Y Bridge bolt holes??

N

nwohiochevyguy

New member
Jan 30, 2013
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So I did a HSP Y bridge and pipes last fall on my 2005 LLY when I upgraded my turbo.

Have had a small drop in MPG and now under harder acceleration I get ALOT of black smoke and she falls on her face. I know it is a boost leak, tester will be build and I will run the test.

My question is when I put the Y on I had one bolt in the head that would not torque down, suspect threads are shot in the head as the bolt looked fine.

If I drill and tap that hole any thing that I could get into if I step it up a size to get to good material?
Also what size are those bolts, I don’t recall.

I have not done the boost test yet, but this bolt not torquing down has me believing that this is where I will find my leak.


Yes I cleaned my air filter & MAF Sensor last night with no change in her behavior.
 
ikeG

ikeG

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Apr 19, 2011
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The bridge bolt holes are in each intake manifold. The intake manifolds bolt down to the heads and are sealed with rtv. So you could replace entire manifold if needed. The bolts and studs are m6. Not sure on pitch

Sent from my SM-G960U using Tapatalk
 
ZeroGravity58

ZeroGravity58

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Mar 23, 2008
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I know alot of guys skip putting the bolts in the bottom front due to not being able to get around the necks of the aftermarket bridges. I doubt one bolt will cause a boost leak like that. I would start looking other places
 
N

nwohiochevyguy

New member
Jan 30, 2013
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That is all good to hear, I will do a leak test when I can and see where it is located.
The bolt in question is the top front on passenger side.

I really hope its not the Y bridge and something simple
 
JoshH

JoshH

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If you have a stock LLY intercooler, they are known to crack where the tank and core meet and cause a boost leak there.
 
NevadaLLY

NevadaLLY

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Feb 24, 2019
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JoshH said:
If you have a stock LLY intercooler, they are known to crack where the tank and core meet and cause a boost leak there.
Click to expand...

^^what he said. I am taking my stocker one out as I have a leak near the driver side bracket. THe truck was in a right front corner T-bone last year and i think the repairs weren't caught. However, I have a leak and i'm stuck with the repairs :violent:
 
N

nwohiochevyguy

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Jan 30, 2013
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Leak test done and all checked out fine.


Called the shop that does some of the work I can't do to have them ride along with me.
Two different mechanics rode with me while monitoring with a CTS and they are baffled.


Next step is have my tuner data log and look at the tunes.


Truck builds boost great then looses it almost completely while veins are still in the correct position. Fuel rail pressure stays right where it should be also. Nothing the CTS can monitor showed any issues.
When loosing boost it falls on its face (almost literally) bellows black smoke followed by some white mixed in. If you hold acceleration constant (stop pushing it harder) it will catch up and quite smoking.
Does this on all tunes we tried it on.



:banghead:
 
Last edited:
TheBac

TheBac

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Apr 19, 2008
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Vanes desired/actual follow closely at all times?


MAP/MAF sensors both reading as they should throughout?
 
N

nwohiochevyguy

New member
Jan 30, 2013
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JoshH said:
I would be looking for a restricted intake or air filter.
Click to expand...




Air filter was serviced last weekend to rule that out & MAF sensor cleaned. Made 0 changes to what she's doing.


AFE Intake and HSP pipes and YBridge - there better not be any restrictions on that side.
 
gmduramax

gmduramax

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Jun 12, 2008
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If there’s nothing strange in the data log, there is nothing wrong with the tune. You need a new mechanic.
 
Chevy1925

Chevy1925

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Oct 21, 2009
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nwohiochevyguy said:
So I did a HSP Y bridge and pipes last fall on my 2005 LLY when I upgraded my turbo.

Have had a small drop in MPG and now under harder acceleration I get ALOT of black smoke and she falls on her face. I know it is a boost leak, tester will be build and I will run the test.

My question is when I put the Y on I had one bolt in the head that would not torque down, suspect threads are shot in the head as the bolt looked fine.

If I drill and tap that hole any thing that I could get into if I step it up a size to get to good material?
Also what size are those bolts, I don’t recall.

I have not done the boost test yet, but this bolt not torquing down has me believing that this is where I will find my leak.


Yes I cleaned my air filter & MAF Sensor last night with no change in her behavior.
Click to expand...

if you changed the turbo, you needed a re-tune. its going to work vastly different than the stock one.
 
N

nwohiochevyguy

New member
Jan 30, 2013
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Data logged tonight by my tuner.

Have an injector (maybe 2) acting up. Causing truck to max out at 80% fuel flow on hard acceleration.
New S&S injectors put in 25K Miles ago (14 months ago) when HG were done. Hope the shop makes it right.
 
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