1995 Sierra-Transmission clunk, power loss, braking issues

[Marauder_Pilot]

I recently picked up a '95 GMC Sierra 2WD for a work truck/town beater, and, considering it was next to free for me, it's been fantastic so far, especially considering it's almost at 350,000 KMs.

However, it's got three problems right now.

First is braking-I've noticed that it pulls a little to the right when braking, and that it occasionally leaks brake fluid from the front right brakes. (Pretty sure these are connected. ) However, I haven't had a chance to get it up on stands to take a look at the brakes, so I'm more looking for suggestions as to where to start here. It's not a serious leak, or a serious pull, so I'm not too concerned about it-I just don't want to try to stop one day and find myself with no brakes.

Second is a transmission clunk when accelerating. It only happens when starting from a stop, and not even every time, but sometimes when accelerating I'll hear, and feel, a thump or a clunk coming from below the footwell, about where the transmission is. Again, haven't had a chance to take a good look at it yet.

Third is intermittent power loss. It generally only happens when accelerating and switching between low gears-IE, I'll pull through a stoplight, and when it switches from 1st to 2nd (Or slow down through one and switch from 3rd to 2nd), it'll stop sending power for a second-the engine keeps revving just fine, it's not cutting out or anything.

Any ideas on where to look for these things? I'm betting a rotten brake line and a bad U-joint for the first two, but I'm at a loss for the third.

[Steve]

What's the maintenance history on this vehicle? I didn't catch if you said when it was last tuned-up and and you have looked at the fuel filters? I'll let others chime in on the specifics.

[Pikey]

I would check those brakes out right away. Pulling could be caused by stuck caliper slide pins, an easy fix. Just clean them and lube them. I am more concerned about the leak. I suspect that it is not leaking, if it were as soon as you press the pedal it would go to the floor and spray brake fluid. In a pressurized system, like your brakes, if there is a hole then the fluid takes the path of least resistance and leaves the system. I have never heard of or seen an intermittent leak on a brake system. It either leaks or it doesn't. The clunk could simply be that the slip yoke that slides into the transmission needs lubed. You would have to pull the drive shaft to do it correctly. At that point you could check your u-joints. But, reading about your "power loss" confuses my some. Are you saying that the rpms go up but the truck does not accelerate? If so, then you might want to have a look at the rearend. That could be the cause of your clunk and the power loss. If the gears are slipping then that would explain the rpms going up but the truck not moving.