Old Hoses and Vacuum Leaks
10-07-2014, 10:46 PM
#1
Registered User
Thread Starter
Join Date: Sep 2014
Location: Coupland, TX, USA
Posts: 121
Old Hoses and Vacuum Leaks
Howdy gents. I picked up my first LT1 Z28 a few weeks ago and have steadily been replacing worn out stuff. The car just turned 140,000 miles and being 17 years (18 on 01/31/15) some stuff just wore out.
One problem child has been the little odd elbow off the throttle body. It has a larger opening on the TB side and a smaller opening on the tube side. I found out that several years ago GM stopped producing the elbow but thanks to a few forum searches I found that a 90 degree spark plug boot works well. I finally stuck one on yesterday and it seems to have helped. The old elbow was cracked in several places and just falling apart in my hands, thus causing a vacuum leak.
Another source was the connection just above that one on the TB. It's a longer tube that connects to a plastic 90 degree elbow and fits in a grommet on the passenger side valve cover. That grommet was old and the opening was enlarged some causing the elbow to move in and out without restriction and for oil to leak out. The tube was also split as it had hardened and lost its flexibility. I found the part numbers on Shoeboxes page and ordered all 3 of those pieces. Now the grommet you can get at any parts store but the tube you can not. After replacing them the vacuum leak there also stopped.
My car had a surging issue, sometimes revving to 2200 or 2300 RPM and hanging there. It made it worse when you let off the throttle while still in gear and the car kept its speed instead of slowing down.
SHbox gets a lot of credit for the website he has and all the helpful info but so does the LT1 community as a whole. Forums like this and doing searches landed me on fixes for surging which include vacuum leaks and a worn Throttle Position Sensor (TPS), which I also replaced. Even if it wasn't bad I don't know how old it was and how many miles were on it so why not stick a new one on there. I also took off the Idle Air Control (IAC) valve and cleaned that all up. Again all to the LT1 community posting their experience online.
I replaced the drivers side spark plugs and wires yesterday. The passenger side is much more daunting. The O2 sensors, well they're rusted in like a Japanese Zero at the bottom of Coral Sea. I may end up paying someone or just waiting until I get Long Tube (LT) headers on next year.
The car is running smoother and so far the surging has gone away. The fixes weren't expensive at all and I wouldn't have done it any quicker had you guys not posted how-to's and such. Tomorrow I take it in for inspection. The check engine light has been on since I bought the car. I don't have a scanner but the nice kid at O'Reilley's scanned it and said the codes were for MAF (which I later cleaned), Misfire and gas cap. Now after reading many threads I found that a misfire can come from vacuum leaks among other things. I'm hoping that's all that is wrong with it. Haven't had a chance to clear the codes yet so the check engine light is still on.
Again, thanks everyone. Keep up the good work!
One problem child has been the little odd elbow off the throttle body. It has a larger opening on the TB side and a smaller opening on the tube side. I found out that several years ago GM stopped producing the elbow but thanks to a few forum searches I found that a 90 degree spark plug boot works well. I finally stuck one on yesterday and it seems to have helped. The old elbow was cracked in several places and just falling apart in my hands, thus causing a vacuum leak.
Another source was the connection just above that one on the TB. It's a longer tube that connects to a plastic 90 degree elbow and fits in a grommet on the passenger side valve cover. That grommet was old and the opening was enlarged some causing the elbow to move in and out without restriction and for oil to leak out. The tube was also split as it had hardened and lost its flexibility. I found the part numbers on Shoeboxes page and ordered all 3 of those pieces. Now the grommet you can get at any parts store but the tube you can not. After replacing them the vacuum leak there also stopped.
My car had a surging issue, sometimes revving to 2200 or 2300 RPM and hanging there. It made it worse when you let off the throttle while still in gear and the car kept its speed instead of slowing down.
SHbox gets a lot of credit for the website he has and all the helpful info but so does the LT1 community as a whole. Forums like this and doing searches landed me on fixes for surging which include vacuum leaks and a worn Throttle Position Sensor (TPS), which I also replaced. Even if it wasn't bad I don't know how old it was and how many miles were on it so why not stick a new one on there. I also took off the Idle Air Control (IAC) valve and cleaned that all up. Again all to the LT1 community posting their experience online.
I replaced the drivers side spark plugs and wires yesterday. The passenger side is much more daunting. The O2 sensors, well they're rusted in like a Japanese Zero at the bottom of Coral Sea. I may end up paying someone or just waiting until I get Long Tube (LT) headers on next year.
The car is running smoother and so far the surging has gone away. The fixes weren't expensive at all and I wouldn't have done it any quicker had you guys not posted how-to's and such. Tomorrow I take it in for inspection. The check engine light has been on since I bought the car. I don't have a scanner but the nice kid at O'Reilley's scanned it and said the codes were for MAF (which I later cleaned), Misfire and gas cap. Now after reading many threads I found that a misfire can come from vacuum leaks among other things. I'm hoping that's all that is wrong with it. Haven't had a chance to clear the codes yet so the check engine light is still on.
Again, thanks everyone. Keep up the good work!
10-07-2014, 11:10 PM
#2
Registered User
Join Date: Oct 2007
Posts: 1,174
Re: Old Hoses and Vacuum Leaks
I guess you have a 1997?You need to buy a scanner ob2.They have them at harbor freight and tool for about $70.00 or so.But first I would disconnect the negative ground on the battery for a couple of hours then reconnect it 
and see if that helps.My money is on bad o2 sensors.Hope this helps.
and see if that helps.My money is on bad o2 sensors.Hope this helps.
10-08-2014, 08:18 AM
#3
Registered User
Thread Starter
Join Date: Sep 2014
Location: Coupland, TX, USA
Posts: 121
Re: Old Hoses and Vacuum Leaks
Yep, 1997. I bought some new upstream O2 sensors but they're pretty rusted in. I tried to get the driver side one out, it's in a very tight place between the manifold and cat converter. PITA. Have to get to it from under the car. After 140,000 miles they need to be replaced. I may limp it out to next year when I invest in a long tube and complete exhaust system.
10-08-2014, 12:19 PM
#4
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,651
Re: Old Hoses and Vacuum Leaks
The elbow you describe is part of the EVAP system, and connects to a full vacuum port on the throttle body.
The hose from the throttle body to the valve cover is not a vacuum line, It supplies filtered air to the valve cover, so the PCV system can pull the clean air through the crankcase to remove the blowby. The port on the TB opens in front of the blades, and is not exposed to manifold vacuum. Always good to fix it anyway.
The TPS is very easy to check with a volt meter.
When you cleaned the IAC motor, hopefully you did not attempt to move the pintle, and you held the pintle facing down, so liquid cleaner could not get into the electronics. Both can damage the motor.
The O2 sensors need to be saturated for at least 24 hours with something like PB Blaster rust penetrant. The O2 sensor will be useless after you do that, because the penetrant will infiltrate the wire opening, and that opening has to stay clear to expose the inside of the sensor to fresh air. It is usually easier to break the sensors loose if the exhaust system is hot... just nasty burns on your arms. Be sure to use a 6-point socket, and a breaker bar.
You can get OBD-2 apps for your phone, or use the free OBD-2 scan software that GaryDoug wrote. It has GM Enhanced Parameters capability, which the cheap scanners generally do not have.
Free OBD2 scanner software - Firebird Nation
There is little, if any benefit in disconnecting the battery for two hours, to clear the PCM. First, you are better off pulling the "PCM BAT" fuse in the under hood fuse box, and then it only takes 30 seconds, no matter where you disconnect the power. You will reset the long term fuel corrections to 0%, which might actually make things temporarily worse until they rebuild to where they belong. If you have driven the car at all since the fixes you made, the long term fuel corrections have been altered to reflect the changes. You may also lose the IAC learned idle counts. Not much else gets cleared by pulling the power to the PCM. If you do pull the cable off the battery, make sure your audio system "security" system is not active, or that you know the pass code, because the stock audio system will be locked up if the security system is active. Pulling the "PCM BAT" fuse eliminates this problem.
The hose from the throttle body to the valve cover is not a vacuum line, It supplies filtered air to the valve cover, so the PCV system can pull the clean air through the crankcase to remove the blowby. The port on the TB opens in front of the blades, and is not exposed to manifold vacuum. Always good to fix it anyway.
The TPS is very easy to check with a volt meter.
When you cleaned the IAC motor, hopefully you did not attempt to move the pintle, and you held the pintle facing down, so liquid cleaner could not get into the electronics. Both can damage the motor.
The O2 sensors need to be saturated for at least 24 hours with something like PB Blaster rust penetrant. The O2 sensor will be useless after you do that, because the penetrant will infiltrate the wire opening, and that opening has to stay clear to expose the inside of the sensor to fresh air. It is usually easier to break the sensors loose if the exhaust system is hot... just nasty burns on your arms. Be sure to use a 6-point socket, and a breaker bar.
You can get OBD-2 apps for your phone, or use the free OBD-2 scan software that GaryDoug wrote. It has GM Enhanced Parameters capability, which the cheap scanners generally do not have.
Free OBD2 scanner software - Firebird Nation
There is little, if any benefit in disconnecting the battery for two hours, to clear the PCM. First, you are better off pulling the "PCM BAT" fuse in the under hood fuse box, and then it only takes 30 seconds, no matter where you disconnect the power. You will reset the long term fuel corrections to 0%, which might actually make things temporarily worse until they rebuild to where they belong. If you have driven the car at all since the fixes you made, the long term fuel corrections have been altered to reflect the changes. You may also lose the IAC learned idle counts. Not much else gets cleared by pulling the power to the PCM. If you do pull the cable off the battery, make sure your audio system "security" system is not active, or that you know the pass code, because the stock audio system will be locked up if the security system is active. Pulling the "PCM BAT" fuse eliminates this problem.
10-08-2014, 09:03 PM
#5
Registered User
Thread Starter
Join Date: Sep 2014
Location: Coupland, TX, USA
Posts: 121
Re: Old Hoses and Vacuum Leaks
After attempting to get it inspected this morning it failed with a code of P0441, something to do with the EVAP. So I went home to let the engine cool, run some errands and get to it later.
Previously when I cleaned the IAC I used electric motor cleaner (residue free) and didn't move the pintle. I read a few threads on it before attempting.
Removing the EVAP solenoid today I found that it had charcoal particles in it and I believe it was full. In fact the tube leading to it had particles and was almost packed so very little air could pass. I cleaned that tube out. The vacuum switch ahead of it was full of charcoal also so that was cleared out. I had picked up a new EVAP solenoid from O'Reilley's for $15 and replaced the old one. Hooked everything back up then went to get the code erased. That seemed to be the fix! I drove around for about 40 miles or so and no "service engine soon" light. Previously when the codes were erased the light came on within a few minutes.
Unfortunately I didn't have time to get it re-inspected so it'll have to wait until next Monday.
The idle surge didn't show it's ugly head this afternoon after the latest fix but was there this morning before the solenoid replacement and charcoal removal steps. The car seems to run better but I also attribute it to new spark plugs and wires on the drivers side (haven't gotten to the passenger side yet), replaced cracked and brittle hoses and cleaned the MAF a couple of weeks ago. It idles smoother too and sits around 1,300 RPM. Maybe that's a little high but it's running smooth now so I'm okay with it.
I'm headed to Phoenix with my wife on Thursday, come back Sunday. We'll be going to her oldest daughter's White Coat Ceremony as she's in med school (1st year, got her Masters in Biomedical Engineering last year). We'll be going to the Arizona State Fair on Saturday. No thinking about the Z28 then. I'll check the forums on Tapatalk probably once or twice.
Thanks for all the helpful input. Fred you're a cornucopia of knowledge!
Previously when I cleaned the IAC I used electric motor cleaner (residue free) and didn't move the pintle. I read a few threads on it before attempting.
Removing the EVAP solenoid today I found that it had charcoal particles in it and I believe it was full. In fact the tube leading to it had particles and was almost packed so very little air could pass. I cleaned that tube out. The vacuum switch ahead of it was full of charcoal also so that was cleared out. I had picked up a new EVAP solenoid from O'Reilley's for $15 and replaced the old one. Hooked everything back up then went to get the code erased. That seemed to be the fix! I drove around for about 40 miles or so and no "service engine soon" light. Previously when the codes were erased the light came on within a few minutes.
Unfortunately I didn't have time to get it re-inspected so it'll have to wait until next Monday.
The idle surge didn't show it's ugly head this afternoon after the latest fix but was there this morning before the solenoid replacement and charcoal removal steps. The car seems to run better but I also attribute it to new spark plugs and wires on the drivers side (haven't gotten to the passenger side yet), replaced cracked and brittle hoses and cleaned the MAF a couple of weeks ago. It idles smoother too and sits around 1,300 RPM. Maybe that's a little high but it's running smooth now so I'm okay with it.
I'm headed to Phoenix with my wife on Thursday, come back Sunday. We'll be going to her oldest daughter's White Coat Ceremony as she's in med school (1st year, got her Masters in Biomedical Engineering last year). We'll be going to the Arizona State Fair on Saturday. No thinking about the Z28 then. I'll check the forums on Tapatalk probably once or twice.
Thanks for all the helpful input. Fred you're a cornucopia of knowledge!
10-08-2014, 10:03 PM
#6
Administrator
Join Date: Nov 1998
Location: Hell was full so they sent me to NJ
Posts: 70,651
Re: Old Hoses and Vacuum Leaks
Enjoy the weekend! We're going to Maryland to visit our grand daughter. Our daughter passed away three months ago, and our grand daughter lives with her father. Been a rough three months. Helping people here helps me get through the day.
10-09-2014, 08:40 PM
#7
Registered User
Thread Starter
Join Date: Sep 2014
Location: Coupland, TX, USA
Posts: 121
Re: Old Hoses and Vacuum Leaks
Yowza, Fred! I'm sorry to hear that. I'm new to the forum so if it was previously posted I was unaware. Enjoy your visit with your granddaughter. You do post a lot here and very lengthy posts too. I enjoy reading them, gaining a lot of knowledge in just a little time.
I looked up on my phone after we landed in Phoenix to see if there would be any cruise nights on Friday or Saturday. My in-laws are here too and they recently got an 87 Corvette to fix up. Father in law is into hot rods so we found a cruise in on Friday in Surprise, AZ, and it's just a couple of miles from our hotels so sounds like we're going.
I also picked up a copy of Hot Rod Magazine (haven't read one in years) and was reminded about the Power Tour. I was a long hauler in 1999 when I lived in CA. I drove my 91 GMC truck that was not modded at all, just had fun and shared hotel rooms with a guy from Long Beach, CA, that had a '37 (I think) Chevy coupe. We rode around Kansas City in it on the "day off", had a blast. I hadn't thought about PT's in several years but if they do it again in 2015 might see if I can hook up in a town or two with the Z28.
I told my wife that the Camaro is running better now that I've replaced a few things. It's driving me (pun intended) from riding my motorcycles, taking up my free time but that's okay. I'll do more riding again. It's fun having a muscle car, something I've wanted for decades.
Forgot to mention, a week ago I had a local shop fix the driver door window. The motor was dead and there were a couple of other parts that broke and needed to be replaced. I couldn't do that myself so paid them. It was less than $290 and is nice having the window working - worth it. That blows my budget for a while too. There's always November!
I looked up on my phone after we landed in Phoenix to see if there would be any cruise nights on Friday or Saturday. My in-laws are here too and they recently got an 87 Corvette to fix up. Father in law is into hot rods so we found a cruise in on Friday in Surprise, AZ, and it's just a couple of miles from our hotels so sounds like we're going.
I also picked up a copy of Hot Rod Magazine (haven't read one in years) and was reminded about the Power Tour. I was a long hauler in 1999 when I lived in CA. I drove my 91 GMC truck that was not modded at all, just had fun and shared hotel rooms with a guy from Long Beach, CA, that had a '37 (I think) Chevy coupe. We rode around Kansas City in it on the "day off", had a blast. I hadn't thought about PT's in several years but if they do it again in 2015 might see if I can hook up in a town or two with the Z28.
I told my wife that the Camaro is running better now that I've replaced a few things. It's driving me (pun intended) from riding my motorcycles, taking up my free time but that's okay. I'll do more riding again. It's fun having a muscle car, something I've wanted for decades.
Forgot to mention, a week ago I had a local shop fix the driver door window. The motor was dead and there were a couple of other parts that broke and needed to be replaced. I couldn't do that myself so paid them. It was less than $290 and is nice having the window working - worth it. That blows my budget for a while too. There's always November!
Thread
Thread Starter
Forum
Replies
Last Post
Nellsw88
General 1967-2002 F-Body Tech
4
05-27-2015 10:27 PM