Brake Pedal bump.

[MuddFlapp]

Here's a new one on me. The temp. dropped to the high teens here in beautiful rural 'Bama' and when I cranked my turck I noticed a "kick Back" on the brake pedal.
When I first start to apply the brakes there is a bump in the peddal. Hard to explain. It seems to get better as the truck warms up but never quite goes away. Also, if I pump the brakes lightly after the second time or so it seems to be gone until it "rests" for awhile. Anyone have any ID's. Other than this "bump" the brakes work fine.


Thanks GE.



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Gene Earl, White '97' 3500 Laramie SLT, Ext Cab, LB, 5 SPEED, 4. 10 Limited Slip, 4X4. Isspro Boost and Pyro, (pre-turbo), SW Fuel pressure, in a 3 guage A-Pillar mount. No muffler. K&N filter. (it's a start).

 

[illflem]

That's a good one Gene,could it be that your vacuum system is getting pressure somehow?Are the climate control functions working correctly when it happens?Water freezing in the vacuum system?It for sure sounds like a booster problem,but what?
All you got from me is questions,no answers,sorry.

 

[jkh]

Hey MUDDFLAPP,I have the same thing with really low temps. I'm one up on you though. I also have a loud whining sound that changes tone/gets louder when I step on the brake pedal. I think it is the power steering pump cause it changes tone when I turn the wheel too but I don't know why it does it when I step on the brake. I have been trying too figure out the brake pedal bump for a while now,glad I'm not the only one.

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1997 2500 4x4,Auto,Cal. e. g. r. (for now),3. 54's,Amsoil throughout,DiPricol egt/trans temp/boost gauges,ready for more power

 

[MuddFlapp]

Bill, I was wondering about moisture freezing in the system, also we had some snow with the low temps. The climate control is functioning properly and as of late the "bump" has gotten lighter. I wonder if it is drying out? Or maybe the gremlin is getting tired.

jhk, sorry but you're not one up on me. I got the same hum\whine the you are describing but forgot to include it in the original post. What were the weather conditions when yours first started? Maybe that's a clue.

Anyway, y'all let me know it you come up w\any ID's & I'll do like wise.

Thanks, GE


[This message has been edited by MuddFlapp (edited 12-22-2000). ]

 

[illflem]

Gene,did you catch this thread? https://www.turbodieselregister.com/ubb//Forum17/HTML/001168.html

 

[jkh]

Gene,
The weather conditions were in the low 20's and clear. That is the only time it does it,when it gets down into the low 20's. I'm pretty sure it is the power steering pump making the noise ,I just don't know why it does it when I apply brakes unless its because the engine comes down a few rpm and it makes the noise more pronounced. I'll keep investigating to try to get a real conclusion.
P. S.
The brake bump is a real treat in a panic situation isn't it. Happened to me this a. m. Grabbed a foot full of brake and it kicked back at me before it worked. #ad
Kinda stops your heart for a split second.

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1997 2500 4x4,Auto,Cal. e. g. r. (for now),3. 54's,Amsoil throughout,DiPricol egt/trans temp/boost gauges,ready for more power

 

[dieselshadow]

Sounds like a huge safety concern. Anybody call DC or take it to the dealer?

 

[Midnight]

Guys replace your p/s fluid and the problem will disappear. Its gets dirty and thick with age. Some new fluids are thicker than others. I have used Valvolines pyroil brand with much sucsess. Good luck.

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[yooper]

I haven't noticed any problem with my brakes, but have had steering shaking at slow turning speeds and the groaning noise from the pump when it's 20 degrees or colder. From what I understand, 97's on up use the power steering pump for power brakes, instead of vacuum. I had to replace my steering gear and thought about replacing my pump too, but I didn't. I have one of those suck/pump guns (looks like a grease gun) used for filling differentials. Every time I change my oil I suck out 10 oz or so and replace it with Valvoline half & half syn power steering fluid and it has improved.

 

[jkh]

Thanks "yooper",for the info. about the power steering pump working the power brakes. That explains the same noise whether I step on the brakes or turn the steering wheel. I have to go get that valvoline synthetic steering fluid. Thanks for the tips!!

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1997 2500 4x4,Auto,Cal. e. g. r. (for now),3. 54's,Amsoil throughout,DiPricol egt/trans temp/boost gauges,ready for more power

 

[Kunze]

My truck doesn't do it but I've seen this with my parents' truck. Since mine's a '94 and theirs is a '99 I think it must have something to do with the brakes using the power steering pump. Theirs doesn't have any other noise to go with it though #ad
. I'll suggest the synthetic fluid to them if they get anything done on the steering system and thanks for the info yooper.

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'94, 2500, 4X4, SLT, 3. 54 gears, Prime Loc, Silencer ring in the tool box, DeeZee bright tread running boards, side box boards and mud flaps. Alpine CD player. I cleared 100K mi while the board was down. Jardine Performance 4" exhaust (sounds just like a Pete, it's great) Schied Diesel put timing to *15 (by timing light), put gauges in on the A pillar (trans temp, boost, and egt) They also set my stock plate up (40 hp 150 ft/lb gain) OH, what a difference a day makes

 

[MuddFlapp]

Problem disapeared When I changed my PS fluid. I didn't have anything on hand but Hydrolic oil for my loader so I used that until I can get some Valvoline Syn. and change it again.