italie |
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MAME owes italie many thank yous, hah
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Another fine moment of "What the hell was someone thinking"
#263548 - 08/31/11 08:45 PM
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Brake booster finally blew out on my Yukon. It's been slowly getting worse, so it wasn't a surprise. I figured a vacuum leak in the diaphragm was the reason I could never get the sponginess bled out from the 1st inch or the brake pedal, so I was actually looking forward to doing it.
Fast forward to me removing the master cylinder to get the booster off:
"Hmm..something isn't right here...Why is there RTV between the master and the booster?...I don't recall this needing to be air tight...And wait, shouldn't there be a push rod between the master and booster pistons? What the....Why is the boosters piston all mashed up.....~awww JEEEZ~...Someone ~couldn't~ have been this stupid, right?"
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| redk9258 |
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Regular
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Reged: 09/21/03
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Loc: Troy, Illinois USA
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263558 - 08/31/11 10:02 PM
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So someone prior to you owning this sealed a leak with RTV? Looks like a trip to the junkyard is in order. I have never seen a brake booster fail before. I'll bet the one on the Yukon is the same for Chevy trucks too. You will have to check that out.
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| italie |
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MAME owes italie many thank yous, hah
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Re: Another fine moment of "What the hell was someone thinking"
[Re: redk9258]
#263561 - 08/31/11 10:22 PM
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> So someone prior to you owning this sealed a leak with RTV? Looks like a trip to the
> junkyard is in order. I have never seen a brake booster fail before. I'll bet the one
> on the Yukon is the same for Chevy trucks too. You will have to check that out.
Nah, worse. They replaced the master cylinder, and in the process they must have lost the push rod that goes between the booster and the master cylinder. The booster has a hollowed out piston that the push rod sits in, and the push rod makes up for a small gap between the booster and master pistons. They RTV'd between the master and the booster, and the seal was tight enough for air to actuate the master piston before the booster piston made contact with it. The minute the booster piston hit the master you'd get a jerky increase in stopping power.
The car always had a spongy pedal in the first inch or so. Never could seem to bleed it out. Mystery solved on that one I guess.
The booster itself was bad, diaphragm ripped. You could hear the "Whoosh" every time the brake was stepped on, and the pedal turned to rock after that 1st inch.
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| DMala |
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Sleep is overrated
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263566 - 08/31/11 11:39 PM
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> Nah, worse. They replaced the master cylinder, and in the process they must have lost
> the push rod that goes between the booster and the master cylinder. The booster has a
> hollowed out piston that the push rod sits in, and the push rod makes up for a small
> gap between the booster and master pistons. They RTV'd between the master and the
> booster, and the seal was tight enough for air to actuate the master piston before
> the booster piston made contact with it. The minute the booster piston hit the master
> you'd get a jerky increase in stopping power.
Holy shit... that's dangerous as hell and is probably illegal. If that seal blew out in the middle of a panic stop, you'd be dead. I hope, at least, it was done by some amateur knucklehead and not by a "professional" mechanic. Unbelievable.
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| Tomu Breidah |
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No Problems, Only Solutions
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263570 - 09/01/11 12:34 AM
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| italie |
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MAME owes italie many thank yous, hah
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Re: Another fine moment of "What the hell was someone thinking"
[Re: Tomu Breidah]
#263573 - 09/01/11 12:46 AM
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> I'd request *pics to see it to believe it  (not that I'm not taking your word for
> it - just to share)... But it's probably too late. (*:sorry)
Sorry, don't usually think "pictures" when I'm in the middle of a swear marathon. I'd take one now but I already turned in both cores.
> ...Makes you wonder what else has been "Jimmy" rigged.
Found a few things when I bought the truck, reversed them immediately (Like the electric motor/fan in the intake as a poor mans "turbo"). Price you pay for getting a deal on the truck you want.
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Re: Another fine moment of "What the hell was someone thinking"
[Re: Tomu Breidah]
#263575 - 09/01/11 12:59 AM
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> I'd request *pics to see it to believe it (not that I'm not taking your word for
> it - just to share)... But it's probably too late. (*:sorry)
>
> ...Makes you wonder what else has been "Jimmy" rigged.
>
> Jimmy gunna fix it, you'll see.
No, the Jimmy was the GMC version, replaced by the Yukon. The Tahoe replaced the Blazer. 
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| redk9258 |
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Regular
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263588 - 09/01/11 03:05 AM
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> Found a few things when I bought the truck, reversed them immediately (Like the
> electric motor/fan in the intake as a poor mans "turbo"). Price you pay for getting a
> deal on the truck you want.
WTF!
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| DMala |
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Sleep is overrated
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263590 - 09/01/11 03:37 AM
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> Found a few things when I bought the truck, reversed them immediately (Like the
> electric motor/fan in the intake as a poor mans "turbo"). Price you pay for getting a
> deal on the truck you want.
OMG, you bought a truck from a moron who figured out how to operate the hood latch. Personally, I would have stayed far away.
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| italie |
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MAME owes italie many thank yous, hah
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three words..one low, low price.
[Re: DMala]
#263593 - 09/01/11 04:03 AM
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> > Found a few things when I bought the truck, reversed them immediately (Like the
> > electric motor/fan in the intake as a poor mans "turbo"). Price you pay for getting
> a
> > deal on the truck you want.
>
> OMG, you bought a truck from a moron who figured out how to operate the hood latch.
> Personally, I would have stayed far away.
Two Door Yukon.
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| italie |
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MAME owes italie many thank yous, hah
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Re: Another fine moment of "What the hell was someone thinking"
[Re: redk9258]
#263595 - 09/01/11 04:07 AM
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> > Found a few things when I bought the truck, reversed them immediately (Like the
> > electric motor/fan in the intake as a poor mans "turbo"). Price you pay for getting
> a
> > deal on the truck you want.
>
> WTF!
Intake airflow = ~750CFM
Electric fan airflow = ~425CFM
The saddest part is that it was probably costing him 20HP...
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| DMala |
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Sleep is overrated
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263598 - 09/01/11 04:52 AM
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> Intake airflow = ~750CFM
>
> Electric fan airflow = ~425CFM
>
> The saddest part is that it was probably costing him 20HP...
So I have to ask... was there duct tape involved? 
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| italie |
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MAME owes italie many thank yous, hah
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Re: Another fine moment of "What the hell was someone thinking"
[Re: DMala]
#263602 - 09/01/11 05:13 AM
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> > Intake airflow = ~750CFM
> >
> > Electric fan airflow = ~425CFM
> >
> > The saddest part is that it was probably costing him 20HP...
>
> So I have to ask... was there duct tape involved?
Why yes, yes there was... 
How else was he supposed to fit this thing inline with the intake ducting"
.jpg)
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Re: Another fine moment of "What the hell was someone thinking"
[Re: italie]
#263624 - 09/01/11 02:10 PM
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> > > Intake airflow = ~750CFM
> > >
> > > Electric fan airflow = ~425CFM
> > >
> > > The saddest part is that it was probably costing him 20HP...
> >
> > So I have to ask... was there duct tape involved?
>
> Why yes, yes there was...
>
> How else was he supposed to fit this thing inline with the intake ducting"
Seriously, if you can't use duct tape on a duct, what good is it?
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Another fine moment of "What the hell was someone thinking"
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[Re: 
(not that I'm not taking your word for it - just to share)... But it's probably too late. (*:sorry) 
