Hello! I just took a 94 Silverado long bed on trade today, and noticed the brake lines are in dire need of replacement. I have the following questions though.

- Does this truck have ABS? I think some of them have rear ABS, would this make it harder to bleed all of the air out of the rear lines like in newer vehicles?
- What size line is used throughout the brake lines?
- Anyone know what size fittings are used?

Thanks!

 

- There’s a couple of different ways to verify if it has ABS:

1) Check the RPO label in the glove box and look for the codes that start with J. If the definition isn’t on the label, find it here - https://decoderpo.com/pages/J.html

2) Check for an ABS control module under the hood. It will be mounted next to the master cylinder or on the driver fender well.

3) Check for wheel speed sensors. If 4 wheel ABS it will have 1 at each front wheel and 1 on the rear differential.

It’s not the ABS on these trucks that cause problems, however. It’s the combination valve that regulates pressure between the front and rear brakes. It’s a very common problem when bleeding and some time ago I posted a write up on what causes the difficulty and how to bleed them properly. https://chevroletforum.com/forum/198...ickups-111386/

- All the lines will be 1/4” with the exception of the lines on the rear axle between the union fitting and wheel cylinders - those will be 3/16”.

- The fittings at the wheels will be 3/8x24 - they’re available for 1/4” and 3/16” lines. The fittings at the MC and ABS valve I’m not sure about.

If you’re looking to replace all the lines, I highly recommend checking the bleeder screws to make sure they’ll break loose for bleeding. If they’re questionable at all, save yourself the time/headache/hassle and just replace the calipers, cylinders, and hoses.

You may also want to consider a pre-made kit using stainless steel lines - Google for options - much easier and faster than making your own.

 

Thanks very much for literally answering every single one of my questions!

Would use premade line kit but I'm not sure how it'd work to be honest. The truck is a 1500 but the rear axle is heavy duty swapped, so not sure if a problem would arise there with the length of the lines.

Will definitely test the bleeders to make sure they open.

Will also look into the proportioning valve issue.

If it does have ABS say in just the rears, how would I even open the ABS valves to push to fluid into the rear lines? I dont know off the top of my head if any OBD1 readers have an autobleed function like OBD2, this is my first OBD1 truck.

Side note heres a video of the truck. Other issues is of course a slipping 3-4 4l60e(3-4 clutch pack), realized this after I made the trade for my old 05 tahoe. And also the engine has the slightest lifter tick or something, not worried about that.(Engine is a used unit with around 60k miles.)

 

It’s unlikely the axle swap would cause problems with line length, but if it really came to it, you could make only the rear axle lines and replace the rest with pre-made.

The ABS can be bled independently of the base brake system. Once the base brake system is bled, bleed the ABS, then bleed the base brakes again to remove air purged during the ABS bleed.

It’s recommended to use a Tech1 (or equivalent) for bleeding the ABS. I’d have to do some research but it’s likely possible to bleed it without a scan tool.

 

Ok thanks! If this truck has a simple rear only ABS system and I'm having a hard time with it, I will more than likely just delete the rear ABS system. It's quite simple to do from what I've read.

 

Well this is happening sooner than I thought! Inspected every brake line today and the rotted one from the rear abs pump[it does have rear abs] was the only rotted one. Just me touching it was enough, went to press the brake in the driveway and it popped on me. All of the other lines are good so I'm replacing the one for now. The fitting to the rear hose is rounded off, but the second half of the line is not rotted. So I cut to where it's good, flared the end and I put a union in. Now I just need to order a roll of line on amazon and I should be good to fix it. Was trying not to drain the master all the way, but it did, so I will bleed that as well. I am first going to try bleeding it with the pedal with flared lines going into the master. I'm worried about getting the air out of it, I owned an s10 and I had a super hard time with it, air was getting in through somewhere.

Also all the fuel lines are rotted and slightly leaking by the tank. Some rubber fuel hose will be the temporary fix until I get new lines.