Looking at a used IDI, Couple questions.
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Senior User
Joined: Apr 2013
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From: Geneva NY
Looking at a used IDI, Couple questions.
Hey all!
I am looking at an 85 f250 with the 6.9l and the c6. I've got a couple questions for ya.
1. I know the factory block heater is a problem. Is the problem the factory block heater itself? Or is the problem the block where it mounts? What I'm wondering is if I can put an aftermarket block heater in the factory location, or if I need to put it elsewhere.
2. Is the factory block heater located under the exhaust manifold on the passenger side?
3. This truck has been sitting alot in the last few years. If I buy it is there a way I can clean the injectors by soaking them in something or should I just run some diesel purge through the system and call it a day?
4. Does old diesel get bad (less powerful) just like old gas?
5. Can I/Should I put anti-seize on the injectors and glow plugs? I would think it a good idea but I don't want to damage anything. I have Permatex Marine Grade Anti-Seize (I believe it is "metal free")
6. Would running a 3" or 4" pipe from the exhaust manifolds or just before the "y" wake it up any? I've heard the factory y-pipe is a restriction.
Thanks guys!
I am looking at an 85 f250 with the 6.9l and the c6. I've got a couple questions for ya.
1. I know the factory block heater is a problem. Is the problem the factory block heater itself? Or is the problem the block where it mounts? What I'm wondering is if I can put an aftermarket block heater in the factory location, or if I need to put it elsewhere.
2. Is the factory block heater located under the exhaust manifold on the passenger side?
3. This truck has been sitting alot in the last few years. If I buy it is there a way I can clean the injectors by soaking them in something or should I just run some diesel purge through the system and call it a day?
4. Does old diesel get bad (less powerful) just like old gas?
5. Can I/Should I put anti-seize on the injectors and glow plugs? I would think it a good idea but I don't want to damage anything. I have Permatex Marine Grade Anti-Seize (I believe it is "metal free")
6. Would running a 3" or 4" pipe from the exhaust manifolds or just before the "y" wake it up any? I've heard the factory y-pipe is a restriction.
Thanks guys!
Logistics Pro
Joined: Apr 2005
Posts: 4,221
Likes: 17
be sure to check out the FAQ for more detail, but here's some quick answers:
6.9/7.3 IDI Diesel tech info
Welcome to the forum and to IDI ownership!! 
Post pics of the new rig!
6.9/7.3 IDI Diesel tech info
Hey all!
I am looking at an 85 f250 with the 6.9l and the c6. I've got a couple questions for ya.
1. I know the factory block heater is a problem. Is the problem the factory block heater itself? Or is the problem the block where it mounts? What I'm wondering is if I can put an aftermarket block heater in the factory location, or if I need to put it elsewhere.
It's the block itself where the block heater is. However this problem was corrected in '85 so your block could be fine. Check the engine serial number to be sure.
2. Is the factory block heater located under the exhaust manifold on the passenger side?
Yes.
3. This truck has been sitting alot in the last few years. If I buy it is there a way I can clean the injectors by soaking them in something or should I just run some diesel purge through the system and call it a day?
I'd see if it runs good then just run some good cleaner through it.
4. Does old diesel get bad (less powerful) just like old gas?
Yes, but it takes a long time to go bad, I've seen diesel many years old burn just fine.
5. Can I/Should I put anti-seize on the injectors and glow plugs? I would think it a good idea but I don't want to damage anything. I have Permatex Marine Grade Anti-Seize (I believe it is "metal free")
Can't hurt, probably a good idea.
6. Would running a 3" or 4" pipe from the exhaust manifolds or just before the "y" wake it up any? I've heard the factory y-pipe is a restriction.
The stock muffler is a restriction too, go glass pack or high-flow muffler.
Thanks guys!
I am looking at an 85 f250 with the 6.9l and the c6. I've got a couple questions for ya.
1. I know the factory block heater is a problem. Is the problem the factory block heater itself? Or is the problem the block where it mounts? What I'm wondering is if I can put an aftermarket block heater in the factory location, or if I need to put it elsewhere.
It's the block itself where the block heater is. However this problem was corrected in '85 so your block could be fine. Check the engine serial number to be sure.
2. Is the factory block heater located under the exhaust manifold on the passenger side?
Yes.
3. This truck has been sitting alot in the last few years. If I buy it is there a way I can clean the injectors by soaking them in something or should I just run some diesel purge through the system and call it a day?
I'd see if it runs good then just run some good cleaner through it.
4. Does old diesel get bad (less powerful) just like old gas?
Yes, but it takes a long time to go bad, I've seen diesel many years old burn just fine.
5. Can I/Should I put anti-seize on the injectors and glow plugs? I would think it a good idea but I don't want to damage anything. I have Permatex Marine Grade Anti-Seize (I believe it is "metal free")
Can't hurt, probably a good idea.
6. Would running a 3" or 4" pipe from the exhaust manifolds or just before the "y" wake it up any? I've heard the factory y-pipe is a restriction.
The stock muffler is a restriction too, go glass pack or high-flow muffler.
Thanks guys!
Post pics of the new rig!
Cargo Master
Joined: Oct 2012
Posts: 3,072
Likes: 48
From: California
Just to add to Chevyeaters comment, old diesel can absorb a decent amount of water, if the cap was loose or it had access to atmospheric conditions. just a reminder if the "water" light comes on.
i ain't rite
Joined: Mar 2005
Posts: 65,421
Likes: 5,506
From: Marlboro Mental Hospital.
to clean the injectors and injector pump, remove the fuel filter, drain it , fill aith automatic trans fluid, and put it back on. start the engine and let idle for 30 seconds, then shut it off and let it sit for 12 hours, 24 hours is better.
start it up after sitting and drive it like you stole it.
the ATF loosens anything sticking in the injectors and cuts anything gumming up the injector pump.
anything done to open up the exhaust will help it run better. also opening up the intake for more air in is an improvement too.
as for the old diesel, down south old fuel can be a problem with algae growth, but up in our colder climates it is not a concern. i am running 13 year old fuel in my trucks with no problems at all, the older fuel is actually better because it has a higher cetane rating than the garbage they are passing off on us these days.
start it up after sitting and drive it like you stole it.
the ATF loosens anything sticking in the injectors and cuts anything gumming up the injector pump.
anything done to open up the exhaust will help it run better. also opening up the intake for more air in is an improvement too.
as for the old diesel, down south old fuel can be a problem with algae growth, but up in our colder climates it is not a concern. i am running 13 year old fuel in my trucks with no problems at all, the older fuel is actually better because it has a higher cetane rating than the garbage they are passing off on us these days.
Thread Starter
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Senior User
Joined: Apr 2013
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From: Geneva NY
Thanks guys!
I haven't bought it yet, I've been mulling the idea over in my head.
I have a 97 Chevy pickup that one of the guys at work wants to buy from me, just not sure I'm ready to let it go. My truck is in decent shape, and this truck will need some love. I'm VERY strongly considering it though.
When I test drove it on Saturday, it was kind of a dog... but it's only been driven about 1000 miles in the last 5 years too so I expected it. The fuel filter says 2005 on it and the air filter has a foam precleaner on it that looks nasty. If I decide to go look at it again I'll buy a fuel filter and some atf to prime it with, take the precleaner off and run it again.
I haven't bought it yet, I've been mulling the idea over in my head.
I have a 97 Chevy pickup that one of the guys at work wants to buy from me, just not sure I'm ready to let it go. My truck is in decent shape, and this truck will need some love. I'm VERY strongly considering it though.
When I test drove it on Saturday, it was kind of a dog... but it's only been driven about 1000 miles in the last 5 years too so I expected it. The fuel filter says 2005 on it and the air filter has a foam precleaner on it that looks nasty. If I decide to go look at it again I'll buy a fuel filter and some atf to prime it with, take the precleaner off and run it again.
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Senior User
Joined: Apr 2013
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From: Geneva NY
The odometer says 13k miles, Truck looks like it's 113k, What would the motor and tranny be worth by themselves? The truck's not too bad but the TTB bushings will need replaced and probably balljoints too. Unless I can find a D60 to swap in. It has a plow on it and it was all over the road. I'm probably going to try to get him down around $1000. He's at $1600 right now but said he's flexible and just wants it gone. Needs new fenders and some paint and a couple patch panels on the bed.
i ain't rite
Joined: Mar 2005
Posts: 65,421
Likes: 5,506
From: Marlboro Mental Hospital.
odometer rolls back to zero at 99,999. so it sould have 113, on it, or 213, or 313, you get the idea.
the 6.9 was never a drag racer to start with. it ia about the same as a VW beetle for get up and go. but it will pull a house down with it's low end power.
an open exhaust, unrestricted air intake, and a little extra fuel lets them "breathe" better which will make them run a bit better.
a turbocharger will wake it up.
the 6.9 was never a drag racer to start with. it ia about the same as a VW beetle for get up and go. but it will pull a house down with it's low end power.
an open exhaust, unrestricted air intake, and a little extra fuel lets them "breathe" better which will make them run a bit better.
a turbocharger will wake it up.
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From: Geneva NY
Yeah I know but it doesn't look as whooped as I'd think 213 or 313 would look.
A stock 6.9 should be able to chirp the tires empty from a stop right? (3.55 gears and c6)
A stock 6.9 should be able to chirp the tires empty from a stop right? (3.55 gears and c6)
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i ain't rite
Joined: Mar 2005
Posts: 65,421
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From: Marlboro Mental Hospital.
not with 3.55's unless it has mini tires on it. my 88 to 92 F350's with 4.11 gears and C6 transmissions would only spin the tires on a start if the road was damp.
that all changed when the turbos were put on them though.
that all changed when the turbos were put on them though.
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From: Geneva NY
What about 285/75/16, they're a little wider yet, but about an inch bigger in diameter? I'd love the 285's but not if they'll kill MPG....
i ain't rite
Joined: Mar 2005
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From: Marlboro Mental Hospital.
i went from the 265 to 285 on my 02 and gained 2 mpg.
when i had the 235 winter tires on it i was only getting 8mpg. the 265's bumped it to 10, the 285's i am now running 12 mpg.
hopefully the new injectors, turbo rebuild and new HPOP will kick me up to around 17-18 mpg.
when i had the 235 winter tires on it i was only getting 8mpg. the 265's bumped it to 10, the 285's i am now running 12 mpg.
hopefully the new injectors, turbo rebuild and new HPOP will kick me up to around 17-18 mpg.
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From: Geneva NY
Whats an HPOP?
That's good news for me! If only it kept going up with tire sizes... I'd run some 37's :P Unfortunately there comes a point where you can't have your cake and eat it too :/
That's good news for me! If only it kept going up with tire sizes... I'd run some 37's :P Unfortunately there comes a point where you can't have your cake and eat it too :/
i ain't rite
Joined: Mar 2005
Posts: 65,421
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From: Marlboro Mental Hospital.
high pressure oil pump. part of a powerstroke engine.
for highway driving, larger tires increase mileage once rolling. for in town driving driving smaller tires are better.
as an example, a truck with 3.55 gears and 37 inch tires will get fantastic mileage on the highway at cruising speed but lousy mileage in town low speed driving.
a truck with 4.10 gears and 31 inch tires will get great mileage in town low speed driving, but lousy mileage on the highway cruising.
back when we had real diesel fuel in the 60+ cetane rating, my 88 used to get 20 mpg out on the highway with 4.10 gears and 37 inch or larger tires, but only around 12 mpg in town. .
now with the 40 to 45 cetane garbage they are passing off as premium diesel, i am lucky to get 15 on the road and 8 mpg in town.
for highway driving, larger tires increase mileage once rolling. for in town driving driving smaller tires are better.
as an example, a truck with 3.55 gears and 37 inch tires will get fantastic mileage on the highway at cruising speed but lousy mileage in town low speed driving.
a truck with 4.10 gears and 31 inch tires will get great mileage in town low speed driving, but lousy mileage on the highway cruising.
back when we had real diesel fuel in the 60+ cetane rating, my 88 used to get 20 mpg out on the highway with 4.10 gears and 37 inch or larger tires, but only around 12 mpg in town. .
now with the 40 to 45 cetane garbage they are passing off as premium diesel, i am lucky to get 15 on the road and 8 mpg in town.