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I think your going to have to start swapping parts. It has to be in the valvetrain, or else in the fuel delivery. I know the feeling you have. It's so frustrating when everything you try fails. Do you have anybody nearby you that knows the b series inside or out?? A good diesel shop maybe?? Might be time for a fresh set of eyes. Alot of times that works for me.
 

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Sorry if you've already answered this, but have you isolated for sure which cylinder is missing yet? I see where you cracked the injection lines and had no luck figuring out which one.

I just scored one of the coolest screwdrivers I've ever had in 50 years of wrenching! It's old, Made in USA of supergood steel and about 18" long, very skinny 1/16" shaft with 3/16" flat tip. Works great as a stethoscope to track down noises. Also you can buy cheapo stethoscopes specifically designed for mechanical testing, with ear tubes and a long skinny sounding probe.

If your hearing is shot out then maybe get a buddy to put an ear to it with a stethoscope.
If you could figure out which cyliner then it would be possible to swap injectors and see if problem moves.

Actually if it's a bad injector there would be a difference by swapping injectors around anyway, because of firing order. I mean you know the loping sound it makes now, and that would somehow change if a bad injector was re-positioned. Seems like that's the easiest course right now and it would solve a very important question.

Do you have white smoke at times, startup or otherwise?
 

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Also didn't you say you had a shop test the pump? If so, maybe you could take the injectors in to them to be pop-tested or inspected with a professional eye? Testing doesn't cost much, and then if bad you could decide on new injectors, or new tips, or clean plus adjust pop-off pressures or whatever the budget allows.
 

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Discussion Starter · #44 ·
Yes, the injectors have been tested, as well as the pump.

I pulled the injectors, tested them and put them back in a different order. Still misses the same.

Pulled the head, replaced the head gasket, put the injectors back in a differnent order. Still misses the same.

My hearing is shot. Lol. I may have to try the stethoscope,
 

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Discussion Starter · #46 ·
Have you tried a temp gun on the exhaust manifold to figure out which one it is?
I had originally, and due to the high mount center turbo it was hard to tell any difference. But, I have not tried since I put it all back. It does NOT seem to be loping like a 3cyl 4bt runs. If you watch the video, its more like a shudder, I suppose.
 

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I watched it, but it was really hard to tell if it was shaking more than it should or not. Mine seems to shake lots sometimes and just purr others. On my airplane, I have egt and cht for each cylinder, so you can see a problem trending when comparing other cylinders, if you had a way to get egts from then individual cyls you could find out which one is imbalanced. You could tap your exhast and move your EGT probe around and put a plug in the holes when you were done.

Or run the $h!t out of it til the weak part fails. then youll know.
 

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Yes, the injectors have been tested, as well as the pump.

I pulled the injectors, tested them and put them back in a different order. Still misses the same.
Pulled the head, replaced the head gasket, put the injectors back in a differnent order. Still misses the same.
My hearing is shot. Lol. I may have to try the stethoscope,
Yeah, we coresponded on some other issues a year or so ago and from that I figure hearing might not be perfect due to range time.

Thing is, mine has something very similar ever since I first installed, like a miss. Noticeable at all rpm's, and on rare occasions it seems to be better than usual. I have wondered how meticulous Cummins was with these remans, like whether they bothered to weigh pistons?

Reason I say that is because the miss or vibration I get is almost identical to what I experienced when I swapped a 318 Polysphere V8 for an LA360. The Poly is internally balanced and the LA 360 is externally balanced. Mopar Performance Chassis book has instructions for drilling the internally balanced flywheel to correct the resulting imbalance problem when used on externally balanced engines.

I didn't bother to drill the Poly flywheel because it's very precise locating for drilling and a large drill bit is required, so it's machine shop stuff. The 360 always had a vibration throughout the rpm range, but not nearly as severe as what I get with the 4BT. Still, it sure felt the same overall except for intensity.

But if it's imbalance, how the heck can it seem to get [slightly] better at times?!!!!

I used a CTD slip-yoke at tranny output, with built in harmonic balancer when I swapped, but the piece looked funky. I've suspected that yoke might be adding imbalance instead of correcting it! Paul in NY sent me another but for various reasons I haven't installed it yet, but hopefully it goes in within a month.

Are you using that same slip-yoke with harmonic balancer?
 

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Well after all that blabbing that slip-yoke still wouldn't explain a shake & shudder when it isn't in gear! Regardless, it feels a whole bunch like a balance problem on mine.
 

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Mc,You said that you pulled the head for a gasket replacement,and it had strange indents on the affected cylinders,this may be from a prior engine if this was a reman.But,it may cause different compression while running.By any chance,did you measure the piston height with the dial indicator,while rotating the engine,to see if they all were the same rise in the cylinder? Did you have the injectors pop tested,and see what spray pattern they have?What about the true VE timing lift,was it checked?? That one takes a fixture at the rear of the pump,and is sort of a pain to do,mine was 1.25,and I adjusted it to 1.35 and it made a world of difference (6bt). Have you tested the fuel pressure at the pump? You may have an issue not getting enough fuel.Or the delivery valves at the VE.Or,as JimmieD alluded to,you may have a harmonic balance issue.I used a 6BT harmonic balancer on my 4BT,and I have the fluid mounts........I still think that you have a fuel issue,and it may be that VE just having some wear and tear,and raise your idle a little.If you set all the systems back to basic,then you have a real good baseline to work from,and will be better off at getting the imbalance sorted out.Good luck.
 

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Adding my answers to questions for Lee here, just in case it might help: Mine's crapola hard rubber motor mounts, plus the NV4500 tailshaft mounts are the same: old, hard used mounts. Might as well have bolted everything together metal to metal!

I know his is a vaguely similar setup and install in a [GREAT!!] Dodge chassis, so possibly similar cause of similar symptoms. On mine I suspect a combination of problems: injectors, balance, mounts.
 

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I watched it, but it was really hard to tell if it was shaking more than it should or not. Mine seems to shake lots sometimes and just purr others. On my airplane, I have egt and cht for each cylinder, so you can see a problem trending when comparing other cylinders, if you had a way to get egts from then individual cyls you could find out which one is imbalanced. You could tap your exhast and move your EGT probe around and put a plug in the holes when you were done.

Or run the $h!t out of it til the weak part fails. then youll know.
Mine also shakes like a sob at idle and feels like it is a miss. I still need to run the valves. I have some of Scotts 50 hp injectors in and the pump timing is advanced. The only way I can get mine to stop shaking is more RPMS. ?? I would also like to know if with the ESN if we could get a report on the engine rebuild.
 

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Discussion Starter · #53 ·
Mc,You said that you pulled the head for a gasket replacement,and it had strange indents on the affected cylinders,this may be from a prior engine if this was a reman.But,it may cause different compression while running.By any chance,did you measure the piston height with the dial indicator,while rotating the engine,to see if they all were the same rise in the cylinder?
No, and i regret that.
Did you have the injectors pop tested,and see what spray pattern they have?
Yes, they were fine.

What about the true VE timing lift,was it checked?? That one takes a fixture at the rear of the pump,and is sort of a pain to do,mine was 1.25,and I adjusted it to 1.35 and it made a world of difference (6bt).
That's done on the truck? No.
Have you tested the fuel pressure at the pump? You may have an issue not getting enough fuel.Or the delivery valves at the VE.
I dont lose power or fuel at 80, which is why i think its NOT fuel..
Or,as JimmieD alluded to,you may have a harmonic balance issue.I used a 6BT harmonic balancer on my 4BT,and I have the fluid mounts........I still think that you have a fuel issue,and it may be that VE just having some wear and tear,and raise your idle a little.
No balancer at all. New motor (square) and transmission mounts.
If you set all the systems back to basic,then you have a real good baseline to work from,and will be better off at getting the imbalance sorted out.Good luck.
I think, if my cam lobes check out, I'll pull the timing cover to verify timing and cam marks.....

I cannot hear, nor feel any difference in adjusting timing advanced, all the way to the block......
 

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I talked to a local guy who does performance cummins builds, he's seen pistons all over the board as far as weight goes. Not as noticible in a 6cyl, but maybe more noticible in a 4cyl. Could be an internal balance issue. But an imbalanced engine doesn't cause poor power and mileage.
 

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Okay,I think you hit the nail on the head.....when you advanced the timing,all the way to the block",and it made no difference,then you are out on the timing gear,and it may have been that way when you got your engine,because idle and all would have changed.......
 

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Stupid question. If you adjusted the timing by rotating the pump with the power steering pump (and it's attached gear) off, could it jump a tooth?
No, the injection pump turns right off the cam gear. The power steering pump doesn't need to be timed with the rest of the gear train.
 

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I talked to a local guy who does performance cummins builds, he's seen pistons all over the board as far as weight goes. Not as noticible in a 6cyl, but maybe more noticible in a 4cyl. Could be an internal balance issue. But an imbalanced engine doesn't cause poor power and mileage.
Thanks! That's exactly what I suspected!!

On that injection pump timing, I read posts by a couple of guys either on 1st Gen Forums or Diesel Truck Resource that said the same thing: advanced to the block, no change. Seems to me that Wannadiesel & KTA said it's possible to get the timing wrong inside the pump when rebuilding unit, so that their subsequent rotation of pump to the block still wasn't even getting timing to stock settings.

I'm at the point of figuring I may have injector problems, plus injection pump wear & tear, plus an imbalance issue with pistons, plus hard crapola motor mounts, plus poor quality fuel, plus some flywheel/clutch imbalance, plus the driveshaft balancer, plus needing a harmonic balancer up front!! Not exactly a win-win situation.

If it's been asked already, ignore, but what kind of mounts are you running, Lee?
 
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