Transmission will not shift into Drive or Reverse when warm

[cameronsaddress]

Weird thing guys,
When my k5 is cold, my auto tranny shifts into gear from park perfectly. After I have driven it for a bit, it hesitates for up to 30 seconds until shifting into drive or reverse.

I have tried to let it roll a bit to see if it will catch, but it doesn't. I have tried to rev the engine a bit, but it doesn't seem to make it engage... it just does it when it is ready.

I have done some reading and I am curious to see if you guys concur. Could it be a vacuum line to the modulator, or a bad modulator? What about a dirty trans filter?

Any ideas?

Thanks again

 

[Greg Ducato]

Must likely the filter is clogging. You can drop the pan and check for debris in the filter and pan to confirm this. Once you shut the vehicle off the pump and converter will drain back throughthe filter, effectively washing some contamination out which is why it will work again after it sits a while. Of coarse it can also be something easy like low fluid level or loose filter to valve body bolts. Good luck with it!

 

[cameronsaddress]

Hey Greg,
I finally got a chance to change the trans filter this evening. I will post some pics in the morning. I bolted it back up, added 4 quarts, then checked level per maintenance manual, and it still hesitates to shift into gear I ended up adding a pint per the dipstick, but it still will not engage right when I select the gear. It seems to want to wait from 5-30 seconds...

Any other ideas?


Cam

 

[Greg Ducato]

Unless the dipstick is wrong for the truck I would guess you have a trans on the verge of failure. As a last ditch effort, try overfilling by a quart just in case the stick is wrong, you can always drain it off by pulling the modulator.

 

[chalet2506]

If its on the way out, a can of Lucas tranny fix wouldn't hurt. Used it in my 72 ths350, it firmed things up a bit and was still going when I pulled it out 2 years later. Greg is the pro though, I'm just cheap and lazy.

 

[Greg Ducato]

If its on the way out, a can of Lucas tranny fix wouldn't hurt. Used it in my 72 ths350, it firmed things up a bit and was still going when I pulled it out 2 years later. Greg is the pro though, I'm just cheap and lazy.

I have some local used car lots that swear by that stuff, it wouldn't hurt to try

 

[cameronsaddress]

Hey guys,
Here are the pics of the pan before I changed everything. How does this look to you?

Old Filter:

After cleaning it:

 

[Greg Ducato]

That kind of metal usually comes from a cast iron part being ground apart, such as a pump or drum surface, which would explain the hesitation to engage gears. Hate to say it, but it appears you will be soon be transmission shopping

 

[ashman]

yeah, what greg said. thats a lot of metal chips!

 

[blazinzuk]

to put it simply, you is blowed up.

time for a new trans

 

[Greg72]

It should be obvious by now that Greg Ducato knows what he's talking about....

He's a humble guy, but if you do a little research (or send him a PM) you'll be able to figure out why he knows as much as he does...

Let's just say that when the time comes for my built 4L80E,he is going to be heavily involved.

 

[sponsoredbydad]

I just happen to have a TH350 from my build left over, $100 and come get it. OK $75 It was rebuilt by AAMCO about 4 years before I pulled it,so It should be ok, better than the one you got now.

 

[cameronsaddress]

I love this forum. Sbd I will pm you.

Thanks guys

 

[cameronsaddress]

Hey guys,
A few new symptoms have cropped up and I am curious to see if you think they could be related to this issue.
I now have a high pitch whistle coming from the torque converter area as well as a knocking sound. There also is a pressure release sound after shutting off the engine. If the torque converter is going bad, could this also cause the issue of not engaging into drive or reverse? If the stator is damaged, would this cause these symptoms? It also jerks when shifting into 2nd and 3rd gears.

Thanks

 

[Greg Ducato]

Whistle sounds like a vacuum hose or vacuum leak at the intake. Pull a vaccum hose off and see if it is still there. The knocking could be loose converter bolts or broken flexplate. Positive shifts are a good thing but if they are suddenly later and firmer than they were look again to the vacuum source of the modulator for possible leak.

 

[mpio13]

donzo. something it giving up, my guess is the pump. that why it'd shift cold and not hot. the cold fluid is thicker (less viscous?) and the bad pump can still make some pressure with it. when it gets warm and the fluid is thinner the pump can't hack it. just my theory.

good news is: its a good excuse to UPGRADE!