uncommon in cases where the injector tip is "lost"...

Nav, go out and buy a lottary ticket !

Yannis wrote:Nav, go out and buy a lottary ticket !

The thing is that lottery is pure luck... And luck had very little if anything to do with my calling this correctly...

scenarioL113 wrote:I think both the block and the head will need to be inspected at the machine shop.

If the head passes a pressure test it should be good to go... Obviously after having some work done... Valves, valve seats and valve guides need to be looked at... The fact that it's "rough" over one hole won't prevent it from working...

scenarioL113 wrote:Looks like a valve let go but I just dont know what caused this.

Part of the valve's "mushroom head" let go... Probably caused by the injector tip "rattling" around...

scenarioL113 wrote:When this happened though it was sudden, like boom and then instantly no power.

Sounds par for the course...

I have the engine entirely apart. PITA but we gotta do what we gotta do.

I brought the head to the machine shop and they are gonna go thru it. At a quick glance he said it did not look to be from anything I did adjustment wise. He said when he pulls the valves out it should tell him more.

I would just like to know what the cause was for obvious reasons.

I am gonna have the block inspected and will also have the crankshaft and camshaft inspected by them as well?
Are there any other parts I should bring to them to "mike" up or inspect? Caps? connecting rods? journals? I really dont know so any advise would be appreciated.

scenarioL113 wrote:Are there any other parts I should bring to them to "mike" up or inspect? Caps? connecting rods? journals? I really dont know so any advise would be appreciated.

You did say one of the reasons you pulled the engine was low oil pressure... I'd say take the block (including all the main bearing caps), the head, the crankshaft, the camshaft and the connecting rods (including the big ends)... But, to be sure, double check with your mechanic...

Wasn't there some sort of factory help from Cummins? There were hundreds of engines that suffered the same fate.

Were they parent bore blocks or did they have liners? It would be nice if you could just replace the liner!

mike your right there was a problem with the injector
tips breaking, and cummins covered it

The injector issue was prone to the 250HP aftercooled version of this engine. Mine is the 150hp version with no aftercooler and is "supposed" to be bulletproof.

Its all apart now and will update as I find out more.

Hi guys,

Been off the grid for a while.

Just got the bad news from the machine shop. The block is shot, the head is shot as well. 2 pistons are bad and 1 connecting rod is bad as well. The cam looks like 2 lobes are worn too. Crankshaft looked good but didnt magnaflux it yet. Kind of in a holding pattern right now bc I dont know what to do just this moment.

I am thinking a short or long block would prob be the ticket but I dont think there is one for my engine. The 4BT marine is pretty rare. There are loads of industrial and agricultural long blocks all over ebay etc starting at 2500 and up. Not sure if I am compatible with any of those.

If not than I have to piece parts out and build from scratch.

Any advice.....lol I know it sucks!


Frank


BTW Happy New Year Merry Christmas Happy Hanukkah and Happy Nothing if it applies.....

Cummins ReCon?
https://cumminsengines.com/showcase-ite ... &#overview

I just checked with a greasemonkey friend (Cummins certified) of mine and he says the marine, industrial and agricultural versions all utilize the same block, head etc... He says he'll ask around for a marine unit but according to him, you'd be good with an industrial or agricultural long block...

Having said that, make sure it's a true 150HP rebuild...

Thanks,

I am trying to research as much as I can. I do think that like you said, the head, block, crank etc are the same. I think it nds to be a turbo long block or otherwise piston compression ratio is different but I am not sure yet.

I think the differences are in the injectors and IP and IP timing. Otherwise all the same? I think, just dont know for sure.

scenarioL113 wrote:Thanks,

I am trying to research as much as I can. I do think that like you said, the head, block, crank etc are the same. I think it nds to be a turbo long block or otherwise piston compression ratio is different but I am not sure yet.

I think the differences are in the injectors and IP and IP timing. Otherwise all the same? I think, just dont know for sure.

We've all heard of the Telephone Game (a.k.a. Chinese Whispers a.k.a. Gossip) right?!... My friend's name is Gary, I will PM you his mobile #... Tell him I sent you... Talk it over with him...

After some research I realize that my CPL calls for 16.5:1 piston which are part # 3907156. Seems the B-series comes in a few varieties regarding compression ratio. 17.5:1 + 16.5:1. Seems 17.5:1 is the common one and what I need is not as common.
I may have to get a bare block and piece mail the parts I need to it and make my own for my CPL.

I will try that guy navatech tho. Thx

they cant bore your block I did on my 6bt

The damage is beyond boring unfortunately....

Frank, I know people with 4bts and 6bts on the road and industrial that have sleeved their blocks after several bores due to many, many, many hours and and a few bores on their engines. I don't know if there is a reason this is not a good idea on a marine application, but someone here will. The cost is the same as a standard bore, plus sleeves/install/hone. People using blocks this way are happy with them.

John

I am using a new block for this project. I located one from a supplier. I am keeping my original block though bc the cummins dealer by me can repair with a sleeve possibly. I will shelf it for future possible use.

I got a new head, block, rods, pistons, and cam. Using my original crank unless it mags out bad. Still waiting???

Due to cost restriction the parts are aftermarket but seem to be good quality. Not sure if cummins even can get a new block for me???

Will be assembling soon and I will post some fun pics.....yah

Frank, I was sorry to see the problems you had. I just turned 250 hours on the 4bt's I rebuilt and did the valve lash adjustment myself. I was very concerned that I may screw it up and drop a cable too. Luckily I have put about ten hours on the motors since and everything is fine.

How is your project coming along.

Troy

Just to resurrect an old thread because sometime when we search old posts it is good to know what the disposition of a situation was.

I ended up installing a new block, new head, new connecting rods, new pistons, new cam, new tappets. I was able to re use the crankshaft bc it was in perfect shape and only needed a polish, and reused the rockers. I rebuilt the CAV pump and got new injectors.
I reused all the other "bolt on" items on the engine (pumps alternator and such).

I was so disgusted that I did not put the boat back in the water until May of 2020.

I was overpropped and had the propellers reworked a bit and got some increase but I am still overpropped. These engines are rated at 2800 but need to see 2900. I am getting about 2750 right now WOT.

I also did some coolant upgrade that Tony from sbmar suggested and added some of my own as an experiment. The 4BT 150's and 6BT 210's have shortcomings on their factory coolant systems.

I increased the diameter of the coolant plumbing fittings to 1" to allow better flow throughout the system "outside" of the block. I also custom made my own expansion tank to increase the capacity of the coolant in the system similar to that of a 6BTA. I prob have 4 quarts more capacity than stock. I left my port engine in original configuration to compare the results.

So far it seems that my "new" starboard engine is maintaining 170F under cruise @ 2500RPM and will stay steady even at short intervals of WOT. Starboard engine will run at 185F and creep slightly up from there under same conditions.

Neither is bad but when I spoke to Cummins mechanic at the dealer he said that the problem sometimes is the "rear jug" on the B-series is the last place that the coolant gets to in the system and can run hotter than the rest of the block. This was the location that I had my catastrophic failure of the valve breaking (#4 cylinder). I plumbed a rear adapter that uses the rear freeze plug opening and I threaded 1" fitting in its place to allow the coolant better flow "thru" the block. I can post pics but not today.

So far so good, only thing is I notice the starboard engine def cools down quick when idling (prob down to 140F area) after 10 minutes and then I will see a light sheen on the water. I am not sure if this is a mechanical problem or a natural occurrence bc the engine is not up to proper temperature and excess fuel is not burning correctly. If I run at cruise and then go to idle for a drift there is no sheen but after 10 or 15 min of idling the sheen begins...Not sure yet but the jury is still out.

Happy 4th to all!

Frank V

Glad your back on the water.