M50D ready to blow?

[Cherrybomb]

Alright heres my porblem. About a week ago i guess it was i posted a thread in the 4cyl section stating that my truck was hesitating. Well i figured that out as just being (i think anyways) the colder weather and i just put a new thermostat(think its to cold). So that hesitation brought up a new issue my transmission is doing the same thing that Squealingtires described his doing before his 5th gear went out. The transmission jerks and hiccups at a low rpm. By the way its a M50D.

It gets worse. My truck is doing this in every gear except 1st and reverse. I do have some gear whine also. But if i keep the motor at a higher rpm it wont do it. It will shift fine if i shift slow, theres not much slop in the shifter its self, and the whining isnt really loud except for the clonking and clicking when it does hiccup.

what scares me is the kid that had it before me didnt know how to set the timing when the belt flew off and had a Haynes manual right there in front of him and couldnt figure it out. He is going to automotive traning school and cant do that. The other scary part is he said he replaced the clutch himself but he cant put the timing belt on. So i have this other transmission that i was going to sell from my wrecked 89. Well now i want to rebuild that one so i have one to go in when this other one detinates on me. It sounds like in the tech library that these transmissons come apart fairly easy. Any special tools im going to need? And how much am i looking to spend on a nice rebuild kit? Id really like to rebuild it myself too because i have never rebuilt a trans before and have always wanted to to see what makes everything tick. Thanks for any info.

 

[MAKG]

No rebuild kit contains what you need. You have to tear down the transmission and inspect everything. You will not (likely) need to replace every bearing, and it is fairly likely that at least some hard parts need replacement. Hopefully not too many.... It's the inspection that's the difficult part of rebuilding; teardown and assembly is easy.

Having said that, I don't see how looseness in the transmission can cause the symptoms you describe in 4th gear. 4th is very special; no power is transmitted through the countershaft. Are you ABSOLUTELY SURE this isn't a road-speed dependent problem? As in, say, the rear end crapping itself?

And how low is low? Most gasoline engines with manual transmissions will jerk if you are well below the powerband. Sometimes, they detonate as well. It's not good for the engine (or drivetrain) to do that, but it isn't a symptom of any problem.

 

[Cherrybomb]

Well im really not worried about the trans thats in the truck now considering im going to be rebuilding the one from my 89, Im worried how long its going to last. The one from the 89 probably doesnt need much it shifted smothly. The shifter does have slop and reverse grined everynow and then and the front shaft( i call it the input shaft) has some slop if u wiggle it up and down which im assuming is a bearing. The reason im 99% sure its coming from the trany is the way it acts fine in reverse and harldy does it in first. And when i say low rpm i mean below the powerband a lil above idle or at idle. couldnt tell you exact rpm since i have no tach. Plus the noise. You can tell its coming right below the floor. Some of the jerking could be from the rear which im defintintly going to inspect this weekend. But when you drive it theres no mistaking that theres something wrong with the trans. Another thing i forgot at idle in netural i layed under the truck and it sounds like theres a lil germlin in side the trans with a box of rocks shaking around. Which from what i have been told is a sign of the throwout bearing going bad. So after i check out the rear is when ill tear into that tranny most likely. So no special tools needed? And what makes the stick sloppy? Any diagrams of this transmission showing what part is what etc..? thanks

 

[MAKG]

Noise in neutral is the kiss of death....

It's probably not the release bearing unless stomping on the clutch changes it.

Driving under load off idle will make your engine/drivetrain jerk even with no problems at all. You aren't making any power at such a low RPM, and the engine management system doesn't know what to do with it. This is VERY BAD for your engine; don't do it. Essentially, you're wiping all the lubrication off the rod bearings.

 

[Cherrybomb]

Heres what i found out this weekend. Tranny has plenty of fluid in it. Did plugs and wires on the intake side.They were never done before and its just getting ready to roll over to all zeros. Took the rear diff cover off. i dont know much about rears but i never seen gear oil all foamy like it was. It was full but very very thin gear oil and foamy. I think the rear is shot. I say this because theres slop in what i think are considered the spider gears. Id say they move up and down about a 1/4 of an inch. But Im also still sure theres something wrong with the trans considering the noise in neutral and the other day i had to slam on my brakes and i heard something fly forward in the trans and rattle around in there for a few seconds. so the slop in 4th gear is expalin by the rear. I think ill just drive it until something flys apart then replace the rear with the one i have out of my totaled truck. I know that rears good becuase theres no slop in that one and when i changed the oil it was clean and everthing looked very nice. Its just a shame because this trucks just getting ready to roll over to 100,000. the kid that had it before just beat the crap out of it.

 

[MAKG]

Sounds like the rear end got water in it. Or else the previous owner was a dips**t and put an inappropriate additive in it.

Some spider gear slop is expected, but I think yours is excessive.

Make sure you look at all the bearings, especially the carrier and axle bearings. Feel the pinion for slop and look at the gear teeth in the ring gear for wear pattern or any chips. Correct wear pattern is a shiny spot away from all the edges of the teeth, and with fuzzy boundaries. Pitting, scoring, or chips indicate a broken gearset.

Don't mix up the bearing races or shims and don't reverse the bearing caps.

Also, don't forget to inspect axle bearings and especially the axleshafts.

If anything is hosed, it may be cost effective to just replace the rear with a good junkyard unit with the same gearset. Small mistakes can lead to very short lifetimes.

 

[Cherrybomb]

Yea im going to use the rear from my 89 and rebuild the trans from the 89 over this winter.