Question 97 350 auto trans shift lag when warm

[Jaxmike]

200k miles on automatic trans. Only when warm, the trans will stay in 1st gear. I have found that if I shift to second using the gear selector, it will move to 2nd then when I manually shift to drive it will quickly shift up thru gear progression. Comes and goes, but only when warm or hot. I am new here but have been reading posts and appreciate this site and any assistance.
Mike

 

[DaveBen]

If you have 200K in the tranny, I would get it to a good tranny shop and ask them. That is a lot of miles for a tranny, before rebuild. My guess is it needs at least the valve body rebuilt and more.

Dave

 

[Jaxmike]

Thanks for your information. Are there any external electronic or mechanical controls that I could check prior to going to a transmission shop? New fluid about 5K miles ago.

 

[trackspeeder]

Generally delayed shifts while hot are pressure issues. Internal leaks or a tired pump.

You can have pressure test done.
With 200k it might need to be freshened up a little.

 

[Jaxmike]

Thanks for the info, gives me a place to start.

 

[BJS]

pressure test are fairly simply and can be done in the driveway
Here is a how to

As has been mentioned before the shift from 1-2 in Drive is related to pressure, low pressure is usually a result of brittle seals in the transmission and occasionally weak pump output. The test above will test the combination of the two.

There are no external electronics or mechanics to test.

There is a possibility that the valve body is sticking giving you a delayed shift, sadly this is very difficult to diagnose and I can't say that I know of a trans shop around town that I'd trust to give you an honest diagnosis, not saying they don't exist I just haven't needed one to find out if I'd trust them and haven't heard of any marvelous customer service from anyone.

 

[Jaxmike]

Appreciate all the advice. My wife and I bought our 7.3 for a truck camper. Tents were getting too difficult to get in and out of, not to mention the lack of facilities. We are very pleased with our truck, but since I am new to PSD, the more information I can gather from helpful people, the more educated I will be when I get service or repairs. Thanks again, I will post what the problem ultimately is so I can hopefully contribute to this community.

 

[BJS]

One other question for you;
Does the transmission shift any differently under full throttle acceleration than under "normal" acceleration

 

[Jaxmike]

It hits high rpms pretty quick from a start so I haven't gotten on it . Tomorrow I'll hit it hard a few times and see if it makes a difference. Thanks again

 

[Jaxmike]

update

Hit the pedal hard and it shifts thru all gears ok. 1st to 2nd happens alot higher rpm though, about 3200. But it does shift normally thru all gears. Thoughts?