Looking at buying 6.9

[Sportsrm125]

I’m looking at downsizing from my current duramax and am intrigued by these IDI’s. I came across a very clean ‘87 F350 crew cab 4x4 with 90k and an ATS turbo. It’s also an auto with gear vendors OD attached to the C6.

What things should I specifically ask or physically look at to ensure it’s a good buy? I’m in so cal so it’s rust free and the paint looks good too.

Im not looking to tow heavy at all. At most I’d flat tow a jeep. I know I’ll be slow and loud compared to my current truck but I don’t use it enough to let a nice truck rot away and lose value.

I just want a simple and reliable truck that’ll do what I want and in this area crew cab 4x4 diesels fetch a premium price but these IDIs are relatively cheap

 

[IDIBRONCO]

I'd crawl around underneath it and look for leaks. If you can see a clean spot on an otherwise dirty engine, the seller may be trying to hide a leak. Check the turbo shaft with the fins attached inside the turbo. A little side to side play is acceptable, but you don't want very much in and out play. If it has much of that, the turbo needs a rebuild. Ask to see a cold start. Feel the engine/radiator to make sure that it's a cold start. If the "wait to start" light doesn't stay on for 8-10 seconds, there's probably a glow plug(s) burned out. If it's 90k actual miles, the numbers on the odometer will all be lined up. If they aren't, it's got at least 190k miles. If it's 90k actual miles, you have a good find there. I'm not a fan of the C6 behind a diesel, but the OD sure helps. Either way, assuming that it has 4.10 gears, it won't be a freeway burner. At 90k miles, the injector pump and injectors are getting close to the end of their life. Some people will say that they last for 100,000 miles. Some people have driven them to 150,000 miles or beyond. I feel like 125,000-130,000 is probably about replacement time. That's just so you're aware. If it is 90k actual miles, the pump and injectors very well could still be original.
If you do buy the truck, I would HIGHLY recommend installing a pyrometer if the truck doesn't already have one. If it does, the probe probably isn't installed in the "correct", most accurate location. The most accurate location for the probe is within 8" of the cylinder head. Right before the turbo, like these kits had them, usually reads about 100* cool. After the turbo will read about 300* cool. That's just more information for you right away. These are really reliable engines. Their biggest issues are usually due to lack of maintenance from previous owners. Most people seem to want to neglect an old truck rather than actually maintain it. They'd rather spend money on new truck payments than to spend money on upkeep for their old trucks.

 

[Sportsrm125]

Thanks for the reply. It does have a boost gauge and EGT gauge but I’ll look for where. I do know EGT should be in the manifold close to the head.

I’ve read swapping the glow plugs and controller to a 7.3 style is popular and sounds easy enough but I’ll definitely give the cold start a try if possible.

Good to know about the injectors and pump lifespans. Are those fairly easily sourced parts? They look very easy to physically access to replace.

I know the autos in most early diesels aren’t great and if it does end up going bad I’d likely swap in a wide ratio ZF5.

I’m not sure when the turbo kit was added but it looks to have been on for a while. I’ll definitely check the turbo. Do they frequently need rebuilding or is that solely a result of poor maintenance. I know these don’t make a lot of boost so I’d expect they last long with appropriate oil changes

 

[IDIBRONCO]

I’ve read swapping the glow plugs and controller to a 7.3 style is popular and sounds easy enough but I’ll definitely give the cold start a try if possible.

The 1987s had a 6.9, but also had the 7.3 style glow plug system.

Good to know about the injectors and pump lifespans. Are those fairly easily sourced parts? They look very easy to physically access to replace.

They are fairly easy to replace. They're just not cheap. There's only three widely known places for quality replacements though. R & D IDI performance, Moose Diesel, and Classic Diesel Designs in no particular order. I'd order from any of the three. Some people say that they do have good luck with smaller, local rebuilders, but I can't confirm them. When you do replace the pump, just be sure to not unbolt the housing that it's attached to. That can and probably will throw off the gear timing.

Do they frequently need rebuilding or is that solely a result of poor maintenance.

I think that, in general, no. Not frequently. Owner use is more likely the cause of premature wear. Poor maintenance, shutting the engine off while the turbo's still hot, things like that will prematurely wear out a turbo.

 

[DirtyWood]

A quality set of injectors and a good IP can make all the difference in the world as to whether or not you like your truck. I recently purchased from R&D IDI and am very satisfied--$850 for IP after core deposit refunded, $420 for injectors.
The only thing about a 6.9 that puts me off a bit is the weaker factory head bolt compared to a 7.3, but keep the boost in check and you should be fine.

 

[Sportsrm125]

The 1987s had a 6.9, but also had the 7.3 style glow plug system.

They are fairly easy to replace. They're just not cheap. There's only three widely known places for quality replacements though. R & D IDI performance, Moose Diesel, and Classic Diesel Designs in no particular order. I'd order from any of the three. Some people say that they do have good luck with smaller, local rebuilders, but I can't confirm them. When you do replace the pump, just be sure to not unbolt the housing that it's attached to. That can and probably will throw off the gear timing.

I think that, in general, no. Not frequently. Owner use is more likely the cause of premature wear. Poor maintenance, shutting the engine off while the turbo's still hot, things like that will prematurely wear out a turbo.

Good to know it already would have the better glow plug set up.

And if/when I’d need injectors and pump I’ll give those companies a look. I’ve seen a few videos on replacing the pump which looks fairly straightforward. Would there be any benefit in getting a fuel system that flows a little more? I’m not looking to increase power beyond what the ATS system can do but if I’m replacing parts and can reliably and effectively upgrade them I will.

I’m glad the turbo is reliable. I know those aren’t cheap either

 

[Sportsrm125]

A quality set of injectors and a good IP can make all the difference in the world as to whether or not you like your truck. I recently purchased from R&D IDI and am very satisfied--$850 for IP after core deposit refunded, $420 for injectors.
The only thing about a 6.9 that puts me off a bit is the weaker factory head bolt compared to a 7.3, but keep the boost in check and you should be fine.

Sounds good. If I do something like that I’d probably throw ARP studs at it just for peace of mind. I’m not looking to increase boost but if a better pump and injectors can maximize what the ATS turbo can do then I’ll do that

 

[DirtyWood]

If you choose studs then definitely pull the engine. I've heard it's possible to do it in-frame but after just removing both cylinder heads in-frame I now understand why so many people post that they'll never do it in-frame again.

 

[Jim993]

With the engine warmed up and running, check for blow by at the oil filler with the cap off. Some mechanics put a rubber glove over the filler with the cap off, engine running to check this.

Oil in the coolant at the radiator is a corrosion warning and a no sale.

Wise diesel owners routinely check coolant condition for PH and freeze protection. Diesels are prone to lowering PH in coolant and if left untreated can result in corrosion of the oil cooler, outside cylinder walls and other crucial engine parts exposed to coolant.

Amazon, $36:

WIX 24058 is a good supplemental coolant additive to correct PH, looking for 8- 8.5.


Amazon, $16:

Phoenix Systems 8006-B Double-Ended Brake Fluid + Coolant Test Strips (15 foil wrapped test strips), 1 Pack​

My truck has 272,000 miles but only 49,000 on the "new" engine.

 

[IDIBRONCO]

The only thing about a 6.9 that puts me off a bit is the weaker factory head bolt compared to a 7.3, but keep the boost in check and you should be fine.

Depending on the turbo, head bolts might be fine. In stock form, only the ATS 093 puts out more than 10 PSI from what I remember. It would be wise to at least break them loose and retorque them.

Would there be any benefit in getting a fuel system that flows a little more? I’m not looking to increase power beyond what the ATS system can do

Honestly, I don't think there's any advantage. What I would recommend is calling the suppliers and asking them what they think. Justin at R&D is a one man show so he can be hard to get ahold of sometimes. I've never talked to him, but going by what I've seen, he's good to talk to.

If you choose studs then definitely pull the engine. I've heard it's possible to do it in-frame but after just removing both cylinder heads in-frame I now understand why so many people post that they'll never do it in-frame again.

Not only this, but I want to add to this a little bit more. To install studs in frame, you'll have to remove the HVAC box for the passenger's side. I remember that the C6 shifting linkages on the steering column will keep one or two head bolts from coming out. That means that you'll also have to install some of the studs at the same time as the head on the driver's side. I'll second AND third what DirtyWood said about pulling the engine out to install head studs. It's not the most pleasant project when the engine's on a stand and there's absolutely no way that I'd ever try it with the engine still in the truck.

I’m glad the turbo is reliable. I know those aren’t cheap either

They are rebuildable though. Actually, ATS kits aren't available new anymore so it does require a rebuild or replacement turbo system.

 

[Sportsrm125]

If you choose studs then definitely pull the engine. I've heard it's possible to do it in-frame but after just removing both cylinder heads in-frame I now understand why so many people post that they'll never do it in-frame again.

I didn’t know access to them would be so tight. If it’s that big of a job I wouldn’t tackle that since it’d be solely preventative and not completely necessary

 

[KansasIDI]

Depending on the turbo, head bolts might be fine. In stock form, only the ATS 093 puts out more than 10 PSI from what I remember. It would be wise to at least break them loose and retorque them.

I concur.

Honestly, I don't think there's any advantage. What I would recommend is calling the suppliers and asking them what they think. Justin at R&D is a one man show so he can be hard to get ahold of sometimes. I've never talked to him, but going by what I've seen, he's good to talk to.

Definitely give Justin a call, especially if you intend to buy his pump and injectors. I was on the phone with him earlier today, sounds like the Stage one injectors sold out yesterday, but if all goes well, sounds like he’ll make another batch soon.

Not only this, but I want to add to this a little bit more. To install studs in frame, you'll have to remove the HVAC box for the passenger's side. I remember that the C6 shifting linkages on the steering column will keep one or two head bolts from coming out. That means that you'll also have to install some of the studs at the same time as the head on the driver's side. I'll second AND third what DirtyWood said about pulling the engine out to install head studs. It's not the most pleasant project when the engine's on a stand and there's absolutely no way that I'd ever try it with the engine still in the truck.

Yo, just pull the cab if you can. Not an option for everybody, but I’ve found that I kinda like doing major work on these trucks that way. A personal preference, just figured I’d throw it out there. Food for thought sort of thing.

They are rebuildable though. Actually, ATS kits aren't available new anymore so it does require a rebuild or replacement turbo system.

Yes.

@IDIoit will sell you an up pipe that has a V band and a bellow if you give him a decent *** of Bennies.

Justin (R&D) makes a 3” V band downpipe and also what he calls a stage one drop in turbo for the ATS 093 kits. This summer he came out with another version of it, sort of a stage two I guess. I have the stage one on my 91, it goes whoosh in ways that make me very happy.

Hypermax makes an intercooler kit that is a complete pain to install and is absolutely worth it once installed.

I recommend these things for pushing the ATS system.

 

[Nero]

I gotta get that guy on the line, I need a HPNA pump built for my dad's idi... And he didnt reply to my email from a few weeks ago.

 

[KansasIDI]

Oh I guess w a d is a bad word

The puter bot censor thingy is a dip w a d

 

[IDIBRONCO]

@IDIoit will sell you an up pipe that has a V band and a bellow if you give him a decent *** of Bennies.

I believe that these are only for the 093/Factory Turbo.