The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support Fuel Injector Clinic
Please Support Rix Racing

Loud air leak

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

SeanCollins

10+ Year Contributor
134
1
Apr 23, 2011
Tully, New_York
I have been doing lots of little things to my car to get her running good but it seems 1 step forward 2 steps back is the way for DSM. Anyway I was under the hood this morning checking things over and I heard a decent leak of air coming around the crank sensor I believe it is,
You must be logged in to view this image or video.
it seems like it's coming from near the bolt under the valve cover, please tell me i do not have a serious problem
 
Did you do a boost leak test? If not, don't post until you do one.
 
It's not a check valve..Or is it..I have never noticed if it was or not..But everytime I have messed with it, it was just a brass looking tube with a rubber line..And I think it runs to the bov..But I don't want to go downstairs and check, to make sure..

If you had it just running, you didn't cause any damage..
 
The car won't idle quite the same with it venting like that but I've not bothered driving it with it unhooked. It's important to have proper crankcase ventilation. Replace the barb and route it back to your intake pipe.
 
It's not a check valve..Or is it..I have never noticed if it was or not..But everytime I have messed with it, it was just a brass looking tube with a rubber line..And I think it runs to the bov..But I don't want to go downstairs and check, to make sure..

If you had it just running, you didn't cause any damage..

Are you saying you think that the valve cover vent line goes to the BOV? WTF I think next time you should go downstairs to make sure before posting terrible misinformation. Here is a quick little lesson in DSM's for you.

The valve cover vent line from the factory runs from the passenger side of the valve cover to the intake pipe so it can pull a vacuum to help remove pressure from the crankcase. There is no check valve. A lot of people insert a catch can along this line to prevent oil and blow by from getting in their intake pipes. It has no relation to the BOV or the BOV line.

If you were talking about the PCV line, it runs from the back of the valve cover to the intake manifold. The PCV (Positive Crankcase Ventilation) valve is threaded into the back of the valve cover. It is a check valve (a variable-restriction valve). A lot of people install a secondary check valve on this line to prevent boost from entering the crankcase though this line. It has no relation to the BOV of the BOV line.

If you need more info you can read Calan's Tech Article which Scott posted a link to. Scott also posted a link to the secondary check valve that a lot of us use and recommend for the PCV line.

Hope this helps!
 
Right, I am missing the valve cover vent line the one to the air intake not the PCV that goes to the manifold. What problems could this make?

I know, I was replying to the other poster's response regarding the BOV line.

Others have mentioned from first hand experience that it won't run right. It's not a sealed system as you can just attach a vent/filter directly to that nipple. However it works best when attached to a vacuum source, like the intake pipe. If you are getting air coming out of it during a boost leak test you need to check your PCV valve like Scott already mentioned and it's always a good idea to install one of those check valves in addition.
 
Right, I am missing the valve cover vent line the one to the air intake not the PCV that goes to the manifold. What problems could this make?

That line that goes from the passenger side of the VC to the intake is a measured line. Because it is between the mass air flow (MAF) it is metered air that the ECU is compensating for. Think of it like a big boost leak...
 
That line that goes from the passenger side of the VC to the intake is a measured line. Because it is between the mass air flow (MAF) it is metered air that the ECU is compensating for. Think of it like a big boost leak...

The line is only metered if it is hooked up to the intake pipe. As long as the port on the intake pipe is blocked off/plugged/capped there is no metered air leak. The port on the valve cover itself is just a vent for crankcase pressure and is not metered.
 
Well I found a diagram that shows the spot in question being ran to a catch can. Also it says to cap the intake manifold side and run the pcv line to the catch can as well. Has anyone else done this or know someone that has done this and if I should explore this path or not. Thanks guys
 
Did you even read over the link I posted? If you have a nipple on your intake pipe, just hook it back up.

It's not imperative that it's hooked up but it doesn't hurt.
 
It seems to me like the best solution would be to hook it up like it's supposed to be, and maybe add a catch can in-line.

As you have it now, oil should spray all over the place when you are under boost, and dirt should get sucked into your crankcase under vaccum.
 
I will do what I can to hook it up the right way but I try and stay out of boost at the moment just until I know everything is Kosher.. So what kind of fitting am I looking for the opening in the valve cover to run it to the intake like it suppose to?
 
I will do what I can to hook it up the right way but I try and stay out of boost at the moment just until I know everything is Kosher.. So what kind of fitting am I looking for the opening in the valve cover to run it to the intake like it suppose to?

If your nipple is broken off you are probably going to need to drill and tap it and screw in a brass nipple. I would take the valve cover off to do it though.
 
You must be logged in to view this image or video.
Well I may sound like a cheap bastard but I decided to just JB weld a 1/4" fitting into it and run a hose back to my intake. Should be dry in 6-12 hours so I will let you know if it holds up or not.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top