Sticky transmission solenoid

[drallan]

TLDR:
Which solenoid is involved w/ shifting from P/R to D?

Backstory:
99 LTD 3.4L 4x4 165k w/ B&M 70264 cool rad bypass

Over the past few months I have experienced an issue where my transmission doesn't seem to want to drop into gear when switching from P or R into D. It happens maybe once a month and generally 1st thing in the morning on cool/cold nights. But not always. I first noticed it back in Jan/Feb when it would get down into single digits, but recently has happened when the temps don't drop below 30.

It is NOT a brake issue.

I usually back out of my driveway in R w/o any problems, but when I shift to D it feels like I am in N. I don't feel the transmission drop into gear and when I give her gas the engine revs but the truck barely moves, if at all. If I drop into 2 I see the same symptoms. HOWEVER, if I drop all the way down into L I can feel the transmission shift and I start to move. Once I reach about 2k rpm I'll shift back up to D and all is good. This happens maybe twice a month.

If I do leave it in D it will take about 30 sec and then I can feel the transmission shift into drive. I have done a lot of searching and research, unfortunately most people post their problems/question, but there is often little follow up onto what, if anything, actually solved the problem.

This has happened when the engine (not transmission) was both warm and cold (let her idle and warm up for 5 min in the driveway). I have also tried sitting in the driveway in R w/ my foot on the brake for 30sec to see if getting the fluid flowing would help to no avail.

I have drained/filled via transmission plug 3 times over the past few months w/ Valvoline MaxLife ATF. My basic math skills has determined that I have about 65% new fluid (see math below). And I have made sure that the fluid level is correct. I check every gas fill up. Flat level ground, w/ engine on, shift from P down through L (stopping at every gear for a few seconds) then back up before checking fluid. It is always between the middle and bottom 'Hot' mark.

This leads me to believe that it is either the tranny going bad, although I experience no other slipping or symptoms, once I get going she is fine all day. Or a sticky solenoid.

Does anyone know which solenoid controls the shifting into D? Any other ideas? I'm not sure if cleaning/fixing the solenoid is a viable option, and I might as well replace it while I've got the pan off and in there. But I'd like to not mess with more than I have to.

Thoughts?
Thanks!


Basically used a derivative of the 1st change being 30% new and 70% old (rounded to make math easier)
10qt old /14qt total (10 old + 4 new) ~ .70 *100 = 70% old or 30% new.

Each drain fill is only 70% new of what ever you put in so drain/fill #2 would be: Drain 4qt * .70 = 2.8 old (1.2 of what you drain is new from last drain/fill).
4(1st drain) + 2.8(2nd drain) = 6.8qt new oil /14 ~ 50/50 new/old

3rd change 2.8*.7 ~ 2.0 old
4qt (1st change) + 2.8qt (2nd change) + 2qt (3rd change)=8.8 / 14 ~ 65/35 new/old

 

[LittleCaesar]

If the solenoids go bad they often throw a code, but I have seen where one was on its last leg by someone actually dropping the pan and using an ohm meter, determining it was due to be replaced. If you need to replace it such is cost prohibitive to just replace all three (they are sold in a kit).

Did you see any metal in the old fluid when you drained it?

Could be a sticking solenoid, valve body sticking, or torque converter.

Greased the driveshaft lately?

 

[Bryan1]

My truck was doing the same thing. Replacing the shift solenoid fixed the problem....but then it started slipping between gears.

 

[HammerHead]

Replace all three if you're in there.

 

[drallan]

If the solenoids go bad they often throw a code, but I have seen where one was on its last leg by someone actually dropping the pan and using an ohm meter, determining it was due to be replaced. If you need to replace it such is cost prohibitive to just replace all three (they are sold in a kit).

Did you see any metal in the old fluid when you drained it?

Could be a sticking solenoid, valve body sticking, or torque converter.

Greased the driveshaft lately?

The old fluid was pretty brown at first, but I didn't notice any obvious shavings. However my drain pan had other fluid in it making it difficult to tell anything.

No codes or CEL light.

Driveshafts were lubed back in Jan when I had rear axle seals done. I haven't counted to make sure all were done, but it is obvious that at the the easy to get to ones were done. I don't understand how unlubed driveshafts could cause transmission slippage.

I'm gonna try 1 more drain/fill and see how she does. Would like to buy myself a few months, but also don't want to be stranded, also don't want to just start throwing parts at her either.

Thanks

 

[LittleCaesar]

If it was me, when you drain the ATF make sure it is in a clean container, grab a magnet and see what is in the old fluid.

I'd also skip using the Maxlife, and try something a little thicker like Castrol Import ATF. In my friend's Landcrusier's A343 he used Maxlife and it really didn't like it. Mixing the two won't hurt anything. Ultimately his torque converter failed (possibly why it didn't like the Maxlife) and after installing a new one the transmission never skipped a beat and was working fine when he sold it.

If you have the extra $200, replace the solenoids if you want to:
http://www.amazon.com/gp/product/B0...d_t=201&pf_rd_p=1944687762&pf_rd_i=B00F8LP2TK
But with it being intermittent I would believe if the solenoid was bad, or heading that way that the problem would occur more often.