bad valve seals?

[IKNOWIMNOOB]

I just got a automatic gsx a few weeks ago and it just feels like its not as fast as it should be. so I tried doing a boost leak test. well the boost was leaking out of the valve cover breather so I couldn't build up any boost to do the test. I also know that my compression is good ( between 155 and 160 across the board) and I checked the pcv valve its good. I'm hoping its not valve seals leaking the boost into the valve cover but don't know what else it could be. any ideas? thanks

 

[yokotabrat]

How did you test the PCV? Did you unhook it from the valve cover and leave it connected to the hose going to the intake manifold when doing your pressure test? That will tell you for sure if it's leaking boost back into the valve cover.

Also, what are you using to pressure test? Compressor or something else?

 

[kenamond]

And make sure you do the boost leak test on a warm motor.

My guess is it's a leaking PCV valve.

 

[IKNOWIMNOOB]

yes I tested it with it unhooked from the valve cover. and I was using a bike pump to do the test I know should use a compressor but don't have access to one right now. but even with the low pressure that puts out, if I put my finger over the breather hole and the pcv hole, after pumping for about 30 seconds, i take my fingers off the holes and air just wooshes out of the 2 holes. something just doesn't seem right.

 

[kenamond]

yes I tested it with it unhooked from the valve cover. and I was using a bike pump to do the test I know should use a compressor but don't have access to one right now. but even with the low pressure that puts out, if I put my finger over the breather hole and the pcv hole, after pumping for about 30 seconds, i take my fingers off the holes and air just wooshes out of the 2 holes. something just doesn't seem right.

First of all, you can't use a bike pump. Go to a hardware store and buy a 10 gallon portable compressed air tank for $30. You'll be doing boost leak tests several times in the future (or you should be), and you can use it to adjust tire pressure, pump up bike tires, etc.

When you do the test, warm up the motor first. Blowby on a cold motor will look like a massive boost leak. Then unscrew the PCV from the VC. Add pressure to the boost leak tester using the air tank until your boost gauge reads 20psi (you have an aftermarket gauge, right?). Check if air is leaking out of the end of the PCV valve snorkel (the bronze-colored tube on the end of the PCV valve), not the hole in the VC that it screwed into. If it's leaking, get a new OEM PCV valve from a Mitsu dealership for $8 (Autozone, Carquest, etc. are not the right thing and will leak out of the box).

If the PCV is not leaking at 20psi, screw it back into the VC. Repeat the test and check how fast the 20psi you added leaks down. Some will leak out of the VC breather due to ring blowby. But you may have numerous leaks elsewhere in the intake. The bottom line is that you should leak down from 20psi at a rate of around 1psi every few seconds...or slower. Check all the normal leak-prone locations with a spray bottle and some super-soapy water. If you fix all the leaks you can, and you're still leaking out the VC breather at too fast of a rate, then I'd suspect intake valve seals. But you won't know that until you fix other leaks.