1987 international with 6.9 diesel. Thoughts?

aye_oka · 07-24-2019, 07:48 PM

Hey all! Currently looking at a 1987 international shorty. Owner says it was owned by a school district, and then church....it has a 6.9 Diesel, which from the forums on here, I think appears to be a pretty good engine. It's an Allison 4speed Automatic transmission. 149k miles. Seems all around pretty good. My only slight worry, is that there are a few rust spots on the exterior, so the chassis might be rusted as well. I'm asking for pictures of it now, but in the meantime, general thoughts on this engine/transmission combo? Thanks!

PNW_Steve · 07-24-2019, 08:15 PM

I have had good experiences with the 6.9and 7.3 idi.

They are simple, reliable and SLOW.

They are known for glow plug issues but that is fairly simple to fix.

The only reason that I would not buy one is that they are undrepowered compared to other options.

aye_oka · 07-24-2019, 08:38 PM

Welp...it just got SOLD! haha that was fast. Thanks for the input!

Johnny Mullet · 07-24-2019, 08:38 PM

Good, solid engine, but it won't win any races. Might be ok in a shorter bus chassis. You might want to test drive before buying.

ToniB34 · 02-17-2020, 06:46 PM

Quote:

Originally Posted by aye_oka

Hey all! Currently looking at a 1987 international shorty. Owner says it was owned by a school district, and then church....it has a 6.9 Diesel, which from the forums on here, I think appears to be a pretty good engine. It's an Allison 4speed Automatic transmission. 149k miles. Seems all around pretty good. My only slight worry, is that there are a few rust spots on the exterior, so the chassis might be rusted as well. I'm asking for pictures of it now, but in the meantime, general thoughts on this engine/transmission combo? Thanks!

I bought a 1987 International Diesel over the weekend!! Drove it about 400 miles and over a 4,000 ft elevation. Slow and steady

bluegoose · 03-03-2021, 12:17 PM

Purchased a 1987 International 6.9 Diesel S-1753 with ~70k miles on it in November. Had some trouble starting it, got the glow plug relay and controller replaced and new batteries on Tuesday. Was running and drove it home Tuesday at 5pm. Tried to start it Wednesday at 5pm, wouldn't start. Will turn over and smoke comes out. Was about 45 degrees out.

Has anyone had this issue? It was originally an air force bus. Does anyone know what other issues we could be having? For anyone with experience with this bus, will it only start when its warm out? Trying to understand if this was a money hole. Not sure how much more money we want to spend if it wont ever start. Oil has been changed and radiator been flushed.

Located a hour from Charlotte, NC if anyone near can help in-person!!!

Danjo · 03-03-2021, 12:52 PM

Do you smell fuel when you crank?

bluegoose · 03-03-2021, 01:33 PM

Not necessarily smell it in the cab, but we do get smoke out the tailpipe.

Booyah45828 · 03-03-2021, 01:37 PM

Test the glow plugs and system.

Without the plugs working, an idi won't start unless it's hot out or the engine is warm. Who changed the relay and controller for you? What brand of components did they use?

Do you have a test light? Are you willing to do the work yourself?

bluegoose · 03-03-2021, 01:52 PM

We had a diesel truck mechanic do the glow plug work for us Tuesday. When we called him today, he said our glow plugs are good. We do have a test light and can go out and check in a couple hours. I will also get the brand for you in a couple hours. Definitely willing to do the work ourselves.

Just from the sound of that though, it seems to me like our glow plugs may not be the problem? I am the unknowledgeable/unexperienced one though, so I truly have no idea.

Ill let you know the answers to your questions in a couple hours!
Thank you so much for willing to help!

Booyah45828 · 03-03-2021, 02:01 PM

Does the wait to start light on the dash illuminate when you turn the key on?

If No: the bulb is bad, there is no power to the cont or controller is bad

If Yes: Use a test light to see if you have power to the glow plug relay, and power out of the relay to the plugs when you initially key on.

Follow this video to see how to test the relay.

https://www.youtube.com/watch?v=ZpkBFEVaotw&t=48s

bluegoose · 03-03-2021, 02:16 PM

The wait to start light does come on. Then it goes off. In the past we would crank once the light went off. But after we had the relay/controller replaced, we were told by the mechanic to wait until the clicking sound stops before we crank (clicking sound from passenger side dashboard area).

We will test the relay after we get off work and get back to ya! Thank you thank you!!!

bluegoose · 03-03-2021, 05:00 PM

The power to the glow plug relay was coming in at 12.5. The power going out was fluctuating ~9.5-10.2.

John 50 · 03-03-2021, 07:00 PM

If the injector return lines got bumped they crack easily when old and can suck air into the system over night or longer but not leak fuel very much. Drove me nuts on a 7.3.

CHEESE_WAGON · 03-03-2021, 07:15 PM

Sounds like partially glow plug controller issue, but the smoke out of the tailpipe is unburned fuel. I like John's suggestion of air in the system, but not sure with the smoke, air in the system would yield insufficient fuel. You might try a shot of WD-40 (NOT ETHER) into the intake, it can help clear a cranky diesel. But I would wait a day, if the cylinders are loaded with diesel (possibly), you might want to wait for it to leak down and then change the oil later once you've gotten it where you can do so. You should never have raw liquid loading up a cylinder on any diesel. And it sounds like it's flooded with fuel (yes, this CAN happen).

Booyah45828 · 03-03-2021, 07:28 PM

You have 12.5 on one and 10.2 on the other lug of the relay? They should be close to even, but with power there, it sounds like your controller and relay are functioning. At least enough for it to start. Now we'll test the plugs.

Pop all of the glow plug connectors off, clip the ground end of the test light to a b+ source, and with the key off, touch the pointy end of the test light to the glow plug terminal of each plug. If it lights, the plug is good, if it doesn't, the plug has failed.

https://www.youtube.com/watch?v=xIUN4oBZcho

Air intrusion can be a problem as well, but if you have fuel vapor(smoke) coming out of the exhaust while cranking, it shows that fuel is being injected and isn't a problem.

bluegoose · 03-04-2021, 09:22 AM

Thank you everyone for your suggestions!!

We will check the injector return lines this afternoon.

We will try the WD-40 in a couple days.

Related to the fuel injector/fuel pump, when we first purchased the bus from our cousin, we initially couldn't get it started and he was insistent on refilling the fuel filter as it would empty out a little every attempt at starting it. He did this back and forth for about 10 times until he got it started. We replaced the fuel filter. I read online that this could be an indicator of an issue with the fuel pump and that we could replace it fairly easily? Or something related to pressure/air in the injector lines, as you mentioned.

We will check the glow plugs this afternoon as well. We checked the relay output twice and got 10.2 both times, so unsure of that imbalance.

Hopefully one step closer to getting it running, thank you everyone!!

Booyah45828 · 03-04-2021, 10:32 AM

If you're sucking air in the fuel system, or leaking fuel back to the tank when turned off, air will rise to the top, the engine won't start, and the fuel filters will have air in them when removed. This phenomenon is known as air intrusion.

If you're seeing white smoke out of the exhaust when cranking, I wouldn't suspect air intrusion to be your issue, because the presence of the smoke is showing that fuel is being injected. If air intrusion was the culprit, little to no smoke would be present while cranking.

bluegoose · 03-05-2021, 12:34 PM

Ok got it. We'll be trying all those things today/this weekend and fingers crossed we can nail down the culprit. Thank you!!!

bluegoose · 03-09-2021, 02:46 PM

Well all. Saturday at noon we gave it 3 good cranks (held the cranks a full 10-15 seconds), and on the 3rd crank it started up. It was about 65 degrees and direct sun, so might have something to do with that. Lots of smoke. This makes me think either A. we werent holding it long enough the times we tried B. It is a glow plug issue because theyre known to work when its warm enough, even if they have issues.

We drove it around/ran it for about 45 minutes. It started again Sunday as well, 60 degrees and sunny.

We may have not figured out the actual issue, but we were jumping up and down that it finally started and we could finally progress on the build.

Thank you everyone for your help. We will be sure to do a full glow plug inspection before we actually take it anywhere.

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