Need help - Recently purchased FJ40 with OM617

[Sabre42]

Hey... I've had a few Jeeps in my time but have always lusted after an FJ40. My TJ is rusting out pretty badly so I had to decide if I want to fix it, or buy something else. So I wandered around Criagslist, and find a '76 FJ40 with a OM617 swap! Now's my chance... I thought. I only had a few days to look at it, and make decision as buyer was moving (military)... so I ended up buying someone's half finished project that came with many issues.

I am partially mechanically inclined, and can't weld... but I have friends who can. I just want to make sure I am doing things right, and need advice from others more experienced. I've spent the last month reading the many threads about these swaps, driveline issues, and other topics, but felt it was time to get some specific advice/ideas.

First and foremost is the distance between the Mercedes diesel and the front axle. The oil pan was modified similar to ones found on here, but you can see the clearance is ridiculously close.

The 40 has a 4" lift on it (TPI) and I don't particularly want to go much higher... this is going to be a daily driver when not using my work truck. I could be convinced to add 2 more inches or potentially a SOA with smaller lift springs if that's the right way. But my initial idea is to raise the engine as high as possible, which likely means altering my driveshafts and axles to make the angles right (more on that later). Right now, the engine sits level

But I think it could raise in the front to give 3+- inches more clearance (similar to angle of engine in this swap thread: Builds - Another OM617 in an FJ40 thread ).

The transmission actually hits the body housing, so either I can also drop the transmission some, or have the housing modified.

The front axel is shimmed the wrong direction, I believe, previous owner shimmed it to point the pinion down when the lift was installed. I understand the angles of the pinion and connection to transmission need to be equal, and they are off by 3 degrees in the front, and 9 degrees in the rear. Also, the driveshafts were assembled 180 degrees out of phase, so that needs corrected too. Once I move the engine up, if I can't get the angles right, I am planning on installing double cardan joints on both driveshafts, which will mean I will need to point the pinions up at the joint. I understand that the front will need to be cut and turned... but the rear doesn't?

One advantage a SOA would offer is potentially moving the front axel forward by an inch... moving it further away from the oil pan. Does anybody have a recommendation for specific kit for this, and for the steering modifications that will be needed?

Thanks.

 

[47coeman]

From what I have seen in other projects is the pan is modified to compensate for the area of the rear/pan to give 4” of space for clearance. Also bump stops are used so you don’t accidentally hit the pan if you over flex.

 

[bikersmurf]

Sounds like the steering shims are installed to improve castor for driving. Driveshaft yoke angles being parallel is less critical for the front axle than the rear.

 

[dodored]

Once you go to SOA it opens up a whole can of "learning curve" that may sour you on an FJ40 ownership. I have spent years on a project only to drive it later and hate it. I would go as conservative as possible in the beginning and see if you can as least get it to drive before I would jump into guessing what the potential problems are and creep up on the modifications. The project stalled before you bought it for a reason - Just a word of caution.

 

[Sabre42]

Thanks everybody! While I don't have welding skills, I have friends who do, and have a really good welding shop I use for my construction company. There's also a really good driveshaft and axle place near if I want to spend the $... which I prefer to do rather than waste my summer not driving it.

You can shift the axle forward with 'simple' shims and new ubolt plate.

Any documentation on this? Something I can research and make a game plan? My first plan of raising the engine is to make the solution as simple as possible... and I think this is the easiest way. Should I have new mounts fabricated, or use use 3" square tube bolted to existing mount at the frame, and then bolt new mounts to the top? Seems the simplest.

Once you go to SOA it opens up a whole can of "learning curve" that may sour you on an FJ40 ownership. I have spent years on a project only to drive it later and hate it. I would go as conservative as possible in the beginning and see if you can as least get it to drive before I would jump into guessing what the potential problems are and creep up on the modifications. The project stalled before you bought it for a reason - Just a word of caution.

That sucks. I definitely want to keep it simple. It feels like the previous owner bit off more than he can chew, and lost interest in the project towards the end. He simply didn't care about researching some things, and didn't even put hose clamps on any of the hoses! So I think he just wanted it unloaded.

 

[Sabre42]

I'm not finding the product I'm looking for. But basically, it looks like a caster correction block but with the upper 'nob' offset.

Another approach is get ubolt plates that have multiple patterns then drill your existing spring pad to one of the offsets. Here is ruffstuff:

Perfect... Thanks!

I'm not ruling out a SOA, and see it happening in my future. But for now I'd like to get her running well enough to enjoy her... and upgrade more significantly later. There's a fair amount of time/effort in engine work and getting the driveline right. I don't see any inherent issues with going SOA, just want to take the time and have the $ to do it right. I wouldn't use stock springs to do that either, but likely a 2" lift at same time... giving me 6 or so inches of lift I believe, maybe more. Right now I am not making her into a rock crawling machine... but something I can enjoy every day, even if it is to get groceries.

 

[daner]

I own the FJ40 with an OM617 that you referenced earlier, and to be completely honest, if I were to do it all over I would take a little more time to find an F or 2F motor and return it to original.

 

[65swb45]

I own the FJ40 with an OM617 that you referenced earlier, and to be completely honest, if I were to do it all over I would take a little more time to find an F or 2F motor and return it to original.

It’s really rare to find someone who will admit that.

I really dropped in just to ask for a pic of the driveshaft that was out of phase by 180 degrees. I have never seen one that was more than 90.

 

[Sabre42]

It’s really rare to find someone who will admit that.

I really dropped in just to ask for a pic of the driveshaft that was out of phase by 180 degrees. I have never seen one that was more than 90.

Haha... fair point... it’s 90 degrees off. Way to make me feel dumb on my first day. Lol

 

[Sabre42]

I own the FJ40 with an OM617 that you referenced earlier, and to be completely honest, if I were to do it all over I would take a little more time to find an F or 2F motor and return it to original.

Well damn. Why is that? Everybody I’ve heard loves this swap... once it’s done, and working right. I prefer diesels for a few reasons, but I’m really interested in hearing why you don’t like your particular build.

 

[Godfather90]

I’m sorry to be tge bayer of bad newsboys but I can strongly second this for the reasons outlined in my thread on here.

The only way to make it livable would to be a close range gear set. Even then, it’s not what most people expect from a Diesel engine.

 

[daner]

Well damn. Why is that? Everybody I’ve heard loves this swap... once it’s done, and working right. I prefer diesels for a few reasons, but I’m really interested in hearing why you don’t like your particular build.

The simple answer is that my engineering and fabrication skills aren't as good as Toyota's: When I drive it I worry that my welds or fabrication will fail, endangering myself and others on the road. Secondly, if something does go wrong and it is beyond my skills, I doubt that I could find a mechanic that would touch a highly modified rig-even getting a local shop to do an alignment would be a challenge. The third reason is that a modified FJ40 is worth about 1/2 to 2/3 the value of a comparable stock rig.

Having said that, I disagree with Godfather on the drive-ability of the OM617. I have a five speed on mine and it drives nice.

That's the short answer.

 

[Sabre42]

I’m sorry to be tge bayer of bad newsboys but I can strongly second this for the reasons outlined in my thread on here.

The only way to make it livable would to be a close range gear set. Even then, it’s not what most people expect from a Diesel engine.

Second what? That a OM617 swap is a bad idea? There are a number of very successful swaps out there. Some are daily drivers, some are rock crawlers. I'm reading thru your build topic now, but if you have something specific I should look for that will help solve my current issues, then I'd love to hear it. Thanks.

 

[Sabre42]

The simple answer is that my engineering and fabrication skills aren't as good as Toyota's: When I drive it I worry that my welds or fabrication will fail, endangering myself and others on the road. Secondly, if something does go wrong and it is beyond my skills, I doubt that I could find a mechanic that would touch a highly modified rig-even getting a local shop to do an alignment would be a challenge. The third reason is that a modified FJ40 is worth about 1/2 to 2/3 the value of a comparable stock rig.

Having said that, I disagree with Godfather on the drive-ability of the OM617. I have a five speed on mine and it drives nice.

That's the short answer.

Thanks for the response. Not to discount your reasons, but it actually helps alleviate some fears. I'm doing as much research as possible to help deal with some of these issues, and have access to a good professional steel fabrication company I use for construction (I understand the forces are different, etc). I bought the 40 for fun, not an investment.

 

[Godfather90]

Second what? That a OM617 swap is a bad idea? There are a number of very successful swaps out there. Some are daily drivers, some are rock crawlers. I'm reading thru your build topic now, but if you have something specific I should look for that will help solve my current issues, then I'd love to hear it. Thanks.

My apologies about the brief message, I was on my phone and being lazy.

I would say that describing something as successful is not much more than an opinion unless its reinforced with data.

The issue I had with the OM617a in my application is that it simply did not have the torque production at low speed that I found desirable. I wont get too far into it but the engine was optimized for performance at higher RPM than people typically see out of diesel engines. The mid range power is easily improved, however the hardware cannot support much more performance in the lower RPM regions. In addition to the performance, the thermal efficiency of the engine is not very good when compared to more modern direct injection engines. The engine would easily run hot and required a fairly large cooling system. As a contrast to my other diesel 4x4 projects, this engine would produce a significant about of heat even at very light load cruising around trains and idling, where you would hear the fans cycling (the other engines would run very cool at light load).

During my time with the OM617a I tried a variety of things to remedy this, but came to the conclusion that in the end it could never be what I wanted it to be.

If you're curious as to what steps I took, I will list them off here. I had a spare injection pump and got familiar with it. After a bit of learning I got into the one installed in my truck. I was able to get the engine past its smoke point at low speed, with little improvement in low speed torque production. The mid and high RPM performance I was able to improve primarily with a few turbocharger changes. I was able to get maximum injection duration with the original internals of the injection pump, but it was not enough fuel flow to get the EGT high enough to require a larger turbocharger (EGT was around 900-1000*f if i remember) and the performance was livable. If I were to spend another ~1200$ to get larger elements installed I could easily have made more power in this region, but never in the lower RPM regions as stated earlier.

I live in California where we have a lot of large hills. It was not uncommon for me to need to get down into 1st gear during some mountain passes because of the lack of engine power. With the H42 it was a very common occurrence to be going up a moderate incline and be constantly hunting between 2nd and third gear due to the lack of low speed output. I had two under drive gear sets back then. I was able to see what the take off would be with a narrower gear set, such as an H55 5-speed by utilizing my 4th gear (1:1) and selecting the low range of either one of my boxes (4:1 and a 4.7:1). I can tell you the 4.7 ratio to start off helped the engine significantly, but was still not enough to satisfy my needs.

I stood a lot to lose by pulling it out for my new setup. I had all the bugs worked out of it, and it was happily nested in the engine bay with on board air and the works. I just knew I wasn't happy with it, it just didn't have the power I wanted (and believe me I didn't want much). It was stressful to drive out here in California where everyone's flying around the freeway, and the thing couldn't get out of its own way. As an engineer in the automotive industry I crunched the numbers over and over again, and finally decided it was time to get rid of it. I was immediately happy with my decision after the first drive with the new engine.

There were some things I really liked about the engine however. It was very smooth and quiet. It was fairly reliable for me, it never left me stranded. The only issues I ever had was alternator failure, and the vacuum pump failure. The engines are readily available and cheap. These engines are also fairly serviceable.

For me, the OM617a engine was not a good match. I prefer the low speed torque production and efficiency of a direct injected long duration burn diesel engine. I love letting the clutch out at idle and having the engine chug along without being worried about stalling.

With that said I stand nothing to gain from saying this but to give a little experience back to the forum. I'm not trying to bad mouth your recent purchase, just trying to let you know what you're getting into before you get too deep.

If you want any details about the OM617a setup I had I can help you there too.

Mike

 

[cult45]

Welcome to the forum and to 40 series ownership.

We didn't get those engines in Aus, but I did some reading. Which generation of the OM617 do you have? I hate to be a downer but for all the work ahead I'd hope it was the later type - and even then 184 lbs ft of torque isn't going to be fun driving unless it got some induction help

Does your budget allow for a return to a Toyota drivetrain?
What could be gotten for the Merc diesel if you sold it?

Just reading your first post, all your issues seem to stem from that engine.

I know its not sexy like a diesel, but an inline Toyota six of choice and a H55 would be pretty neat. I think a good 2F could be had for $700. A 3FE even cheaper? And there's always a 2UZ/A750F.

Cheers mate, hope you git'er sorted!

 

[John in Utah]

Thanks for the response. Not to discount your reasons, but it actually helps alleviate some fears. I'm doing as much research as possible to help deal with some of these issues, and have access to a good professional steel fabrication company I use for construction (I understand the forces are different, etc). I bought the 40 for fun, not an investment.

Sorry but this is naive. You’ve done the necessary force calculations to determine the thickness and grade of your material? How does raising the engine by 1” change the torque on the engine mount welds? What about 2”? What happens when you hit a speed bump going 45? Lock the brakes up at 70?

Whether your modifications are stronger or weaker than stock you are still making guesses without the proper engineering to back it up. There is always an inherited risk when modifying a vehicle away from stock. Not saying you should be afraid, just don’t brush it off.

I would say that describing something as successful is not much more than an opinion unless its reinforced with data.

Glad someone else said it. The internet is full of success stories, but anecdotes are not the same as data.

All that said I’m excited to see what you end up with. I love a good engine swap, especially a diesel into a 40. Welcome!

 

[Sabre42]

Thanks everybody!

I am certainly not wanting to be naive... but I am currently as I am just getting into this and absorbing as much information as I can from here, thus the reason for my post. I really appreciate everyone's opinions. No, I have not done the force calculations... but I am not just brushing it off, I am looking for the right solution. I have been an architect for over 25 years, and now own a custom home building firm that I am solely responsible for reviewing structural drawings, so, while it is obviously much different, I do have some understanding of forces involved in structures. One of my solutions is to over-build, or use aftermarket products that have been proven.

It is hard to evaluate opinions, facts are obviously way more reliable. I also understand that when someone spends a lot of hard earned money, and all their spare time, it's much harder to admit that it didn't live up to their expectations. And, like I said, I bought someone else unfinished project without much time, experience, or knowledge before jumping off the deep end... but here I am. As I told my friends, I am not sure if it was a good decision or a bad decision, but it was a loud decision. For right now, I am going to run with the OM617 as that's what I have, and if I figure out a better solution later, then head down that path.

One of the keys is that I like the reliability of Toyotas and of simple diesels. My work vehicles are always in the shop for one reason or another. I am not expecting to win any races, be super comfortable, or even listen to music while driving this.

Godfather, I may end up coming to the same conclusion as you... luckily eastern Virginia is pretty flat.

Thanks everybody... I'm looking forward to getting her on the road, one way or another.

 

[bikersmurf]

I found Advance Adaptors Fj40 engine conversion manual to be very worth while when I swapped in a 350. I realize it’s a different engine but the same principles apply. I also studied the Downey manual. Between the two I ended up with a very nice conversion that works extremely well.

The other thought is that shortening driveshafts is always way more economical than extending them. If you can get an extra front shaft it will likely save you money.