Need help with vacuum lines - The 1947 - Present Chevrolet & GMC Truck Message Board Network

KCKC · 01-27-2009, 09:00 AM

Hi Guys and girls. As said, i need some help with the vacuum in my 83 K10 diesel engine. What is the problem? Changing the lever in the dashboard unit does not give any change in the aitflow. In no matter what position the air flow comes out of the lower air ducts on the floor. I have been checking for any leaks, but could not find anything. When i put the lever to defrost position and rev the enigine, the defroster door opens. when i release the throttle the door closes again. I tried to locate the connenction to the intakemanifold but could not find a connection. So where does it get its vacuum from??? Please let me know. Cees.

rcbildr · 01-27-2009, 04:45 PM

There is a vacuum pump on the back of the engine, look where the distributor would be if it was a gas engine. It's bolted in the same way too. Most likely the vacuum pump is shot and will need to be replaced. I have that same problem on my suburban. I have a worn out pump in my shop somewhere and one of these days I'm going to dig it out and see what it would take to rebuild it.

KCKC · 01-28-2009, 06:57 AM

Hi rcbildr, thanks for your reply. I have seen that pump but was not sure if that provided the vacuum. It is located behind the intakemanifold. You say it is bolted in the same way as the distributor. That means take out a bolt and pull it out of the engine, or do i have to remove the intake manifold ? Cees.

rcbildr · 01-28-2009, 09:45 AM

You don't have to remove the intake. If you have a fuel filter bolted to the back of the intake (IIRC 82 and 83 had it), removing the filter will make re-installing the pump easier.

KCKC · 01-28-2009, 11:43 AM

thanks again. i will start this evening with the work. i will keep you posted.

KCKC · 01-29-2009, 12:38 PM

Hi, had the pump out and checked the pumping by turning the shaft with a drill. It pumped like new. Do not know what happened. Perhaps diafram got stuck during the years. The pod was changed in the year 95. So I installed the pump again and connected the line to the plenium directly to the pump and hey presto...........the doors opened and closed at idle speed. I think the next thing to do is to change the rubber lines. Some of them looked a bit dried out. Thanks a lot for the tip about the pump. I really thought that there was connection to the intake manifold like in cars with gasengines. Bye the way..............it was an easy repair. like you said........remove the fuel filter for good access. The only struggle is that it is way back in the engine bay. You will have to lay on your belly to reach for it but it came out fine.
cees

01-27-2009, 09:00 AM	#1
KCKC Registered User Join Date: Sep 2008 Location: Rotterdam, Netherlands Posts: 16	Need help with vacuum lines Hi Guys and girls. As said, i need some help with the vacuum in my 83 K10 diesel engine. What is the problem? Changing the lever in the dashboard unit does not give any change in the aitflow. In no matter what position the air flow comes out of the lower air ducts on the floor. I have been checking for any leaks, but could not find anything. When i put the lever to defrost position and rev the enigine, the defroster door opens. when i release the throttle the door closes again. I tried to locate the connenction to the intakemanifold but could not find a connection. So where does it get its vacuum from??? Please let me know. Cees.

01-27-2009, 04:45 PM	#2
rcbildr Registered User Join Date: Sep 2000 Location: Gold Bar, WA Posts: 1,216	Re: Need help with vacuum lines There is a vacuum pump on the back of the engine, look where the distributor would be if it was a gas engine. It's bolted in the same way too. Most likely the vacuum pump is shot and will need to be replaced. I have that same problem on my suburban. I have a worn out pump in my shop somewhere and one of these days I'm going to dig it out and see what it would take to rebuild it. __________________ My Projects: 1960 GMC 1/2ton with 305 V6 (daily driver) 1963 Chevy 1/2ton 2wd...converting to 4x4 1967 Suburban 1/2ton 2wd My Girlfriends Projects 1985 Chevy Suburban 3/4ton 4x4 with 6.2L diesel, 4" lift, converted to TH-400, Warn Premium manual hubs, & Wildcat 315/75/R16 tires. (daily driver) 1978 Camaro Type LT with a Marine 350 & vortec heads, Rochester Carb, & roller cam 1978 Camaro Z28 Last edited by rcbildr; 01-27-2009 at 04:47 PM.

01-28-2009, 06:57 AM	#3
KCKC Registered User Join Date: Sep 2008 Location: Rotterdam, Netherlands Posts: 16	Re: Need help with vacuum lines Hi rcbildr, thanks for your reply. I have seen that pump but was not sure if that provided the vacuum. It is located behind the intakemanifold. You say it is bolted in the same way as the distributor. That means take out a bolt and pull it out of the engine, or do i have to remove the intake manifold ? Cees.

01-28-2009, 09:45 AM	#4
rcbildr Registered User Join Date: Sep 2000 Location: Gold Bar, WA Posts: 1,216	Re: Need help with vacuum lines You don't have to remove the intake. If you have a fuel filter bolted to the back of the intake (IIRC 82 and 83 had it), removing the filter will make re-installing the pump easier. __________________ My Projects: 1960 GMC 1/2ton with 305 V6 (daily driver) 1963 Chevy 1/2ton 2wd...converting to 4x4 1967 Suburban 1/2ton 2wd My Girlfriends Projects 1985 Chevy Suburban 3/4ton 4x4 with 6.2L diesel, 4" lift, converted to TH-400, Warn Premium manual hubs, & Wildcat 315/75/R16 tires. (daily driver) 1978 Camaro Type LT with a Marine 350 & vortec heads, Rochester Carb, & roller cam 1978 Camaro Z28

01-28-2009, 11:43 AM	#5
KCKC Registered User Join Date: Sep 2008 Location: Rotterdam, Netherlands Posts: 16	Re: Need help with vacuum lines thanks again. i will start this evening with the work. i will keep you posted.

01-29-2009, 12:38 PM	#6
KCKC Registered User Join Date: Sep 2008 Location: Rotterdam, Netherlands Posts: 16	Re: Need help with vacuum lines Hi, had the pump out and checked the pumping by turning the shaft with a drill. It pumped like new. Do not know what happened. Perhaps diafram got stuck during the years. The pod was changed in the year 95. So I installed the pump again and connected the line to the plenium directly to the pump and hey presto...........the doors opened and closed at idle speed. I think the next thing to do is to change the rubber lines. Some of them looked a bit dried out. Thanks a lot for the tip about the pump. I really thought that there was connection to the intake manifold like in cars with gasengines. Bye the way..............it was an easy repair. like you said........remove the fuel filter for good access. The only struggle is that it is way back in the engine bay. You will have to lay on your belly to reach for it but it came out fine. cees



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