engine lags/stalls in H2 not in L4 (1 Viewer)

[M1A1cruiser]

Odd problem here, gang. I'll try to be brief and succinct.

BJ40, B engine, swapped in a used H55F, split case, new clutch.

The engine runs OK, a little excess blow-by, a little bit of leaky valve I think, but generally OK. Idles fine, revs fine, doesn't get hot, doesn't smoke more than I'd expect a 40-year-old un-rebuilt diesel to.

If I'm in H4 on the transfer I can drive around in 1st gear just fine, but as soon as I shift to second (or any higher gear - I've tried going from 1st to 3rd, or starting in 2nd) it's like there's not enough power to keep going and the truck stalls. No different than if you try to start from a dead stop in 4th, or engine lagging when going uphill and you have to downshift to keep applying power.

I thought it was fuel delivery, BUT on a whim I put the transfer into L4 yesterday (hubs not locked) and was able to drive like I would normally expect to be able to. Obviously a little slower, being in low range, but no issues shifting into second, or third, or even climbing the no-road side hills around the place. I thought maybe the used H55 was shot, but being able to shift/drive through the gears with txfr in LOW makes me think the transmission gears are as OK as I need thme to be.

So I'm flummoxed. I know the B engine is underpowered, and I know no one needs an H55 in a B-engine 40 (call it a bad whim during the build) but clearly I should be able to take a slight uphill grade on a dirt road in second gear without being in L4. The truck is at the ranch - a couple hours from me - so I can't exactly go out and try this or that. But I'd be interested in any opinions or thoughts from the experts, or even non-experts (HA!).

Thanks.
Trav.-

 

[charliemeyer007]

Not a diesel guy, but doubling the gear ratio and it can move indicates to me your engine is worn out. Yea maybe weak/clogged injectors, tired high pressure fuel pump, bad valves, worn rings.

I'd be fixing it now while there are parts and places to do the work - or find a better engine.

 

[M1A1cruiser]

Yeah. Good chance the engine is just not there anymore.

Thanks for the clarity on gear ratio, I *felt* like that was an indicator but I am just too close to the problem to reason through it. Might be an engine swap is in the future. I know B rebuild kits are like unicorn poop.

 

[charliemeyer007]

I would think you could do a compression test and a fuel pressure test easy or cheap enough if you have to pay to get it done. That information would be my guidance for what to do next.

 

[peesalot]

Is the e-brake on ?

 

[M1A1cruiser]

Is the e-brake on ?

That's a good suggestion too, but no.

And in fact I have the rear drums adjusted way out (in? loosely, not much braking power) to do that much stopping/holding just because I redid the rears and would rather tighten them up later than have a stuck or rubbing pad. And I haven't pulled the ebrake enough for them to self-adjust.

This problem is with relatively few miles since going back together, and most of that on the ranch roads so I am not too worried about the "oh sh*t" braking of actual daily driving.

Thank you for the input, though. Every bit helps.

 

[Pin_Head]

Wrong gear ratios in the HF55F for a gasoline engine.

 

[peesalot]

So diesel & gas had different ratios in the trans not just different trans all together ? Kurt, Georg, Onur, anyone have a data sheet with the ratios listed ?

 

[whitey45]

A worn b diesel will make about 50hp to the wheels, a good upgrade would be 3b with a turbo.

 

[peesalot]

That would splain it, did the diesel trans get a tighter spread on ratios to compensate ?

 

[45Dougal]

Whatever the ratios are, you should still be able to drive it at 60mph so long as engine speed sounds normal, which you clearly can't.
Did you change anything on the injector pump / throttle linkage during install?
Have you checked your valve clearances?
Are the injectors all bled?
How smokey is it?

 

[-MaTTi-]

A worn b diesel will make about 50hp to the wheels, a good upgrade would be 3b with a turbo.

Even with 5 hp you should have able to change gear to 2nd. Something is not right.

@M1A1cruiser What’s your top speed in low range? Do you have enough power to change all gears through?

 

[MOTOV8R]

if you went through the gears in 4L (~2:1), 4th gear (1:1) should have been less gearing than 2nd gear in 2H (2.6:1). So it should have stalled out there as well. If it didn’t, seems like maybe something is wrong with the tcase (some binding or mechanical losses). Does seem like even a worn out B would be able to get you through the gears (5th might be useless).

gear ratios (to 1): 1st: 4.843. 2nd: 2.619. 3rd: 1.516. 4th: 1.000. 5th: 0.845. rev: 4.843

Couple other questions, what size tires and what gears in the diffs?