Tranny, starter, or something else?

I've got a question and I thought I'd get some suggestions before I start tearing things apart. The other day I went out to my 84 M1008 and noticed a bolt on the ground, it was sheared off through the threads. It came out of the the starter (looks like one of two that hold it on), which I though was rather strange. The shear and spot where the washer had been was clean metal, so it was a recent break. Looking at it, everything seemed secure for the time being and since I had to go haul some stuff with the truck I figured I'd deal with the broken bolt later. It started and drove normally. Went about 50 miles and parked. Started up a few hours later and drove about 20 miles when the truck started making a loud whining noise and really slowing down. I pulled over and can't remember if I shut the engine off or it stalled on it's own. When I tried to start it again, it tried but it would not turn over, felt like trying to start a manual in high gear, but without the lurching forward.

I'm a bit perplexed, I would think there is a problem with the transmission, but I have limited experience working on automatic vehicles, could that prevent the vehicle from cranking freely? The shifter moves fine through PRN12D, the truck rolls when in neutral and holds in park. I understand the TH400 is a pretty bulletproof and simple transmission. The recently sheared-off starter bolt sure is strange, but I can't think of any starter-related problem that would cause the truck to have any problem after starting and hitting the road. Maybe a starter that didn't fully disengage? Any ideas to point me in the right direction??
Thanks!

Is the starter still in the proper position being held on by one bolt? Next time a starter bolt breaks that makes your truck NMC. (not mission capable)

The starter bolt and the whine are not directly related. The starter bolt should be replaced ASAP. And use new bolts if you are not sure of the age and stress that has been applied to the starter bolts. Torque the starter bolts or just make sure they are tight. Not gorilla tight. A shorter 3/8" ratchet and tight will get you in the correct range. No impact and hammering on them to get them tight. Not sure get the torque wrench out. They are NOT torque to yield bolts. Also keep in mind the bolts are METRIC. They are M10 X 1.5 I know for a fact that a 3/8" 16 will fit up in there and get tight. It will NOT remain tight. I still recommend a little snugging / torqueing at oil changes or as a monthly routine. Never hurts to give every piece of equipment a good all over look see on a regular basis. I do it on everything. I lay under my brand new truck and look at everything as much as I do an old tractor or pick up truck. I seldom find things but many times I catch things that are small and can be repaired easily before a major repair is needed. Also make sure the starter support bracket is in place and tight. Again the bolt going into the block is METRIC M8 X 1.25. I also seen bolts of different sizes jammed in that hole and the bracket dangling from the starter stud. It is a simple task to do it right the first time. So get down and get dirty on that CUCV and fix it right the first time. Back to the Whine. I think the whine is coming from the TH400 and the filter screen is in need of being changed. That is a messy job if you don't have a drain plug on the transmission pan. You will need to remove the 13 bolts holding the pan to the transmission. Do one side and let the pan hang as you slowly loosen the other side. Take the front end and back end bolts out of the pan first to allow the pan to tilt and drain. Get a drain plug pan if you can find one before reassembly. But change the filter and the ATF fluid and I think the whine will go away. Many have been poorly maintained in private hands and priority's are not in order. Big tires and lift kits are more important than proper maintenance and safety items. Have a Great Day and Be safe.
CUCV 6.2 Diesel starter bolt torque 40 ft-lb

40 ft-lb is the correct value, and it is easy to put the torque wrench on the two main bolts at EVERY oil change.

cucvrus said:

The starter bolt and the whine are not directly related. The starter bolt should be replaced ASAP.

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Thanks, I definitely plan to do that. Hopefully the snapped bolt remnants can be extracted without too much trouble. Is there a particular replacement bolt type I should use? I did read the TM about starter removal and replacement, does not seem too difficult. I'm just wondering why the engine won't turn over right now. I also watched a few videos of TH400 filter and fluid replacement, I know mine defiantly needs it, the pan seal is leaking. so it was on my to-do list. Do you just fill the new fluid into the dipstick hole or is there another access port?

Fill it thru the dipstick tube. Put 6 QTS in and check it. Top it off from there. 6 to 10 QTS is average. Your engine may not turn over because the starter has eaten a hole on the flex plate or the gears are too far apart to engage. I would not attempt to engage until you get the broken bolt replaced. Unless you need a lesson on flex-plate changing. I have that lesson also. Take Care and Be Safe.

And may I recommend the flanged starter bolts. https://www.summitracing.com/parts/ado-11610633?seid=srese1&gclid=EAIaIQobChMIsPbB1b6n6gIVHP_jBx3HOwa-EAQYASABEgJFBfD_BwE


That was easy. Take Care and Be Safe.

Not to mention the Heli coil starter mount thread repair and broken block at starter mount flange lesson. Had the first one, know a guy who junked an otherwise running engine over the second.

I reccomend changing both bolts every time I change the starter if I was not the mechanic putting in the previous one. So many guys over torque these. Of course you don't want to under torque either.

Took the bell housing cover off to see why the engine won't crank over... Is it even possible that the flywheel ring gear is hitting the housing?? It looks like it's almost, or is, touching. Can't even get a knife between them. The other side is tight but absolutely has more clearance.

My guess is flex plate got bent when starting with only one bolt. It should have same clearance on both sides.

dependable said:

Not to mention the Heli coil starter mount thread repair and broken block at starter mount flange lesson. Had the first one, know a guy who junked an otherwise running engine over the second.

I reccomend changing both bolts every time I change the starter if I was not the mechanic putting in the previous one. So many guys over torque these. Of course you don't want to under torque either.

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I tried searching for the "helicoil starter mount" thread and can't find it... do you have a link? You're right I don't want to destroy my engine block by messing that up...

I don't think you should assume you need to do the Heli coil yet. From your picture it looks like the broken starter bolt should come out and threads may be OK. Often times they come out with little resistance. I'd start with a reverse drill bit, more than half the time that works. Next thing to try is properly sized "easy out", just make sure you don't bugger the bolt hole threads when you drill the hole for it. A center punch divit in center of broken bolt helps keep the bit from wandering, drill strait, use goggles, don't use too large a bit. Use a reverse drill bit when drilling for EZ out, even if it did not work at first, you may get lucky.

On to the flex plate, which may have been bent when you started with one bolt, or it may have gotten bent and caused the broken starter bolt. The only way I can think that would happen is if flex plate bolts broke or came loose first. If you want to confirm it is bent or loose, take out glow plugs to get rid of compression, turn engine clockwise with socket on the 15/16s bolt that holds on harmonic balencer. Probably easiest thing would be to get a helper to observe plate while you turn it, but maybe you can vidio with phone. If there is any side to side movement of flex plate at all (what you are calling the flywheel ring gear), then it is bent or came un bolted and is also probably bent. You will need to inspect torque converter mounting holes and replace flex plate.

I think I recall a thread about installing a Heli coil in starter bolt hole, I'd search Heli coil and CUCV, it would have been a while ago. The one I had to do was on a civy 6.2 that had been worked on by many people, and before this forum existed.

Just get yourself a flywheel tool. Saves removal of glow plugs and makes turning and inspecting the ring gear and flywheel as easy as pulling the handle. From the looks of the teeth on the ring gear I would say the mesh was not even and maybe tight. You can change the flex-plate/flywheel without dropping the transmission from the truck. About a 4-5 hour job laying on the ground. Easier on a lift. I do mine in the grass with a sheet of 3/4" plywood as a hard surface. Want to know how? Ask. Take Care and Good Luck. Close and almost touching don't count. All engines / mechanical things have close tolerances.

cucvrus said:

Just get yourself a flywheel tool. View attachment 804698Saves removal of glow plugs and makes turning and inspecting the ring gear and flywheel as easy as pulling the handle. From the looks of the teeth on the ring gear I would say the mesh was not even and maybe tight. You can change the flex-plate/flywheel without dropping the transmission from the truck. About a 4-5 hour job laying on the ground. Easier on a lift. I do mine in the grass with a sheet of 3/4" plywood as a hard surface. Want to know how? Ask. Take Care and Good Luck. Close and almost touching don't count. All engines / mechanical things have close tolerances.

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How do you do that? I've seen some clips on Youtube where they put a jack under the transmission, put some all-thread long bolts through the mounting holes, drop the drive shaft, and slide it back. What's your procedure?

14ghz said:

How do you do that? I've seen some clips on Youtube where they put a jack under the transmission, put some all-thread long bolts through the mounting holes, drop the drive shaft, and slide it back. What's your procedure?

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Basically the same but all thread would make a lot of friction to slide that assembly back. I use 4" grade 8 4" x 16 tpi and slide it back. It's very easy and requires no helper. The plywood lets the floor jack travel back and forth. Do remove the starter and heat shield. Also the dipstick tube will need pulled up and a new dipstick grommet at reassembly. Its a -$5. item replace that and the 9449 National tail shaft seal on the transfer case during reassembly. Good Luck. https://www.summitracing.com/search/part-type/flexplates/make/chevrolet/engine-size/6-2l-379/ring-gear-tooth-quantity/139-tooth

cucvrus said:

Basically the same but all thread would make a lot of friction to slide that assembly back. I use 4" grade 8 4" x 16 tpi and slide it back. It's very easy and requires no helper. The plywood lets the floor jack travel back and forth. Do remove the starter and heat shield. Also the dipstick tube will need pulled up and a new dipstick grommet at reassembly. Its a -$5. item replace that and the 9449 National tail shaft seal on the transfer case during reassembly. Good Luck. https://www.summitracing.com/search/part-type/flexplates/make/chevrolet/engine-size/6-2l-379/ring-gear-tooth-quantity/139-tooth

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Thanks for all your help! I have never worked on a transmission before so I'm new to this. . I have a few questions...

1) I have removed the starter, but what do you mean by the heat shield?
2) Removing the dipstick tube... does it just pull out or twist out?
3) Besides those 4 bolts, is there anything else that needs to be loosened? I'm guessing the cross member under the tranny? Linkages/vac line/cooling hoses?
4) To remove the driveshaft, do I unclamp it at the rear diff and it pulls out of the transmission? Anything for the front drive shaft?
5) When I removed the transmission oil pan (it had a horrible leak so I figured this would be a good time to do that) I noticed the bottom 3" of the dipstick had broken off inside the tube (when I was on the side of the road this lead me to think there was no fluid!). But I can't seem to find a replacement dipstick for the CUCV or K30 diesel... do you know where I can get one?
6) Do you put the jack on the tranny oil pan? How do you get it up that high and be stable?


Thanks again! I just ordered the ring gear, oil seal, grommet, and new starter bolts!

14ghz said:

Thanks for all your help! I have never worked on a transmission before so I'm new to this. . I have a few questions...

1) I have removed the starter, but what do you mean by the heat shield?
2) Removing the dipstick tube... does it just pull out or twist out?
3) Besides those 4 bolts, is there anything else that needs to be loosened? I'm guessing the cross member under the tranny? Linkages/vac line/cooling hoses?
4) To remove the driveshaft, do I unclamp it at the rear diff and it pulls out of the transmission? Anything for the front drive shaft?
5) When I removed the transmission oil pan (it had a horrible leak so I figured this would be a good time to do that) I noticed the bottom 3" of the dipstick had broken off inside the tube (when I was on the side of the road this lead me to think there was no fluid!). But I can't seem to find a replacement dipstick for the CUCV or K30 diesel... do you know where I can get one?
6) Do you put the jack on the tranny oil pan? How do you get it up that high and be stable?


Thanks again! I just ordered the ring gear, oil seal, grommet, and new starter bolts!

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1. It should have a heat shield, but it's common to not be re-installed after a starter replacement.
2. Should pull out. Held in place by a grommet.
3. From what I remember, just the transmission mount. Maybe the linkages. Lines and hoses should have enough slack?
4. Like you said. Be careful with the U-joint. Don't let the caps come off. Use some (painters) tape to keep them in place.
5. Can be found. It's not CUCV/K30 specific. Here's one.
6. I'd prefer a transmission jack, but that's kind of expensive for a 1 time use. Since you're only moving it back a bit, use some wood on the jack to spread the load. Maybe a ratchet strap between the frame rails to be safe? You don't want that transmission to drop when you're lying underneath it.

Yes you will have to remove the linkage , down shift wire, vacuum line from modulator and the cooler lines. There are 6 3/8" hex 9/16" bolts holding the transmission bell housing to the block. You must remove the bottom half of the flex-plate cover. Remove the 4 bolts holding the crossmember to the frame and leave it attached to the transmission / transfer case spacer. Don't forget the 6 flex-plate to torque converter bolts. I didn't list everything because you mentioned seeing a video on YouTube. I also didn't want to micro manage the job. But when you take the bell bolts at 2 & 3 o'clock out put the 4" long bolts in place. Also the same on the left 9 & 10 put 4" long bolts in place. It only needs to slide back about 3-4" max. Reach up and change the fly wheel / flex-plate. 11/16" bolts hold it fast. Not metric. because it would need a 17.5 mm socket. CUCV's are a tool box full of different sizes standard and metric. Good Luck. I hope it works out for you. Be Safe. Use a floor jack and a 2 x 6, 2 x 8, anything to jack on the crossmember and transmission. No strap needed it can't turn or fall with the bolts in place.

Blocking the engine on the oil pan as to not push in bottom with a 2x6 and a small hydraulic jack will help articulate the angles of both assemblies, trans and engine, so that the angles line up on assembly and to disassemble without getting into a bind, sliding on the pilot bolts much easier.

On reassembly blue loctite on the flywheel bolts will keep them from backing out. Blue loctite on the torque converter bolts a must also.

And one more item that I would address while having the trans pulled back would be to Replace the torque converter seal. For 5 bucks and it is pulled apart already, you should replace now.

Or you can spend hours on a different day and replace just the seal because it is leaking?

Sorry. You MUST remove the transmission to replace the torque converter seal. There is not enough space to remove the torque converter. It is just enough to replace the flex-plate. I only replace the flex-plate like this when that is all I want to replace. Follow a simple rule. If it ain't broke don't fix it. I mean at this point if I owned the vehicle or knew nothing of the vehicles history. I would drop the transmission and get it rebuilt. Lets keep it simple. I think getting the front seal in the transmission would be a treat with it slid back on bolts. Take Care and Enjoy the 4th of July. Be Safe.

Sorry I would not use 4inch bolts to do the job anyway.

Nothing I have read makes me think that the flywheel is damaged. Now the man is unbolting the trans to replace the flywheel. It will not hurt to replace.

I could give many reasons for the engine not turning over. And to eliminate any trans problem with starting I would just take out the torque converter bolts, keep it simple, Right.

Allot of assumptions and some good advice also. The flywheel tool, good that will tell him the condition of the flywheel, and if there is a clearance issue, loose bolts, cracked bolt flange. It will help with seeing if the engine is free to rotate, and the symptoms thereof.

I read in another thread about starting at the [top of the hill] when not paying attention to the start, how prophetic.