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6.9IDI VS 351C or W

Just out of curiosity what would you choose if we're buying a 4 wheel drive pickup, that would mainly be used to tow 2-5000lbs down the highway and in the mountains? The IDI has a turbo on it and 5 speed. The 351 has a 5 speed and is carbureted. Both Ford trucks about the same years.

Thanks
idcwby
 
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CowboyBilly9Mile

Charter Member
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442
USA
Taking into consideration the approx $ value of the two in question, IMO I'd look at option #3. That would be a 97+ F-150, anything BUT a standard cab, equipped with the 5.4 and an automatic. Automatic because, there are times when towing something that it's really nice to be able to not have to screw with a manual (boat launch, for example).
 

SuperCab

Moderator
Staff member
10,068
547
Montana
An idi with a turbo isn't a bad setup. Probably a little more powerful than a 351 but not by any huge amount.

5,000lbs isn't a terrible load at all... Like bill pointed out a little bit later half ton should handle it fine as well.

Do you want a diesel or would a gas engine suit your uses better overall?
 
Bill's third option is out of my price range at the moment. Doesn't mean there not out there, but I haven't seen one yet with a long bed. I had been looking for a 351 and than I ran across a good deal on a IDI, so it got me thinking what would the better option be.
As far as diesel vs gas, I've driven both styles over the years so there isn't a big difference to me cause each has its own advantages. I keep leaning towards the IDI because I believe it'll get better mileage down the road, but I may be wrong on that and I may need to tow up to 8,000-10,000 very rarely.

Thanks
idcwby
 

Sparky83

Virginia Chapter member
5,566
219
Norlina NC
something to keep in mind with both.. reputation of an engine and drivetrain can be a good thing as a deciding factor... but neither take into account the maintenance factor that becomes a big unknown when buying used... if the engines and drivetrains were not properly maintained things will get expensive fast.. yes it might run nice when you test drive it and take it home... but you could get it home and catastrophe strikes because someone didnt keep oil in the engine.. or change it periodically..

dont get me wrong im not trying to scare you or say either one would be bad.. im just trying to say sometimes a setups reputation doesnt always fit the vehicle your looking at because of other factors that are not taken into consideration... you will have to ultimately decide which one works better for your needs..

as for tow ratings.. i have a 79 suburban that use to tow a 7000 lb trailer behind it frequently.. tow capacity for it was about 5K-8K depending on the setup at the time.. and that was pulling with a crate 350.. ive known people to tow 20K with a f150 before stating they didnt having problems with it.

personally though i think you will be fine with either one you pick...
 
Thanks for the input. I think there both up to the job, just trying to decide which would get better mpg when towing. From what I've been reading they both get about 15mpg on the highway and I'm assuming that's unloaded. Trying to determine it the diesel is worth the extra cost or will it pay for itself because it gets better mpg?

idcwby
 

Fellro

Moderator
Staff member
The other thing to consider is maintenance cost and operating cost. The 351W is a little less on torque, but the parts are fairly cheap. The oil change on an IDIT is nearly 3x as much, as they hold I think 14 quarts, but might be as low as 12. The water pump is about 2x as much, but the fuel system is where it really hurts. The injection pump is about $300 minimum, $600 for a good one, Injectors aren't so bad though, around $100 or so a set.

Now if that is not an issue, then I would go diesel myself if I wasn't concerned with the cost to keep it running. I have both a 6.9 NA and a 351W, so I know this stuff as I live with it. If maintenance cost is a problem, you have to stay gas.

My 6.9 4 speed would commonly get 10-12 all the time with 4.10 gears. I want to put in a 5 speed and see how it goes. I hear results of high teens to low 20's, but can not validate that at all.
 
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The other thing to consider is maintenance cost and operating cost. The 351W is a little less on torque, but the parts are fairly cheap. The oil change on an IDIT is nearly 3x as much, as they hold I think 14 quarts, but might be as low as 12. The water pump is about 2x as much, but the fuel system is where it really hurts. The injection pump is about $300 minimum, $600 for a good one, Injectors aren't so bad though, around $100 or so a set.

Now if that is not an issue, then I would go diesel myself if I wasn't concerned with the cost to keep it running. I have both a 6.9 NA and a 351W, so I know this stuff as I live with it. If maintenance cost is a problem, you have to stay gas.

My 6.9 4 speed would commonly get 10-12 all the time with 4.10 gears. I want to put in a 5 speed and see how it goes. I hear results of high teens to low 20's, but can not validate that at all.

How often have you had to put in new injectors and injection pump?

My biggest debate at the moment is which would do better on fuel when towing. The 6.9 that I'm looking at has a gear vendor over drive and the ats turbo. The guy is claiming he can get around 17mpg empty down the highway at 70mph.

Thanks
idcwby
 
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Sparky83

Virginia Chapter member
5,566
219
Norlina NC
as to the oil change cost between gas and diesel.. yes a diesel takes more oil.. but something people tend to forget is that in a diesel you are not changing the oil as often.. depending on how often you choose to change your oil with the conventional oils.. if your still changing your gassers oil at every 3K.. your diesel will typically go 7-10K between changes.. so at every 3K on the gasser your changing the oil 2-3 times more often than you are on the diesel... people tend to forget this when comparing the oil change costs and just compare the costs for a single change..

now if you go off todays conventional recommended intervals.. gassers are recommended for 6-7K for oil changes.. where diesels if hard worked every day or for long periods frequently yes they still recommend every 6-7K just like the gasses.. light duty you can run every 12-15K between changes..
 

Fellro

Moderator
Staff member
Typically the injector pump and injectors last for about 100,000 miles, but can go longer. I had to do mine, but got lucky with a used pump. The first used pump was pretty much done, the second was fine.

As to oil changes, I generally go 5-7000 on both gas and diesel as I do mostly highway...
 
Shawn with the gas motor, running non synthetic oil I'd probably change the oil every 5000. With the diesel, since I'm not working it very hard probably change every 10000. So they would almost cancel each other out for those costs.

If it's below freezing, is the IDI going to have difficulty starting or would glow plugs be able to handle it? I'm asking this because when I'm hunting in the fall/winter there will be times I can't plug in the block heater.

Thanks
idcwby
 

Sparky83

Virginia Chapter member
5,566
219
Norlina NC
Shawn with the gas motor, running non synthetic oil I'd probably change the oil every 5000. With the diesel, since I'm not working it very hard probably change every 10000. So they would almost cancel each other out for those costs.

If it's below freezing, is the IDI going to have difficulty starting or would glow plugs be able to handle it? I'm asking this because when I'm hunting in the fall/winter there will be times I can't plug in the block heater.

Thanks
idcwby

the glow plugs should be able to handle it but just depends how cold it gets.. coldest my diesels been in was temps that were down to single digits on the negative side.. but it still started.. was a little grumpy about it but started.. but i also didnt have it plugged in at those temps either the first few times.. later when i could plug it in it was much easier... when the glow plugs start getting old and weak itll be harder to start at those temps.. but youll know when temps start dropping towards freezing if theyre an issue or not.. when its really cold out you can also cycle the plugs a couple times before trying to start it and should make it easier.. diesel owner from michigan told me about that trick.. i tried it after they had told me about it and it did make it easier.

also diesels will come with block heaters to combat the cold for easier start ups..if your home just plug it in at night and let it warm your engine.. while itll help you at home anywhere else your kind of sol unless your boss lets you plug it in.. would also recommend a timer for home use... that 1000w heater element drives the electrical bill up fast when used daily.. lol i have the timer set to kick the heater on 2 hrs before i leave as it takes awhile to heat the blocks..

but something to keep in mind with the block heaters.. if the vehicle was ordered for the south ford had a tendency to install the heater element but did not always install the plug cable.. so if you get one like that youll probably just have to buy a replacement cord...

hope that helps..
 

Fellro

Moderator
Staff member
Around 0 most diesels start to have issues. 32, not so much. I have been able to fire it in sub zero temps before, but it does grumble about it.
 
never owned or dealt with either of the trucks or power trains. noticed no one has said anything about fuel lube additives on the on the db2 pump for the 6.9 . seemed that the db2's on the many 6.2/6.5 the family used to run got better then 100,000 (about 150,000) when running some type of lube with the diesel.
i would say go with the diesel in my other truck exspeincs while they do have higher maintenance costs, fuel usually counter acts that cost. the other factor is how often will you be towing. if its with any regularity i would go diesel it seems they hold up better over the long run then gas when towing or being ask to run at high engine loads. while diesel do require high cost low frequency repairs vs lower cost higher frequency repairs of the gas engines it still is possible given the age of the 6.9 (and know having any furhter info on it) that the 351 maybe a better choice as the 6.9 may need typical high diesel repairs like an injection pump sooner then the 351 will need something major. but after ther both used and there for have many unknowns

just thoughts as i read from a diesel and a gas guy
 
Thanks for the information everyone. After getting to look over the diesel, it wasn't worth the money had more problems than the guy was telling me over the phone.

I did come across a good deal on a 91 with the 351 and auto transmission, it's only down fall was the power locks don't work. I think if I can figure them out I'll have a nice truck.

Thanks again,
idcwby
 

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