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IDI Mileage

Discussion in '6.9L IH & 7.3L IDI Diesels' started by andrew123, Aug 24, 2019.

  1. andrew123

    andrew123 Registered User

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    I have a Automatic 1993 F250 7.3 IDI, approaching 219,000 miles.

    I have heard these diesels can go 500,000 miles....seems high to me, I guess it depends on how you maintain it.

    Mine is still original as far as I know (headgasket has never been replaced).

    What type of mileage do you have, and any ideas on how long these engines will last?

    I am on at least the 2nd transmission rebuild.

    Thanks.
     
  2. Macrobb

    Macrobb Full Access Member

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    It's hard to get numbers unless you happen to have good records - remember the <92 trucks reset every 100K miles, and the 92-94 every 400K miles(399,999->300,000).
    Also hard to determine if something has been replaced or not, unless you can see an obvious mark(like serial number being way out of whack, or an intake manifold with a way different year in it.

    I have a good 5 trucks:
    Tan '88 - Unknown miles(but probably in the 300s), motor needed to be rebuilt due to massive wear/rings gone.
    Blue '88 - looks like original motor, again unknown miles... motor works fine.
    White '87 Cab & Chassis - again,unknown mileage; saw reference to 200xxx in paperwork found; has a rebuilt motor in it(has a 7.3, not the 6.9 it originally came with).
    Blue '92 - Speedo reads 3xx, has a rebuilt motor in it
    Red '93 - Speedo reads 3xx KM(canadian truck); we know it's rolled at least twice, came with an '88 block rebuilt in '01... which needed head gaskets after the serp tensioner broke and the engine overheated a bit. Currently has a '93 IDIT motor in it that seems to be all original... again, unknown miles.

    My take on things is that it's really hard to find mileage, or even worry about it. You look at the condition of the motor in the vehicle(mainly in terms of oil usage if it's not leaking, and possibly compression), and if it's good, she'll run for another long time as long as you keep oil in her.

    Injectors and IP are a wear item and seem to always be worn if you are buying a low-price truck; most people think the motor's shot when you see blue and white smoke due to the IP timing being way off.

    Also, IMHO, blow by is not a useful metric for anything. New motors produce a ton of blow by(large ring gaps), worn ones do as well, and it all goes down the intake and gets burned.


    I do know of a couple of people with over 400K miles on their engines, people who bought the truck new and actually know it.

    Also, while only tangentally related, a friend of mine has a 7.3 PSD with 500K miles on it. Motor still runs great. Trans(auto) has been replaced once or twice and needs it again real soon.
     
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  3. andrew123

    andrew123 Registered User

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    i have replaced the injectors and the injection pump - I do get blue or black smoke when I am going up grades - i was told it was normal. when driving on a flat road, no smoke.

    I am not using much, if any oil, so I guess that is good.
     
  4. Macrobb

    Macrobb Full Access Member

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    Black smoke is OK, if it's just a little at WOT - that's too much fuel, so you just get carbon that didn't have oxygen to be burned.
    If it's a lot of black smoke at WOT, you can always turn the 'max fuel' screw down a bit(one flat of the allen wrench or so) until it goes away.

    Blue smoke... you may need to advance the timing. Did you get it dynamically timed when you replaced the IP and injectors?
     
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  5. andrew123

    andrew123 Registered User

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    no, i did not get it dynamically timed....i used the 7.3 manual i bought, as i recall there were 2 places I had to set the timing - i would have to look at the manual again, i can't recall exactly. this was a couple years ago, but not very many miles ago. I think the smoke is black....a bit tough to tell when i'm driving up mountain grades.
     
  6. Macrobb

    Macrobb Full Access Member

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    When you line up the marks, you get it "close enough" to run. Then you are supposed to take a timing meter that clamps on the #1 injector line and has a magnetic pickup that goes into a hole next to the crank, and it will give you a timing number in degrees(at a certain RPM, usually 2000). You then rotate the pump a little until you get the correct timing in degrees.

    You can also just do it by 'ear' or 'feel' - adjust it one way by a dime's width, see how it drives - if it's got more pep and feels stronger, keep going until it feels worse, then go back.
    If it feels worse, go the other way.
    The setting that's 'strongest', will also be good for fuel economy - you are finding the spot the engine is 'fighting itself'(on the advanced side) least, while being as advanced as possible(for more power extracted from the fuel).
     
  7. andrew123

    andrew123 Registered User

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    that is good information to know...i did not do this after changing my IP....it runs pretty good, I will have to check MPG, i know it is pretty bad, around 10mpg without pulling a load, but I will check what it is getting exactly at my next fuel up.
     
  8. Golden Helmet

    Golden Helmet Full Access Member

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    I bought my truck from the original owner with 290K miles on it, original engine and second transmission. I had the compression checked at 295K and all 8 were above 400psi. It leaks a bit of oil, but burns almost none. Now it's got just under 325K on it, still going strong.

    These engines live a very long time, everything around them will rust and crumble but the engines themselves live damn near forever as long as you treat them right.
     
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  9. Macrobb

    Macrobb Full Access Member

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    It's also a case of 'survivorship bias' - The ones that weren't made quite right, or the castings were very cavitation-prone are now made into Hondas, whereas the ones that are still around are the ones that made it past the early failure stage... and like anything with a "bathtub failure curve", now the failure chance is low.
     
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  10. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    With good maintanance, 300,000 miles is nothing on these engines.
     
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  11. franklin2

    franklin2 Full Access Member

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    This is very true. I worked in factories for years. All parts have a tolerance. Everything is thrown together on the assembly line as fast as possible. Some products are right down the middle as far as fit and performance, some are on the edge, just enough to pass and are sent on down the line. It's the way things are made.
     
  12. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    Personally I have had 4 plus the ones in my fleets over the years.

    83 F250 6.9 all stock from the original owner in 1990 with all records. Sold it in 94 because I got a great deal on a 90.... 83 had 300k miles nothing but pump, injectors, water pump.

    90 F250 7.3 w Banks bought in 94 with 97k on it. A week later it hydrolocked due to cavitation of the cylinder wall. Yes it really happens and this time under 100k. So I tore it down, machine shop claimed they new what to do so they sleeved the cylinder. bored all to .020, new pistons bearings and valve job. Ran great for a year or so and started burning just a little coolant. Never really caused an issue just knew something was brewing. Finally with 100k on the rebuild I tore it down again.
     
  13. oregon96psd

    oregon96psd Full Access Member

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    My 86, 1st engine went 110k don't know what went to hell with it, 2nd ran away and destroyed the block 40k later , now the third, the one I bought it with has 43k.

    The 94 idit I drove for work went 94k and spun a bearing, when I quit it had ~120k
     
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  14. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    Continuing on the 90... So I find the first machine shop didn’t know how to fit sleeves and even worse, had cut intake seats into the heads. The cutter actually cut into the water jacket and coolant could get past the seat and into the intake port. I found an old school machinist that located and fitted an oversized sleeve in the block and lock n stitch the valve seat area plus installed sleeves in the water ports in the heads that pass between the intake and exhaust ports. No more problems. Even did a little port cleanup work on the heads. Probably the best running 7.3 IDI I came across for the next 100k. Would easily whip a stock OBS Powerstroke. Finally traded it in on a 96 PSD CCSB in 2003 because our teenager was over 6’. The 90 made 300k with only the engine issues mentioned, the first time due to maintenance ( no coolant additive) and the second due to a machine shop owner that had a good rep but retired the week after I got my engine. It (and the 83 as well) made many trips to the high Sierra with a heavy old camper and dragging 3 horses behind.
     
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  15. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    So meantime I needed to replace my Dads old 454 flatbed gooseneck hauling cattle feeding truck. Probably could have afforded a Powerstroke but opted for the simplicity of the IDI. Bought a super clean 91 7.3 IDI with Banks Sidewinder and 120k miles from the original owner. Still have it with 200k and only pump and injectors, water pump, lift pump. Runs and tows awesome, leaks nothing 1 qt oil per 2000 miles. Engine never apart 28 years.
     
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