I had a PCV Valve on my valvecover, but a mechanic I know told me to remove it and put a regular breather in because it was vaccuming oil. Is one better than the other? What are the pros and cons?

 

You *should* have a PCV valve in one valve cover, usually drivers side, hooked up to a manifold vacuum port on your carb, and the other valve cover should be set up to pull in clean air, factory it goes to your air cleaner, with a small filter, aftermarket people usually use a little chrome breather.

so your carb would suck in air from your PCV valve, through the crank case, from the other valve covers breather.

if you just use 2 breathers, usually they both have air going outwards. It's ok, but I've heard it doesn't work as well.

Not sure why your stock pcv valve would be vacuuming oil though....?

 

Pro's of PCV:

1. Keeps oil clean
2. Makes engine last longer
3. Keeps car from smelling like burnt old used oil

Con's of PCV:

1. .

Now let's move to the worst case scenario:

This "mechanic" built the motor, and the motor has so much blowby that it's forcing oil into the intake via the PCV hose; and the "mechanic"'s solution to this, is to do away with the PCV. In spite of the fact that there are millions and millions of motors running around WITH their PCV hooked up properly, that DON'T burn oil; built of course, by other people, who evidently do a better job of it than he did.

Of course, if this is the case, and you "clean up" :barf: :spank-off: the engine bay by eliminating the PCV, the blowby will STILL be there; and oil will STILL be forced out; and the oil is going to go SOMEWHERE; and without the PCV, that SOMEWHERE will be, ALL OVER YOUR MOTOR AND ENGINE COMPARTMENT; and your car will stink of burning oil 100% of the time, because there will ALWAYS be lots and lots of oil everywhere.

I hope, for your sake, that (a) this "mechanic" didn't build your motor; and (b) you don't have any kind of oil consumption problem in the first place; and (c) you ignore anything else this "mechanic" tries to tell you; and (d) you have someone else to get to work on your car when you genuinely need something done that you can't do yourself which I also hope is not very often.

 

I brought the car in to have fuel lines redone, and he made that suggestion. It seemed to make sense at the time, because the oil was being pushed out, but now it just comes out the breather and runs down the side of the engine.

 

Hmmm....

A better course of action would be to try to figure out why the engine has so much pressure in the crankcase.

A super common cause, with stock heads, is bad intake gaskets; the exhaust crossover passage can leak into the crankcase. Most aftermarket heads don't have that passage and so can't cause that to happen.

Hopefully, it's not poor ring sealing.

Keep the PCV. Make sure there's an inlet to the crankcase in the other valve cover, letting in clean filtered air. Make sure your valve covers have baffles under the PCV holes; most aftermarket ones don't, for some unknown reason. If yours don't, put the stock ones back on. "Looks" or whatever, aren't worth disabling the PCV over.

 

I also thought maybe your valve covers didn't have proper baffeling at the pcv, but it looks like you've found the source of your problem : mega blowby.

hey, everyone likes to re-ring an engine every once and a while, and look, it's friday, now you have your weekend planned

 

No, i'm ****ed. Now the engine seems to have rod knock (only judging from the loud rattle I get at 2500). Last time I buy anything off of ebay...

 

Bummer.

It's not eBay's fault though; don't give up on it. You can get lots of REAL cool stuff off there sometimes. Just have to be more careful with who you're dealing with next time.

Is that how you bought your engine? Who was the actual seller? Have you tried contacting them?

 

I bought the whole car on ebay, i've put over $2,000 into it since I bought it in feb. It was supposed to be working fine. I contacted the seller, and all he said was "it was sitting for awhile and might have had problems he was unaware of". That was never stated in the auction. I actually use ebay all the time. I've bought a few cars and this was my first bad experience. I'm trying to get my money back right now. I don't know how much a rod bearing replacment is going to cost me.

 

What type of repairs for $2K have you had to do? Did he disclose any of this in the auction?

 

He disclosed none. I rewired 70% of the car, replaced all the fuel lines, replaced the starter, etc. In short, I spend 2k just to find out that when I finally got it started it has rod knock...

 

Ha, I've been through that before.....def. sucks



live and learn i guess

 

I use breathers instead of PCV valves nowadays, I used to be a firm believer of PCV valves, but that was before doing a slew of disassembly. for all vehicles, carbureted or FI, the PCV inlet always seems to be where black vapors contaminate the otherwise pristine intake tracts. I got tired of pulling off the plenum or carburator base, and cleaning up the black residue attributable to the PCV port. Now, if you're going to run breathers, you absolutely have to have good baffling under the breathers. Baffles that work, usually some kind of sheet-metal. I use the K&N-style breathers, the ones like circle-track style. They work pretty good, provided you do a good job with baffling. if you don't have baffles under the breather tubes, or breather hole, you are doomed to a perenial mess with oil drips.