Transmission Bogs down...

Hello all...

I have a 1984 K10 Pickup with a 305.. 4X4.. Auto Tranny ... A good work truck..


When driving at a cruising speed, the transmission seems to bog down. If I press the gas it accellerates.. And when I backoff the gas it bogs down again. When at a light it accelerates fine. This only happens at cruising speeds..



CK

what exactly do you mean the tranny bogs down? just that it slows down? if this is the case, it's probably not too big of an issue. just dont let off the gas and it wont slow down. im assuming that you have a turbo 400 or turbo 350, (probably the turbo 350) both of which are 3-speed automatics.
your bogging down effect is likely just the fact that these are only 3 speed trannies that cause you to be spinning at probably 2500 or more rpm's at 60 miles an hour. when you let off the gas, the motor just tries to return to idle rpm and is in effect engine braking. i used to drive a truck similar to yours, just it had 2 wheel drive and i loved how you could slow down quickly on the interstate by just letting off the gas and letting the engine slow ya down.

of course this explanation only applies if you have a feeling that it simply wont coast or something like that, if it is really slowing down bad, and it has never done this type of thing before, like you were slamming the brakes or something, then i have no clue what it could be...

if it is having trouble keeping up speed at part throttle, it may be a carburetor problem. i tried to switch out a carb on my truck for some other carb and it would only run strong at full throttle.

is the tranny slipping or anything, like it revs and then catches or whatever?

what exactly do you mean the tranny bogs down? just that it slows down? if this is the case, it's probably not too big of an issue. just dont let off the gas and it wont slow down. im assuming that you have a turbo 400 or turbo 350, (probably the turbo 350) both of which are 3-speed automatics.
your bogging down effect is likely just the fact that these are only 3 speed trannies that cause you to be spinning at probably 2500 or more rpm's at 60 miles an hour. when you let off the gas, the motor just tries to return to idle rpm and is in effect engine braking. i used to drive a truck similar to yours, just it had 2 wheel drive and i loved how you could slow down quickly on the interstate by just letting off the gas and letting the engine slow ya down.

of course this explanation only applies if you have a feeling that it simply wont coast or something like that, if it is really slowing down bad, and it has never done this type of thing before, like you were slamming the brakes or something, then i have no clue what it could be...

if it is having trouble keeping up speed at part throttle, it may be a carburetor problem. i tried to switch out a carb on my truck for some other carb and it would only run strong at full throttle.

is the tranny slipping or anything, like it revs and then catches or whatever?

when I speak of bogging down, I actually mean lose of power. When driving the speed limit here of 55-60MPH the truck seems to lose power. The only way to bypass this is to:

1. Switch to overdrive - the "D" within the circle..
2. Change the tranny fluid - which will only last a month or so..

Will a faulty idle stop solenoid cause this problem?. Haven't changed out the carb...

The tranny isn't slipping at all...

what exactly do you mean the tranny bogs down? just that it slows down? if this is the case, it's probably not too big of an issue. just dont let off the gas and it wont slow down. im assuming that you have a turbo 400 or turbo 350, (probably the turbo 350) both of which are 3-speed automatics.
your bogging down effect is likely just the fact that these are only 3 speed trannies that cause you to be spinning at probably 2500 or more rpm's at 60 miles an hour. when you let off the gas, the motor just tries to return to idle rpm and is in effect engine braking. i used to drive a truck similar to yours, just it had 2 wheel drive and i loved how you could slow down quickly on the interstate by just letting off the gas and letting the engine slow ya down.

of course this explanation only applies if you have a feeling that it simply wont coast or something like that, if it is really slowing down bad, and it has never done this type of thing before, like you were slamming the brakes or something, then i have no clue what it could be...

if it is having trouble keeping up speed at part throttle, it may be a carburetor problem. i tried to switch out a carb on my truck for some other carb and it would only run strong at full throttle.

is the tranny slipping or anything, like it revs and then catches or whatever?

when I speak of bogging down, I actually mean lose of power. When driving the speed limit here of 55-60MPH the truck seems to lose power. The only way to bypass this is to:

1. Switch to overdrive - the "D" within the circle..
2. Change the tranny fluid - which will only last a month or so..

Will a faulty idle stop solenoid cause this problem?. Haven't changed out the carb...

The tranny isn't slipping at all...

when I speak of bogging down, I actually mean lose of power. When driving the speed limit here of 55-60MPH the truck seems to lose power. The only way to bypass this is to:

1. Switch to overdrive - the "D" within the circle..
2. Change the tranny fluid - which will only last a month or so..

Will a faulty idle stop solenoid cause this problem?. Haven't changed out the carb...

The tranny isn't slipping at all...

Well, if changing the tranny fluid ACTUALLY seems to fix this for a month, I guess I would not be too concerned with the carburetor and or idle stop solenoid at this point.

Guess I still don't understand why you say it seems to loose power. Do you have to keep giving more and more gas to maintain speed or what?

Change your Fuel Filters. You may have 2 of them.. one on the fuel line under the bed and one at the carb.

It sounds to me like the tranny is going into lockup.... That is 100% normal... in 84 even the TH350 had lockup solenoid..

When you are normally driving down the road the torque converter slips the transmission to keep power up. When you get on the highway and get to 60mph and maintain that for x amount of time it goes into what is called "lockup" it is hwere the torque converter locks and puts all the power throuhg the transmission.. This is mostly for fuel mileage and to keep the transmission temperature down.
If you don't mind running your transmission hot, you can disconnect the lockup on most 700R4's by pulling the 4 pin 1 wire plug on the drivers side of the transmission.. but if you don't mind it, leave it alone.. You'll get better mileage and your transmission won't heat up as much!

Change your Fuel Filters. You may have 2 of them.. one on the fuel line under the bed and one at the carb.

Where is the fuel filter located on the carb exactly?. I wouldn't suggest that it looks like the regular one thats attached to the fuel line..

It sounds to me like the tranny is going into lockup.... That is 100% normal... in 84 even the TH350 had lockup solenoid..

When you are normally driving down the road the torque converter slips the transmission to keep power up. When you get on the highway and get to 60mph and maintain that for x amount of time it goes into what is called "lockup" it is hwere the torque converter locks and puts all the power throuhg the transmission.. This is mostly for fuel mileage and to keep the transmission temperature down.
If you don't mind running your transmission hot, you can disconnect the lockup on most 700R4's by pulling the 4 pin 1 wire plug on the drivers side of the transmission.. but if you don't mind it, leave it alone.. You'll get better mileage and your transmission won't heat up as much!

This problem doesn't happen while driving the truck at cruising speed in overdrive. Only during while cruising using the "D". I'll unplug the connector and see what happens. If this is the case, is there any adjustments that can be done to fix this?...

The 700R4 still goes into lockup in D.. Theres not really much you can do other than disconnect it to keep it out of lockup..

Where is the fuel filter located on the carb exactly?. I wouldn't suggest that it looks like the regular one thats attached to the fuel line..

The fuel filter is much smaller in the carb, maybe the size of the tip fo your finger to the first knuckle. There will be a round screw plate (about an 1" in dia) on the side of the carb. remove the screw plate and the filter will be sitting there. On most carbs it is on the same side as the fuel line.

My 1989 full size blazer has the 700-R4 tranny and it does the same thing above 65 mph on the highway.Its just that when you press the gas the tranny shifts down into 3rd then when you let off it will shift back into over drive which slows the engine and trans down which also has to do with the tc lockin up and unlocking.Or atleast thats what it seems like with mine.When yours bogs down is it like that or is it like driving down the road in OD or D and then shifting down into 2nd where it goes to a lower gear and slows everything down?

The fuel filter is much smaller in the carb, maybe the size of the tip fo your finger to the first knuckle. There will be a round screw plate (about an 1" in dia) on the side of the carb. remove the screw plate and the filter will be sitting there. On most carbs it is on the same side as the fuel line.

Thanks for the location update. On my truck it has the fuel line attached to it. Checked under the bed for the in-line fuel filter and didn't see one. Didn't check for too long, but I followed the lines from the tank to the engine...

My 1989 full size blazer has the 700-R4 tranny and it does the same thing above 65 mph on the highway.Its just that when you press the gas the tranny shifts down into 3rd then when you let off it will shift back into over drive which slows the engine and trans down which also has to do with the tc lockin up and unlocking.Or atleast thats what it seems like with mine.When yours bogs down is it like that or is it like driving down the road in OD or D and then shifting down into 2nd where it goes to a lower gear and slows everything down?

It only occurs in "D".. in OD I don't have this problem at all. Checked under the hood this past weekend and found a broken vaccum hose that was making a hissing sound. Replaced the hose and it seems to run alot better. Still bogs down, but not harly like it was doing before...