# Brake vacuum pump overheating



## tomofreno (Mar 3, 2009)

The brake vacuum kit I have came from evcomponents. Made in Taiwan I think. Today when I stopped the car after driving about 23 miles, I heard something still running. I opened the hood and smoke poured out. Not good I thought.  Turns out it was the vacuum pump still running. Apparently it got so hot the oil in the exhaust muffler started smoking (haven't actually crawled under there to check yet). The 40A fuse blew about 30 seconds after I opened the hood, and stopped the pump, so it was pulling a lot of current. When I got home I shorted the fuse. The pump didn't start. I turned on the ignition key, and it started, so that worked. It ran a while then shut off. I thought it was ok, but then I pulled the fuse I had shorted with a wire and found the wire had burned in half. I'm wondering if the relay stuck closed, or pressure switch stuck, and why it is drawing so much current. Anyone have experience with this?


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## rillip3 (Jun 19, 2009)

Might check for a small hole/leak in the cansiter, if it's drawing all that current, either it just got an exposed wire creating a short (not much you can except try and take it apart and hope you can put it back together) or there's a leak somewhere and it's running continuously under high load to try and keep the vacuum despite the whole. Just my $.02 of thinking, haven't gotten to that point yet with my conversion.


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## tomofreno (Mar 3, 2009)

Thanks rillip. I put in a new fuse, turned on the ignition and the pump started. Blew the fuse in less than 15 seconds, so looks like a problem with the pump. It got so hot yesterday it melted the muffler where it contacts the pump.


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## Stunt Driver (May 14, 2009)

i had something similar with used VW-audi pump. First one I got from ebay - drawed tooo much current, so that my wire from computer PSU was heating up to where i can't hold it.
pump broke shortly. I took it apart - armature was damaged, and plastics mented.
Pump was runnin noticably slower than it should. just like an yothe rseries motor - it draws more current when runs slow.


Did you notice if your pump runs slower?


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## tomofreno (Mar 3, 2009)

It doesn't seem to run slower now, but difficult to say since it usually ran for only a very short time, and I couldn't hear it during normal driving.
Edit: this is the same pump kit as sold at evsource for $348 without reservoir. The relay had stuck closed since the pump kept running after I turned off the ignition. I am guessing the pump has no thermal shut-off so overheated causing damage to the pump.


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## tomofreno (Mar 3, 2009)

I contacted the manufacturer of the pump and related the story (got their web address off a label on the pump). They think there must have been a vacuum leak that kept the pump running. They said when it runs that long it burns the oil out of it, and that's why it is pulling so much current. They are sending me a new relay (because it remained closed after I turned off the ignition after the failure), oil for the pump, and a new muffler. They were very helpful and easy to interact with by email, considering the time difference.

I guess I will start by plugging the vacuum line at the pump to see if the pump shuts off quickly, then work my way through the check valve to the booster on the car. Any suggestions from someone who has checked for brake vacuum leaks would be appreciated.


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## gdirwin (Apr 7, 2009)

I have the same pump, also from ex EVC. I don't have many miles on it yet, but it installed and held vaccuum right away. I added a larger reservoir (made from 4" ABS) so it would not cycle on/off too much.

Once the vac pressure is reached, the pump stayed off virtually indefinetly (until I pressed the brakes at least), even with the car turned off. Without the reservoir, I would hit the brakes for 1 on/off cycle and the pump would come on for a few seconds. With the reservoir, it would take about 2.5 cycles before the pump came on again.

I have heard from others that had leaking brake boosters (the big round thing on the firewall) and had a lot more cycling/leakage.


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## tomofreno (Mar 3, 2009)

> Once the vac pressure is reached, the pump stayed off virtually indefinetly (until I pressed the brakes at least), even with the car turned off. Without the reservoir, I would hit the brakes for 1 on/off cycle and the pump would come on for a few seconds. With the reservoir, it would take about 2.5 cycles before the pump came on again.


 Uh huh, that's how mine operated for about 8 months prior to the failure. I hope it is something like a failing check valve or simple to fix vacuum leak. Too bad I didn't hear it running while driving. I guess there is some advantage to a louder pump.


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## rillip3 (Jun 19, 2009)

Aha! I was right! Unfortunately that's little solace. Checking the line would be easy - hook it up to an air source, coat it in some bubble solution, it'll bubble where there's a leak. Checking the pump itself, I can't think of how to check without getting things in the pump.


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## tomofreno (Mar 3, 2009)

I finally received a remanufactured vacuum booster and installed it with a rebuilt master cylinder. I had already installed the new relay, muffler, and oil that the pump manufacturer, YT Stable Tech, sent me right after the pump failed and I emailed them. It took some time to pump down initially, but the pump remained cool. Eventually it pumped down, and now only comes on for about 2 seconds when I depress the brake pedal. It's fixed! So the booster failed, and that caused the pump to remain on and overheat. 

Part of the delay was due to the fact that the Cardone reman'ed booster was unpainted, and looked like it had been sitting outside for about 10 years. I sanded it and gave it two coats of paint on the outside. Turns out the original master cylinder was ok, no leaks, but I thought for $58 I may as well replace it since I had to drain and remove it to replace the booster. The concern was that the 9 year old original might develop a leak in 2 or 3 years and damage the booster seals, requiring me to do the whole thing over again. Hopefully it will last a while now.


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