2006 V70 2.5T - Brake Booster Vacuum Pump Cycling

DraftyBread · Post by **DraftyBread** » 22 Dec 2014, 12:20

Hi.

Like the title says, I have a V70 2.5T that the vacuum pump is cycling on and off constantly. it only does it with the key in the car and on position 2. Engine running, engine not running (but key on). It doesnt matter.

It will run for 2 or 3 seconds, shut off for ten or so then repeat. Driving it till warm doesnt change the behavior. It will run and on off like this non-stop.

What I've tried:

- Could not hear any vacuum leaks anywhere.
- Unplugging the vacuum switch makes the pump stop and wont restart until I plug it back in.
- Drove it around till the engine was warm, no change.
- The two connections from the vacuum switch to the pump and manifold are good, without tears or hissing.

I tried to pull the lines off the vacuum switch but the refuse to come off, yet spin freely on the connection... Maybe its just hard to remove because its cold out?

I was thinking about maybe clamping the hose to the manifold and to the booster and seeing if that will change the behavior if there is a leak downstream.

Any suggestions? Would My idea work?

Thanks.

Post by **Vovo_merz** » 23 Dec 2014, 18:43

most likely its your vacuum switch going bad, I had to replace multiple of those one few cars, one of them had exact same symptoms as your and swapping the switch that sits next to your air filter fixed the issue

DraftyBread · Post by **DraftyBread** » 23 Dec 2014, 19:20

I think im going to try that.

Today it did it in the morning, I drove to town and it didnt run once. I even pumped the brake repeatedly while parked to try to get it to kick the pump on, it didnt.

Then when I got home it came on in the driveway for a couple of seconds and didnt do it again.

I got a vacuum tester today, I will test it. Also my PCV system is way clogged. Could this cause a vacuum issue for the brakes? The stealership quoted me $650 to replace the system.

Post by **vtl** » 24 Dec 2014, 16:05

No. If intake does not have vacuum (is under boost), vacuum pump does it.

DraftyBread · Post by **DraftyBread** » 30 Dec 2014, 23:40

Update...

I had the dealer perform the PCV service, The car had neutral pressure on the diagnostic test. After replacing the system, It is now -0.4kPa. Turns out the lower return was partially clogged and the small hose on the upper PCV hose was completely clogged.

As for the brakes... The problem seems to have gone away? Maybe the cold weather (Below freezing) is causing the hoses to shrink and leak when the car is cold?

The car also developed a misfire on #2 on the drive to the dealership, a new coil pack from the auto parts store fixed that one. Dealer wanted $310 for this job. Part cost $55 and did the work myself in the parking lot of the parts store with their tools. Easy job to do.

To do List:

I have an intermittent P0027 code pops up randomly now, the service tech told me it needs the rear exhaust cvvt solenoid replaced. Ill do this one myself too, just need to order the part.

Rotors are warped causing shuddering under braking.

A/C fan is noisy and thumps about like something is in it when cold, but after a few minutes it works fine.