Gear befuddlement

[Rodzbuck]

I want to tell whole so every variable can be considered. I was driving east over narrows bridge, I was in inside lane. When I got to purdy exit I went to switch to outside lane but there was a car to the right of me so I gave it a little gas and to get ahead of him. (Speed went from 65 to 70) He then gave it gas to match. I then mumbled some colorful expletives out of frustration and punched it. ( Went from 70 to 85+maybe 90, speedo don't go that high) I made the exit and everything was fine. About 6 miles later I was in 4th and down shifted to 3rd thats when I heard the knocking for the first time, knocking in every gear but 4th. Limped home in 4th gear, did some reading and everything pointed to countershaft bearing. I have opened up gearbox, msg-5k '82' and here's what I found. I lost all fluid, none of the bearings on the counter shaft or top and mainshaft are bad. 7 teeth missing out of the counter shaft gear. All other gears look ok. All I can think of is the low fluid and high rpms caused the hardened steel teeth to shatter. I want to rebuild but I don't know if the rest of the gears have been compromised. Any ideas?

[JoeIsuzu]

I can't answer your question, but I wanted to explain why your topic was moved. Although you have a diesel, this particular subject is not diesel specific.

Jack

[Rodzbuck]

Agreed, msg was used in both gas and diesel.

[Rodzbuck]

One other thing I did notice is heat discoloration on front lower bearing

[puttputtinpup]

Perhaps you might consider finding a 5speed from an 88-95 Isuzu pickup and swap it out. It's a stronger 5speed. When used as a diesel upgraded transmission, the front halves of the cases have to be swappped out. Since you already own a gasser, it might just be plug & play except for the output shaft spline count (with matching size U joints) and speedometer gear tooth count.
I can't recall if the speedo gear from the old one will swap. Don't think it will. There's a gizmo that you can buy to chg the cable speed and the speedometer be more accurate. Your truck should have a 3.73 rear end. The newer trucks have 4.10
More information under the How To section /diesel/5speed upgrade

[Rodzbuck]

Am already looking for an upgrade for my c223 but this could take a while. Ive read alot of literature on this site. I've also have an opportunity to get a 5 speed out of an 80s s10. Do you have any info on wether or not it would work in my luv.

[JoeIsuzu]

I've also have an opportunity to get a 5 speed out of an 80s s10. Do you have any info on wether or not it would work in my luv.

Unfortunately , it's difficult to search the site for "S10" because the "search term" is too short. But it's a great question, and would make life a lot more simple. The C223 was offered in the S10 (and GMC S15). It used a GM transmission. If you could find the bell housing from a diesel S10/S15, you'd have all kinds of options. But those are nearly impossible to find.

Jack

[isuzu Specialities]

The only gears that are for sure compromised are the gears that were under load when the failure happened.
All other gears could be comprised however no guarantee. With that said all other gears & components will require a close inspection for reuse. Keeping a keen eye open for heat fatigue, chatter fatigue, warpage, and teeth runout. Calipers, a good light, magnifying glass, straight edge & feeler gauge are your friends for this part of the rebuild. Verify the case is square and line bore is true is a highly recommended, Heat and shock loads will destroy a lot of things really fast.

[Rodzbuck]

I'm still at a loss how I can destroy a gear without losing any bearings. A friend of mine suggested a foreign object maybe a piece of broken metal no longer suspended in fluid it was free to bounce around in case until it got caught up in gears. Either way you are right, I'm going to have to go over everything with a bright light and a magnifying glass. The answer is in there, I just have to find it.

[Rodzbuck]

S10 also used an isuzu s101

[isuzu Specialities]

I'm still at a loss how I can destroy a gear without losing any bearings. The answer is in there, I just have to find it.

Harden stee & hard-faced steel fused onto specially made hard alloy steels all acts very odd when it is stressed to the edge of its maximum limits. Gear teeth have different shock load and harmonic displacement paths than a bearing, Bearings have a larger surface contact area than gear teeth and the rotating axis and loading of the main shaft and the intermediate are totally different than each other. All of these factors plus other not mentioned pay a significant roll into the failure of this gear box. No doubt the lack of oil had a part in this. What give out first is difficult for a super computer to predict. There are simply far too many variables to consider

[Rodzbuck]

I have found further heat related discoloration and stress cracks on the top shaft gear and 5th gear. I think it's safe to say that high heat has taken my gear box past the point of no return.short of replacing everything inside the housing this rebuild is off the table.

[Rodzbuck]

I have access to a 70s 4 speed. It's a downgrade but is it feasible?

[JoeIsuzu]

I have access to a 70s 4 speed. It's a downgrade but is it feasible?

The best we can tell you is, "maybe". The bell housing won't work, because gas and diesel bell housings are not interchangeable. Your bell housing MIGHT swap over, but only if the front bearing cover inside the bell housing has the same bolt pattern on both. The early ones had four bolts, and later had seven (if I recall correctly). If the transmissions are out, that's easy enough to check.

Second, your slip yoke probably has 17 splines. The 4-speed output shaft may not. I've seen these with 11 splines.

Jack

[puttputtinpup]

Am already looking for an upgrade for my c223 but this could take a while. Ive read alot of literature on this site. I've also have an opportunity to get a 5 speed out of an 80s s10. Do you have any info on wether or not it would work in my luv.

We have a member in ohio willing to sell his S10 diesel stuff. Send Tigman a PM for more information. The S10 might be a hydraulic clutch setup though. I'm not 100% sure though.