M1008 quick starting causes starter to grind - is this normal?

[KallyLC]

I've owned my M1008 for a couple of months now, it's all good, but I've been wondering about the manner in which it starts.

Every time I go to start it, it after waiting for the glow plug light to go out, it fires up pretty much instantly. It fires up so quickly in fact that it can be hard to get off the key fast enough to avoid a little grinding from the starter. Usually you can just bump the key quickly and it'll fire immediately with no noise, but other times you bump it for just a fraction of a second too long and it grinds, or you try to pre-empt it and get off the key before it grinds, but end up not letting it crank for long enough. It's apparently been doing it for a while as the previous owner mentioned something about that causing damage to the flywheel in the long term, so I'd like to know if this is normal or if it's an issue I need to fix.

I don't think the starter is sticking or anything, as it will only grind when you're on the key, just as mentioned it starts so fast that it's hard to get off the key fast enough to avoid it sometimes.

I checked out a few videos to try to get an idea of what other people's trucks are like on startup, but all I can find seem to be 'cold start' videos starting in very low temperatures with fairly long cranking times, so it's hard to get a feel for what's normal at the fairly mild British autumn/winter temperatures I've been driving in. For reference, It's been around 30-50F here during the time since i bought it.

 

[Barrman]

How does your key turning action feel? Sometimes they get gummed up and hold the starter on just an instant after you let go. The fast starting is something your muscle memory gets used to.

 

[KallyLC]

It feels pretty free moving, not obviously sticking or anything. It's only engaging the starter when you have the key forward so it seems to me like it's just a matter of timing on releasing the key.

Is the fast start normal, then? It did surprise me that a 35 year old diesel starts as quickly as it does.

 

[Squibbly]

What kind of clearance do you have between the bendix and flexplate teeth? There is usually a hole that you can fit an Allen wrench into to pull the gear forward for checking clearance.

Are your starter bolts tight?

When I was installing my flexplate and torque converter I’d take the inspection cover off, and film what was happening with my phone. You may want to do that until you narrow it down.


Sent from my iPhone using Tapatalk

 

[cucvrus]

Sounds to me like 1 thin shim. But I had this issue back in the dark ages and I did find this post that was helpful. Not the same post but basically the same information. Shimming a starter (thedieselpageforums.com)
Make sure you have a good starter and the bendix is operating as designed. I had a local starter rebuilder that was just packing grease in old parts and replacing the needed parts and passing them off as rebuilt. I have since learned the hard way that there is much more to rebuilding alternators and starters then just taking them apart and reassembling them with new parts. I have a new shop and they have some very pricey equipment and my rebuilt parts have outlasted the vehicles I installed them on. I have been known to be hard on starters and alternators on CUCV's. Good Luck. And let's do it right the first time and drive on. Happy Holidays.

 

[Squibbly]

Sounds to me like 1 thin shim. But I had this issue back in the dark ages and I did find this post that was helpful. Not the same post but basically the same information. Shimming a starter (thedieselpageforums.com)
Make sure you have a good starter and the bendix is operating as designed. I had a local starter rebuilder that was just packing grease in old parts and replacing the needed parts and passing them off as rebuilt. I have since learned the hard way that there is much more to rebuilding alternators and starters then just taking them apart and reassembling them with new parts. I have a new shop and they have some very pricey equipment and my rebuilt parts have outlasted the vehicles I installed them on. I have been known to be hard on starters and alternators on CUCV's. View attachment 853679 View attachment 853680View attachment 853676 View attachment 853677 View attachment 853678 View attachment 853681 Good Luck. And let's do it right the first time and drive on. Happy Holidays.

Good God. Why don't you have a little starter with that dirt.

 

[cucvrus]

That starter was only on there for 1 weekend at Trucks Gone Wild 2017 Yankee Lake Ohio. I drove less then 20 miles and wore out all 4 wheel brakes.

 

[nyoffroad]

It feels pretty free moving, not obviously sticking or anything. It's only engaging the starter when you have the key forward so it seems to me like it's just a matter of timing on releasing the key.

Is the fast start normal, then? It did surprise me that a 35 year old diesel starts as quickly as it does.

My old truck (now gone) would start really quick, many people commented on it. If yours is grinding as or after the engine starts, I'd suspect the overrunning clutch on the starter gear drive assembly. It's easy enough to check and replace. JUST MAKE SURE YOU REPLACE WITH ONE FOR A 1984!!! THE PART CHANGED IN 85.

 

[MarcusOReallyus]

Is the fast start normal, then? It did surprise me that a 35 year old diesel starts as quickly as it does.

Quit complaining!

 

[98G]

.

Is the fast start normal, then? It did surprise me that a 35 year old diesel starts as quickly as it does.

The 6.2 in my 1986 M998 starts nearly instantly also. As in, you just hit the switch and immediately release and it's running.

Not exactly the same, but close.

The 8.3 in my M936A2 is the same. Just bump the switch and it starts, probably the first time any of the 6 pistons comes up on compression stroke, certainly less than a full revolution.

So old diesels starting instantly is well within expectations. When compression is like it should be, and the fuel doesn't lose prime or suck air, and your glowplugs are working at spec, this is to be expected.

My suspicion on your starter is that it isn't retracting like it should. But I don't have anything helpful to add. I defer to the superior wisdom and experience of @cucvrus.

 

[KallyLC]

Fair points, it's the first MV I've owned and the first diesel I've driven, so it's all new to me. The starter only seems to grind when you have the key on so I'm still thinking it's user error and not a sticking starter at this point. If it continues or gets any worse, I'll do some testing on the starter as suggested.

Absolutely not complaining about the speed at which it fires up. The M1008 starts better than any other vehicle I've driven, so it was a surprise, though not an unwelcome one.

I appreciate all the advice, thanks guys.

 

[MarcusOReallyus]

Absolutely not complaining about the speed at which it fires up.

Just ribbing ya. I hate the smileys on this new forum software. That was supposed to be a big grin, but it's really hard to tell.

 

[cucvrus]

The starter only seems to grind when you have the key on

Lets hope it is not grinding with the key off. But there is no operator error. It should not grind. It's like anything else a little grind here and a little grind there and eventually you have an expensive item that requires a lot of time and money to repair. It should NOT grind here or there it should not grind anywhere. Not in the mud. Not in a flood. It should not grind anywhere under normal use. I doubt GM built in a grind factor into only certain few CUCV's. Just saying get the issue fixed or prepare for flywheel replacement or worse broken starter bolts. Have a Great Day. It could already have issues on the ring gear /flex plate/ flywheel teeth and that is what you are hearing.

 

[ezgn]

Fair points, it's the first MV I've owned and the first diesel I've driven, so it's all new to me. The starter only seems to grind when you have the key on so I'm still thinking it's user error and not a sticking starter at this point. If it continues or gets any worse, I'll do some testing on the starter as suggested.

Absolutely not complaining about the speed at which it fires up. The M1008 starts better than any other vehicle I've driven, so it was a surprise, though not an unwelcome one.

I appreciate all the advice, thanks guys.

User error I would rule out. Otherwise everyone else would be having the same problem. You have been given some sound advise, take it and run with it and get it fixed before you do more damage than what has already been done.

 

[KallyLC]

So I did a bit more investigating regarding this, and have come up with some questions.

I tried to remove the cover to inspect the flywheel and check clearances on the starter, but I couldn't get it past the transmission cooler lines to remove it completely. They didn't want to move, and I didn't want to break them, so I just inspected the teeth of the flywheel through the gap I'd created. From what I was seeing, I thought all of my teeth were chipped, but a quick google revealed that the 'chip' I was seeing was just the ramp that they're meant to have to help the starter engage. Whatever the noise is, the flywheel appears to be just fine.

Reading the TMs, I saw a note about vehicles built prior to July 1985 having defective starter relays that would cause the starter to stick on. I'm aware that even the later relays are prone to sticking, too, but the originals apparently so much so that they put it in the TMs and noted to replace them. I don't know when in 1985 my vehicle was made, and I would've guessed a bad relay would've been replaced in the 35 years since it was built, but I suspect my issue may be the starter relay sticking on, so I thought I'd check.

There are two of them, someone left the original(?) where it's meant to be, and zip-tied a second one (which is actually connected) to a bracket. The one that's connected presumably works, but I don't know why they left the old one in if it's broken.

Both of these match the one shown in the manual.



So this is where I have questions.

If I search the part number for the starter relay, the ones that turn up are a different looking L-shaped unit, with the bracket at a 90 degree angle to the relay.



Are the relays I have the original units? I have my doubts that they'd bother to update the diagram in the TM to reflect the relay if it did change, and the fact i can't find any images of relays like mine makes me think they might be the original unit that the TM says to replace.

I've read up on the doghead relay mod, but I can't get that part over here and would need to find an equivalent alternative. I'm more likely to be able to find a replacement ACDelco or GM unit like the one pictured above.

 

[cucvrus]

The after grind is not related to the relay. I can promise you that. As far as the cooler lines you may need to get a crows foot line wrench and remove the cooler lines. You need a better look at the flywheel 360* and really inspect it. My experience has been the engine will stop at 3 places. One area is its sweet spot. I suspect that area has damage to the teeth of the flywheel/flex plate/ring gear. However, you slice it and dice it your truck has an issue. I would also get the starter rebuilt at a reputable dealer. Not just say hey it works and bench test it. Throwing a few parts in and getting it operational is not considered a rebuild in the real world. I see the work that gets done on people's vehicles. Do it correctly the first time and spend the coin. It is much less expensive in the long run. Get that cover off and do a thorough inspection and go as far as checking that the bolts are all in place and tight and you do not have a stress cracked warped flywheel. There will be signs in there that tell you this. Rusty grindings and metal dust. Use a magnet if you have any doubts. Light metal dust is normal. Very light. But I encourage you to do this job right. Good Luck. Report back on your findings. I am positive we can talk you thru any repairs and get this situation handled. Take Care and Be Safe.

 

[shepherm]

So mine just started this today too. A little backstory; I had to replace the solenoid because it was hanging when cold. After I replace it, it was all good and started normal. I then decided to change out my battery terminals, now it starts crazy fast and has a slight grind.

I already have the doghead relay mod, so I don't think that is your problem. What glowplugs do you have? 12v straight or through the resistor on the firewall?

I have 60g running straight 12v with 2-10 ga wires, so there isn't much voltage drop. I know going through the resistor supplies less voltage than what I have with the plugs on. I haven't got to check it yet, however, I believe the glowplugs are heating faster and hotter, which is causing the fast start. I'm going to remove one of my wires and see what it does, then I will test through the resistor too.

 

[cucvrus]

So mine just started this today too. A little backstory; I had to replace the solenoid because it was hanging when cold. After I replace it, it was all good and started normal. I then decided to change out my battery terminals, now it starts crazy fast and has a slight grind.

I already have the doghead relay mod, so I don't think that is your problem. What glowplugs do you have? 12v straight or through the resistor on the firewall?

I have 60g running straight 12v with 2-10 ga wires, so there isn't much voltage drop. I know going through the resistor supplies less voltage than what I have with the plugs on. I haven't got to check it yet, however, I believe the glowplugs are heating faster and hotter, which is causing the fast start. I'm going to remove one of my wires and see what it does, then I will test through the resistor too.

I don't care how fast it starts the starter will not grind. When hot I just tap the switch momentarily and they start when everything is according to Hoyle as designed and fully operational as designed. Adding hacked up relays and different glow plugs does NOT equate to starter grindage. I know grindage is not a word but it should be. No aduible grindage from the starter should occur period. Find the problem and fix it. It sure isn't the new battery cable clamps causing it. Please report back. Be Safe and Get Busy.

 

[shepherm]

I don't care how fast it starts the starter will not grind. When hot I just tap the switch momentarily and they start when everything is according to Hoyle as designed and fully operational as designed. Adding hacked up relays and different glow plugs does NOT equate to starter grindage. I know grindage is not a word but it should be. No aduible grindage from the starter should occur period. Find the problem and fix it. It sure isn't the new battery cable clamps causing it. Please report back. Be Safe and Get Busy.

Okay so clearly I didn't explain my thoughts. I don't think its the battery terminals, the relays or the glow plugs grinding, that was just back information. I think changing the terminals helped with a connection problem.

However, I believe the different glow plugs AND larger wire is causing more heat during prestart up. Thus, starting faster than needed/expected and I'm not releasing the switch fast enough. One could argue that's a user error, however I think cold start at 60F should take more than half a second. Like you said, when its hot you just tap the switch, in this case I would just tap the switch cold starting. That's why I'm going to investigate the too much preheat first, then look for a mechanical problem. This is why I ask the original poster what his glow plug set up was like. It's possible we both have too much of a good thing. Sorry KallyLC didn't mean to hijack your post.

Edit: I just went out and test started it at 22F, started fast (couple seconds maybe) and no grinding. I'll continue with my wire test next week when it warms up a bit.

 

[nyoffroad]

No such thing as "starting to fast". You could (as said) be a bit slow releasing the key OR there could be some oil built up on the Bendix and that can cause it to stick a bit.