Engine Stuttering and Power Brakes Not Working on 95 Silverado
August 17th, 2014, 12:33 PM
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Engine Stuttering and Power Brakes Not Working on 95 Silverado
All,
am new here, and new to working on Chevy trucks. My grand daughter HAD to have an old used lifted 95 4WD Silverado, so we bought it for her a couple months ago and now I'm stuck fixing everything that goes wrong with it. And tomorrow is the first day of school so she thinks her world will end if I don't fix the problems today.
The truck has a 5.7 gas engine with auto trans. I'll try to describe the problems, but the truck has had a lot of work accomplished by shade tree mechanics, so I can't guarantee things are as they should be.
Thanks in advance to anybody who can help resolve these problems.
The troubles started a couple days ago after we took the truck to a shop to have her new 35 tires mounted and balanced. The truck ran fine on the 5 mile drive home. The next day my grand daughter drove it 3 miles to the dentist, and the truck started acting up on the drive home. (problem 1) It was stuttering/coughing above 40 mph so she pulled over. A couple guys stopped to try to help her, but they couldn't find anything wrong so my wife followed her as she slowly drove the truck home. I tried to resolve when I got home. Talk on the forum seemed to point to the problem being with the EGR, so we removed and tried to clean it, soaking it with PB Blaster and letting it sit overnite. While doing this, I also noticed one of the spark plug wires was turned to press against the exhaust and the wire was burned thru. We bought an AC Delco replacement set of wires yesterday, and installed them the next day along with the slightly cleaner EGR valve. The truck test-drove great and we thot the problems were resolved.
Later yesterday, my GD drove the truck 12 miles to work. (Here comes problem 2) the power brakes suddenly turned into regular brakes and she almost ran into the back of another vehicle. She continued driving and made it to work safely. On the way back home, the truck started having problem 1 from above again, altho it wasn't as bad as before.
Looking at the truck this morn, I'm getting diagnostic code 35, which tells me there is a problem with the IAC system (GM OBD 1 Trouble Code Information). I suspect that may be the cause of the stuttering (prob 1), but would appreciate any thots on this, and resolving it.
I'm more concerned with the brakes, tho. Looking at the brakes today, the fluid is at the correct level, and I'm not seeing any unusual leakages. (It's 20 years old, so there is plenty of normal (?) leakage.) When pressing on the brakes, there is a hiss that seems louder than it should be, (I'm really not familiar with the normal sounds of this truck), the engine revs for as long as the brake is depressed, and brake fluid bubbles back up into the reservoir. And there is definitely no power-assist on the brakes. Any thots/ideas?
Don't know if any of these problems originated with anything intentionally or accidentally done by the guys mounting the tires, or the good Samaritans who tried to help her on the road. Timing of all of this is kinda suspicious, tho. And it sounded as if the guys putting on the tires resented a 16yo girl having a truck like that. Turning the spark plug so the wire pressed against the exhaust would have been real easy by reaching thru the wheel well. But maybe I'm just paranoid. Also, I don't >think< these two problems are related, but wanted to present all the facts to you.
We'd really appreciate any help or suggestions anybody can offer.
am new here, and new to working on Chevy trucks. My grand daughter HAD to have an old used lifted 95 4WD Silverado, so we bought it for her a couple months ago and now I'm stuck fixing everything that goes wrong with it. And tomorrow is the first day of school so she thinks her world will end if I don't fix the problems today.
The truck has a 5.7 gas engine with auto trans. I'll try to describe the problems, but the truck has had a lot of work accomplished by shade tree mechanics, so I can't guarantee things are as they should be.
Thanks in advance to anybody who can help resolve these problems.
The troubles started a couple days ago after we took the truck to a shop to have her new 35 tires mounted and balanced. The truck ran fine on the 5 mile drive home. The next day my grand daughter drove it 3 miles to the dentist, and the truck started acting up on the drive home. (problem 1) It was stuttering/coughing above 40 mph so she pulled over. A couple guys stopped to try to help her, but they couldn't find anything wrong so my wife followed her as she slowly drove the truck home. I tried to resolve when I got home. Talk on the forum seemed to point to the problem being with the EGR, so we removed and tried to clean it, soaking it with PB Blaster and letting it sit overnite. While doing this, I also noticed one of the spark plug wires was turned to press against the exhaust and the wire was burned thru. We bought an AC Delco replacement set of wires yesterday, and installed them the next day along with the slightly cleaner EGR valve. The truck test-drove great and we thot the problems were resolved.
Later yesterday, my GD drove the truck 12 miles to work. (Here comes problem 2) the power brakes suddenly turned into regular brakes and she almost ran into the back of another vehicle. She continued driving and made it to work safely. On the way back home, the truck started having problem 1 from above again, altho it wasn't as bad as before.
Looking at the truck this morn, I'm getting diagnostic code 35, which tells me there is a problem with the IAC system (GM OBD 1 Trouble Code Information). I suspect that may be the cause of the stuttering (prob 1), but would appreciate any thots on this, and resolving it.
I'm more concerned with the brakes, tho. Looking at the brakes today, the fluid is at the correct level, and I'm not seeing any unusual leakages. (It's 20 years old, so there is plenty of normal (?) leakage.) When pressing on the brakes, there is a hiss that seems louder than it should be, (I'm really not familiar with the normal sounds of this truck), the engine revs for as long as the brake is depressed, and brake fluid bubbles back up into the reservoir. And there is definitely no power-assist on the brakes. Any thots/ideas?
Don't know if any of these problems originated with anything intentionally or accidentally done by the guys mounting the tires, or the good Samaritans who tried to help her on the road. Timing of all of this is kinda suspicious, tho. And it sounded as if the guys putting on the tires resented a 16yo girl having a truck like that. Turning the spark plug so the wire pressed against the exhaust would have been real easy by reaching thru the wheel well. But maybe I'm just paranoid. Also, I don't >think< these two problems are related, but wanted to present all the facts to you.
We'd really appreciate any help or suggestions anybody can offer.
August 22nd, 2014, 8:56 AM
#3
well if your brakes are effected obviously don't drive it outside the neighborhood or on hill first question is whether you know engine vacuum is used to power brake assist ? if vacuum is leaking (if that's what you hear) you'll have both engine problems and hard braking. it might be a hose leaking, or failing that a seal inside the booster
August 24th, 2014, 10:50 AM
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Judging by the number of responses to my orig post, this appears to be a new issue here on this forum, so here's the closure for anyone else who may experience the same problem.
We replaced the brake booster yesterday and that resolved the problem with the brakes. Kinda painful getting my old neck up under the dash like that, but we made it happen. Would hate to try it without both regular & deep sockets, and a universal joint, but could be done. The hissing noise we were hearing was only audible in the cab of the truck (tried to provide all the detail I could think of in my orig post, but don't think I mentioned that fact), which made me pretty sure it was not a vacuum line issue. From what I understand now, the diaphragm (in the brake booster) closest to the firewall had failed, and the noise was coming out the back of the brake booster and thru the hole in the firewall. The thing that gave me pause was that several sites on the web described tests to determine whether a brake booster had failed, and the brake booster on the truck seemed to pass each test. Oh well, $110 and it's resolved now.
Thanks much to the two of you who took the time to respond to my post and try to help me. Now I get to go work on the issue of it coughing, stuttering, missing a beat or two (or however you want to describe it) when it gets to 40 or 50 mph. My cup runneth over.
joel
We replaced the brake booster yesterday and that resolved the problem with the brakes. Kinda painful getting my old neck up under the dash like that, but we made it happen. Would hate to try it without both regular & deep sockets, and a universal joint, but could be done. The hissing noise we were hearing was only audible in the cab of the truck (tried to provide all the detail I could think of in my orig post, but don't think I mentioned that fact), which made me pretty sure it was not a vacuum line issue. From what I understand now, the diaphragm (in the brake booster) closest to the firewall had failed, and the noise was coming out the back of the brake booster and thru the hole in the firewall. The thing that gave me pause was that several sites on the web described tests to determine whether a brake booster had failed, and the brake booster on the truck seemed to pass each test. Oh well, $110 and it's resolved now.
Thanks much to the two of you who took the time to respond to my post and try to help me. Now I get to go work on the issue of it coughing, stuttering, missing a beat or two (or however you want to describe it) when it gets to 40 or 50 mph. My cup runneth over.
joel
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