Pcv Screen

Jennifr

New Member
Sep 15, 2017
2
0
1
Hi all. I was given a '90 Mustang that wasn't working and hasn't been driven for 15 years. After lots of money and parts replaced it runs, but sucks a lot of oil through PCV valve. I put a catch can on it today and it was smoke free for 1.5 mile than I went 3/4 throttle and my horse roared, and than soon after smoked. I checked the catch can and it was full, half quart of oil. I than replaced the PCV valve, but it did the same thing on the same drive after. After searching the internet I read there is a screen below the PCV valve. People say if it is clogged you can suck oil. I have not checked it yet, but if it is clogged is there a reason to keep it? Why would it be necessary to have if it clogs and oil is sucked through? Can I just toss it and keep my catch can setup and eliminate the oil altogether?

Sorry I am just learning through reading and trying to work on it myself because of limited funds. The engine is built, cam, don't remember name of it, bored new heads and trick flow upper lower intake. Thanks Jnfr
 
  • Sponsors (?)


With that much oil in the catch can I would check to see if the screen is even there, also there should be a baffle attached to the lower intake under the screen, that could be missing.
If all that checks out next would be to do a leak down and compression test to see how valve seals and rings are.
 
Hi Steel1. The screen was there and looked brand new and clean. The car idles fine and runs really strong, very frustrating. I don't know how to do a compression test so I guess I will have to take it to a shop.
 
Here' some help in the how to dept...

Google and YouTube are your friends in the how to department for general stuff.
See https://www.google.com/search?sourc...i22i30k1j33i22i29i30k1j33i160k1.0.Sv_YC3IVKIg

Post your Mustang specific questions here on Stangnet and you'll get good, solid technical information

Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Notice the brass fittings on the picture below – they screw into the spark plug home and then the test gauge screws into them
0fd36fdc-62b5-442a-965b-1b3d031a9ac7_1.2074e444f0786fb70bb7ae2ce2988c52.jpeg


Your local auto parts store may have a compression tester to rent or loan if you have a credit card. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.


With the engine warmed up, remove all spark plugs and prop the throttle wide open with a plastic screwdriver handle between the throttle butterfly and the throttle housing. Crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 PSI. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.

A heavy duty battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Leave it connected while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.
 
Last edited:
Hi Steel1. The screen was there and looked brand new and clean. The car idles fine and runs really strong, very frustrating. I don't know how to do a compression test so I guess I will have to take it to a shop.
Yeah looks like your engine needs a little further investigation, could be bad valve seals, rings etc.
jrichker gave you a good link on diy testing, you could rent the test equipment from your local parts store if you wanted to give it a try.
If not find a mechanic you trust and have them run the tests so at least you know where you're at.
Good luck!