1990 F150 with AOD transmission seems to be shuddering

[cbrf3]

Unit was rebuilt 4 years ago and now has 15k miles on it. Son wants to change the fluid and the filter; unit has no drain plug.
He feels the trans sort of hesitation only in over-drive at about 45 mph with no slipping. It currently has Motorcraft Mercon V in it.

He has read about the Mobil 1 fluid being good but not sure about drain and fill with the 2 fluids mixing. Any advice here?

 

[eljefino]

This could also be a tune-up issue, cap, rotor, plugs, wires, get good brands.

 

[BMW Dom]

With only 15k miles on the rebuild I doubt it's a trans issue. I would follow the reply above and check the other things first. No worries would the fluids mixing as long as the new fluid meets the spec

 

[wlk]

I have Mobil1 ATF in my 04 Expedition as recommend here by members and it is fine. I switched it out over 4x siphon and refill thru the dipstick just fine. No issues mixing fluids at all but I had no issues to start with I wanted a better fluid for towing out camper. If you think it is a shudder add a tube or 2 of Lubegard Shudder Fixx or a bottle of Lubegard Red to it. I would verify a tune up isn't the cause as well.

 

[meep]

The mobil1 fluid is great stuff. And I’ll second the lubegaurd additive, though I wouldn’t add it until all other things are addressed first.

Consider plugs/coils/wires, especially if the vibrations are under acceleration and the engine shifts into a dropped rpm.

 

[SubieRubyRoo]

Dump 8-10 ounces of Lubegard Red into it and drive it for a few days. You’ll likely be pleasantly surprised and save yourself a lot of headaches and money.

 

[cbrf3]

Son adjusted the TV cable and it seems to have helped. He is going to check the ignition components. and drain, replace the filter and fill the trans fluid with M1.

Have read about rotating the motor to access a plug on the torque converter to drain it. Is this a safe practice?
Not sure how quickly it refills/potential damage short of pulling the transmission and manually fulling the converter.

Thank you for all the great replies!

 

[Marcozi]

Your truck has obd2 diagnostix so scan the engine computer for codes. The Service Engine Soon (whatever Ford calls it) is lighted only when an emission related code is present.

 

[D60]

Your truck has obd2 diagnostix so scan the engine computer for codes. The Service Engine Soon (whatever Ford calls it) is lighted only when an emission related code is present.

'90 is OBD-I and not sure the AOD will throw ANY codes. E4OD, yes

 

[someonesomewhere]

'90 is OBD-I and not sure the AOD will throw ANY codes. E4OD, yes

He seems to be telling everyone they have OBD II. There's a 94 Honda thread in Mechanical sub that he says the same thing. Lol

 

[LDM]

Your truck has obd2 diagnostix so scan the engine computer for codes. The Service Engine Soon (whatever Ford calls it) is lighted only when an emission related code is present.

No 1990 vehicle has OBD2, that would be OBD1. Earliest OBD2 functional was started in 94 on very few select vehicles and some 95 vehicles in the California market but none of those vehicles have full OBD2 compliance. 96 was the first year that full OBD2 was required for light passenger cars in the US, but that only applies to the engine and transmission. Various other systems like ABS had later date requirements to move to OBD2.

I doubt there would be any OBD1 codes for a 1990 Ford AOD transmission, most OBD1 ECMs did not have that functionality. Maybe someone with more Ford experience could say for sure, my knowledge is in the OBD1 GM systems.

 

[D60]

No 1990 vehicle has OBD2, that would be OBD1. Earliest OBD2 functional was started in 94 on very few select vehicles and some 95 vehicles in the California market but none of those vehicles have full OBD2 compliance. 96 was the first year that full OBD2 was required for light passenger cars in the US, but that only applies to the engine and transmission. Various other systems like ABS had later date requirements to move to OBD2.

I doubt there would be any OBD1 codes for a 1990 Ford AOD transmission, most OBD1 ECMs did not have that functionality. Maybe someone with more Ford experience could say for sure, my knowledge is in the OBD1 GM systems.

As I said, my '90 Bronco could at least throw a code for torque converter slippage. E4OD which came behind the 5.8. The 5.0 and I6 got the AOD in '90

 

[Chris142]

With only 15k miles on the rebuild I doubt it's a trans issue. I would follow the reply above and check the other things first. No worries would the fluids mixing as long as the new fluid meets the spec

those transmissions were junk when new. The biggest issues were the electrical connections on them.

No 1990 vehicle has OBD2, that would be OBD1. Earliest OBD2 functional was started in 94 on very few select vehicles and some 95 vehicles in the California market but none of those vehicles have full OBD2 compliance. 96 was the first year that full OBD2 was required for light passenger cars in the US, but that only applies to the engine and transmission. Various other systems like ABS had later date requirements to move to OBD2.

I doubt there would be any OBD1 codes for a 1990 Ford AOD transmission, most OBD1 ECMs did not have that functionality. Maybe someone with more Ford experience could say for sure, my knowledge is in the OBD1 GM systems.

You need a special code reader but they do throw codes