Loose belt, hard to start?

[Jack Lope]

This is a new to me. It seems when a belt is loose, the truck doesn't want to start. Lots of cranking, then when it finally starts the belt squeaks like crazy for a bit. The first time this happened a couple months ago, I couldn't believe it was a belt. Why would the belt have anything to do with it starting? May not have power steering, may not have alternators charging the batteries, but it should still start I would think. Anyone else noticed this? At least, I'm hoping it's just the loose belt.

 

[Matt1970M35A]

What truck are you working one?

 

[Jack Lope]

This is M1008 CUCV with 6.2 Diesel.

 

[dependable]

Loose belts, alternators not charging batteries, batteries low, hard starting, seems logical to me.

 

[Adam86CUCV]

I agree, when I got mine it was one belt short and the gen 2 battery was shot and the gen 1 battery was in poor shape from having to do the starting practically on it's own...it also explained why the PO drove it to meet me, instead of going to his place...filed that under lessons learned.

Loose belts, alternators not charging batteries, batteries low, hard starting, seems logical to me.

 

[MarcusOReallyus]

These things like well-charged batteries. If your GPs are marginal, and your batteries are marginal, you can expect hard starting.

Have you done the resistor bypass? How's your GP relay?

 

[Jack Lope]

Loose belts, alternators not charging batteries, batteries low, hard starting, seems logical to me.

D'oh, now this thread is going the wrong direction. None of that is the case. The batteries are brand new. The truck has no problem cranking.... cranking good and for a long time. It's like the belt turns a fuel pump? That's what it seems like because it almost wants to start. Cranking for a while, then holding the pedal down a bit when it's almost starting gets it going perfectly, along with the screech of the belt. This same thing happened a couple months ago. Tightened the belt, and not a problem until now. I guess I'll tighten the belts again, but just can't figure out why that would matter. The GP relay is fairly new... at least, it looks like it. I also replaced all the plugs with 60G's and it's 100 degrees in summer in Texas. [edit] And belts are new... replaced about 3-4 months ago.

 

[jw4x4]

Belts have nothing to do with starting. You may have a very tiny leak in the fuel system and it's losing prime.
As for the squeaking belts at start up, it is probably the glow plugs still cycling (normal). Either tighten the belts or they may need to be replaced (always replace in pairs so that proper tension can be achieved). Another possible cure for squeaky belts is to use an abrasive (household cleanser like Comet) in the pulley grooves to provide more grip on the belts.

 

[porkysplace]

D'oh, now this thread is going the wrong direction. None of that is the case. The batteries are brand new. The truck has no problem cranking.... cranking good and for a long time. It's like the belt turns a fuel pump? That's what it seems like because it almost wants to start. Cranking for a while, then holding the pedal down a bit when it's almost starting gets it going perfectly, along with the screech of the belt. This same thing happened a couple months ago. Tightened the belt, and not a problem until now. I guess I'll tighten the belts again, but just can't figure out why that would matter. The GP relay is fairly new... at least, it looks like it. I also replaced all the plugs with 60G's and it's 100 degrees in summer in Texas. [edit] And belts are new... replaced about 3-4 months ago.

New batteries get low when alternators are not charging . The starter draws high amps and away from the rest of the system . Just because it cranks good doesn't mean it has enough power for the fuel solinoid on the IP.

 

[rsh4364]

Bad lift pump,mine did this,discovered rubber fuel line bent way to tight,as it got older it closed up more and more.Now I have elect.pump and spin on filters with pressure gauges on input and output side.Its something to look into.

 

[MarcusOReallyus]

New batteries get low when alternators are not charging . The starter draws high amps and away from the rest of the system . Just because it cranks good doesn't mean it has enough power for the fuel solinoid on the IP.

That's been my limited experience. It does'nt take the batteries being down much to put you in hard start territory.

 

[Jack Lope]

Bad lift pump,mine did this,discovered rubber fuel line bent way to tight,as it got older it closed up more and more.Now I have elect.pump and spin on filters with pressure gauges on input and output side.Its something to look into.

This sounds interesting. I like the idea of a mechanical fuel pump, though. Love the idea on the pressure gauges. Would the "lift pump" be the "fuel pump", separate from the injection pump? Just strange that the only times the belt squeaked after starting, was when the truck was having trouble starting. I can't believe that's a coincidence twice. The belts are new and have been re-tightened in the past month or so.

 

[MtkNoob]

...Just strange that the only times the belt squeaked after starting, was when the truck was having trouble starting. I can't believe that's a coincidence twice. The belts are new and have been re-tightened in the past month or so.

I'm brand new here, and don't have much of a background in auto/truck systems and repair, but reading this thread and that quote made me think that perhaps you have belts which for whatever have twice loosened over time, causing your alternators to inadequately charge your batteries, ultimately leading to the situation where you experience hard starting. At this point, NOT coincidentally, your belts are loose enough to squeak, which would only emerge upon restarting after the engine has cooled down. Chicken/Egg, Cart/Horse, etc...

I know that with my recently bought M1008, since I changed the glow plugs (only 2 were functional) and other parts of the GP system, my truck has started up MUCH more quickly, requiring only a few seconds of cranking after the GPs cycle pre-ignition. Maybe your GP system is also marginal, as others have suggested, which exacerbates your problem in terms of hard starting, especially in situations where your batteries are not FULLY charged.

 

[acesneights1]

This sounds interesting. I like the idea of a mechanical fuel pump, though. Love the idea on the pressure gauges. Would the "lift pump" be the "fuel pump", separate from the injection pump? Just strange that the only times the belt squeaked after starting, was when the truck was having trouble starting. I can't believe that's a coincidence twice. The belts are new and have been re-tightened in the past month or so.

You are looking at it backwards. You think your belts squealing is a cause of the hard starting. It's not, it's the result. When the truck is starting hard you are draining the batteries hence when it starts the alts are in full output putting more strain on a very poorly designed belt system. Fix your hard start.
Many reasons. Air leak , bad LP, bad IP, bad glows etc etc. Search hard starting and diagnose that first. Tighten the belts . They may still squeal. The pulleys could be worn or the belts glazed.

 

[Keith_J]

Voltage equates to starting speed, if the batteries are low, you have lower starting speed. In the diesel, starting speed (as in crankshaft rpm), is the heat needed to ignite diesel. Slower speeds don't heat the air as high.

you could measure voltage to confirm.

 

[MarcusOReallyus]

You are looking at it backwards. You think your belts squealing is a cause of the hard starting. It's not, it's the result. When the truck is starting hard you are draining the batteries hence when it starts the alts are in full output putting more strain on a very poorly designed belt system. Fix your hard start.

This.

 

[Recovry4x4]

You are looking at it backwards. You think your belts squealing is a cause of the hard starting. It's not, it's the result. When the truck is starting hard you are draining the batteries hence when it starts the alts are in full output putting more strain on a very poorly designed belt system. Fix your hard start.
Many reasons. Air leak , bad LP, bad IP, bad glows etc etc. Search hard starting and diagnose that first. Tighten the belts . They may still squeal. The pulleys could be worn or the belts glazed.

This.

I also concur.

 

[acesneights1]

Voltage equates to starting speed, if the batteries are low, you have lower starting speed. In the diesel, starting speed (as in crankshaft rpm), is the heat needed to ignite diesel. Slower speeds don't heat the air as high.

you could measure voltage to confirm.

This is absolutely true however in the case of the CUCv , they were upgraded to a 24v started which draws alot less amperage than the 12v civilian counterpart starter that the 6.2 was designed around. In most cases a CUCv can start fine on weaker batteries than the original 12v civilian design. I had a worn IP on mine for 2 years that was sucking air around the throttle shaft seals and It still started because of the faster 24v starter in cold weather. That is the one thing I miss whdn I converted fo 12v. That truck would spin over like mad on the coldest day.
The old Mack trucks from the 70s used to use a series parallel switch to run a 24v starter.
That said you could havs a bad starter as well.

 

[Matt1970M35A]

Bleave it or not but you alternator s do provide some current while cranking the engine. Learned this the hard way.
Check your voltage while cranking the engine over. Your batterys may not be up to 100% charge. While it shows 12 volts with no load it may drop to 8 volts under a load with rated amperage output. Simple test that may help find your problem.

 

[rsh4364]

This sounds interesting. I like the idea of a mechanical fuel pump, though. Love the idea on the pressure gauges. Would the "lift pump" be the "fuel pump", separate from the injection pump? Just strange that the only times the belt squeaked after starting, was when the truck was having trouble starting. I can't believe that's a coincidence twice. The belts are new and have been re-tightened in the past month or so.

Duel fuel pressure gauge easy,can be done with mech.pump,Do spin on fuel filter mod,use housing with 2 intake and 2 outlet ports.1 gauge in each extra port.