gte718p

I have a really basic question. I've never wheeled an auto before and would like to know if this is normal or not.

My truck is an 86 4runner with the auto. Should it have any compression braking in 4 low. I lost my brakes going down hill and almost lost the truck. I know there is no direct connection like on my manuals, but it seems there should be some fluid resistance. I had absolutely none.

I'm also having a problem going up hill. Level ground it works great. As soon as you put it on an angle, I loose all power. The engine spins and spins, but its is not even trying to turn the drive shafts. Fluid is full.

Schnayke

iTrader: (1)

I'm interested in this discussion so that's mainly why I am replying.
However as long as I turn off overdrive on my ford focus it has compression braking and is an auto.

yotayes88

Had this same problem in a bronco i owned a while back. Only owned it for about 3 days before i jumped it and rolled a few times. So i never figured out what the issue was.

Kiroshu

Sounds like we have two separate issues at hand.

Intermittent brake system and Automatic Transmission faults.

Brake system fluid level correct..?

Verify no brake system lines/hoses/hydraulics are leaking brake fluid and or damaged.

Verify linings and friction surfaces are in good condition.

Brake pedal assembly damaged..?

Brake booster assembly fault..?

Any other symptoms with automatic transmission assembly..?

Does it pull well during all other ranges..?

The automatic transmission assembly may be "tired" or worn out internaly.

Poor tourqe converter operation..?

Fluid level incorrect..?

Incorrect fluid type..?

Fluid filter..?

Engine throttle body assembly fault..?

JasonYota

iTrader: (1)

An auto will compression brake to an extent. Will it slow you down to idle? No. How fast were you going on 4lo? Did you have the transmission locked in 1st? Did it actually hold 1st?

Gevo

Yah, I use 4lo transmission/engine braking ALL the time while descending steep hills in the dirt. It's a must!

gte718p

I didn't really address the brake failure in this thread. I wrote a little more about it in my build thread. I strongly believe the brake issues are with the load sensing valve. I have great brakes on level ground and going up hill. It will lock the tires at 60 mph if you step on it. It is only going down hill that I have an issue. Lines are in good shape. I had it apart last week when I installed the locker. New fluid and no air. Shoes could be replaced, but are well within wear limits. Pedal has a good feel on the level, but goes to the floor on steep downhills.

For the transmission, it is not leaking. It was however a little low on fluid. I also managed to overhead it. I filled it with the correct fluid and it got better, stopped overheating, but still not right. Now that I'm home I'm going to drop the pan on the trans and transfer case. I'll dig in the FSM tomorrow., but any suggestions on things to check? Truck has 245k on it. I don't have the full history on the truck it is entirely possible that the transmission is worn. I just don't have a good baseline on what normal should be.

gte718p

I wasn't really watching, but it was over 30. It was in low, I didn't feel a gear change, but I didn't feel any drag either.

JasonYota

iTrader: (1)

Definitely shouldn't go that fast in 4lo. What was your RPMs? I'd make sure the transmission is holding in gear.

gte718p

Its a base 4runner. I only have 3 guages. Unfortunately a tach is not one of them.

RJR

It sounds like it didn't stay in first gear, but shifted up into the higher gears. Otherwise it's unlikely you could have hit 30mph. 30mph in first gear on an auto tranny in lo range would be over 7000 rpm. You'd have carried the engine home in a basket if you did that.

Are you sure you had it pulled into low gear, or was it still in drive?

I drive a manual for my offroading these days, specifically because I like the better downhill speed control. However, I have wheeled with automatics in the past, and generally found engine braking to be adequate when forced into a low gear, although not nearly as good as with a manual. Where the auto really fails you is if the engine dies. Without the front pump working, it's pretty much into free wheel mode. Couple that with the loss of your power brake assist and it gets exciting real fast on a steep downgrade shelf road with a 1000 ft dropoff off the side and a 3-point hairpin turn coming up.

gte718p

I'm sure the shifter is in low, I'm not sure low was actually engaged.

I prefer manuals. My crawler is a 5 speed with double a double reduction box. I rarely even use the brake on down hills. Unfortunately this truck came with an auto. I built it for the wife and she likes the auto so it is most likely staying.

RJR

Understood. Sounds like you're plenty experienced and know what you're doing on the trails - sorry if I seemed like I assumed otherwise.

I think I'd take it out on a quiet highway, accelerate to about 40 mph in 2wd, and progressively pull the shifter from "D" into "3", "2", and then "1", waiting for it to slow down appropriately for each shift. You should feel significant engine braking each time you downshift. If it refuses to downshift, then you have some troubleshooting to do. There are controls which prevent it from downshifting, even manually, if speed is too high - could be something wrong with that part of the system.

gte718p

Did this. However, I only have D, 2, L. Anyway at 35 mph shifting to 2 nothing, shifting to L nothing. Did it a few more time occasionally when I shift to L it drags. There is not a lot of drag, and it doesn't happen consistently.

I also tried it in 4 low. There is no difference in 2 High and 4 low which seems to reinforce the idea it is not engaging gears. I'm also getting some god awful noises out of the tranny/transfer case. It is s clicking/creaking sound. It sounds like an auto locker that is clicking when not engaged.

I also checked the fluid. I'm overfilled a little. Color is good, it smells a little burnt, but not horrible. I'm still going to change it and drop the pans this week.

JasonYota

iTrader: (1)

If it smells burnt change it ASAP. You might get lucky and it didn't do any damage.

gte718p

at this point I think damage is a given, it is only a matter of how much.