Stepping on the gas but truck doesn't go forward?

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Sniggles

New member
It's a 1986 GMC Sierra S15.
We noticed that the truck was leaking some fluid from the transmission fluid container, the dipstick was always empty compared to the oil and other ones..
We are wondering if it's a possible hole in the transmission line somewhere that's causing the leak and if it is, is this why you have to floor it to barely go anywhere?
I will provide more details if anyone needs them, we're just really curious if it is the transmission that is causing the problem of it not really accelerating.
The truck is an automatic if that helps any..
We haven't been driving it like that long at all, we would fill it and then start it to move it but I think the fluid would always drain quickly, and we've been under the truck and we believe it is near the pan gasket area, it only leaks when running (obviously haha)
 
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michael

Active member
well frst off, i dunno if u are checking ur trans fluid properly, but your vehicle needs to be running, around the average normal temp as if you were driving around. then you check it. that will give you 100% accurate reading.


i need more details please. but if its leaking trans fluid than yes thats a problem. go to a trans place and get a diagnostic done. your tranny could possible just be going bad. a 1986 is a long tranny. also check the spark plugs for corrosion and the wires might need a replacing. has the fuel filter every been replaced? replace it incase even if its not the problem and get fuel injector cleaner in there. hope i was a help =]

and if its not accelerating get a code on it at a auto shop, culd be your throttle sensor. it culd be a list of things tho honestly.
 
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Oscar

Member
Yes, transmission lines get holes in them all the time, so does the radiator, and transmission. If you have been driving it that way for any amount of time, it is very likely you have burnt up the clutches in the transmission and it needs rebuilt. If you have plenty of fluid you could need a new transmission filter.
 
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jeffs

Member
Can you feel the transmission shift? Considering its age, I would assume it typically makes a jerking motion when changing from park to drive/reverse/etc.

Also, is it just the Drive gear that doesn't work? Or is Reverse also inoperable?

Sounds like there isn't enough fluid to get the transmission shift. If it doesn't shift after you add the appropriate amount of fluid then either the fluid is draining out too fast, you have plugged up tranny fluid filter, or you have a dead transmission. But it's uncommon for all gears to die at the same time. Typically you'll lose reverse before you lose forward gears. And when you lose forward gears you usually lose the higher ones first. At least in my experience with bad GM transmissions, and I've gone through a few.lol

I have a 94 Suburban, and I remember one morning I went out to move it out of the way of my 94 Suburban. And when I shifted it, I didn't get the usual jerk that accompanies a shift from park to reverse. So I tried drive, and nothing. I was kinda freaked, but then I checked the fluid and it wasn't even registering on the dipstick. So I filled it to the appropriate level, and it works fine now.

In my experience the transmissions in the 80's era Blazers/Jimmy's weren't the greatest. We had an 85 S-10 Blazer and we had to replace the transmission because it wouldn't go beyond 2nd gear.
 
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