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Vacuum pump & mechanics

Adam Leinss
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Adam Leinss New Member

Adam Leinss

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I have a 2014 Silverado with 42K miles. On Sunday, I was pulling into the garage after a short errand and I lost most of the braking power. I was able to stop the truck by pressing the brake pedal hard. I immediately drove backwards and it did the same thing. I had it towed to a local mechanic on Monday to have the braking system checked out. They had it for about 4 hours and could not find anything wrong. They showed me an article how the ABS system can kick in if the system is over worked due to hot weather, driving up hills, frequent stops, etc. However, I just was away for 15 minutes: it's in lower 60s and I wasn't doing hills or frequent stops. The mechanic did 2 test drives and he told me the braking system was fine.

 

I carefully drove it to the GM dealership for a 2nd opinion and within 15 minutes they diagnosed it as a weak vacuum pump. It was only doing 10 in Hg and it should be doing 27 in Hg. My question is having a vacuum pump as part of a braking system exotic? Is this something a normal mechanic should have been able to diagnose? I found the TSB here by Googling vacuum and 12669488 as the part # which describes the problem perfectly: http://m.gm.oemdtc.com/TSB/SB-10081053-2280.pdf

 

I guess my worry is that this mechanic gave me a clean bill of health on the braking system which shakes my confidence in any future work he may do for me. Are these 2014+ Silverados just too new or specialized to be worked on by normal mechanics?

 

 

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300 Blackout
300 Blackout

That depends if oil was found in your vacuum line. If it was then the recommendation is to replace the additional parts of the braking system. If no oil was found in the line and they don’t suspect oi

newdude
newdude

AFM is why. It allowed them to change the AFM so it runs more with low/no load. When you drop 4 cylinders, you drop your vacuum supply. Helps for added brake assist to increase pedal feel over the

montytx
montytx

This happened to me today. Ordering a new pump. I can tell you this, you have to push down really hard to bring these to a stop. I assume they included them in the engine because they drop to 4 cyl.

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GsBowtie Enthusiast

GsBowtie

Posted
Posted

Short answer, no. You're local tech should have been able to check vaccum. However, these new trucks are very complex so it takes some understanding of how everything is integrated.

 

It's not getting any easier by any means

newdude Senior Enthusiast

newdude

Posted
Posted (edited)

Hopefully they checked for oil/fluids in the vacuum pump lines...

 

#PIT5361B: Diagnostic Tip - Additional Brake Pedal Effort - (Jun 28, 2016)

 

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern

In some rare situations, a customer may comment on a hard brake pedal or that increased effort is needed to depress the brake pedal. Also, in some cases a tick or ticking noise may be heard, which may sound like an exhaust manifold leak. While performing normal diagnostics, fluid may be found in the brake booster and/or the booster vacuum line.

 

Important: Pay close attention to the fluid and if it is determined to be engine oil, it could be coming from the vacuum pump. The vacuum pump is belt-driven and mounted to the side of the engine block. It is lubricated by pressurized engine oil.

Recommendation/Instructions

If engine oil is found, it is important the following parts are replaced. If not, the condition will return.

  1. Vacuum Pump
  2. Vacuum Line between the booster and the pump
  3. Brake Booster
  4. Master Cylinder
  5. Vacuum Pump Belt

 

Edited by 15HDriver
Adam Leinss New Member

Adam Leinss

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Yeah, I hope so too. I was reading one story where a guy's vacuum pump was defective and pushed back bits of metal back into the engine block and toasted it. Since the dealer did the repair they should be responsible if anything like that should happen.

2016 Sierra Owner Senior Enthusiast

2016 Sierra Owner

Posted
Posted

Did you report this as a safety issue?

 

https://www-odi.nhtsa.dot.gov/VehicleComplaint/

 

Why would he need to do this? It's no different than losing the power steering pump and you have to actually use some muscle to steer. The vacuum pump just assists the breaks in that you don't have to push so hard on the pedal to apply the breaks. He never lost breaking just had to push the pedal harder to stop. Would it be surprising to be in this condition. Absolutely Yes however he has done the right thing and had it towed to the repair shop. Try letting your truck roll in neutral with the engine off. You have to press the breaks hard but, it will stop.

kstruckcountry Senior Enthusiast

kstruckcountry

Posted
Posted

Vacuum pumps were on the earlier 2000 pickups IIRC... not really a rare system, or very complicated to check vacuum.

 

Sent from my SM-G920V using Tapatalk

Nathan79 Enthusiast

Nathan79

Posted
Posted

 

Why would he need to do this? It's no different than losing the power steering pump and you have to actually use some muscle to steer. The vacuum pump just assists the breaks in that you don't have to push so hard on the pedal to apply the breaks. He never lost breaking just had to push the pedal harder to stop. Would it be surprising to be in this condition. Absolutely Yes however he has done the right thing and had it towed to the repair shop. Try letting your truck roll in neutral with the engine off. You have to press the breaks hard but, it will stop.

Doesn't matter that you can figure out how to stop in this situation. It is a safety issue and if systematic should be a safety recall. Reporting the issue to NHTSA can help force an investigation.

OldBlue61 Enthusiast

OldBlue61

Posted
Posted

I hope this doesn't sidetrack this thread, but I was unaware that these trucks had a vacuum pump. The engine doesn't develop enough vacuum on it's own?

newdude Senior Enthusiast

newdude

Posted
Posted

I hope this doesn't sidetrack this thread, but I was unaware that these trucks had a vacuum pump. The engine doesn't develop enough vacuum on it's own?

 

AFM is why. It allowed them to change the AFM so it runs more with low/no load. When you drop 4 cylinders, you drop your vacuum supply. Helps for added brake assist to increase pedal feel over the last gen as well.

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2016 Sierra Owner Senior Enthusiast

2016 Sierra Owner

Posted
Posted

Doesn't matter that you can figure out how to stop in this situation. It is a safety issue and if systematic should be a safety recall. Reporting the issue to NHTSA can help force an investigation.

 

I fail to see is why it's a safety issue. The breaking system Never failed. You just have to press the pedal harder. When the power steering pump goes out it's a safety issue to? You don't lose steering just the assistance to turn the wheel easier.

  • 5 months later...
montytx Enthusiast

montytx

Posted
Posted (edited)

This happened to me today. Ordering a new pump. I can tell you this, you have to push down really hard to bring these to a stop. I assume they included them in the engine because they drop to 4 cyl. What a pain, 43K miles and my brakes go out, I wonder how many lawsuits they are going to get from this? Also, the power steering is mentioned as a defense. Big difference, braking is way above PS in importance. I litterally braked, turned and then barely stopped before hitting a car. I had no warning, and I am a big guy.

Edited by montytx
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  • 2 months later...
bgmartin New Member

bgmartin

Posted
Posted

Same thing happened to me yesterday. Very heavy and hard pedal when parking or applying brakes several times at low speed. 2014 Chev Silverado, 5.3 V8, 42K miles. Chev dealership diagnosed it today, vacuum pump not pulling enough vacuum. Seems a common fault...

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