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Need help: F800 with 12 valve Cummins. What to watch out for?

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  • Need help: F800 with 12 valve Cummins. What to watch out for?

    OK guys so here’s the situation. I am in the process of selling off an old half ton F series and looking for a truck meant for really pulling and hauling. I found a 1997 F800 regular cab flatbed and I feel it fits the bill nice as a tow rig and if I plan accordingly, considering swapping to an extended cab or a crew cab and install a duallie box.
    Im used to Ford 1/2-1 tons but the medium duty trucks would be something new.
    this truck has a sand spreader, was used for sanding parking lots locally. I would be ditching the spreader.
    It was not used with salt for the most part.
    frame and body are clean, considering my region.
    what do I need to look out for when it comes to Cummins diesels?
    here’s the info:
    Rare 12 Valve Cummins Engine
    -Idle Control for Quick Warm-Up
    -Electric Parking Brake Works Fantastic
    -Good Brakes
    -New Briggs & Stratton 10.5 HP Sander Engine
    -Sander RUNS GREAT
    -Air-Ride Driver's Seat
    -Heat Works Very Well
    -5 Speed Manual Transmission
    -Sander Controls Inside Truck i.e. Idle/Engage/Disengage/Lights
    -Tow/Trailer Hitch
    -Clean CARFAX
    -227,000 miles

    I have been pricing superduties but everything up here is rotted bad.
    1972 Ford Gran Torino Sport and other FoCoMo problem children

    2020...year of getting screwed by a Narcissist and learning hard lessons into trusting the wrong people on a business venture.
    2021...year of singing "99 problems but an asshole ain't one"

    Moved cross country twice on a role of the dice...I left Nebraska and came back to Nebraska.

  • #2
    Oh yeah. I am in early to follow this build. Great idea. Air ride the cab though - your kidneys will thank you.

    At the boat factory we upgraded from a 1-ton dually that we pulled its guts out over & over again, just too much load for it. Went to a Kodiak which did the job without suffering physical damage to the unit, but beat the cab occupants to pieces. Racing boats will do that by itself, no need for the ride there to get a headstart on the beating.

    Click image for larger version

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    Of all the paths you take in life - make sure a few of them are dirt.


    • #3
      It looks and sounds like a solid truck. The 5spd should be an Eaton/Fuller FS3005 or FS4005 unit (think SM465 on steroids). That era of Cummins is very stout and has the desirable P7100 injection pump that you can ramp up if you so desire. It should have Lucas Girling juice brakes which can be a bit pricey to service, but they're pretty simple to work on as long as the trucks not a rot bucket. My buddy had a late 80's F700 429 gas Allison automatic with similar specs. It was a tank, it would pull anything at 65mph all day, that's it though, 65 was the limit! I suspect the Cummins has a bit more grunt than the old tall deck 429's had. I'd take a gamble on the F800, it looks like a good deal.


      • #4
        Looks like an in-town truck, probably an Eaton trans w/ 1:1 final and 4:10 or higher rear, not for going 70 on the highway. That motor only has a couple-hundred horsepower, diesels tout torque but when pulling a load it's horsepower that gets you up the hill. Those would be the negatives for long-distance towing, but maybe in NE you're not worried about hills much. I'd suggest getting it out on the highway and seeing how it feels keeping in mind the motor's most efficient at probably 1800-2000 rpm and tops out around 2500. Motor is likely in fair shape, and can be modified for more power, and more cooling can be added to the rear of the block where it doesn't get much if you do so. My project 12-valve had the head gasket be finished at 270K miles, pistons and bearings were good. Heads crack and are almost considered a normal replacement item but are inexpensive. Exhaust manifolds may crack near the turbo, again are cheap to replace.

        Highly suggest to find a competent diesel guy who is not a thief, to have a look at it too. Just to say, I've found nobody in my particular area who meets both qualifications although I'm sure they're out there, so good luck.

        Eaton overdrive transmissions are around if you went to look, and ended up wanting lower hwy rpm. The Spicer 7-speed overdrive from that era is to be avoided.

        I just bought a '97 Powerstroke/Spicer 5-speed from a wrecked UPS truck for our old motorhome project to replace the IDI I had intended to use, and am now looking for a 3.31 Dana-IHC 80 so we don't have to plod along at 55 everywhere. Cheaper than a Cummins, was a main reason.

        Truck stuff is kinda fun when you get into it.

        At the end of it here I'd have to say however, going from a half-ton truck to what you're looking at is quite a jump. You might be happier with a F350 crew cab, my big bro has an '07 with a flatbed that he really likes, but selling for 8K I think as he's having CA registration problems with it, and yeah it's in CA. Do avoid older automatics that might ever fail as few people can seem to fix them so they stay fixed.



        • #5
          Originally posted by Loren View Post
          At the end of it here I'd have to say however, going from a half-ton truck to what you're looking at is quite a jump. You might be happier with a F350 crew cab,

          I second this motion. Not telling you what to do by any means, but that is indeed quite a jump.

          I have pulled with a 1/2 ton - probably more weight than I should have - and stepping up to a 3/4 and 1 -ton version of basically the same tow rig was a huge improvement.

          The Kodiak we ended up with at the boat factory was hauling a big cigarette boat thousands of miles at a shot. Florida Keys one weekend, Arizona the next, back to Ohio for refitting, New York next weekend. Found some pictures of it - tough load to haul for a 1-ton.

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          Of all the paths you take in life - make sure a few of them are dirt.


          • #6
            I pulled for years with various rigs.
            Really liked Dad's old 60 Suburban 1/2 ton built to tow 348/4 speed
            Then my own that I put lots of miles on was a 77 1/2 ton 4X4.. One ton springs, went thru rear 3X..
            Then I pulled with a sick flatbed... Went and bought my own and just love it.
            Son has a F-350 crew cab dualie and we pull derby cars hours away.. I have been 90 mph with it pulling a trailer.
            He took the bus to S.Oregon to pick up the International pickup for his former employer... Cab and seat were air ride but still rode rough. Top speed was 65-70 mph on freeways.
            I will agree bigger rigs make small jobs easier.
            I almost bought a retired mobile home toter, too many miles and man did it ride ROUGH...
            Something to consider is plates/licenses.
            My flatbed was a "T" plate..$90 every 3 months. I had pickup plates put on it telling DMV I wanted to pull my boat.. $80/2 years. Limited to 8k# but I often go 12-16K. If you do not hold traffic back or look like you are having problems, weigh police might scale me. So far, never have had to.. I always like the towing rig to be as heavy or heavier than the load f no brakes on the trailer..

            The flatbed is my daily driver when my wife needs her car. .
            Flatbed, crew cab dualies do not really fit in parking stalls. Maybe if the flatbed was a little narrower.. Flatbed's rear outer rims ride in the same ruts an a dualie's inners
            Loren has put a flatbed in a regular pickup and I believe he said he could not get a sheet of plywood/sheetrock between the rear wheels

            I carry a 6' step ladder so I can get in the bed if needed.

            Hope you have some food for thought.


            • #7
              the front bearings, spindle etc
              crazy wheel/rim.

              ..and if rear springs decide they are overloaded, tires rub the bed.

              that is a nice motor for that setup.
              Previously boxer3main
              the death rate and fairy tales cannot kill the nature left behind.


              • #8
                Pove the truck . If I wouldn't have had to park it on the street I was planning to buy a C50 with a dump grain bed that you could take the sides off and just b.c. have a dump flat bed instead of the suburban I bought .
                Previously HoosierL98GTA


                • #9
                  That Cummins is a 6BT and mine is an ISB (later version w/24 valve head). Both are tough. The 6BT is easier to tweak but the 24 valve has more HP potential - that's why Cummins spent $$millions to develop the 24 valve head. But the 6BT should be tweakable to get you plenty of power for towing. Loren may well be right (he almost always is) and you may need to swap out the rear gear for your purposes. Now is it worth that? - that's your call!



                  • #10
                    Oh I'm right about half the time, and wrong about half the time. The trick is, knowing which half to keep my mouth shut for.

                    Whoops my bro's truck is an F450. 19.5 wheels, dually, tough stuff purchased from the Oregon Hwy Dept. I think Not an option on it that I know of. The sister-in-law has a single-cab flatbed hay hauler that is a late-nineties F350, 16" wheels/dually and for what it's worth, for it's smaller size is still a wonderful tow rig. If I had to get another truck today and didn't have my Dodge, I'd be thinking about something like either of those two.

                    Bob it was around 1999 I stuck a flatbed-style narrow 14-bolt DRW rear under my 3+3 Chevy pickup and "tubbed" the bed to fit, that one then couldn't fit a sheet of plywood flat on the bed. The truck had it's positives and negatives to be sure but certainly towed very well.

                    That 3.31 rear I'm looking for (for the motor home) will have a 14K weight rating which is just at the low end for a medium-duty truck I think, such as catering trucks or a FedEx van. The heavier rears such as probably should be in the F800 don't seem to come in any taller gears than 4.10 or 4.33, seems like you have to get into the semi-truck axles before you can find something with gears in the threes.

                    And, I could be wrong...