OM engine swap into 1976 Scout

[IHC]

Dave here,

Wanted to pick your collective brains on good candidate OM engines for a Diesel Swap on my 76 Scout Terra.

I hear a lot of people talking about how durable the 606 engine is. But I'm apprehensive about putting a 606 into my truck because I flat out do not want any computers in the power train.

Is the 603 mechanically or electronically controlled?

Is the 603 as robust as the 606?

Can the 606 heads be installed on the 603 block?

Are the I5's as good as the I6's?

What do you think of the 617, or 605?

[mike-81-240d]

A 606 with a 603 injection pump is the way to go.

Still mechanical. Just starter, alternator, glow plug, and temp sensor wiring. Same as a 617. I've noticed more and more 617 turbos developing knocks and or failing over the past 5 years, starting to leave a sour taste in my mouth. In fact my 617 currently sounds like it has a knock of some sort at 209k miles, but I need to rule out injectors and accessories first.

If you can financially swing it, go for the 606. Hell it has 24 valves, and a crossflow head.

[Mölyapina]

Yup, the 606 made in 1995 had a mechanical IP and the later ones can be swapped to a 603 IP. The 603 IP would be a better choice than the 606 NA IP because it will allow for more fuel for the turbo. I say go for it!

[rscurtis]

Put a 4BT Cummins in it and be done with it.

[t walgamuth]

Originally Posted by rscurtis

Put a 4BT Cummins in it and be done with it.

and 22" truck tires?

[t walgamuth]

Originally Posted by rscurtis

Put a 4BT Cummins in it and be done with it.

Set a cummins 4bt on the ground and it will still stick out the hood of a sedan by 6" I bet.

[Dan Stokes]

I'm putting my eggs in the OM617 basket, mostly because it was cheap (I bought a whole running car for $900 and probably overpaid). So far so good but I have yet to fire it up in it's new body ('86 S-10). You may want to look at my build thread on here. Besides, when I chose this engine I didn't know any better!

Whatever engine you choose I strongly recommend that you buy one you can hear run and preferably drive down the road. The Benz Diesels are pretty tough but some have been abused/lack maintenance to the point that they are not well. Harbor Freight offers a compression tester with M-B adaptors and while not as useful as a leak-down test it will give you some assurance of the engine's condition. Of course you'll want to check oil pressure, look in the radiator for signs of overheating or bubbles while running (head gasket or cracked block/head) and all the other normal checks. These items are the same as any engine but when buying an engine with a ton of miles as our Diesels often have they're even more important.

While I agree that the 4BT is a tough engine I also agree that they are hard to package in most vehicles. They're just a BIG engine. Not sure how a Scout could eat one - but maybe. They are also relatively low RPM and likely would require a differential gear ratio change or two, assuming that the Scout is 4 WD.

Good luck

Dan

[97 SL320]

Originally Posted by mike-81-240d

I've noticed more and more 617 turbos developing knocks and or failing over the past 5 years, starting to leave a sour taste in my mouth.

You have unrealistic expectations. The newest 617 is 30 years old and the oldest 40. Many will have high miles and are going to fail at some point.

Same can be said for any engine / car as more failures will occur at high mileage / age then when new.

[97 SL320]

The 304 / 345 engine in a Scout is physically large so a 4B will fit thought there likely will be some front axle / oil pan issues. But the steel sheetmetal oil pan makes mods easy. ( A 4B fits where a much smaller than a IH motor 350 Chevy V8 fits. This was a popular repower for chip trucks. )

The 4B is heavy and not always the best choice in a smaller truck.

If you go with a MB engine, they have a aluminum upper pan and a small steel sump in the front making oil pan mods difficult. I'd be real tempted just to put a single pickup dry sump in the engine to eliminate pan depth issues and off road oiling problems.

With some creative thinking, a old hydraulic pump ( low friction ) can be used as a scavenge and the original oil pump be used for pressure.

A tempting choice is to use a IVECO / UD or some similar cab over box truck that had a Chrysler Torqueflite making the Scout swap easier. ( the Scout uses a TF trans )

[rscurtis]

The Scout was available with the IH 345 V8, which was a true truck engine that was used in dump trucks and full-sized school buses. It probably weighs more than a 4BT.

[charmalu]

I had a IHC 266v8 in a 64 1/2 ton, good engine as well as the 304 and 345.
I have a 345 in my 67 1 1/2 ton 1500. a strong engine but built to work, so don`t expect great mileage. it gets 13mpg on a good day.

Not very many left any more.


Charlie

[IHC]

Thanks for all the input everyone. Makes me feel a lot better about my plans. I have found a number of mid turbodiesel MB's on Craig's List for under a grand all the time.

I know that means questionable maintenance, but if I can't drive the car, I ain't going to buy the car. A driving donor also means I'll have all the ancillaries I need to install the engine.

The reason I want to upgrade to diesel is to save on fuel, while gaining power and durability. I want to use a OM diesel because it will give me all of those, and with a small amount of jigery poking (I watch way too much bbc) much more.

I don't want a 4bt because its very heavier. It actually weighs more than the 392 (754 lbs) and produces less power than any of the IHC engines in stock tune. Sure, i could get insane power out of the 4bt, but thats not what i'm going for.

4BT
HP 105 @2300
Lb. Ft. 265 @1600
Weight 782 Lbs.

IH 304
HP 193.1 @4400
Lb. Ft. 270.5 @2800
Weight 698 Lbs.

345
HP 196.7 @4000
Lb. Ft. 309 @2400
Weight 727 Lbs.

I want a lighter engine. I searched around and saw a post where someone had their 606 hanging from a scale registering 245.5kg. At roughly 150 pounds lighter than the 304, it has only acceptable power.

OM606.692
HP 174 @4400
Lb. Ft. 243 @1600
Weight 540 Lbs.

Looking at the specs of the 606 I will have to get custom pistons made. That 22:1 compression ratio is a little high to be pushing 35 to 40 psi of boost. So I will have to take the compression height down .06" to reduce the compression ratio down to about 16:1. I'm also going to try to find a head stud kit for it.

Any suggestions of where I should look to find someone to build my intake manifold and exhaust headers? I found turbobandits, but I'd rather not have to have these items shipped all the way from Sweden.

Where should I look to get a 603 fuel pump? I've heard the 606 pump ports were larger, or something like that. Are there any aftermarket pump distributed here in the US? Or do I have to get that shipped from Sweden?

Also, what are my transmission options? Is it true that the trans bell is often divorced from the trans case, even on autos? If so, building an adapter shouldn't be that difficult. I'd love to be able to put a TKO or T56 behind this engine. The granny low (6.32:1) first gear in my T19 is nice, especially since my Dana 20 transfer case only has a 2:1 4x4L, but the .5:1 over drive of the t56 would let me run a much lower axle ratio.

With 4.3 axle ratio I'll be able to do 65 in 6th at 1600 rpms on 245/70R16 rubber. And for crawling I'll be able to enjoy a total ratio of 40.22:1 if I replace the low gear in the transfer case with a 3.15:1 set.

[300GD]

Originally Posted by 97 SL320

You have unrealistic expectations. The newest 617 is 30 years old and the oldest 40. Many will have high miles and are going to fail at some point.

Same can be said for any engine / car as more failures will occur at high mileage / age then when new.

I agree. The OM617 was an engineering masterpiece from a reliability/durability standpoint. It was all-mechanical and featured all-cast-iron construction. I believe it was the last Mercedes diesel engine with a cast iron head.

To the OP, you didn't say how you plan to use the Scout. If you're going to be exploring the far reaches of the Maze district in Canyonlands National Park, or off-roading in Alaska, I vote OM617. If reliability isn't of such paramount importance, the more modern engines may suit you better.

Also, what is your pain threshold for custom fabrication? If you'd rather have a more off-the-shelf solution, you might want to look into the Nissan SD33T engine, which was actually an OEM engine option for the Scout in the 80s. I don't know anything about them, but just saying, that sounds like less fabrication to me.

[bayou]

I have a love for the 4bt, but it is a loud clattering rock and roll engine, heavy and vibrates a lot. that said in my daily driver Toyota 4x4 that I'm building I'm using an om617 due to its higher redline, less vibration, and more gas engine like driving. but the front sump on the 617 does not like steep angles very much, if I was going to off road the truck a lot I would go with the 4bt because of the rear sump oil pan and off idle torque. that's my 2 cents

[Tmadia]

Cummins B3.3T

I may use one of these in my Willys Wagon project.