Dodge Diesel Brakes

JimS · Nov 29, 2014

Tonight when driving home my brakes failed on my 1990 Dodge Ram 250 diesel.

My pedal became extremely hard, braking dropped off to almost nothing, and the "brake" and "anti lock" warning lights came on. Fluid levels are fine. Any thoughts are appreciated.

JimS

JD Seller · Nov 29, 2014

Master cylinder. I have had to replace the one on my 1990 Dodge W350 3-4 time since new. The only good thing is that they are not that high of price anymore. I think around $75-85 new not rebuilt.

4play · Nov 30, 2014

Check the vacuum lines and pump, you can unplug vac line from booster and see if its pulling vacuum with the engine running, if not follow line to pump.

MikeJM · Nov 30, 2014

2nd that, check your vacuum lines, then check your vacuum pump make sure that's pumping. Sometimes those diaphragm type pumps fail. If you have vacuum to the booster, check the booster for leaks.

JDemaris · Nov 30, 2014

Rock-hard pedal, brakes working, but weak is the vacuum booster not working. If it's the pump a new vaccum pump is $80 IF you have the 5.9 with no intercooler (vacuum pod like a Chevy or Ford). If you DO have an intercooler - vacuum pump is piggybacked on the injection pump and $250. New master-cylinder (new, not rebuilt) is only $40.

D7fever · Nov 30, 2014

I thought the brakes on those trucks are hydraulic assist, it is on my 1998 and 2000

fixerupper · Nov 30, 2014

I'm pretty sure my 98 is hydraulic assist too. When it runs low on power steering fluid the brakes get funny. Maybe the earlier ones were vac.

JDemaris · Nov 30, 2014

I have a 1992 W250 with the 5.9 intercooled Cummins diesel. Has vacuum brakes with the vacuum pump attached to the back of the Bosch injection pump.

MikeJM · Nov 30, 2014

As far as I know and I know because we've had just about every year dodge diesel. 97 or 98 was the first year for hydraulic brake boosters.

The vacuum pump has never been attached to the injection pump. The power steering pump has been piggy backed on the vacuum pump for all years up to 2002. 2003 common rails are a different animal.

JD Seller · Nov 30, 2014

With the anti-lock and brake light on it would not be the booster. I am pretty sure it is the master cylinder as mine acts this way when it acts up.

Being a 1990 dodge diesel it has a vacuum booster. The vacuum pump is driven of the timing gears under the injection pump.

Also the anti-lock is just on the rear brakes as this is a first generation anti-lock. So there is no sensor that would monitor brake boost.

Cowmechanic · Nov 30, 2014

Sounds like vacuum booster or vacuum pump went out.Also check for vacuum leak between vacuum pump and brake booster.Like other posters said vacuum pump mounts directly to engine and power steering pump is piggybacked off of vacuum pump.I have a 91 and a 92 5.9 cummins.Same setup just different styled vacuum pumps.

MT RON · Nov 30, 2014

I had a 90 and had to replace the booster on it.They never had brakes to start with,I unplugged the wires that go to the rear brakes anti lock located over the left rear axle,put tape over the light and had better brakes after that.Ron

JimS · Nov 30, 2014

Thanks;

I did not have a vacuum pump handy. I pulled the large vacuum line to the booster and could not feel a pull. I put it against my cheek,face cheek, and felt a very slight pull. With the engine off, I blew gently in the vacuum line and heard a kazoo like sound. I think you are right.

Dodge Diesel Brakes

JimS

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JD Seller

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4play

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MikeJM

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JDemaris

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D7fever

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fixerupper

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JDemaris

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MikeJM

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Cowmechanic

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MT RON

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JimS

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