Is my trans toast?

[79gmc15]

Th350

First off, the trans shifts awesome and no crazy sounds.

But when I take the dipstick out I looks okay, until I wipe it off, it's black and doesn't smell burnt. I know it leaks fluid, I think from the cooler lines and the radiator is shot(in process of finding a new one). I am worried that it might be leaking coolant into the trans. I can see a couple black spots in the coolant (not the motor, fresh rebuild). 

Is it gone for? Or can I drop the pan and filter and add new fluid?

Thanks, Matt

[Blazin]

An automatic trans is good until it slips! No slip, its not bad!

[454Man]

X2. The th350 is one tough transmission. Ive run low on fluid alot of times. Mine leaks at the pan so I have to keep an eye on fluid level.change your fluid and you'll be good to go.

[bd]

The only caution is: if enough antifreeze finds its way into the transmission, it will delaminate the paper clutches and cause them to flake apart.  So, if you are getting coolant in the trans, don't let it continue too long.

[79gmc15]

Ok, cool... it hasn't been driving very long with it like this.

The last time it was serviced was about 7 years ago and 3 k in miles.  I am "thinking" (pending on money) to do the backyard trans flush. I would rather have the trans fail in the driveway then when I am moving or possible towing a trailer... I just wish I knew for sure if it was going to be ok or not. Lol I was thinking about flushing it with the old filter then drop the pan, try to save the fluid then refill so I know it's for sure at the right level.  Any advice? Sound good or bad?

Also, I have the trailering special, do you know what class hitch they used? Also, I am thinking about a trailer around 20-23 feet... is that too long possibly? The trailers I am looking at are from the 70's-80's.

Thanks! Oh, Chris, I tried pming you but I can't. Do I have to have more post count to?

[srgrimes]

I bought a 79 Chevy C-10 last week and drove it 40 miles home just fine.  Two days later on the way home from the parts store (3 miles) the th350 quit shifting as though it had fallen out. I rolled to a stop and tried all gears in manual to find nothing. I shut the truck off and restarted it and the transmission came alive only to drive a mile and quit again. I found a rotted hose on the manifold side of the modulator valve tube and the Fluid appears new but also seems to be overfilled. I crawled under the truck to see what appears to be a new/rebuilt transmission with no dirt or grease compared to the rest of the undercarriage and engine. The modulator valve was not new, but appeared to be an old or original one. Today I will drain some fluid out and replace the rotted hose. In the meantime if anyone has any ideas please feel free to submit them.  Signed...Desperate in Texas.

[454Man]

Yeah id just replace it and the hose. then you should be good to go. With out it being hooked up to a vac source the Trans won't shift out if first gear.

[srgrimes]

I replaced the vacuum hose and the problem still exist. It won't go into any gear once the transmission warms up. I can hear a slight buzzing sound coming from it as it tries to engage. If I shut off the truck engine and wait 30 seconds it will start up and go into gear only long enough to get the truck rolling then quit completely.

[bd]

Was there any ATF in the vacuum hose when you pulled it off the modulator valve?  Is the tranny still full of fluid?  Does the fluid on the dipstick become foamy when the problem occurs?  Does it have the correct dipstick?  "Buzzing" could be a pump problem, an internal leak, or a converter.  I wonder if the PO flushed the cooler?  You might call him/her to get some history on it.

If you wish to pursue it, purchase an ATSG repair manual (see below; $25-$30) and check the transmission fluid pressures per the table in the guide.  You can also drop the pan to check the filter, filter mounting, and inspect for debris in the pan, but will need to reassemble to check pressures, if not already performed.

[454Man]

Check the fluid level.I hope its just low.any how add more and if there was Trans fluid in the vac line our coming from the modulator then the modulator is bad.

[srgrimes]

the rubber hose I changed at the top showed no fluid. The dipstick is not original and I am suspicious of the correct level! JB weld was used to seal the new Chrome dipstick Guide tube at the Housing. I have never seen a transmission reset itself when the engine is killed and restarted. It appears that once the pressure is built up that the transmission quits or it's the other way around and it's not building pressure once it warms up. there is no foam in the fluid. Time to hit the books! Thanks for all the feed back.

[Captkaos]

Yes, but emailing me at webmaster at 73-87chevytrucks.com gets me MUCH faster during the day...

Thanks! Oh, Chris, I tried pming you but I can't. Do I have to have more post count to?