The new one is from reputable dealer but I believe they are all over seas made.
Thanks in advance.
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How do you test old style pcv ?
- Thread starter Syleng1
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The new one is from reputable dealer but I believe they are all over seas made.
Thanks in advance.
Plymouth 65
I'll be in the shop
I believe it just has a check ball type valve inside. I would make sure the ball moves freely and isn't gummed up. 65'
Never give old stuff away till you test the new stuff. Not sure how to test vacuum on one of those. It should not allow full vacuum. Plug it temporarily and see if the problem goes away. We just made sure they were not clogged shut and the check valve worked. Those will last forever, just soak in carb cleaner, flush and install.
I was not sure if the test as a pressure or vacuum test and what are the specs. Like the newer valves that have a spring and the spring wears out and the pcv leaks. That valve can be assembled with a multitude of springs rates. This one seems “looser” than others. I also want to put a gauge on that port to see what type of vacuum the engine is pulling and see if maybe the engine is pulling more vacuum than the pcv can handle and it is staying open always. In which case it’s garbage and I need to find a new way to evacuate the crank case.
Lord Sparky
Well-Known Member
They say to replace the Crankcase Ventilation Valve every 12 months. Excessive? Just spray some Gumout?
An engine should not pull that kind of vacuum. My brothers 67 273 would cruise at 18 inch of vacuum, no problem. Those valves were all the same as far as I know. If you changed the valve and all of a sudden there is a problem, it was probably what you just did.
We used to do that, back in the day when they cost a couple bucks. I wish I had kept more. I grab all the old steel ones I can get now, since I have never seen one wear out.
You boys are sure making me feel old. Here is the tool for measuring the effectiveness of your PVC. On a running engine pull off the breather on the v/cover opposite the PVC. Lay device over the hole. If there is adequate vacuum in the crankcase the check ball will be pulled into the safe zone.
I'm old too, just never had a PCV tester.
bcschief
Well-Known Member
Basically a PCV valve is a controlled vacuum leak to suck vapors from the crankcase the check valve and the spring are there to prevent backfires from entering the crankcase. So generally speaking soaking the valve in solvent to clean it should suffice. As long as the valve isn't plugged with gunk and the spring works the valve is good. You changed them in the old days because it wasn't worth your time to clean them.
mopar head
Well-Known Member
Does the old metal ones even have a spring?
The ones I have you can shake them and hear the check ball rattle, and to me means good to go.
The ones I have you can shake them and hear the check ball rattle, and to me means good to go.
cudamark
Well-Known Member
I guess I'm old too! I used to have one of those testers......I wonder what happened to it? Hmmm....
Give it to the Wife, should be able to suck air thru it from carb side, but not be able to blow any air out the engine side. Only test needed.
cudamark
Well-Known Member
I always just pulled the valve assembly out of the valve cover with the engine running, stuck my finger over the hole in the end of the PCV valve, and it it went "thunk" and the idle dropped a bit, it was good enough. If you had the wrong valve that allowed too much vacuum, you'd also have a rough idle. That might be tough to determine if you have a performance cam with very little vacuum to begin with. You may have to run a full compression/leakdown test to make sure your engine didn't just develope a problem.
Lord Sparky
Well-Known Member
Just did an internet search, none for sale, sometimes on eBay.
I have always tested them the following way:
- With pcv valve removed from the engine, give it a shake test. If rattles thats good. If not clean it.
- Pucker up and blow into both ends (one at a time and in normal operating position) one should allow air flow. One should not.
bcschief
Well-Known Member
I just looked in my 63 service manual and it recommends servicing the valve every 6 months by soaking the valve in carb cleaner and blowing out with air. If the valve is severely plugged it can be disassembled and cleaned the spring height is 9/16". It also says all V8s and the 225 use the same P/N valve but the 170 uses a different P/N.
Thanks Guys! But your kinda missing my issue in a round about way.
if the ball is not seating properly because the thing is garbage from bad production it could be sealing one moment and not sealing as the ball inside turns. Kinda like a bad valve job. If that makes sense. Typically that valve is closed and not sucking at idle or up to a certain amount of pull like say 5”hg after 5”hg it pulls off the seat creating the suction into the crankcase. But if the ball does not always seat it leaks. As for a spring- the spring can or cannot be there to control the ball especially when it’s a plastic ball because plastic is a lot lighter than metal.
I understand how it works but just could not find a spec to test when it “pulls open.” After all the dialogue- I now assume there is no spring or spec.
thank you!
if the ball is not seating properly because the thing is garbage from bad production it could be sealing one moment and not sealing as the ball inside turns. Kinda like a bad valve job. If that makes sense. Typically that valve is closed and not sucking at idle or up to a certain amount of pull like say 5”hg after 5”hg it pulls off the seat creating the suction into the crankcase. But if the ball does not always seat it leaks. As for a spring- the spring can or cannot be there to control the ball especially when it’s a plastic ball because plastic is a lot lighter than metal.
I understand how it works but just could not find a spec to test when it “pulls open.” After all the dialogue- I now assume there is no spring or spec.
thank you!
because every engine, even factory fresh, is never exactly the same as as the one next to it. the factory valves were probably a "best average" type of guess. whether you use one of these or not, there's some interesting info HERE
The PCVs I have pulled apart do not have a ball inside, they have a spring & a pintle. A shape like a golf tee. That is because there is some airflow at idle around the stem of the pintle, through a carefully calibrated orifice. Once vacuum diminishes with more throttle opening, the pintle drops away increasing the gap for more airflow into the engine.
cookietruck
Well-Known Member
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