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Unread 09-28-2013, 06:13 PM   #1
bigal389
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Om617 or rebuild 2.5

This is my first post but I have been lurking for a while. I have an 87 with a 2.5. That is a daily driver with no off roading. I'm planning to either rebuild the 2.5 or do an engine swap. Give me your thoughts on both. I know I can get a little more power from the 2.5 but the om617 will have more
Thanks al

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Unread 09-28-2013, 06:56 PM   #2
Mean Max
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You'll need an AX-15 & a compatible NP231 in order to pull off an OM617 swap. I did an OM615 swap a while back, and it worked out nice, but the naturally aspirated OM615 is fairly anemic.

Rebuilding the 2.5L may be more cost effective.

Another option, if you're in a state with no inspections (like us here in Florida) or loose emission testing (we have none) there are alternatives. I just swapped a 2.5L/AX-5 out of a '91 YJ for an '81 CJ7 258/T176 arrangement. The original NP231 YJ transfer case (21 spline input) was utilized with an adapter from Advanced Adapters.

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No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

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Unread 09-28-2013, 08:06 PM   #3
bigal389
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Yeah I'm in SC so no emissions. How did the Cj engine and trans do with the 4.10 gearing? I had also considered the 4.2 and using a 4.3 gm throttle body and injectors. I will have to do something this winter, the 2.5 has a wrist pin that's rattling. I had also considered doing a 3.0 mercruiser swap. Not crazy about a V8 or V6 swap so it will be an i4 or an i6. I plan to start the swap around November just have to figure out what route to take.
Thanks, Al
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Unread 09-28-2013, 08:17 PM   #4
Mean Max
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The 4.2 from the CJ went great, we used a 38mm Weber & an HEI ignition system.

The 4.10 gears make it have killer "roll-on" acceleration, and it's on 31x10.50 BFG A/T tires.

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No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

There is no situation that cannot be improved with a small but well-placed explosive.
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Unread 09-29-2013, 02:57 PM   #5
bigal389
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That sounds good. Right now i have no lift and stock tires. I guess it's time to make a decision and start rounding up all the parts needed.
Thanks, Al
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Unread 09-29-2013, 08:21 PM   #6
czjeeper
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I think if you were to keep the 2.5, it would be worth upgrading to the MPFI of the later 2.5.
The 2.5 is a great engine, maybe just a little under powered for what it's asked to do in a lifted, large tired Jeep!
I would definitely do the AX-15/external slave upgrade at the same time.
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Unread 09-30-2013, 07:17 AM   #7
bigal389
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If I decide to keep the 2.5 I am definitely doing the mpfi swap on it. Just to decide which route to take.
Al
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Unread 09-30-2013, 07:21 AM   #8
czjeeper
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Unfortunately for the fate of the 2.5, I don't think you are going to find many lovers of it on this board.
I do remember reading a post about a guy that went through and totally rebuilt his 2.5 with OEM components, and as I recall was pretty amazed at the ability of the fresh engine.
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Unread 10-01-2013, 08:28 AM   #9
bigal389
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Yeah I'm leaning towards the Om617. Does anyone have any suggestions for the do's and don't's of the swap? I want to be able to get all my ducks in a row before starting and don't want to end up wasting a bunch of money on learning what needs to be done.
Thanks, Al
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Unread 10-01-2013, 09:19 AM   #10
SeanB95YJ
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no suggestions - I'm more of a gas guy myself, but this thread has me curious... why the mercedes rather than a 4bt?

yes, the OM617s are probably more readily (easily) found than the 4bt... but once you have the engine, I'd think parts would be much cheaper and easier to source for the cummins as (unless I was given wrong info) most of the parts of a 4bt can be had from a 6bt (Dodge Ram)
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[FONT="Comic Sans MS"][COLOR="Blue"]Sean B. - Schenectady, NY - 95 YJ, 350/700r4/NP241, JB Shorty SYE, 8.8 rear, 2" BDS, 1" homebrew shackles, Daystar 1" BL, TJ flares, 35x12.50 General Grabber AT2 on 15x10 Bart D-Truckers, Polyshield polycarbonate windshield, HD over/under crossover steering
[/COLOR] [COLOR="Red"]swap/build thread: [url]http://www.jeepforum.com/forum/f22/after-almost-4-years-finally-my-own-build-swap-thread-1542284/[/url][/COLOR][/FONT]
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Unread 10-01-2013, 10:02 AM   #11
bigal389
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You are correct on the parts availability for the 4bt, same bore and stroke as the 6 but it weighs a ton. Believe me I'm a dodge fan when it comes to the diesels but for the cost of the 4bt alone I can do a complete swap with the om617 since I can get a mercedes local for less that $1000 and then scrap what I don't need and get half I that back. Plus this is a daily driver that just needs a little more power and the fuel milage will be a plus.
Thanks, Al
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Unread 10-01-2013, 11:34 AM   #12
Shadownwpa
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I'm planning on the mercedes swap after I'm done with rest of the jeep, maybe this spring I'll tear into it. While I was at Bantam this summer I was helping a buddy out with his booth right next to the Koch guys and their conversion kits - I was convinced. I spent a while talking with them and checking out the setup... the only thing in your oem gauges they can't get to work is the tach (stick a mini digital over top of it). If you get one from 81-85 out of a 300d (sd, cd, whatever) it's likely gonna be turbo. The adapter plate will hook it right to whatever trans you have, they have one for the ax-5 but it's not as recommended because it isn't likely to last as long due to the torque so it's a good idea to upgrade. I'd rather change motor mounts, trans, and tc for the mercedes than gut the entire thing and try to cram in a overweight 4bt or 6bt.

The Koch guys were also claiming 20+mpg on the trip up from York... and you can run it on fryer oil.

http://www.mercedesdiesel4x4.com/
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Unread 10-02-2013, 11:47 AM   #13
bigal389
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That was kind of my train of thought, I didn't want to have to build my jeep around an engine if I go with a diesel. But I would like to know how labor intensive the swap will be for just one person and what kind of time frame it would taken.
Thanks, Al
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Unread 10-02-2013, 01:18 PM   #14
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Quote:
Originally Posted by bigal389 View Post
That was kind of my train of thought, I didn't want to have to build my jeep around an engine if I go with a diesel. But I would like to know how labor intensive the swap will be for just one person and what kind of time frame it would taken.
Thanks, Al
I found the Koch guys pretty informative on that, wouldn't hesitate to call them.
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Unread 10-02-2013, 05:58 PM   #15
Mean Max
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Quote:
Originally Posted by Shadownwpa View Post

I found the Koch guys pretty informative on that, wouldn't hesitate to call them.
I spent a lot of time on the phone with Nathan Koch while working through a not so common OM615 swap. Their kits aren't designed for these engines, but we worked around the hurdles and made it work flawlessly!

Nathan was a huge source of technical info, and was real pleasure to work with. I recommend him highly!

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Quote:
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No one here knows what they are talking about. You should try Pirate 4x4 they will be happy to help you.

There is no situation that cannot be improved with a small but well-placed explosive.
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