How much power loss with vacuum leaks? - ZR-1 Net Registry Forums

01-22-2004

I am newbie and while checking out vacuum pump discovered all rusted out and replaced. While testing determined that pump cycles every 6 seconds and indicated leaks (left disconnected for now since it will wear out new pump quickly at this rate). Purchased Mityvac vacuum pump gauge to test line under plenum, big time leak and will have to pull plenum. Bought some parts mentioned on site for correcting vacuum leak problem. It will be a few weeks until I can get to this project and was wondering how much power am I actually losing. The car is still very strong and hauls butt, but being a newbie I'm sure not full potential. I'm am not looking forward to pulling plenum but I might as well start used to it and not be intimidated with all the help available here and having the factory service manual and correct tools for the job.

Next questions, ZR-1 has 50,000 miles and since plenum will be removed should I replace the starter now. 14 years old and maybe the starter will be good for awhile. For the cost of one and since I'm under the plenum it this a good idea?

Thanks in advance for input.

By the way, I now see what all the hype is about the ZR-1. I love this car and I think it will be worth some of the headaches that come with it. I'm just not sure how it will be to keep it for the next 20 years as part as scarce for some items. I had to search the entire US to find the one known front exhaust bracket (discountinued and in stock) that bolts to rear of tranny. I hope I don't regret passing up the 71 454 LS6 and I chose the ZR-1 over. I know I can get parts for that years to comel, no comparison to the ZR-1 though.

Tom · 01-23-2004

Do you have a factory corvette shop manual? It has an explanation of how the system works. The pump only runs if the vacuum drops below a certain level. I believe if you repeat the test with the engine running the vacuum pump will never come on since the engine manifold vacuum will be sufficient. The vacuum pump should only come on with the engine running if you stay at wide open throttle long enough for the vacuum to drop below the level where the pump comes on. It comes on then to make sure the secondary butterflies stay open.

01-27-2004

Thanks Tom, I really appreciate your input. I will check it out. Sorry to take so long to get back, had to go overseas for a few days.

01-22-2004	#1
HAWAIIZR-1 Guest Posts: n/a	How much power loss with vacuum leaks? I am newbie and while checking out vacuum pump discovered all rusted out and replaced. While testing determined that pump cycles every 6 seconds and indicated leaks (left disconnected for now since it will wear out new pump quickly at this rate). Purchased Mityvac vacuum pump gauge to test line under plenum, big time leak and will have to pull plenum. Bought some parts mentioned on site for correcting vacuum leak problem. It will be a few weeks until I can get to this project and was wondering how much power am I actually losing. The car is still very strong and hauls butt, but being a newbie I'm sure not full potential. I'm am not looking forward to pulling plenum but I might as well start used to it and not be intimidated with all the help available here and having the factory service manual and correct tools for the job. Next questions, ZR-1 has 50,000 miles and since plenum will be removed should I replace the starter now. 14 years old and maybe the starter will be good for awhile. For the cost of one and since I'm under the plenum it this a good idea? Thanks in advance for input. By the way, I now see what all the hype is about the ZR-1. I love this car and I think it will be worth some of the headaches that come with it. I'm just not sure how it will be to keep it for the next 20 years as part as scarce for some items. I had to search the entire US to find the one known front exhaust bracket (discountinued and in stock) that bolts to rear of tranny. I hope I don't regret passing up the 71 454 LS6 and I chose the ZR-1 over. I know I can get parts for that years to comel, no comparison to the ZR-1 though.

01-23-2004	#2
Tom Join Date: Jan 2004 Location: Southern CA Posts: 108	Power loss Do you have a factory corvette shop manual? It has an explanation of how the system works. The pump only runs if the vacuum drops below a certain level. I believe if you repeat the test with the engine running the vacuum pump will never come on since the engine manifold vacuum will be sufficient. The vacuum pump should only come on with the engine running if you stay at wide open throttle long enough for the vacuum to drop below the level where the pump comes on. It comes on then to make sure the secondary butterflies stay open.

01-27-2004	#3
HAWAIIZR-1 Guest Posts: n/a	Thanks Tom, I really appreciate your input. I will check it out. Sorry to take so long to get back, had to go overseas for a few days.