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Thread: Olds 350 Diesel in Jeep CJ7 - Crazy?

  1. #1
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    Question Olds 350 Diesel in Jeep CJ7 - Crazy?

    I'm thinking about swapping a diesel into my 80 CJ7 - the 258 straight 6 runs fine but is getting tired, so...

    I know all about the bad rep of the olds diesels (most of us are used to it, owning 6.2/6.5s ), but am thinking it may be good in this application, since I mainly use it as a trail jeep and am not after high horsepower.

    I know the 6.2/6.5s are more plentiful, and I'm more familiar with them, but I'm thinking the 350 wouldn't be as heavy - I found some info that list the 350 diesel to be around 600 lbs, about what my current 258 weighs. The power specs on the 350 diesel are very close to the 258, so I'm thinking I wouldn't notice that much difference in performance.

    Anyone know what a 350 diesel weighs?

    I'd like to retain my stock Jeep 4-speed. I know 350 diesels were never offered with a manual trans, so I'm wondering if the crank could be bored for a pilot bearing? The 260 V8 diesel was offered with a manual, so I think a flywheel for it would work on the 350.

    It seems advance adapters makes an adapter for a Buick V6 to the Jeep trans - anyone know if the BOP bellhousing pattern on the olds diesels is the same as the older Buick V6s?

    Course, this all depends on if I can find a decent olds diesel, but they seem to pop up from time to time.

    I'm open to other engine suggestions, although I don't want to spend the $$$ for a 4bt or similar, plus I'm not wanting to add a lot of weight to the front end.

    Thanks in advance.

    Joe.
    2006 Chevy K2500 LLY Duramax/Allison Crew Cab!
    1996 Chevy C2500 6.5 auto Ext. Cab LB

  2. #2
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    Probably not what you want to hear, but I'd probably go 6.x before I used the 350 diesel.

    6.x is somewhere close to 750 lbs. 150 over the 600 lbs.

    Lets not forget the rest that will go with it for weight. IE: dual batteries for starting, heavier flywheel, etc.

    Of course, dual batts could be a plus if you winch a lot.

    You're also going to have to figure out your brakes with a diesl. IE: no vacuum. You need manual brakes or a hydroboost swap.

    The 350 is kind of an orphan child. Its not as much it's rep that i would worry about as it's parts availability.

    The 6.x's are a liitle bit better in this respect. Not a lot, but still better.

    Go DB2 and it's a drop in swap ant of teh swap parts you can get for a jeep and a small block.


    But honestly, in a 4x4 rig I'd probably go for a gasser for better fuel availabilty on the trail (syphoning off you buddies rig can get you home) and lighter weight than a diesel.

    Off camber a fording would be a diesel strong points, but deep mud and soft trails not so much....

  3. #3
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    I really looked into doing this exact swap 25 years ago (1987). The Olds diesels were plentiful and the 6.2s were still really expensive. The main issue was the bell housing. Back then the availability of automatics with the dual mount system was limited but the standards could be used with the bellhousing off the 4 4 2 Olds gassers with the 4 speed.

    The clutch style flywheel from the 455 would bolt on but I seem to remember there was a balancing issue. Externally balanced????

    I agree with Great White in that the 6.x is a better choice, especially if you do any off roading. Just the on again - off again loading of the engine would tend to dynamite the 350 whereas the 6.2 is considerably stouter. I believe the concensus that the 350 should only be used infront of an automatic makes sense. The 350 would be more economical fuel wise but the 6.x is a better choice over all.

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
    94 Cadillac Fleetwood (sold)
    08 Aerolight 23TT
    06 Vortec Max Silverado CC SB (sold)
    10 Avalanche (electronic quagmire but love the truck)

  4. #4
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    Thanks, guys - Good points.

    I guess I was considering this mainly from the potential cost savings (350s shouldn't cost much, although maybe more now since they are getting rarer...)

    I notice some folks are using the Mercedes 5 cyl TDs in swaps, and there seem to be more trans adapters available for them lately. This may be viable. The consensus seems to be they are reliable, although not overly powerful - probably about what my 258 has.

    Something else to consider, I guess.

    Joe.
    2006 Chevy K2500 LLY Duramax/Allison Crew Cab!
    1996 Chevy C2500 6.5 auto Ext. Cab LB

  5. #5
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    Quote Originally Posted by joed View Post
    Thanks, guys - Good points.

    I guess I was considering this mainly from the potential cost savings (350s shouldn't cost much, although maybe more now since they are getting rarer...)

    I notice some folks are using the Mercedes 5 cyl TDs in swaps, and there seem to be more trans adapters available for them lately. This may be viable. The consensus seems to be they are reliable, although not overly powerful - probably about what my 258 has.

    Something else to consider, I guess.

    Joe.

    The 300 TD has almost the exact power specs as the last varient of the 350. They are also available with either the automatics or the standards. Not uncommon to see these engines with a million miles on them. Heads need to be watched and the valves have to be adjusted at least yearly. Bosch in-line pumps and cheap injectors (same as the 6.2) are bullet proof. Vacuum system is troublesome but re-buildable and have enough volume to keep a vacuum brake system working.

    Actually, the Mercedes is a better choice for the Jeep as they are a high speed engine, 5,000 RPMs, and can go all day at 4,500 RPMs and not feel it. No need to play around with gears. They are happy between 2,500 and 3,000 RPMs. Not much grunt, but at least as good as the 350. After 2,000 RPMs they really turn on (turbo kicks in). Lots of go-fast bits available for these engines from Europe.

    Only conversion issues are with the oil pan (front sump) and the Mercedes hydraulic motor mounts must be used, especially if you have dentures .

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
    94 Cadillac Fleetwood (sold)
    08 Aerolight 23TT
    06 Vortec Max Silverado CC SB (sold)
    10 Avalanche (electronic quagmire but love the truck)

  6. #6
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    Quote Originally Posted by convert2diesel View Post
    They are also available with either the automatics or the standards.

    Only conversion issues are with the oil pan (front sump) and the Mercedes hydraulic motor mounts must be used, especially if you have dentures

    I didn't think they were available with a manual? At least here in the US I've never seen one.

    Thanks for the tip on the motor mounts - wasn't aware they were hydraulic. The front sump could be a problem, although my Jeep has a 4-inch lift on it, maybe if would clear the front diff.

    Thanks. Joe.
    2006 Chevy K2500 LLY Duramax/Allison Crew Cab!
    1996 Chevy C2500 6.5 auto Ext. Cab LB

  7. #7
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    My understanding is that the manual transmissions were never imported to the US.

    A number of Toyota guys have been using the Mercedes diesel in conversions. 4x4Labs has a couple adapters available to mate the engine to either GM or Toyota transmissions. People have commented that they're pretty pricey, though, for what they are. Others have machined their own adapters.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
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    Diesel Page Member #2423

  8. #8
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    Arrow

    My neighbor owns/operates a German auto repair, and I've owned a few 300D's over the years. I've never seen a manual tranny in the 300. I've seen a couple in the 240D, but don't know anything about their durability or ratings. If you want a Diesel engine with power comparable to the 258, there are a lot of options, including the 240TD (the other million mile engine). N/A, they're an absolute dog (while making 50 MPG in the cars), but really wake up with a turbo. It's essentially a 300, minus a cylinder, much smoother running, so might be acceptable with traditional mounts. They aren't as common, but parts are available. It would make a nice package for a Jeep. There are also several VW and Isuzu TD options.
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  9. #9
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    The 5.7 olds will be more of a conversation starter,.they'll rev pretty good too will no ill effects,. you can use 1 gear further etc,.
    great little motors with a few tweaks,.definitely invest in a twin remote oil filter setup, and modify for positive flow,.

    nick
    1999 chev suburban C2500
    300,000 mi

  10. #10
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    Quote Originally Posted by trbankii View Post
    My understanding is that the manual transmissions were never imported to the US.

    A number of Toyota guys have been using the Mercedes diesel in conversions. 4x4Labs has a couple adapters available to mate the engine to either GM or Toyota transmissions. People have commented that they're pretty pricey, though, for what they are. Others have machined their own adapters.
    Could be a Canadian thing. Have seen both the 123 and the 126 (S class) with the standards in them. Why anyone would order an S class with a standard I don't know.

    Have seen the 123s all over the world being used as taxis and especially in 3rd world apllications, the standards are the norm. While considered fairly good, the Mercedes automatics are expensive to overhaul and do fail periodically.

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
    94 Cadillac Fleetwood (sold)
    08 Aerolight 23TT
    06 Vortec Max Silverado CC SB (sold)
    10 Avalanche (electronic quagmire but love the truck)

  11. #11
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    Quote Originally Posted by trbankii View Post
    My understanding is that the manual transmissions were never imported to the US.

    A number of Toyota guys have been using the Mercedes diesel in conversions. 4x4Labs has a couple adapters available to mate the engine to either GM or Toyota transmissions. People have commented that they're pretty pricey, though, for what they are. Others have machined their own adapters.
    Could be a Canadian thing. Have seen both the 123 and the 126 (S class) with the standards in them. Why anyone would order an S class with a standard I don't know.

    Have seen the 123s all over the world being used as taxis and especially in 3rd world applications, the standards are the norm. While considered fairly good, the Mercedes automatics are expensive to overhaul and do fail periodically.

    Bill
    91 Buick Roadmaster/Avant 6.2 NA conversion (gone but not forgotten)
    94 Cadillac Fleetwood (sold)
    08 Aerolight 23TT
    06 Vortec Max Silverado CC SB (sold)
    10 Avalanche (electronic quagmire but love the truck)

  12. #12
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    Quote Originally Posted by phantom309 View Post
    great little motors with a few tweaks,.definitely invest in a twin remote oil filter setup, and modify for positive flow,.
    nick
    Thanks.

    Can you elaborate on this, why it would be needed? Because of operating on inclines while on trails?

    Joe.
    2006 Chevy K2500 LLY Duramax/Allison Crew Cab!
    1996 Chevy C2500 6.5 auto Ext. Cab LB

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