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95 Chevy 1ton possible steering issues.

dbrannon79

I'm getting there!
Messages
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Location
Seguin, TX
Hey guys I started talking about what I think is a possible steering problem on my truck in another of my threads, so a started a new thread here. So here goes...

I bought this truck a little over a year ago, when I got it, it had all kinds of power steering leaks. At the same time the steering was a little tougher than I thought was normal to steer plus the brake pedal was also stiffer than what I was used to, but this is my first truck that has a hydro boost and that is a diesel so I just figured it will feel different than a gas 1/2 ton pickup. to give an example of how the brake pedal feels is I get so used to it and when I get into my wife's car and everyone that doesn't put their seat belt on gets to kiss the windshield lol

anyway, throughout a period of about 6 months, Ive replaced the steering gear three times, the booster twice, and the PS pump twice all due to them leaking (warranting the other out). something I do remember on the booster was the OE one had a little tube on it jumping from one port to another on the top that the one I have now doesn't have, not that that is important. And I did get these parts from the local auto parts house before I knew better than to get remanufactured units. all the while replacing these parts, the leaks are now stopped but the steering and brake pedal stiffness hasn't changed a bit.

I know this is a long bed 4 door heavy pickup and it's got 265-75-16 tires on it so sure it's gonna take a little more work from the PS pump to make the tires turn. but to me it just doesn't feel like it should.

another thing I noticed just yesterday is that I had gone into town, parked in a parking lot and shut off the engine while I still had my foot on the brake pedal, as soon as the engine was off the pedal sank to the floor with the weight of my foot! I did release it, came back up, tried pressing the pedal again with the engine off and it was hard and stiff as I would expect without the motor running.

I don't have access to a PS pressure tester or flow meter but I'm really not sure if these trucks are just the way they are or there is something possibly not up to par like the PS pump not having enough flow.

I've been doing a lot of reading in several forums trying to find info on this sort of problem and discovered that apparently GM made a P185 pump for heavy duty applications. but by application for mine shows the P135 pump. the only difference that I can find online between the two is the end cap on the back side of the pump is ether concave or convex having larger internals. both of the ones I've replaced were concave. not that this has anything relevant to my truck, I might be barking up the wrong tree here.

with the symptoms I am seeing and seem not to feel right, I wanted to inquire on others who drive these 1 ton mile long rigs and see how their steering and braking compare to what I'm seeing and to how a smaller 1/2 ton pickup is. frankly you can but it's harder to steer it with one hand let alone try a slight turn on the highway with your fingers. I know the PS pump is working because you really have to use both arms and body weight to steer with out the engine running lol

other things Ive done that relate to steering and brakes, I have already completely rebuilt the front suspension ( 2WD ) and replaced all the front and rear brakes.

below is a couple of photos of what my original booster looked like and the reman one I have now looks like. notice on the first photo there is a tiny bypass pipe that my OE one had and the reman unit doesn't. could this missing piece be part of my problem?

OE booster.jpgreman booster.jpg
 
What is the GVW on the driver door label? 8600? Also look in the glovebox for the RPO option codes. There is a light duty and heavy duty brake system out there. Different hydro booster depending on what system was used.

It's a mistake to compare your truck to "not HD trucks of this era". They are not exactly a light touch to drive. The feel hasn't changed from the leaking stuff being changed so I suggest it's normal.

The hydrobooster has a reserve so if the engine stalls/blows up/quits you get 2-3 presses of the brake pedal from the accumulator. (Same as the vac booster reserve 2-3 assisted brake applications. ) It's the round gold can looking thingy on the lower left. It does some weird stuff during engine startup and shutdown if you have your foot on it. For example if you are stopping and cranking a dead engine over that decides to start runing the PS flow and pressure come up so you have full stopping power. This puts people and cargo into the windshield.

To test the hydrobooster accumulator: start the engine, stop the engine. Press the brake pedal and fully release it 4 times. Did you have assist for at least 2 pedal presses? No: the hydrobooster is bad. (and is a ticking time bomb going off if the engine stalls.) You need to test this frequentaly to make sure it don't quit on you before you need it. Use the reserve wisely during a stall: step on the brakes once and then keep your foot in em till you stop.

Have a plan for an engine stall and know what to expect from your vehicle capabilities.

The hydrobooster is "first in line" for PS flow and pressure. Stomping the brakes and holding them down can make it harder to steer.

Does the steering wheel turn easier one way than the other? Yes: the steering box is a internal leaker.

What specific oil you pouring in the PS system? It matters.
 
I attached a photo of the door sticker for the GVW, it shows 9,000 on the sheet I have. the RPO codes I saw (had to get the sheet from the dealer a while back since my glove box was missing) shows JB8 and a code 92 for brake pressure modulator. I can post the sheet I have if needed. truck has a single rear wheel full floater rear with 13x3.5" shoes if that info helps.

I also forgot to mention that on stopping power i feel as if my rear brakes aren't working great but I have jacked up the rear and they do stop. holding the pedal a little bit and the rear will start to slowly turn while in gear in the air but the pedal doesn't bleed down. I've double checked the adjustment. it just feels the power isn't there. brake fluid is there also when bleeding them. ABS unit is disconnected too. (I did that since front right wheel sensor is bad. I was reading somewhere about a recall or TSB on the proportioning valve issue but I can't find where it was. Probably need to take it to a shop for the rear brakes.

Door Sticker.jpg

I will have to do that test on the booster and see what happens.

the steering isn't harder to turn one direction than the other that I've noticed

on the fluid, I've used the "house" brand from Advance Auto. it did show compatible with GM. I will have to find a bottle to get the spec. although I was in there the other day and my buddy who works there was telling me they just replaced all their "house" brand oils with the Fram crap. power steering, brake and coolant included.

I have been reading in the how to's and read Thefermanator's thread on flushing the PS system. I may do that this weekend. also about to read up on using synthetic fluid and good and the bad on it.

on a curious note, the two boosted I posted a photo of... what is the difference between them or what is that little tube on the return port that my original one had?
 
I just researched online what JB8 was and it's specs. didn't say anything about the hydroboost type but it did say I should have a MC with a 1.312" bore. I can easily check that. when I did the brake job, I found that one wheel had the smaller bore wheel cylinder (1-1/16") and the other wheel had the larger dually wheel cylinder (1-3/16") I replaced them with the 1-1/16" bore that Advance showed for the SRW trucks. maybe I went wrong there too!

here's the specs I found searching online...

JB8 (10000lbs)
1.312" Bore MC
Conventional Calipers 3.4" piston
Front Disc- 12.50x1.54
Read Drum- 13.00x3.50
Hydraulic Hydro Boost
1 3/16 rear wheel cylinder
 
TSB on the proportioning valve

This was for Suburbans and put more pressure to the rear. I don't know if it applied to crew cab pickups. That is also a higher GVWR rating for the crew cab than what we commonly see. YMMV as you have a crew cab as to what GM used for brake parts. However the following thread explains brake options and those rear cylinder diameters.

 
As far as the brakes go, would anyone have a link or know what I need to search for in finding the TSB's for the proportioning valve on the Burb's also for others that might pertain to my truck without asking at the GM dealer? Reading Thefermanator's thread WarWagon linked. I need to make sure all that is good before I do anything like swapping the wheel cylinders and such.
 
TSB 99-05-24-001A

And maybe you are throwing good money after bad... Maybe go with a GMT-800 brake system.
 

Attachments

  • TSB 99-05-24-001A.pdf
    66.9 KB · Views: 3
Thank you @WarWagon

ya know, just reading into that TSB, I do get the slight pull to the right or left at times when coming to a stop. I need to research these part numbers in the TSB and see what I used when I did the brake job. also look and see what valve I actually have on the truck. would anyone know where to look for the GM # on the valve? I have been told that it's built into the ABS unit next to the MC on the drivers side fender.

I'm thinking that since the valve is only for the Burb's and not pickups I shouldn't need to worry, but its always nice to verify numbers and knowing what is on your vehicle. I think right now the cheapest and easiest thing I can do is first verify part numbers, verify the PO hasn't replaced the MC with the wrong bore since when doing the brakes I found mix matched wheel cylinders. then also replace all three brake hoses before doing anything else. that's the one thing I didn't do when I did the brakes. re-bleed everything and go from there.


:banghead: yes, I know, don't tell me. the one thing I didn't replace can be the cause of all my problems. at least for the brakes that is. I should know better.
 
Come to think of it. A guy over here had a SB chevy pickup that one time had a 6.2 diesel in it. His MC went to leaking. He goes to tje parts store and gets a reman MC, has a fair decent mechanic install and bleed it. His brakes are always mushy, bleed, bleed and bleed some more. He has the mech remove that MC, takes it back and exchanges it for another one. Same problem.
Wifey talks me into helping him out, against my better judgement, she nags until i finally give in.
Removed the MC and took it back to the parts store. It took about five attempts before i got through to the counter man that this is not a vacuum boost, this is a hydro boost diesel. He had to order for next day.
Got the correct MC, installed it and his brakes was good from there on out.
 
That's a good one. it's very possible I have the wrong parts on the truck. this reminds me of all the crap I've done in the past that has backfired on me and yet I still don't learn.

Around my town everyone that goes to the auto parts stores always get the cheapest part they list. I'm guilty of that myself! and let me think a minuet... how many time have I kicked myself on the hind side for it.... I lost count, and yet I'm still guilty of doing just that lol
 
That's a good one. it's very possible I have the wrong parts on the truck. this reminds me of all the crap I've done in the past that has backfired on me and yet I still don't learn.

Around my town everyone that goes to the auto parts stores always get the cheapest part they list. I'm guilty of that myself! and let me think a minuet... how many time have I kicked myself on the hind side for it.... I lost count, and yet I'm still guilty of doing just that lol
Check the part number for the MC that You have, then check with the PH to see what number they list for the hydro boost system.
If You have a part number for the installed unit.
If not, have them get one in, take off Your MC and haul it into the PH and do a comparison.
You will be able to see the visual differences if Yours is for the vacuum boost unit. I dont remember what the differences was but You will be able to tell.
If You have the correct unit already, have them send the one they ordered in back. Parts stores here does that without a complaint.
 
well, got home this evening and decided to do two things. test the booster and pull the MC back and try to identify it.

and.... well I'm not sure that my booster is working properly, at least siting in the driveway with the engine running and pressed on the brake pedal a couple of times. let off and waited a few moments and shut the engine off then stepped on the pedal with the same force. the pedal go down almost the same but took a little more force to get it down where it was while the engine was running. I pressed it the same a few more times with the engine off and it felt the same each time. a little more force to get about half way down.

so I cranked it up and drove down to a back street in the neighborhood. got the truck up to about 25mph, popped into neutral and shut the engine off. stepped on the pedal and I had to give it significantly more force to feel the brakes grab. I let off and did it again a couple more times before I slowed to a craw and the pedal force was the same, putting lots more force to feel the brakes grab.

My conclusion is the booster isn't holding any pressure.

got back in the driveway and unbolted the MC and drew if back off the studs, used my handy caliper ruler to measure the bore on the piston. 1-1/4" or 1" and 8/32" on my ruler.

I found a number stamped on the front nose of the MC that reads MF 8212 but I can't really make out the "8" . I looked up the application on Advance Auto and they only show one that has the same size bore, but when you look at what other vehicles that same MC fits, it shows other trucks with 350 and 454 engines, nothing for 6.2 or 6.5 even though I entered my vin into the site.

the specs on JB8 shows a 1.312 bore MC. would anyone have a GM or AC Delco part number for the correct MC I could maybe cross reference to see what the specs are or see if Advance pulls up a different MC?

I'll post photos of the MC with my phone in a second. maybe someone can make out what the stamped number is or ID it telling me some hope!
 
Just looked up by application on Napa and O'reilly's, Napa was the only one that shows an HD variation having a larger reservoir and a 40mm bore, but everything else I see is all 1.25" bore. I looked up the hydro boost on Napa's site just for the heck of it and there is also a different one between a C3500 and the HD. C3500 shows a 53-7336 (again picturing one with the little tube thingy mine had) and for the HD version a 53-7338 booster (picture looks the same as what I have now without that tube thingy on the return port)

What gives! now I'm real curious if I screwed up replacing the booster with a reman and not getting one off a junker and rebuilding it!
 
Don't feel bad..I've replaced my hydro boost multiple times. And master cylinder.. and p.s. pump... I've pretty much gave up on trying to get the right parts... AutoZone sold me parts there computer said we're right.. then looked up at advance and there computer says something different...we have a napa but I can't spend there prices when they don't give me a unconditional life time warranty. (There significantly higher prices).. mines a 97 crew cab dually. Not sure if our parts are same since yours is SRW. Gonna post door sticker pic for comparison... Watching your thread to get ideas for my truck... Other big prob is you buy a new part and install from one of these parts houses and come to find out the new one is no good but you don't realize it so start looking for other problems
 
Take the spec sheet to GM parts store. Ask them to look up the proper Booster and master cylinder GM part numbers.
Than You’ll have some good numbers to work with.
You might be able to try on Rock Auto too.
 
Don't feel bad..I've replaced my hydro boost multiple times. And master cylinder.. and p.s. pump... I've pretty much gave up on trying to get the right parts... AutoZone sold me parts there computer said we're right.. then looked up at advance and there computer says something different...we have a napa but I can't spend there prices when they don't give me a unconditional life time warranty. (There significantly higher prices).. mines a 97 crew cab dually. Not sure if our parts are same since yours is SRW. Gonna post door sticker pic for comparison... Watching your thread to get ideas for my truck... Other big prob is you buy a new part and install from one of these parts houses and come to find out the new one is no good but you don't realize it so start looking for other problems

YES!!! EXACTLY!!! Re read that last sentence like 5 times in a row and let it sink in.
DIAGNOSTICS IS CHEAPER LONG TERM 95% OF THE TIME.

Keep in mind- AC Delco wasn’t trying to sue Amazon over knock off spark plugs...
 
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