Hi there everyone. I seem to be having a recurring problem with my 91 xjs. I just had the valve cover gaskets replaced as well as some hoses and now the trans would shift gears when in drive. I had the mechanic recheck all the hoses as last summer I had a similar problem when the fuel injector hoses were replaced.All the hoses are attached properly. The mechanic seems to think the trans itself may be the problem. Apparently it has what looks to be a GM 700 transmission?? Is it possible that the trans could be the problem. The hoses all seem to be attached. Any help or input would be greatly appreciated. Art D. steered me in the right direction last time. I'm hoping to avoid a trans job if I can.

Thanks,

Don Verrico

Submitted by michel@dinomar… on Sat, 04/10/2010 - 09:12

Hello Donald,

I had the same problem, took my 1985 in for A/C work and then the transmission shiftted only first and second. all hoses were in place, all was looking good, but the mechanic found one hose pinched.To fix the problem the car had to be cold., so I think the hose was located in a difficult place to reach.

I hope this will help.

michel

Submitted by silver007@shaw.ca on Fri, 04/02/2010 - 21:14

PS, if you can run the engine , also pull off the vacum line at the mod valve, , put your finger on the end of the hose and make sure there is vacum there. if none or little it may be apart or torn somewhere along the line to the intake manifold.
good luck.... just get me a green card. I hear you have a good club there...

Submitted by DVerr94100@com… on Fri, 04/02/2010 - 20:51

Thanks for the info, Art. Fluid level is good, so I'll check out that modulator hose. I've been reluctant to get the RPMs up to 6,000...... it's a 3 speed to I guess it's a 400. I'll let you know how this shakes out. Again, the info and advice is much appreciated.

Don V

Submitted by silver007@shaw.ca on Fri, 04/02/2010 - 20:14

Hi Don,
to my experience I have found that these trannies will not shift good for one of two reasons............ most common is LOW TRANSMISSION fluid, hey if it drips it may be low for sure.......
The othere one is the transmission modulator valve. Transmission is probably a Turbo 400.... the modulator valve sticks out of the rh side just above the pan. the hose that attaches sometimes is / has fallen off or just a loose fit . if it is not a snug fit on the end of the valve vacum will be low and the tranny won't shift easy to the next gear...........it will eventually but that will be around 6,000 rpm..........
Good luck. Art

Submitted by DVerr94100@com… on Fri, 04/02/2010 - 18:55

Thanks George and Philip for responding so fast!. The car will go in reverse, neutral,low gear, 2nd gear and into drive. Once in drive (again it is an automatic) it will not shift out. It seems like it is in 2nd gear.....The mechanic says he has checked all hoses and everything is attached.I don't know if he's missing something or not. The strange thing is before going in,the trans worked smoothly. To my knowledge,it is stock vehicle, so I guess it is a GM trans.. If I do have to have it rebuilt,perhaps I would go for a 5 speed as well. Good idea Philip! I still think it's a hose,but I don't have the expertise to repair it. Apparently either does the mechanic.....

Submitted by SE98-32482CJ on Fri, 04/02/2010 - 16:01

Donald you repeat all the hoses are on so we should assume the vac mod is connected--right? That being assumed please tell us what exactly is happening--will the car go in reverse? Will the car go into first but not shift to second? Will the car--fill in the blanks and I think we can help you---While we wait your mechanic talk any about linkage?