Glad to hear you did the leverage test on the Pitman Arm. It may hold up OK, despite its appearance.

If it is a standard TC, I can guarantee you the stall speed isn't in the 1200-1500 RPM range. Torque is what gets you moving from a dead stop, so gasser TCs pretty much all have a stall speed somewhere in the 2000 RPM range. That puts the stall speed closer to their torque peak.

The 2.8L peaked out at 145 ft/lbs torque @ 2400 RPM and I'd be not only surprised but actually shocked if the stall speed on that converter is anything below 2000 RPM.

The 3.54 gears are the only thing making it driveable with the high stall speed of the TC (lots of slippage at low RPMs). That and the fact that the OM617 revs a lot higher than most diesels (~5100 RPM redline). Still, with 4.10 gears and the high stall converter the RPMs would be so high it would be scary so its a good thing you have the 3.54s. Keep in mind though, high slippage in the TC=lots of heating of the fluid and heat is the #1 killer of automatics. I'd use synthetic fluid and a BIG cooler if you're going to stick with the A904 TC...

The 4.3 that I'm putting in mine makes 165 ft/lbs at 1600 RPMs - and redlines at ~3800 RPMs. That's why I had my custom converter set up for a 1400 stall speed. It also I also have 4.10 axles (it was a 4-cyl automatic) so the the low stall converter was a must. But it is going to mean a lot less slippage and give me more usable power in the lower RPM range, as well as the option to go with oversized tires. I want to do at least 2-3 inches of lift and run 31's on mine when its done...

 

Thanks for the update John. Hi oldsinner, about the turbo I see a puddle of oil inside on the exhaust side just past the housing and it feels like there is a little too much play on the shaft. Also it had some blue smoke when running, thats why I did the comp test to try to track down the cause. Also there is no visible blow-by from the breather.I am new to deisels/turbos but learning more every day, thanks for all the help!! About using the 700r4 in the jeep, will the trans bolt up to the stock jeep t-case or do you have to adapt or change? Hi cheeperjeeper, Will that 4.3 hold up to boost? The reason why I question is I used to work at a GM dealership back when those olds diesels came out (they were just gas motors converted to run on diesel using cast crank&rods) and most spent more time in the shop than on the road. I am talking about the ones in trucks where they were worked as apposed to the ones in the cars. My point is they were n/a and barely held together so adding boost is a recipy for disaster.

 

Nope, Jeep t-case has a 6-bolt mounting flange 10"" or so in diameter. Chevy has a 5 bolt flange around 8" in diameter. You can buy and adapter kit to bolt them together for around $500, or you an get a 700R4 out of a 4WD application and use the t-case that came with it. That's the route I went - bought a 700R4 and NP207 out of an 85 S-10 blazer.

VERY common misconception. The Olds 350 diesel is a completely different, and much heavier built block. It has different heads, crank, con rods, pistons, and cam than the gasoline 350. What they did is to use the same tooling and production line to machine both engine blocks. So they have the same headbolt size and pattern, as well as the same bore and stroke. They also share valvecovers, water pumps, timing components, and timing cover.

Using the same number and size of headbolts and headbolt pattern was their undoing. Ten 1/2" headbolts per four cylinder head is enough for a gasser with 10:1 compression. It isn't enough for a diesel with over 21:1 compression. They also made the mistake of using TTY (torque to yeild) headbolts which are torqued until they just start to stretch. This made them even more prone to stretching and blowing head gaskets. On top of that most GM mechanics at the time didn't know the head bolts were TTY, so when one blew a head gasket they would replace it but re-use the headbolts - which would stretch a little more and blow another headgasket right away.
Better hedgaskets are available now that if installed with a set of ARP head studs will pretty much fix the headgasket problems. There was a 4.3L V8 produced for 1 year (79) that pretty much had all the same problems as the 350 - just a half inch smaller bore.

The engine I am using is the 4.3L SIX-cylinder. TOTALLY different animal. They were designed from the ground up as a diesel and didn't share anything other than their displacement with any gasser motor - though they do share the same bearings, con rods, and pistons with the 350 diesel. They have 14 headbolts per 3-cylinder head and the headbolts are bigger - 14 mm (basically the same as a 9/16"). And they aren't TTY bolts either. They have no issues with blowing headgaskets. Their only issue is that they have aluminum heads that are somewhat prone to warping if they are seriously overheated.

On a 4.3L V8 or a 5.7L (350) V8 I would have to agree with you. On a 4.3 V6, not so much. They should hold up to a mild 7-8 PSI boost just fine since they have the hexagonal 6-bolt per cylinder pattern (with 2 shared between each pair of cylinders) like a proper diesel should. I'm also plumbing a set of oil squirters in the oil pan to cool the bottom side of the pistions.

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BTW, their compatability with 350 BOP gasser heads, pistons, and external accessories made the much stronger diesel blocks really popular with drag racers. Dish out a set of diesel pistons and swap on a set of gasser heads to get the compression ratio down to 12:1 - 13:1 and you could easily build a 600-800 HP motor without doing much of anything else to make it strong enough to hold up...

 

Hey cheeperjeeper,sorry my lack of knowlege on the GM stuff. That was 30 years ago anyway. Sounds like you have it all figured out! About the trans/t-case are you going to clock the t-case or swap to a pass drop axle? How is the oil pan clearence with that motor, what's it weigh? Keep us posted!

 

No problem man. 95% of the people out there have that same mistaken belief - and its easy to see why. Same displacement, same bore & stroke, same external tin pieces, same accessories, heads swap back and forth - you almost have to get the two blocks side by side to tell the differences. Heck, you worked at a GM dealership and didn't even know they were different. No wonder the general public thinks they are the same motor!

Neither. The NP207 is a driver's side drop. But you had me going for a minute there - I had to go double-check 'cause you had me thinking maybe you knew something I didn't or that I had overlooked!

TIGHT - to put it mildly. I'm having to make a custom oil pan by combining the top 1"-2" of the original oil pan with the bottom half of a 4.3 gasser pan - and even then I'm probably going to have to bevel off the front DS corner of the sump section to clear the corner of the pumpkin. Fortunately I've always planned on doing 2"-3" of lift to run 31" tires anyway, so that helps a lot. With that in mind I shopped long and hard to find an '84 (emissions exempt = no need to go through the hassle to re-register it as a diesel), 2-door (personal preference), with a 4 cylinder and an automatic (so I got the factory 4.10 axle gears).

I don't know the exact weight of the motor, but it is definitely heavier than the 4.0 I-6 that they put in almost all of the XJ's since 91. I have a set of heavier springs from a V8 Grand Cherokee to support the extra weight and give me the 2"-3" lift I want.

 

Yea, I guess I should have included that while I did work at a GM dealership, It was after high school sweeping floors! About the t-case, isn't that the one that came with the 84xj? Does the 700r4 use the same? I too will be using the 84-86 xj to keep from emisson tests. I may try to swap in the aw4 but I havent had any luck as to weather or not they will bolt up to the early t-cases. If you say I can bolt up the 700r4 to them than I won't mess with the 904 or aw4. I would only consider an 86 if it ran and passed emissions before I did the swap, then it will be exempt by the next test. Considering you are just up the road, I'd like to see yours when it's done! Good luck and thanks for all the info! P.S. hey John, sorry for cluttering up your thread!

 

They did put the NP207 in some early XJs, but mine came with the NP 229. If they are out of a Jeep then either will bolt up to any XJ tranny, but if you're using an XJ transmission (like an AW4) then an NP231 or NP242 either one would be a better choice. But none of the Jeep transfer cases will bolt up to the 700R4 without an expensive adapter. That's why I used the NP207 out of the Blazer - along with the 700R4 from the same rig. I bought them as a set, so that they bolt right up to each other as well as to my 4.3L diesel motor.

Bolting either the AW4 or 700R4 to the MB 3.0L will involve all the same challenges - fabbing a custom mating plate, making the torque converters compatable, etc. But controlling the tranny is a differnt story altogether. The advantage to the 700R4 is that it is purely hydraulicly controlled with just a downshift cable (a.k.a. TV cable) to deal with.

The AW4 is an entirely different kettle of fish. It is electronically controlled. While it has its own separate computer - the Transmission Control Unit (TCU) - I believe the TCU gets its shift signals from the main engine management computer. The main engine computer uses signals from the Throttle Position Sensor (TPS) to measure how hard you're stepping on the gas, and the Crank Position Sensor (CPS) to measure engine RPMs. It then tells the TCU to shift the tranny based on those inputs. So, somehow you have to mimic the TPS and CPS signals and feed them to the main computer and then let the main computer control the TCU to shift the tranny. I may be wrong about that, and the TPS and CPS signals may go straight to the TCU, in which case you could do away with the main computer, but even if that's the case, you still have to mimic the CPS and TPS signals so it knows when to shift, so it gets pretty complicated.

That's why the 700R4 is such a good choice - it is also a 4-speed auto with OD and a locking torque converter, but it can be set up with no computer to mess with, and when you're using an old-school diesel with no computer control or sensors, that's a good thing. The only other thing you have to add is a switch to lock up the TC - if you want to use the TC lockup. That is normally computer controlled, but can easily be done with a switch. My plan for that is to use a momentary pushbutton to activate a self-latching relay with a NC brake pedal switch to break the relay latching circuit. That way when I'm on the highway I can just tap the button to lock the TC and it will stay locked until the first time I hit the brakes. It will also allow me to lock the TC in any gear. A simple LED indicator light will light up when the TC is locked.

 

Thanks that helps to clear alot up. There is alot of info on how to use the aw4 in other swaps with the tcu and tps from doner rig, but it looks like your option is way better. If the rig I end up with has a good 904 I will probably just go with that until it breaks,then swap over to the 700r4. The adapter should be the same so long as I get one from a 2.6 s10. I plan on making an adapter plate between the benz flex plate and t-conv.

 

Can you point me to a couple of these sites? The only swaps I have been able to find are into Jeep Wranglers - TJs and YJs. I can't even find any info on swapping one into a newer GRAND Cherokee...

BTW, one other advantage of the 700R4 vs the AW4 is the lower 1st gear (3.06 for the 700R4 vs 2.80 for the AW4)

 

Yea, the aw4 sites were for tjs @ yjs I am checking out a 700r4/231 combo out of an 88 s10 4.3 tomorrow. Then I can get working on the bell adapter.