I'm looking to buy a Ford diesel, I don't want the psd, I'd like an IDI for the simplicity of them. But I'm not sure what to get, if I get a 7.3 I'll get the stock turboed version. I've heard the 7.3 has cavitation problems, does that include the stock turboed version of the 7.3idi? How much boost can the 7.3idi handle? i know the 6.9 with an aftermarket turbo can handle about 12-15 and still be reliable, 20 with head studs. if I get a 6.9 i would turbocharge it.
Brett

 

Get a late 1985-1987 6.9, and studs, turbocharge it, and don't look back. Change the rocker as well if you want.

All 7.3L IDIs are more vulnerable to cavitation including the factory turbo. Theres no way of knowing how bad any potential block erosion even is until it happens. Service records and SCA testing strips can help reduce concerns though. Getting a later 87-1994 truck also means a slightly more comfortable truck with overdrive transmissions but you are stuck with the 7.3.

Sleeved blocks are supposed to be getting better, but the idea still makes me nervous.

Personally I would not go past 10 PSI with a 6.9 and limit a 7.3 to 15psi.

 

ok thanks for the help

 

If you do head studs on a 6.9, up to 20 PSI boost is no problem.
With stock head bolts you should keep the 6.9 below 10 or 12 PSI.

A 7.3 is basically a 6.9 bored out 110 thousandths.
That makes the cylinder walls much thinner and more subject to cavitation.

 

Well I’m glad that somebody asked this question because I’m kind of looking at the same thing. The only thing is that my uncle(I goto him for car advice) said that I should avoid turbo diesel’s because of the super high compression and that it breaks things like connecting rods, and wrist pins. Since I know next to nothing about diesels and I’m sure there is a big difference between the big rigs and the ones in the F- series. I’m trying to research all I can before making a post, but there is just a lot of info, I think that I want to get a Navistar which I think is the IDI, because I hear it’s cheaper to work on and parts are cheap, but I’m on a tossup between the 7.3 or the 6.9. I have read some sites say the 6.9 is garbage, and should avoid it, and sites claim the 7.3 IDI is without a doubt the most dependable and durable diesel in pickups. I’m sorry that this question might start a flame war, which was not my intent, I’m just trying to figure out what engine I would like to get in a 80’s early 90’s f250 and a work truck, and a truck that could be used for other things to attract the females

 

Hey don't worry about it, GOOD questions.
A lot of what you've heard so far is hog-wash.
I know TWO diesels pretty well: IDIs and Cummins 6BT/5.9L/etc. (the one used in Dodges).
The Cummins was made from the ground-up to be turbo charged so there is no problem.
The IDIs (yes they are Navistar but so are ALL Powerstrokes) were not desighned to be turboed BUT they are built heavy-duty enough to handle it. There are a few mods. that should be done if you run over 10 PSI or so but the rods etc. are good enough. The only thing I know of that bends rods in the IDIs is fluids (water,too much diesel) in the combustion chamber.
There may be some truth to the GM diesels and turbos, I honestly don't know as I've never really messed with them but the motors are definitaly not as "beefy".

The 6.9L is better than the 7.3L in almost every way. Actually a hybrid of the two makes the best motor. I had never heard anybody say the 7.3L was better until I came to this forum but appearantly it's a common myth.

The IDIs are ABSOLUTELY cheaper to fix than a Powerstroke, period.

BTW l like your "icon", I grew up watching the origional Transformers cartoons and playing with the toys. Now my son's into it so it's cool to kind of relive it through him. I have to say the origional series was better than the Japanese made version of today. The movie was OK but I expected more.

I live in the Western Oregon area, maybe we'll run across each other sometime.

 

The 6.9 has a couple weaknesses, some can be avoided by year, some need parts changed.

The early 6.9 block, 83 thru mid 85 has a weaker block in the block heater area, they have been known to crack with prolonged use of the block heater.
This can be eliminated if you install and use a hose mounted heater, or a tank heater that plumbs into the cooling system.
This problem was corrected mid year 85, so late 85, 86 and 87 blocks are good to go.

All 6.9 engines had 7/16" head bolts, know for stretching and causing head gasket leaks.
A set of ARP head studs eliminate that problem.

The 83 thru 86 valve rockers have an inferior fulcrum setup, the 7.3 style is a direct bolt in swap.

7.3 turbo valves are the best made, and will drop right in a 6.9.

There you have all the bad parts of a 6.9 engine.

A 7.3 is very close to the same block as a 6.9, but to make it a 7.3 they bored the engine 110 thousandths.
This made the cylinder walls very thin, cavitation is a problem with them.

You can address every 6.9 problem cheaper than you can can fix the 7.3 issue.

 

So ok, from what have been reading and the info that everybody has given me, it sounds like if I get a new set of studs, and valves I should be ok. but I did have another question but it’s starting to go off topic, is all I know about diesels is from the show truck!(when Stacey was on it and how it works segment) and they were showing a engine with sleeves that allow the engine to run for next to forever, now I don’t know if they use something similar in smaller trucks, why I ask is that after I buy it I might want to do a once over with the engine out and since I already would have the heads off and replacing valves might as well just dive right into it. I guess it’s that I want to see how to work on a diesel and mainly use this truck as a project truck, and maybe a big truck for the jobs that need a little more than what a 2.3 ranger can’t handle

Dodge/Cummins, I love the transformers, they are awesome, wasn’t a big fan of the movie, although the new one that’s on cartoon network is a bit funny, but I still have my toys that I but on display although they have many "battle scares" maybe I should paint this truck red and have a couple of autobot symbols on the extended part of the cab, this could turn into a fun project.

 

T1m3_Sh1ft3r,

What are you posting with?

I went to remove the line of HTML and was blown away by how much there was in your post.



I think you saw a large diesel that had wet sleeves or liners that can be changed when they wear out.
Those engines weigh about as much as your truck does, but can last for millions of miles.

 

oh my bad, i wanted to spell check it, and copied it in word then copied it back, sorry about that, so ok the liner is what i saw and i guess they don't put those in light duty diesels, fair enough, kinda thought that's how diesels were made across the board for some reason, but i guess i can understand that big rigs need that kind of set up.

 

Yeah, that was a 14L Cummins if I remember right.
I don't think any "pick up size" diesels have liners.

Those two guys that took over for Stacy David together can't make the show anywhere near as good. He had a show on ESPN2 called Gearz that was even better, alas it seems it only lasted a season.

 

T1******* You stated that you was told that the rodes and other components may break from high compression?

I wouldn't worry about it expecially if its left stock. We have litterly hundreds of diesels at work and I have only seen one break a rod, thats when it sucked water in and hydroloked it. Diesels just bother those who are not familer with them. He may have seen one or experienced one in the past and held it against them since. Their not as bad and fragil as some make them sound. Now modifiying them without knowing or paying attention to what your doing could be desastorus but under normal use and light mods, should have no problem at all.

 

No problem with the HTML, but when there was one line showing in the post, then I hit edit post to remove it......I kept scrolling down trying to find the text.

After I switched back to the forum post twice to see there was text and what it said, I finally found it "WAY" down at the bottom.

I had to laugh a couple times as I scrolled down, so I guess it was good since I needed a laugh.


As for rod strength and high compression, I am running 25 pounds of boost on stock 1986 connecting rods.
And I have over 40,000 miles on it running boost that high.

Yes I have milled the pistons down to lower cylinder pressures with boost that high.