Rebuild the IDI, or swap in a Cummins

[Agnem]

There was a time in this country when the ONLY light truck on the road pulling a 3 car trailer was an IDI. The Dodge/Cummins combo didn't exist, and if it did it had less power and fewer add-on goodies. Nobody even thought of Dodge, and Chevy's market share was way low. Every ambulance. rollback, tow truck, farm truck, brush truck, etc, was a Ford, with an IDI in it. I know, because I was there, and remember it distinctly. Every accessory catalog had all the stuff for our trucks, that they have for the new ones now. Of course things are different today. Folks sometimes think the IDI is worn out, and incapable of the things that people took for granted back in the 80's. Well if your IDI wasn't doing the things you thought it should, like start when it is fridgid out, or not hold it's own on the highway, even without a turbo, then it hasn't been maintained, or it really is "worn out" and needs rebuilt.

 

[david85]

Umm, My Dad has a 1993 mechanical 6.5 turbo. It will not get anything close to 25 MPG. All time best was 18 MPG a few years ago with a bed cover and high sulfur diesel. They are a ***** to work on as well since everything is so tangled together on the engine.

Also, if you keep the boost levels around 15 psi or less, head studs are not needed with the 7.3L IDI. 6.9s can have problems if you go past 10 psi, hence the ARP studs I used in my rebuild.

The 6.9 certainly can get 25 MPG under the right conditions (24.9 my personal best), but thats not going to happen at 75 MPH pulling a trailer.

An IDI will pump out 250 Hp and close to 500 ft/lbs of torque reliably without a fancy pump or intercooler or internal mods. Just add the turbocharger, turn up the fuel slightly and you're on your way. Internal upgrades have been done and well and over 300Hp is possible but it gets more costly.

What sort of blowby are we talking about here? Is it like this?:

http://www.youtube.com/watch?v=WlWzbhnXEdY&feature=related

 

[RLDSL]

These things will pull just fine. Back when they were new, I maintained a whole fleet of school busses with these engines in them, In the mountains, they would outrun the cummins equipped units.
My old , worn out n/a engine would pull my 10k pound 5er no problem, even pass a few big trucks on some grades once I figured out that it wasn't governed down to 2800 like the busses were and wound that puppy up ( can't ask for much more than that ), the fresh engine with a turbo will pull it along at highway speed without a problem, but if you want to run 70-75 while pulling, your fuel mileage will go in the toilet. These days, with fuel prices what they are, a more realistic goal for towing is around 60, unlelss you just want to dump all your cash in the tank.

A PSD turbo has been done. but it requires custom fabbing all of the pipes and fittings . I had one that someone had rigged to work with an IDI up pipe, but I opted against using it and traded it off and bought an older ATS non wastegated setup.

Towcat's revelation on price for a cummins conversion is a realistic price to get the job done start to finish. Any custom engine swap involves a whole lot more than buying an engine and a few adapters, there is always a ton of little things that have to be done to complete the project that will hundred dollar you to death. If you do a little research, that's about what most folks end up spending by the time they are done.And remember, just buying a used cummins is no gaurentee that you have a good long lasting engine. Any used engine is buying a pig in a poke and you have to consider it nothing more than a rebuildable core and if you have to go into it, you'll be crying for the days when you were complaing about the prices at the IH dealer

If you're looking to use something for a regular run, especially if you are trying to make money with it, you are best off sticking with stock engine and standard parts . Nothing worse than being down out on the road with custom equipment. you find out real quick that getting certain things in dirtwater USA isn't as easy as it is at home. With a stock IDI, most anything could get to you in a day or two, with a custom installation, you could spend days trying to locate replacements while running up a whopper of a motel bill

 

[Darrin Tosh]

Will a Turbo IDI to what I want to do with it (three car trailer, 75 mph, passing, blah, blah)?

No, it wont. It will pull it comfortably at 60 to 65 as long as you have a good aftermarket radiator to keep it cool.

Another problem that I see, that nobody has mentioned, is that you want to do this with a F250? If you want to haull a 3 car goosneck you will be way overloaded. You woulld really need a F350 Dually to keep it legal, and safe.

However if you got a 2 car setup I would say do the IDI with a Turbo.

If you want to do a 3 car, get a different truck.

Third, 10 grand for a Cummins swap? Am I missing something? I figure $2500-$3000 for the motor, adapter, and motor mounts, and may be another $1000 for all of the miscellaneous stuff. I'm not sure about what I'd do with the other $6000.

It does not take long to get $10K wraped up in a Cummins Conversion, but it can also be done cheaper. Most of the major conversion companies say bring me a Ford and a Dodge and 10K and you can drive away with a Ford Cummins. Another company charges $5K just for labor alone.

When I did my Cummins swap, I bought a 85 Ford F350 that had a conversion done on it in 2000, and the owner spent $15,000.00 for it. That was with a new Cummins reman $8500, Gearvenders OD $2500 and the rest was parts and labor. 10K miles later a tree fell on the truck and was totaled out.

It really takes a lot of time especally if you want to do it right.

RSDL has a great point, If you want to take the truck cross country you might want to keep it more origional where it is easy to get parts for.

 

[funnyman06]

I would think that with a fresh engine, turbo, and a GV you would be able to tow quite nicely. My truck has the C6 and at 65 MPH it is screaming, or so it seems. I would think that with the GV and an intercooler you could run enough boost to keep the EGT's down, but the intercooler would keep the boost low enough to keep the heads on. Plus with the GV you could keep your RPMs low.

 

[Agnem]

4:10's a ZF and a Gear Vendors produces a far better combination than Ford was able to do. Get the stump pulling power you need, and the economy and low RPM's for efficient operation the rest of the time. I'd take a stock IDI with that combination over a PSD or Cummins with an automatic any day. Pretty soon, you probably won't be able to get a manual in a new truck, so these older rigs are worth holding on to.

 

[MIDNIGHT RIDER]

I am gonna stick my nose in this discussion.

I had (and still have it hanging on a chain-hoist) a fire-breathing 6.9 IDI with a Hypermax Turbo and many many goodies.

In half-a-million miles of HEAVY cross-country live-stock transportation, 41 states worth, I never had it leave me stranded; it always brought me home.

BUT, it absolutely drank fuel and had absolutely ZERO low-RPM torque; on several bad steep hills, I have had it smother down and die, then the truck, trailer, and load of cattle would slide backwards down the hill; this was on blacktop highways, not 4-wheeler trails.

The T-19 4-speed had a first gear more suited for a Mustang convertible and fourth-gear was direct with no over-drive.


A Fuller Nine-Over with deep-reduction splitter would have been a much more suitable transmission.

That old T-19 was, and still is, bulletproof; it just didn't have much of a gear selection.


In various other trucks, we never could get a ZF-5 to last much over a year, without catastrophic failure.




Then, at the half-a-million mark, I stuck in a very low mileage 1989 Cummins and Getrag 5-speed.

I researched and researched and bought the Cummins/Getrag and swapped it in for much less money than it would have cost to completely rebuild my old 6.9-IDI, and got a much more suitable transmission in the bargain.


I more than DOUBLED my actual fuel mileage and it feels like I tripled the power.

I would not hesitate to do it again.

I still have that old 6.9 and someday it may get built and stuck in another truck; but, I have since bought THREE more 1st Gen. Cummins trucks on the merits of that first engine swap and would buy another before bedtime tonight, if the price was right.

 

[memphisrain]

You all have some really interesting points and ideas to consider. Thanks guys!

The blow by that I'm referring to is a "chug-a-chug-a" sound that comes through the exhaust on one bank of the motor. I've done some web research and talked to some people, and it seems that it is displaying symptoms of worn valves or valve guides. I haven't pulled off the oil cap to see if it has a symptom similar to the one in the video.

As far as my towing scenario, I was using that as a maximum of what I want the truck to be able to handle. Mostly it will be a normal everyday truck used to haul wood, equipment, junk, tools, hot chicks, etc. I plan on getting one ton springs for it during the rebuild, and possibly a D60 from an F350.

Ultimately, I'm rather tired of long runs up to 65mph without a downward hill, losing speed as I travel up hills with a relatively minor load, and having to plan to pass miles in advance. I want a truck that will haul some ass, and may be spin the tires, when I put her down. I would say all while being fuel efficient, but then I would be smoking something.

One question not answered so far is whether or not it is even a good idea to consider a turbo at this many miles. I realize it depends on the condition of the motor, but I'm wondering if it would just be better to plan on a full rebuild rather then getting the motor all back together just to blow a ring off with the new turbo.

Thanks guys

 

[Diesel JD]

I think you need to go ahead and do the headwork for sure. I think you have correctly diagnosed an exhaust valve that is about to let go...and when it does unless you're very lucky you'll HAVE to swap in some other kind of engine or buy another IDI without a core. Usually the valve takes out at least its piston and bends the connecting rod, often it puts a window in your block and causes the total loss of the engine. I'd be pulling the valve covers for confirmation. It might be worth doing a compression check before you fix it to see how bad it is but I wouldn't be driving it unless I had to till those valves got fixed. At your mileage you're prime for having a dropped valve. Other than that if its had good SCA maintenance its probably going to live pretty long once you get the valves fixed so yeah a turbo isn't a bad idea. If you get it too hot or boost it too much you'll be shortening its life span. If you keep the fuel settings reasonable and don't add too much boost you might even help it some in terms of reliability since your EGTs will be very low. Realistically towing that heavy at 70-75mph your fuel economy would be 8-10mpg with an IDI maybe a bit better with the Cummins, that's asking a lot out of the truck..it can do it but the cost is high at $4.29/gallon diesel is it really worth it?? The Cummins for sure could get 20+mpg empty or lightly loaded. Your IDI could get close to 20 with correct gearing and lightly loaded. The big difference is the Cummins makes its peak torque and HP way down low, the IDI at much higher RPM almost like a big block gasser. On the Chevy stuff, I think the 6.2 was the one that got the great fuel economy along with the 5.7s. The 6.5 could be good but it is a very different animal than the 6.2 and 5.7 or the IH stuff. I just wonder how that DS4 pump that isn't worth 2 craps holds up in Iraq in 130* heat. I guess the military mechanics are pretty good at changing them out in a hurry, unless they've improved those things lately.

 

[memphisrain]

I think you need to go ahead and do the headwork for sure. I think you have correctly diagnosed an exhaust valve that is about to let go...and when it does unless you're very lucky you'll HAVE to swap in some other kind of engine or buy another IDI without a core. Usually the valve takes out at least its piston and bends the connecting rod, often it puts a window in your block and causes the total loss of the engine. I'd be pulling the valve covers for confirmation. It might be worth doing a compression check before you fix it to see how bad it is but I wouldn't be driving it unless I had to till those valves got fixed. At your mileage you're prime for having a dropped valve. Other than that if its had good SCA maintenance its probably going to live pretty long once you get the valves fixed so yeah a turbo isn't a bad idea. If you get it too hot or boost it too much you'll be shortening its life span. If you keep the fuel settings reasonable and don't add too much boost you might even help it some in terms of reliability since your EGTs will be very low. Realistically towing that heavy at 70-75mph your fuel economy would be 8-10mpg with an IDI maybe a bit better with the Cummins, that's asking a lot out of the truck..it can do it but the cost is high at $4.29/gallon diesel is it really worth it?? The Cummins for sure could get 20+mpg empty or lightly loaded. Your IDI could get close to 20 with correct gearing and lightly loaded. The big difference is the Cummins makes its peak torque and HP way down low, the IDI at much higher RPM almost like a big block gasser. On the Chevy stuff, I think the 6.2 was the one that got the great fuel economy along with the 5.7s. The 6.5 could be good but it is a very different animal than the 6.2 and 5.7 or the IH stuff. I just wonder how that DS4 pump that isn't worth 2 craps holds up in Iraq in 130* heat. I guess the military mechanics are pretty good at changing them out in a hurry, unless they've improved those things lately.

Funny thing is that the truck has had that symptom for at least 6 or 7 years. May be since I bought it. However, the truck is parked now, just because it needs so much work, so no threat of valve drop now. I just have never been able to fix it due to lack of money, time, and workspace while I was in college. By the way, what does the machine work for rebuilding a set of these heads cost? How about a good supplier for valves, guides, and seats? I'll obviously be doing the removal and replacement myself.


mR

 

[Diesel JD]

Good question! If its had that symptom all along maybe it doesn't need valve work. Pull those valve covers and see what it is before you go any farther IMO. Not knowing your skill level you might even be able to do the work yourself, it would probably be beyond my skill level.

 

[DeepRoots]

lotta time one injector being off from the rest of them makes a similiar sound

 

[memphisrain]

lotta time one injector being off from the rest of them makes a similiar sound

Would that be a timing issue or an injector issue?


mR

 

[MIDNIGHT RIDER]

Addition of a turbo will not shorten the life of an aged engine, nor will it quicken it's demise.

As little boost as most I have seen put out, if the heads/studs can't take it, they were not long for this world anyway.

What will destroy any engine, new or old, is UN-MONITORED and IGNORED exhaust gas temperatures.

Most diesel engines can take 1250*F, all day long, with no issues (measured PRE-turbo, in the manifold itself; a post-turbo EGT measurement is about useless).

Short bursts up to 1500* shouldn't kill it, but sustained grades above 1325* will soon start things to melting.



What happens is people spend their money on a turbo and have none left to buy proper gauges.

The first thing they do is crank up the fuel at the injector-pump.


With no gauge to show them just exactly how hot they are making things, and all the new-found power begging to be used, they get about half-way up the long side of Sunshine Mountain, with a big load, and melt a hole through a piston.

 

[memphisrain]

Well, I've been doing a lot of thinking. I guess the first order of business is to run a compression check and see whats going on there. I had just planned on rebuilding the heads, but if it is possible that the noise I've been hearing isn't valves, then it may be a lot less money to get the truck back up to par. What is the psi rating of these motors supposed to be?

mR