NEED HELP 06 transmission slow enagement

[captain150]

Hi just wondering if this is a problem or normal 4L60E behavior.
Transmission seems to take longer than other transmissions to engage drive. Sometimes close to 2 seconds. Reverse is usually faster to engage but sometimes slow as well.

Happens cold and hot. Seems worse when cold. Transmission works flawlessly otherwise. All shifts are good and strong. Fluid level and condition are good.

If it's a solenoid or other simple fix I can make by dropping the pan that'd be awesome. If it's a worn transmission I'll run it till it fails.

Truck has ~180,000 miles. No DTCs related to the transmission.

 

[NJTB]

As long as the fluid was changed and in good shape, and the trans is working correctly, I wouldn't worry about it. I'm suspecting this happened when the weather was real cold. Does it work better when it's over about 35 degrees?

 

[Reprise]

The quick reply is that you can probably continue to drive it, as-is. Monitor to see if it gets worse, or other issues start. It may be worse when cold (ambient temp). Pricey fluid or additives won't help, either.


One thing you could try is shifting from P > R > D (keep in in R for a second or two before proceeding to D). However, the time spent in doing this would be about the same as going P > D and waiting the 2sec for engagement. But you could see if the engagement is smoother (I do this in my vehicles out of habit.)

As far as 'cause' of the issue... you may have low fluid pressure, or a worn boost valve. Or, your pump could be at fault (which would be contributing to the low fluid pressure.)

For the first, you'd need a transmission line pressure gauge to check. Min pressure at idle should be not less than 60psi in Drive (Reverse is higher, but you're not having a problem with that.)

The second can be done in-car - the boost valve goes in the outer pump assembly, and is visible / accessible without disturbing the valve body (it's in the orifice that the filter feed tube sits in.) However - in March of '05, GM added an Input Speed Sensor as part of this assembly, and if you have it, you'll likely have to drop the trans to remove it to, in turn, get the boost valve out (it connects in the pump body, which can't be removed in-car)

If you wanted to check the boost valve, you'd be looking for movement within the bore (fluid escapes in the gap between the valve & the bore and subsequently lowers line pressure). If present, oversized valves are available. The valve can be tricky to get out - you'll need a pair of snap-ring pliers with a long nose, as the ring is recessed within the bore, and care must be taken not to scratch / gouge the valve or the bore. I left mine alone when I put in my TransGo kit, btw, as I saw no evidence of wear.

In order for you to detect gap / movement, however, that valve / bore would have to be pretty worn; the larger valves tend to be only .001 - .002 bigger. In short, you'd have bigger problems; if it were that worn, you'd probably never engage in D.

I have a hunch that you'd find the line pressure within spec, and no evidence of a worn boost valve. If that were the case, I'd put everything back together and drive it as-is. In the absence of the issue getting worse, or other issues developing, this alone won't 'break' the trans. It would be more of an 'annoyance' issue. If it eventually does start worsening (longer and longer delayed engagement, shifts start becoming delayed / harsher), your pump will likely need to be replaced. If you go that route, and plan on keeping the vehicle, you'd be better off to do a full rebuild, not just an R&R on the pump, especially with 180K - even maintained (stock) 4L60s will start giving up the ghost about 200K or so.

Finally, one easier way to increase the line pressure is via a tune on your PCM. However, you will notice that the shifts will increase in firmness, depending on how much you boost it, and it's more stress on the pump. With your mileage, I wouldn't do this, personally.

 

[captain150]

Thanks for the detailed info! I didn't get the email notification so didn't realize I had a response on this thread.

It was particularly cold here this morning (about -30C) and the first drive engagement took multiple seconds. Once the transmission warmed up a bit it went back to normal. In the OP I said it happens warm or cold, but when warm I'd say it behaves normally.

Since once drive is engaged the transmission seems to work fine otherwise, and as you said it won't break anything, I'll just drive it as-is for now.

The truck is an 06 but I bought it used. I know it had a lower mileage 2004 engine put in. I'm not sure of the transmission history, I wouldn't be surprised if it's already been replaced or rebuilt once...given that the engine was replaced.

 

[Reprise]

Don't assume a new trans always accompanies a new engine (or the other way around). If one of the two is working w/o issues, it tends to stay put, since they fail independently of one another.

Since you don't have the delay when warm, I'd especially leave it as-is. If you can manage it, a little more warmup time in the morning *may* improve the engagement delay, but it would be a long shot, to be honest.

-30C is pretty damned cold, and I'll bet you get even colder temps on occasion in Edmonton. If you haven't changed out your trans fluid in a while, a drain / fill with 5qt of a full synthetic Dexron VI might help w/ the cold temps (but again, that 'fixing' the cold engagement issue itself is probably wishful thinking.)

If you can manage it, the 'flush' routine that's in several places on this site would give you all fresh fluid - even better to do if the fluid looks bad / smells burnt. I'd get a helper so one person could pour in the new & start / stop the engine while the other drains the old. Don't have a shop machine 'flush' it, as it can knock out a higher mileage transmission - especially if it's a 'reverse flow' machine. Full replacement takes 12qts of fluid, btw. Good to have 1-2 qts more than that on hand, 'just in case', on a manual 'GMTNation-style flush'.

If you know when /what mileage the engine was replaced at (and mileage on the 2004 when installed, but that's unlikely), you can subtract that from the 180K on the clock. Assume 15K / yr, if you don't have info. That would remove a minimum of 30K off 180K total, giving you 150K on the new motor (minus what it already had on it.)
If it runs well currently, you might get a comfortable 100K additional miles on the motor. 250K total miles (and more) is certainly attainable on a well-maintained 4.2L.

Assuming the trans is the original one, with 'all' of that 180K - be ready in another 20K miles to make a decision on whether to rebuild / replace the trans, or replace the vehicle. A stock 4L60e on these trucks tends to bite the dust about 200K or so. Anything you get past that would be great, and it does happen - but expect that you'll need to start your tranny or vehicle fund before too much longer.

Good luck!

 

[miketx]

All I can add here is that after 30 years of working on transmissions, I don't recall ever seeing one fixed by changing the fluid. It sounds like it may be low on fluid, but I don't live where it gets anywhere NEAR that cold. You say it happens hot and cold, so first check the fluid, even if it shows full, add a quart. If it still does it, you may have a clutch problem inside the trans.

To put the fluid change in perspective, I used to tell people that wanted me to change their fluid when they had a problem with the trans that if their motor wouldn't start did they think changing the motor oil would help it.

 

[captain150]

I checked the fluid level when it was fully warm, if anything it might be slightly overfilled. It was beyond the "hot" hatch mark on the dipstick.

Anyway the problem isn't really there when the transmission is warm, it's just when it's cold. I'll just drive it till it goes completely.


Also FYI the engine has about 130,000 miles. Seems to run really well, good oil pressure, no leaks.