Something wrong...feels expensive.... Need help

[jd21476]

My '73 K20 has the 3 speed Powerglideand it has been running fine. I started it up today and went to back up and it would not engage reverse. It felt like it was in neutral so I went back to P and tried again. Same thing. After the third time, I gave it some gas and it clunked in to reverse and started to back up. Then it ran fine. Tried it in drive then reverse a few times and it seemed fine. Took it in the highway and it shifted fine.

Got home and put it in reverse to back down my driveway and it seemed ok but then stopped. Now I was on a downhill, in reverse, and she would not move. I finally gave it some more gas and it started clunking backwards until I got her parked.

Kind of feels like when you are in 4WD and turn the wheels too much and it sort of lumbers along but this has somewhat of a hard metal feel.

Any ideas?
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[geezer#99]

Check the obvious!
Fluid level.

[TheBlueBomber]

what does the fluid look like? I would pull the cover off and look to see if there is any metallic/metal bits in the pan. My sisters 99 exploder did just that and I had to get it rebuilt.

also when was it last serviced/rebuilt? warranty?

[jd21476]

Does it seem more tranny or re diff related?
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I just bought the truck a month ago so I have no idea when it was serviced or rebuilt

[geezer#99]

FWIW you don't have a powerglide. It's a turbo 350 or turbo 400.
Find the tranny dipstick. It's on the passenger side by the valve cover at the firewall. Pull out the stick while the truck is warm and idling. Check the level on the dipstick. If it's low add some fluid. Dexron 2 works. Also look at the color of the fluid on the dipstick. Real Dark red is bad. Also smell the fluid. If it smells like burnt toast that's also bad.

[TheBlueBomber]

Originally Posted by geezer#99

FWIW you don't have a powerglide. It's a turbo 350 or turbo 400.
Find the tranny dipstick. It's on the passenger side by the valve cover at the firewall. Pull out the stick while the truck is warm and idling. Check the level on the dipstick. If it's low add some fluid. Dexron 2 works. Also look at the color of the fluid on the dipstick. Real Dark red is bad. Also smell the fluid. If it smells like burnt toast that's also bad.

The fluid in my TH350 is black. Its amazing how well these trucks hold up with little to no maintenance.

[geezer#99]

Originally Posted by TheBlueBomber

The fluid in my TH350 is black. Its amazing how well these trucks hold up with little to no maintenance.

I hear the ghastly sound of a lot of bucks being ripped from your wallet soon!!
Then again, it might go another 100,000 miles.

[jd21476]

Originally Posted by geezer#99

FWIW you don't have a powerglide. It's a turbo 350 or turbo 400.
Find the tranny dipstick. It's on the passenger side by the valve cover at the firewall. Pull out the stick while the truck is warm and idling. Check the level on the dipstick. If it's low add some fluid. Dexron 2 works. Also look at the color of the fluid on the dipstick. Real Dark red is bad. Also smell the fluid. If it smells like burnt toast that's also bad.

Why do you think I have a turbo 350 or 400? I match the pan with one on the Internet for a Powerglide. I assumed they were fairly common.
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[Zane M]

Originally Posted by jd21476

Why do you think I have a turbo 350 or 400? I match the pan with one on the Internet for a Powerglide. I assumed they were fairly common.
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To start, the powerglide is only a 2 speed.

[jd21476]

I checked the fluid with it warm, running, and in idle. It is a clear and clean red color and does not smell. The level looked good but possibly even a little on the high side.
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[jd21476]

Originally Posted by Zane M

To start, the powerglide is only a 2 speed.

Wow, really? I had a complete posting about what tranny I had and none of this came up. Everyone agreed that I had a 3 speed Powerglide.
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[TheBlueBomber]

linkage maybe?

Originally Posted by geezer#99

I hear the ghastly sound of a lot of bucks being ripped from your wallet soon!!
Then again, it might go another 100,000 miles.

Its all good. I've been seeing craigslist posts around my area for sm465/np205 all day for around 200-400 bucks. knowing my luck that would be the time they all get bought up

[Corts60]

Unless somebody has put a power glide in there, you do not have one. As mentioned above, they are a two-speed trans that mostly came in passenger cars and never in a 3/4 ton application.

T350 or T400 is what you have. T400 pan will be longer front to back and will have an electronic kick down. T350 will have a kickdown cable from the carb and the trans pan is a little more square-ish than the T400.

As mentioned above as well, check your linkage connections (with engine OFF and wheels BLOCKED, climb underneath and have somebody operate the shifter while you check below at the trans to see that it is responding correctly with every movement.)

[donut]

What they all said.
Turbo 350 was stock for a '73 K-20.

[jd21476]

Originally Posted by Corts60

Unless somebody has put a power glide in there, you do not have one. As mentioned above, they are a two-speed trans that mostly came in passenger cars and never in a 3/4 ton application.

T350 or T400 is what you have. T400 pan will be longer front to back and will have an electronic kick down. T350 will have a kickdown cable from the carb and the trans pan is a little more square-ish than the T400.

As mentioned above as well, check your linkage connections (with engine OFF and wheels BLOCKED, climb underneath and have somebody operate the shifter while you check below at the trans to see that it is responding correctly with every movement.)

Ok ok good to know. I don't know much about this truck yet. Is the T350 a decent trans or if it broken should I go to a 700R4?
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[1slo_camaro]

correct me if im wrong but most of your th400s came with a BBC infront of it correct?

But the way he is talking it also sounds like maybe the rear is binding up a little, i would pull the diff cover and take a look its good for a few reasons.... you will get some fresh fluid in her and you can see if there are any issues.


I dont know enough about transmissions to go into detail about it, but if it was me i would drop 40$ and do a fluid/filter change. when you dump the fluid out of the pan have a strainer to dumb it through and see if you catch anything that you shouldnt.... fingers crossed you dont find anything that looks like a brake pad for the clutches and bands eating apart. but you can normally find th350s/400s on clist and junkyards decent priced. Unfortunately you are in cali i have a spare 350 laying around.... also now would be a perfect time to throw a 700R4 in her and pick up overdrive IF you have to go into the trans and play inside..


Good Luck and post up what you have

[1slo_camaro]

Originally Posted by jd21476

Ok ok good to know. I don't know much about this truck yet. Is the T350 a decent trans or if it broken should I go to a 700R4?
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a 700r4 is essentially nothing more then an extra gear added to a th350. stock for stock i would feel comfortable putting more power to a th350 cause i have never broke one even with 400-450 hp motors but i have MURDERED 700R4s with 350hp motors but i also have a dent in my floor board under my skinny pedal lol

[INSIDIOUS '86]

Sounds like it may be a pump issue. Usually reverse is the first to suffer from internal leaks and pump inadequacies
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[1slo_camaro]

Originally Posted by INSIDIOUS '86

Sounds like it may be a pump issue. Usually reverse is the first to suffer from internal leaks and pump inadequacies
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didnt think of that..... thats what happened to a 4l60e and it never even clicked reverse would come and go as it pleased and we replaced the pump and it was back to ops normal.

[jd21476]

Originally Posted by INSIDIOUS '86

Sounds like it may be a pump issue. Usually reverse is the first to suffer from internal leaks and pump inadequacies
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Would the pump cause it to lock up while trying to back up?
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[1slo_camaro]

Originally Posted by jd21476

Would the pump cause it to lock up while trying to back up?
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this is what is throwing me off...... I have never had a trans lock up and then unlock

[INSIDIOUS '86]

Originally Posted by jd21476

Would the pump cause it to lock up while trying to back up?
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It would cause it not to fully apply reverse if the pressure is not high enough. When you give it has the pressure spikes and the fact that the rpm is high will make it slam into reverse.

If it locks up then your rpm won't be able to climb in gear.
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[jd21476]

So I drained the fluid and dropped the pan and found.....
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[jd21476]

#2
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[Corts60]

Sorry brother, it's time to pull that tranny.