Gary Lewis Posted September 1, 2020 Share Posted September 1, 2020 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. An '85 will have the 1G alternator with a regulator on the passenger's fender. And if it is bad the alternator will not charge correctly. As for the grounds, here's the appropriate page from the 1985 EVTM. You can see the grounds. And below that page is the page showing where the grounds are. So you should check out your wiring to see that you have those three grounds on the batteries. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 1, 2020 Share Posted September 1, 2020 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. That suggests that something is getting hot, and the starter can certainly do that. A starter naturally gets warm when you crank the engine. But a worn out starter will start dragging internally as it gets hot, and dramatically reduce the cranking speed. Link to comment Share on other sites More sharing options...
Scraptor Posted September 1, 2020 Author Share Posted September 1, 2020 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. That suggests that something is getting hot, and the starter can certainly do that. A starter naturally gets warm when you crank the engine. But a worn out starter will start dragging internally as it gets hot, and dramatically reduce the cranking speed. That does make sense, and thanks for the diagram. I think the previous owner made some modifications, I read about the alternator upgrades in the documentation section and the 1G has an internal fan whereas the 2G has an external fan. The original alternator mine came with had an external fan, and the replacement did as well (since that was what I had to work with wiring wise). Given that I lack the resources and that I'm not sure how much I can trust the diagram regarding what is currently installed in my truck; I'm probably going to have somebody more qualified look at it. I really appreciate all the information though and I'm sorry if this ended up being somewhat futile! I'll have to dedicate some time to getting more familiar with what I have going on under the hood once I get it fixed. Thanks again though guys Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1, 2020 Share Posted September 1, 2020 An '85 will have the 1G alternator with a regulator on the passenger's fender. And if it is bad the alternator will not charge correctly. As for the grounds, here's the appropriate page from the 1985 EVTM. You can see the grounds. And below that page is the page showing where the grounds are. So you should check out your wiring to see that you have those three grounds on the batteries. It's interesting that the starter motor is shown connected directly to the batteries by a '00' cable. I wasn't aware that diesels of this vintage were using this kind of starter. And what the heck is with the starter relay diagram? No trigger or output shown... Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1, 2020 Share Posted September 1, 2020 That does make sense, and thanks for the diagram. I think the previous owner made some modifications, I read about the alternator upgrades in the documentation section and the 1G has an internal fan whereas the 2G has an external fan. The original alternator mine came with had an external fan, and the replacement did as well (since that was what I had to work with wiring wise). Given that I lack the resources and that I'm not sure how much I can trust the diagram regarding what is currently installed in my truck; I'm probably going to have somebody more qualified look at it. I really appreciate all the information though and I'm sorry if this ended up being somewhat futile! I'll have to dedicate some time to getting more familiar with what I have going on under the hood once I get it fixed. Thanks again though guys 1G and 2G both had external fans. The 1991 3G's started using twin internal fans. Good luck Ron! You're always welcome to ask questions if there's anything you have trouble understanding. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 1, 2020 Share Posted September 1, 2020 It's interesting that the starter motor is shown connected directly to the batteries by a '00' cable. I wasn't aware that diesels of this vintage were using this kind of starter. And what the heck is with the starter relay diagram? No trigger or output shown... Jim - I hadn't noticed that it shows the starter motor directly connected, much less with a 00 cable. So, PMGR starter? Or at least one with its own relay/solenoid? And the starter relay drawing doesn't give much info. But I'd bet it is supposed to be just like the gas-powered vehicles in that respect, save for the trigger wire that must have gone to the starter. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1, 2020 Share Posted September 1, 2020 Jim - I hadn't noticed that it shows the starter motor directly connected, much less with a 00 cable. So, PMGR starter? Or at least one with its own relay/solenoid? And the starter relay drawing doesn't give much info. But I'd bet it is supposed to be just like the gas-powered vehicles in that respect, save for the trigger wire that must have gone to the starter. Well! Look at me. Captain Obvious, again! I'm on my phone, so I'm not inclined to go look at pg 41. But evidently diesel starters of this era are far different than gas engines. I'm not sure pmgr starters were a thing back then (except for Tilton) Could be a normal moving pole starter with solenoid onboard, like GM. IDK Link to comment Share on other sites More sharing options...
Scraptor Posted September 1, 2020 Author Share Posted September 1, 2020 1G and 2G both had external fans. The 1991 3G's started using twin internal fans. Good luck Ron! You're always welcome to ask questions if there's anything you have trouble understanding. It's also rated for 70 Amps as apposed to the 40ish I thought the 1G was marked for. You guys really do know a lot though, this forum is a blessing for somebody just getting their feet wet like myself. Hopefully my next post will be a more happy one Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted September 1, 2020 Share Posted September 1, 2020 It's also rated for 70 Amps as apposed to the 40ish I thought the 1G was marked for. You guys really do know a lot though, this forum is a blessing for somebody just getting their feet wet like myself. Hopefully my next post will be a more happy one 70 was a heavy duty option, and standard on diesels, because of the two batteries. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 1, 2020 Share Posted September 1, 2020 Well! Look at me. Captain Obvious, again! I'm on my phone, so I'm not inclined to go look at pg 41. But evidently diesel starters of this era are far different than gas engines. I'm not sure pmgr starters were a thing back then (except for Tilton) Could be a normal moving pole starter with solenoid onboard, like GM. IDK I think you mean Page 48? That certainly shows it. I'd never looked at that before. But they still ran a #8 to trigger the starter, so that solenoid is pretty serious and not like the PMGR's. Link to comment Share on other sites More sharing options...
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