1999Tahoe 5.7 soft pedal brakes - solved

[d_w79]

(I posted this recently as a reply to shawnkfl then realized it should be a thread).
My experience on the soft pedal:
Have had my 99 Tahoe for 10 years and have spent well over $2,000 to several shops and shade-trees trying to solve the low, soft pedal. Booster and master cylinder replaced twice and all the other things mentioned here. One shop told me that all these tahoes have low soft pedal and that is normal!
I always had drive line 'clunking' on stop and go.
So, for my money I got Nothing!
I checked the booster hose connections for vac tight and found it was easy to turn on the booster connection. There was the little spring clamps that wouldn't compress a kleenex. I put on a 'real' clamp and now I have high, firm brake pedal, the clunking is gone, and the engine is peppier and smoother. Now I have to find a way to get in to the engine end of the hose and change that one. (Got it done and all is Fantastic, including increased engine power) Hope this long story helps some save $$ ...dw

 

[Slammed]

Not sure how this stop's the drive line clunk?

 

[d_w79]

Only thing I can figure is that I had a constant vac leak that affected the engine performance. To me that makes sense while on the brake, but the increased power indicates I had a constant vac. prob.

I am by no means a mechanic so I just had to try something and it worked. After ten years it now feels like driving a new Tahoe - sure hope it hangs in! ...dw

 

[Mr_smiles]

I have the same problem. Can you walk me through it please, before i spend money on new brakes. My level of car knowledge is minimal, but pick up quickly. would be much appreciated.

 

[d_w79]

You betcha. I don't know much either but it worked for me! Go to your Brake Booster and see the vacuum hose coming to it from the engine. Mine had a skimpy little spring clamp there that allowed me to spin the vac hose on the booster connection. I removed that and put on a regular hose clamp and screwed it down until I could no longer twist the hose on the connection. I went ahead and did the other end connection to the engine. You have to raise the breather to do that one - it is not handy but you can do it.

 

[lesterl]

The spring clamps put equal pressure all the way around whereas the worm drives have a small extra pressure point below the screw that can crack plastic and cause leaks.

You wouldnt have had enough of a vacume leak there to cause those issues, bet you knocked something else back into wack when you were working on it....

 

[Mr_smiles]

Thank you both. I will try that and let you know how it works out.

 

[d_w79]

Problem with that Lester is that I hadn't been working on it.

Maybe I should better clarify the full story:
Booster, Master cylinder, Linings, the whole kabash has been done over and over thru the years!!

After 6 days in the shop and writing a $446 check the Owner told me that low, soft brake is 'Normal' for Tahoe. (I knew that was not true)

I asked him about the loose hose connection and he said that is no problem!
I didn't believe that and I knew it was too dangerous to continue on in our heavy traffic. I stopped by AZone and got a pair of clamps.
That hose is heavy wall and as I said before - 'tighten just to where it no longer twists'.

Nothing else was done or touched. Immediately on startup the brakes were firm and very high. My driveline clang is 90% gone. An added bonus is the engine is very noticably 'smoother and peppier'!!

There is no other explanation but that I have been losing an excessive amount of vacuum at that one point, for 10 years and 'over' $2,000 shop charges.
Hope it works for someone else. ...dw

 

[lesterl]

May have to check mine, you said the hose on the check valve to the booster was loose?

 

[d_w79]

Hi Lester, no check valve. It is where the vac hose slips directly onto the nipple on the side of the booster. That nipple has a 'raised ring' (?) with the spring clamp behind it as a retainer.
I was one happy lad when I cranked up and found I have a new '99!!
Take care my Friend. ...dw

 

[MarkD51]

Hi Lester, no check valve. It is where the vac hose slips directly onto the nipple on the side of the booster. That nipple has a 'raised ring' (?) with the spring clamp behind it as a retainer.
I was one happy lad when I cranked up and found I have a new '99!!
Take care my Friend. ...dw

Now this is something I cannot quite understand here?

As far as I know, your 99 Hoe uses the exact same power booster as my 97 does. And that there is only one vacuum line going to that booster, no more. That Vaccum Hose inserts into a right angle plastic check valve which inserts, and enters the front left face of the booster, correct?
Mark

 

[lesterl]

Yeah, I decided to abandon the argument, it was going no where with the check valve.... kinda pointless....

 

[d_w79]

Yes Mark you are correct all the way. I can see now that would be a check valve the hose connects to. Sorry about that, I made it clear I'm no mechanic so now I have proved it! ) ...dw

 

[d_w79]

My goof Lester. That would be a check valve the hose connects to.
I have good high brakes and a peppy engine - first in ten years and that is all I know. I do not know why but Ill take it. ...dw

 

[lesterl]

Was it leaking hose to check valve then?

 

[MarkD51]

No Doubt with vehicles that are our age, every rubber (and many plastic) parts begins to rot, harden, deteriorate.

This is something I myself will probably, and should address in the next coming weeks, going through my Tahoe, inspecting, and at least treating all of the rubber, cables, hoses sheathing, etc under hood and elsewhere on the vehicle.

Last year I did re-do all Coolant lines, what a PITA! And a new Serpentine Belt when I had the AC Compressor replaced.

I've got a lot of pretty good products on hand, like CarPro Perl, Wolfgang Exterior Trim Sealant, Opti-Bond Tire Gel, Ultima Exterior Trim Sealant. No, no Armor All, I'll never use such again on anything.
Mark

 

[d_w79]

Was it leaking hose to check valve then?

Yes Sir - at the check valve.