Hi, I'm new to the forum and need some help. I've got a mint 1990 W150 Extended Cab 4X4 with a 5.2L Automatic. Here's my issue : When I have Overdrive turned on and am in overdrive (cruising over 50 on country roads), the truck runs fine....as soon as I start going up a hill or an not too steep incline, the truck hesitates and stutters....as if it doesn't know how to kick down to a lower gear. I tried turning the overdrive off and it seems to work fine.......anyone got any ideas????

Thanks, I really appreciate it!

Jim
maco12

 

Yes, this is a common issue with most overdrive vehicles (at least all the ones I've driven)...

The overdrive 'border' (where it shifts) is around ~50 mph, but while most vehicles with O/D will kick into O/D at 52, they will not shift back down until 48-50 or so, so there is a gap, the exact mph depends on the vehicle but whatever...

Now, once in O/D, if you're at the bottom of the range (so right around 50mph), the engine is operating at a very low rpm and there exists little vacuum, which is required by the transmission to operate properly.

Unfortunately, the best solution I can give is to tell you to keep driving the way you are, or change your driving style slightly, which involves you getting used to this quirk in the O/D trannies. Basically, either go a little faster (like 55-60 is a healthier O/D speed), or if that pushes the legal limits, a little slower (keep'er around 48 to stay out of O/D), *or* push the gas some when it starts to act stupid and she should downshift at that point (then you should be able to let back up a little and hopefully it stays out of O/D, and I dunno if this is hard on the tranny thou).

p.s.: And yes, it is kinda annoying, but it's just the way it is, your transmission is fine.

 

Thanks for the info!!! I really appreciate it. I don't drive on the highway much....so I'm going to try leaving it out of OD and we'll see how it goes.

Thanks again,
Jim
maco12

 

OK guys....I was wrong.....I've been driving it OD off (big difference in gas mileage).....and the hesitation is still happening. Any suggestions on what to check? I'm probably going to have a tranny expert look at it....but I want to have an idea of what it might be.....just in case it's something small. I don't want to get the "you need a new tranny" BS when it's a PCM module or something like that.

Thanks,
Jim
maco12

 

Found it.....just a reminder...always make sure your 4wheel driveis completely disengaged....yep...feel like an idiot. But a happy idiot....the truck runs great!!!! I'll post pics soon.

Thanks,
Jim
maco12