My annual "low vacuum" thread.

[BlackMetal]

Think I've gone through 2 seasons now knowing that my car is running at 12in/hg.

Tried carb cleaner all over the place, never heard a change in idle speed. Been dreaming of hooking up a smoke machine and finding the problem but don't know where I can get that done.

So while it's still early in the year, I'd like to finally take care of it.

Any chance my autometer boost/vac is wrong? Doubt it.

Should I tighten intake bolts or remove and replace intake gasket?

1 Plenum bolt started to slip a little bit when I installed Power Plate, but didn't completely strip it. No indication that there's a leak here when spraying carb cleaner but could that be it?

Sprayed around the throttle blade shaft where I hear seals are common to leak, didn't notice anything.

I would remove the entire vacuum block and take all vacuum lines out of the equation at once, BUT then my boost gauge wouldn't function so I wouldn't know if it improved or not.

Any ideas? FIxing this would be great.

 

[GNRick]

What are your blm's?

 

[413turbo]

i did get a bad autometer boost guage last year. they did replace it, but that was it.... check it.

 

[87bigcut]

You should get one of the leak detectors (or make one like I did) that attaches to your intake tube on the turbo. Then you loosen the rocker shafts, and put 20-30 psi of air into the whole intake system...you will be amazed at how many places air shoots out

Boost Leak Detector

like that or make the same thing to attach to your turbo inlet....

Joe

 

[BlackMetal]

What are your blm's?

Not sure right now. Car has been garaged for the winter, I take it out occasionally on a nice day, but then it sits for 2 weeks again and the battery dies, so with the ECM resetting all the time I can't count on it being accurate right now. But as far as I remember last year it was pretty close, 125 or so. But not certain.

i did get a bad autometer boost guage last year. they did replace it, but that was it.... check it.

Interesting. I don't have a spare one to compare it to though.

You should get one of the leak detectors (or make one like I did) that attaches to your intake tube on the turbo. Then you loosen the rocker shafts, and put 20-30 psi of air into the whole intake system...you will be amazed at how many places air shoots out

Boost Leak Detector

like that or make the same thing to attach to your turbo inlet....

Joe

Yeah, I've known about those for a while. Guess that would be my best bet next to finding a smoke machine. Haven't bothered with one so far because I don't have an air compressor at home but found out my neighbor has one so I guess I could go that route. I guess my project for tomorrow could be to make my own.

 

[charlief1]

I'm gonna bet it's your intake gasket but it's leaking under the intake. You need to smoke it for sure.

 

[Gary Wells]

Before incurring any major expenses I would borrow another vacuum gage from someone in your local area and temporarily hook it up and see if the readings duplicate. Some of those gages are not accurate from the get-go.

 

[1KWIKSIX]

Pressurizing Turbo inlet to find vacuum leaks etc.

Don't mean to hijack this thread...but I'm in the middle of chasing down some high blms' at the moment.

I've got the pressurized cap in the turbo inlet bell...and set regulator on air compressor to introduce around 15psi into the valve on cap and into the system....you can hear the system pressurizing.....and then very faintly some air hissing (escaping somewhere).

I've purchased a smoke pencil (the kind you can get for testing for air leakage used by HVAC trades) and between the hissing of air and also the tell tale sign of smoke drifting away when in the area of the leak......was able to find 1) a leak around wastegate solenoid where hose connects and 2) also a leak around the front edge of vacuum block on TB. I wasn't able to determine if it was the edge of the block or not....so changed over all the small pieces of tubing connecting the vacuum block and the black metal vacuum lines running off this........also removed the machined vacuum block and appied a tacky copper spray on gasket by permatex.....

I also changed over a few of the other vacuum lines with new silicone rubber hoses.

I'm going to chase down some more tonight.

Question: I never removed the valve covers, and loosened the rocker arms.....Is this a critical step in the process? or can I get by with not touching the valves and leaving the valve covers on?

Also, I opened the throttle to allow this pressurized air to enter easily beyond the normall closed TB blade & into the system.

FYI.....I too was not very happy with the feel when I tightened my rear bolts on the plenum after installing my RJC Power Plate......felt like the bolt was too short and was stripping......So I installed studs in the back of the Plenum.....now I can tighten down fully and have no fear of leaking or stripping threads......was easy to do.....

Anyone with experience on chasing down vacuum / exhaust leaks please chime in.

Good Luck in your efforts in chasing your low vacuum issues.

dave

 

[BenPutnam]

Autometer

i did get a bad autometer boost guage last year. they did replace it, but that was it.... check it.

+1

I have not had mine replaced yet but it off quite a bit.

 

[BlackMetal]

Well I should have mentioned, at one point my gauge was reading in the normal range 15-16, I know it's still a possibility that it's the gauge, but just want to make it clear that it's not like I hooked the gauge up from day 1 and had a low reading, then I'd definitely susepect the gauge. Must have been something I modded or something starting to leak on it's own, because one day I noticed the gauge reading low. But at one point I did have a good vacuum reading, just to be clear.

Question: I never removed the valve covers, and loosened the rocker arms.....Is this a critical step in the process? or can I get by with not touching the valves and leaving the valve covers on?
dave

You will be losing a lot of your "test" air pressure through whatever intake valves are open, through the cylinder, and out the exhaust. So yeah I'd say if you're serious about tracking down the leaks you'd want to remove the rockers and let the valves stay closed. Makes your air pressure test more effective if it isn't leaking past an intake valve and having to pressurize the cylinder too.

That's why I'm doing today. Just came in from the garage. Got the driver's side (aka EASY side) valve cover off and loosened the rockers. Now time to tackle the annoying passenger side with wiring harness, heater box, downpipe, and heatshields to work around.

 

[BlackMetal]

What's the bare minimum for getting the passenger side out? GNTTYPE.ORG talks about removing heater hoses, I'd rather not make a mess and leave those attached even if it costs me a few extra minutes of struggling to get the cover out.

Passenger side

1. Removed all spark plug wires and pushed out of the way .

2. Removed the heater hoses at the firewall.

3. Removed the two small water lines that branch off the metal water line that is parallel to the fuel rail line.

4. Remove the 1" hex nut attached to the water line.At this point , the whole water line unit can be raised straight up and over toward the drivers side.

5. Remove the heat shield attached to the air condition box.

6. Remove the valve cover bolts and roll the cover upward and pull it straight out.

Has anyone been able to do it leaving coolant lines attached?

 

[Heg87t]

I had an easier time with my passenger side a couple of weeks ago. Had to fight the wire harness loom on the driver side. I didn't take any heater hoses or pipes off. Best memory went like this.

removed plug wires
removed wastegate solenoid
removed bolts from valve cover
removed breather from front of valve cover
removed breather heat shield from turbo bracket
removed valve cover

I do not have the heat shield on the AC box or any AC parts for that matter.
I would try to get it out without pulling the hoses first. Rotating the engine to get the # rockers down may help.

 

[BlackMetal]

Thanks for your input, I was actually able to get it out before coming back inside to check for any tips. Got spark plug wires and big loom out of the way, then the back corner of the valve cover was getting stuck on the heater box heat shield, but I could see where it was scraping and gave the heat shield a swift smack to bend it back a little and then no problems.

After all this work it seems like all the valves were basically shut. Oh well, my valve covers could afford to be cleaned/painted anyway.

I've got a spare valve stem right here, just gotta go to Home Depot and find a pipe plug for the silicone hose, and then track down my neighbor and borrow an air compressor.

Excited to potentially get this figured out.

Will this work filling with a tire gauge instead of running the compressor line straight to it with a regulator set to 20psi? Or am I not gunna get enough volume of air through this.

 

[DailyDrifter]

Maybe this question was asked before, BUT do you have it cammed up?

 

[sabersaw30]

Pull your egr and make sure your gasket is good.Believe me I changed out a good cam from thinking it was a bad cam.My vacum was gone.It gets real hot on the intake around your egr.