Off the road '96 2500 V10 running again *no brakes*

[lloydh]

I've just got my 1996 Ram 2500 V10 4x2 running again after nearly 3 years off the road.

After an oil change, new spark plugs and some fresh gas the engine started right up and seems to be running sweetly. Unfortunately the same can't be said for the brakes.

The brake pedal feels extremely light (continually, after numerous presses) and even stomping on the pedal doesn't stop the rear wheels from spinning (fortunately the vehicle was on axle stands when I learned the brakes weren't functioning).

Is it possible that the brakes just need bleeding or am I likely facing a bigger problem here? What should my next step be in diagnosing the problem?

For reference my 2500 has barely done 30,000 miles, despite her years.

Thanks.

 

[SmokedRam]

Pull the wheel and drums off the rear and check for broken wheel cylinders...I'd have to look up the part number on another forum for you, but you can run GM wheel cylinders in the Gen2 trucks and drastically improve your braking performance.

 

[Hotroder383]

Start by pulling the drums and looking for leaks, same with front rotors. Check fluid level and start with a bleed down. Furthest wheel first working closer to master cylinder. From there it gets a bit more in depth and I am not the one who can explain it all on screen. sorry =/

 

[lloydh]

Thanks for the replies.

I had a chance to inspect the brake system earlier and took some photos.

It does look to me as though the left rear wheel cylinder may have leaked from the gasket/boot. Saying that, there wasn't any brake fluid on the components beneath and the master cylinder reservoir level is fine.

SmokedRam, thanks for the tip about GM wheel cylinders. I found this forum thread and some GM 1 ton WCs look like they would be a nice upgrade; I'm running wider street tires than stock so the added traction should also mitigate locking.

Even assuming a slight WC leak, I'm amazed that there's no brake pedal at all - not even enough to stop the wheels spinning in neutral... and the MC reservoir level is normal. Would air in the brake system from a leaking WC make it to all of the brakes, making them effectively useless?

The red "BRAKES" dashboard warning light stays on - I should probably look into what sensor triggers that.

I checked over the MC, brake booster and the lines I could see but found no leaks.

A little rust but no wetness.

I had my dad watch the MC and brake booster as I depressed the brake pedal and he said that when I held the pedal down firmly (at the end of it's incredibly spongy travel) the booster's cover and the MC would visibly contract inwards under the vacuum - no strange noises. To me, this and the light pedal suggest that the booster's still working.


I noticed that the 98+ 2G Rams used a different MC design with a more standard round reservoir cap and also a larger capacity. I remember reading that they aren't directly compatible with the pre-98 brake booster but, if necessary, could the newer 98 MC and brake booster be installed together on a pre-98 Ram?

Thanks for any insight you can provide.

 

[Bigtman07]

It might be a long shot but pull the abs fuse. It looks like you have the rear abs only system. If you pull the fuse it will go to normal power brakes. I'm just wondering if the brake controller isn't allowing the rear to activate.

 

[Mopar1973Man]

It might be a long shot but pull the abs fuse. It looks like you have the rear abs only system. If you pull the fuse it will go to normal power brakes. I'm just wondering if the brake controller isn't allowing the rear to activate.

My 1996 Dodge 1500 is the same way if the truck is on jack stands and you mash the pedal the brakes will slow but never stop the rear axle. So if you disable the RAWL system then you'll see the rear axle lock instantly.

 

[lloydh]

It might be a long shot but pull the abs fuse. It looks like you have the rear abs only system. If you pull the fuse it will go to normal power brakes. I'm just wondering if the brake controller isn't allowing the rear to activate.

I do actually have the 4 wheel ABS option (TBH only discovered this when I got a build sheet from Dodge last month, but I double checked). If there's a chance that pulling a fuse could fix the brakes (or at least diagnose the problem area / rule out fundamental hydraulics) I'm up for giving it a go. Pulling fuse 14 20A labelled "RWAL/ABS" in the cabin fuse box should do the trick, right?

I checked the service manual for causes of the brake warning lamp:

The purpose of the switch is to monitor fluid pressure in the separate front/rear brake hydraulic circuits.

A decrease or loss of fluid pressure in either hydraulic circuit will cause the switch valve to shuttle forward or rearward in response to the pressure differential. [...] This closes the switch internal contacts completing the electrical circuit to the warning lamp.

I guess a loss of pressure could be the result of a leak but it could also be ABS-related... and I don't know whether a master cylinder failure would have this result.

 

[Bigtman07]

That is a good question.

I feel for ya though. I also have the awabs. It should be a 40A under the hood marked ABS

 

[lloydh]

OK I'll give it a shot tomorrow. Thanks for your help.

 

[lloydh]

I pulled the 40A fuse and ABS relays in the PDC as well as the 20A fuse in the cab (which I think is just for problem code retention). Unfortunately it didn't make the rear brakes jump back to life or change the pedal feel, but worth trying nevertheless.

My dad was on hand to help out again so I had him press the pedal while I listened to the rear brakes. As before there was zero wheel cylinder movement but I could hear a gurgle from both sides. I'm starting to think that it might be as simple as a lot of air in the brake lines in conjunction to a WC failure as SmokedRam suggested. I guess a good flush and bleed is in order.

Regarding the front brakes, do you guys think that the rust on these discs will clean up with use or will they need some work or even replacing?

I also noticed that the exposed portions of the front caliper pistons are looking a little crusty even though the dust boots seem OK. Presumably that shouldn't be a problem so long as the area of the piston in contact with the seal isn't rough?

Thanks again.

 

[Bigtman07]

I think the discs will clean up great. I don't see an issue with the calipers.

A Good bleed won't hurt at all. flush the whole line and you should be good to go.

 

[Mopar1973Man]

Good gawd! That a heep of rust wow!

Here is the proper way to bleed them out. Disassemble them, wash them out, put new seals in, reassemble, and then bleed.

Because if you don't break down the callipers the dirt settles to the bottom of the calliper with the water and then start rusting them out. As you can see mine are factory fresh. Every 60K miles they get broke down and cleaned up.

 

[lloydh]

I think I could probably get away with just bleeding the callipers but I'm going to have to break the front end down before too long to install new lower ball joints so I suppose that might be a good time for an overhaul. When the time comes I might shot blast and paint the callipers to hold off rust in future.

Should I order new pistons as well as a seal replacement kit or is that unnecessary?

Also, are there any other bits I should be ordering in relation to the front callipers or rear wheel cylinders? New bleed nipples? Special bolts? Special washers?

EDIT: I'm seeing alternative parts for '96 2500 (7500lb GVWR) and 2500HD (8800lb GVWR). I've never seen my truck referred to as a 2500HD or its GVWR - which parts should I be looking at? (I mainly ask in case the V10 uses 'HD' parts). Thanks.

 

[Bigtman07]

Th v10 may be a HD version. I know they made the 2 versions but have never seen where they distinguish between the 2. I would go off the GVWR.

 

[lloydh]

I found out from the driver-side doorjamb sticker that my truck's GVWR is 8800lb and the sales code for "GVW/Payload Rating" on my build sheet is Z2BS. I think this makes it a 2500HD.

Then I found this TSB which specifies the different size calipers used across the Ram model range (75mm, 80mm and 86mm).

It seems all 2500s have 80mm calipers except for the 4x4 8800lb which uses 86mm calipers (same as the 3500s).

I'm now thinking that I'll pick up some remanufactured calipers (most likely ACDelco / Raybestos) because they're pretty cheap and it saves me having to clean up the stock ones.

 

[Bigtman07]

Well have at it bud. I hope that helps you out. Let us know how it turns out.

 

[lloydh]

Removed and stripped a caliper today, confirming that it's 80mm.

Oddly the mounting pin bushings/bolt seals on the stock caliper look like the 75mm caliper (fitted to 1/2 ton trucks) as depicted in the service manual.

My caliper (note the bushing design):

Service manual:

Weird, right?

Hopefully the mounting points are the same so whatever bushings I get on my reman. calipers will work OK.