85 6.9 IDI trouble turning over

[Scraptor]

Hey guys, hopefully I'm posting this in the right place (feel free to correct me if not, I'll repost it elsewhere). Anyways I have had this truck for a little while and have done a few cosmetic projects as well as replaced a few more meaningful components (I replaced the old batteries with 900 cca Die Hards, put in a new alternator, and had the fuel pump replaced). When I first purchased it the truck started up pretty okay, but I had to go help a family member move and left it sitting for about a month and since then it's been having trouble starting. When it does start it takes anywhere from 3-15 seconds of labored cranking to turn over and the last two days in particular have been quite bad which is why I replaced the old batteries in hopes that maybe they just weren't holding a charge as they were old and from a brand that I can't find anywhere online (intercontinental? and when I searched the model number on the batteries nothing came up, they were also pretty old cause when I tried to wipe the dust off them the letters/numbers on the stickers just brushed right off with it). I also thought it was the batteries because it left me stranded twice within 6 hours after I turned it off and it started up again whenever I got a jump from roadside assistance. I am willing to learn, but not the most mechanically experienced (especially with diesels, as this is my first time owning one) so I really am not so sure what the issue might be at this point. I'd greatly appreciate any insight that you guys have to offer, I'm probably going to take it in to a shop at some point today unless I can get it starting reliably because it's my only source of transportation. Thanks again!

[ArdWrknTrk]

Hi Ron!

You mention labored starting even with new batteries.

First are you sure the glowplugs are working?

I hear that the relays that control them are often suspect.

***Caveat, I am not an IDI guy, so more knowledgeable folks may have better answers***

Also check that the ground cable has a clean tight connection to the engine block.

When you try to get it to turn over look (or feel) for hot cables or a little puff of smoke.

You can trigger the starter by jumping the small S terminal to the battery+ connection on the starter relay.

Hot cables can be a sign of internal corrosion.

A non-contact IR thermometer can be a great help here.

 

[ArdWrknTrk]

Hmmm, I see you have no problem when you get a jump.

Do you have a voltmeter?

Can you check the 'at rest' voltage of your batteries (1 hour after shutdown)

What the voltage is while you're turning the truck over, and what the voltage is with the engine running at about 2,000 rpm?

[Scraptor]

Hmmm, I see you have no problem when you get a jump.

Do you have a voltmeter?

Can you check the 'at rest' voltage of your batteries (1 hour after shutdown)

What the voltage is while you're turning the truck over, and what the voltage is with the engine running at about 2,000 rpm?

Hey thanks for the reply, you seem to know more about my truck than I do so I appreciate the suggestions. I don't have a voltmeter unfortunately, nobody else in my immediate family is really into working on their cars/trucks and I'm trying to get into it so I'm building a collection of tools and gadgets from the ground up (on a younger "gentleman's" budget). I'll ask around and see if I can get one to borrow though. Are there any diagrams for the glow plug relay and/or ignition related wires floating around? The previous owner ran a diesel shop and I get the feeling that not exactly all the wiring is the same as an original example so it'd be nice to see what is stock and what's not. The glow plug light in the cab comes on and turns off as it did when I got the truck, though I am not certain of whether or not that is any evidence that the relay is functioning correctly. Also, when I put in the new batteries the truck turned over faster than it had in a while, turned over okay the second time I turned it on, then was right back to not starting on the third attempt.

[ArdWrknTrk]

Hey thanks for the reply, you seem to know more about my truck than I do so I appreciate the suggestions. I don't have a voltmeter unfortunately, nobody else in my immediate family is really into working on their cars/trucks and I'm trying to get into it so I'm building a collection of tools and gadgets from the ground up (on a younger "gentleman's" budget). I'll ask around and see if I can get one to borrow though. Are there any diagrams for the glow plug relay and/or ignition related wires floating around? The previous owner ran a diesel shop and I get the feeling that not exactly all the wiring is the same as an original example so it'd be nice to see what is stock and what's not. The glow plug light in the cab comes on and turns off as it did when I got the truck, though I am not certain of whether or not that is any evidence that the relay is functioning correctly. Also, when I put in the new batteries the truck turned over faster than it had in a while, turned over okay the second time I turned it on, then was right back to not starting on the third attempt.

Glow plug and start diagrams here (along with troubleshooting)

http://www.garysgaragemahal.com/start--glow-plug-controlrun-diesel.html

You can find the entire 1985 EVTM at the top of any page under Documentation/Electrical/EVTM's/1985

[Gary Lewis]

Hi Ron!

You mention labored starting even with new batteries.

First are you sure the glowplugs are working?

I hear that the relays that control them are often suspect.

***Caveat, I am not an IDI guy, so more knowledgeable folks may have better answers***

Also check that the ground cable has a clean tight connection to the engine block.

When you try to get it to turn over look (or feel) for hot cables or a little puff of smoke.

You can trigger the starter by jumping the small S terminal to the battery+ connection on the starter relay.

Hot cables can be a sign of internal corrosion.

A non-contact IR thermometer can be a great help here.

Ron - You've posted in the right place. Good job.

And, like Jim, I'm no diesel guru. I've never owned one nor even worked on one in reality. But I think Jim is onto something with the suggestion about the cables.

One way to test the cables is via the voltage drop method, as described on the page at Documentation/Electrical/Voltage Drop Testing. But for a quick check, put your DVM on the 20 volt scale and put the positive lead on the battery's positive post, not the cable terminal but the post. And run a jumper down from the negative lead to the starter's hot terminal. Have someone crank it over and watch the DVM. With good cables you shouldn't see much voltage drop at all. But if you do then you have a problem.

Similarly, put the DVM's negative terminal on the battery's negative post and the positive lead on a clean spot on the engine's block. When you crank it there shouldn't be much drop, but if there is you have a ground cable problem.

EDIT: I missed your post about not having a voltmeter. But you may need to get one. Simple ones are very inexpensive and can help significantly.

[Gary Lewis]

... Also, when I put in the new batteries the truck turned over faster than it had in a while, turned over okay the second time I turned it on, then was right back to not starting on the third attempt.

That may indicate that your charging system isn't working. If the new batteries were freshly charged and it turned over faster initially, then just ok the second time, and now is slow that suggests that the batteries are not getting charged.

Again, you need a volt meter. Many of the local auto parts stores carry inexpensive ones that will suffice.

[ArdWrknTrk]

Hey thanks for the reply, you seem to know more about my truck than I do so I appreciate the suggestions. I don't have a voltmeter unfortunately, nobody else in my immediate family is really into working on their cars/trucks and I'm trying to get into it so I'm building a collection of tools and gadgets from the ground up (on a younger "gentleman's" budget). I'll ask around and see if I can get one to borrow though. Are there any diagrams for the glow plug relay and/or ignition related wires floating around? The previous owner ran a diesel shop and I get the feeling that not exactly all the wiring is the same as an original example so it'd be nice to see what is stock and what's not. The glow plug light in the cab comes on and turns off as it did when I got the truck, though I am not certain of whether or not that is any evidence that the relay is functioning correctly. Also, when I put in the new batteries the truck turned over faster than it had in a while, turned over okay the second time I turned it on, then was right back to not starting on the third attempt.

Your description of it turning over quickly on fresh batteries, slower the second time, and sluggish the third makes me think the batteries are not being charged (or not getting a chance to charge)

An inexpensive voltmeter would 'prove' the alternator is indeed charging the batteries.

But obviously a later model alternator would be a better alternative at the low rpms most diesels see.

I think your best tool purchase at this point is a battery charger.

They used to give away voltmeters at Horrid Fate, and while they were flimsy and not too accurate they would give you a good indication of something like charge voltage.

You don't need some whiz-bang digital mapping, auto-ranging, true RMS meter with a thermocouple.

You just need something that can read volts and ohms for most diagnostic work.

[Scraptor]

... Also, when I put in the new batteries the truck turned over faster than it had in a while, turned over okay the second time I turned it on, then was right back to not starting on the third attempt.

That may indicate that your charging system isn't working. If the new batteries were freshly charged and it turned over faster initially, then just ok the second time, and now is slow that suggests that the batteries are not getting charged.

Again, you need a volt meter. Many of the local auto parts stores carry inexpensive ones that will suffice.

Alright, I'll see about getting a voltmeter. Also, I'm not certain but I think the ground on my truck isn't on the engine block. It looks like it's bolted to the top of the bar that the headlight assemblies are mounted on and the wire itself looks pretty rough at the connection to the negative cable and grounding point. I also thought that there might be an issue with charging, but I replaced the alternator and have had no issues with it losing power while running since before I replaced the alternator so I get the feeling that it's more of a wiring issue this time around. Unless it could be some other component related to charging the battery.

[Scraptor]

Your description of it turning over quickly on fresh batteries, slower the second time, and sluggish the third makes me think the batteries are not being charged (or not getting a chance to charge)

An inexpensive voltmeter would 'prove' the alternator is indeed charging the batteries.

But obviously a later model alternator would be a better alternative at the low rpms most diesels see.

I think your best tool purchase at this point is a battery charger.

They used to give away voltmeters at Horrid Fate, and while they were flimsy and not too accurate they would give you a good indication of something like charge voltage.

You don't need some whiz-bang digital mapping, auto-ranging, true RMS meter with a thermocouple.

You just need something that can read volts and ohms for most diagnostic work.

I'm even less confident with electricity than I am with mechanical work, I'm kind of at the mercy of my family unfortunately though and I have to respect their wishes so I might have to be taking it to a shop since I don't think they'll be willing to give me a ride to an auto parts/hardware store (which I don't have any within a few hours of walking here). It could be the alternator, but the strange thing is that if I leave it and come back it cranks harder/faster than when I left it before so it's not like consistently getting lower each time. If I try to start it multiple times consecutively I do get the effect where it's weaker each time though.