Couldn't find a decent car group but I know there are some folks here who know automotive well.
In preparation for a smog check (was marginal for HC at 15mph last time) I also swapped out the PCV valve for crankcase venting. 1996 Toyota Corolla. The old one rattled when shaken. I thought the spring had broken. The new one is a MicroGuard PCV385 and ... rattles just like the old one. No spring action can be felt on the plunger.
Is this normal? How can they work with the plunger just sloshing around in there?
I did notice that the new one has more travel in the plunger so maybe the old one is a bit dirty inside.
Look for a vent blocked by gunk. (Other side of the block if it's a V-8... I don't know about weenie engines ;-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
It's what you learn, after you know it all, that counts.
When I blow through it air passes both ways but with different resistance. For the old PCV valve as well as the new one. I have just never seen anything like that.
I know roughly how it works and that there usually is a spring inside. However, in the ones for the 96 Corolla there isn't, neither the old not new one. Different mfgs and it is highly unlikely that the new and the old one are both broken. It's weird.
As others have said, they are supposed to rattle. On my old 80's 90's cars, I would replace them at every tuneup. They were not real costly back then. But a mechanic told me to stop wasting my money. He took them and soaked them in a some carb cleaner. Shook them a few times during the soaking. (Or sprayed pressurized carb cleaner into them). Then blow a little compressed air thru them and they were good as new.
Always make sure the grommet they push into is good and the hose connected to them is also good, and clean on the inside. (more carb cleaner and comp. air to clean hose if it's still good).
For auto newsgroups, look to alt.autos.******* and alt.trucks.******* Not much activity these days, but still some.
That is normal for most cars. The weight inside is the calibration. If it g ets dirty the flow goes down and the crankcase fumes get spewed instead of going into the intake manifold to get burned.
If you have an engine with high blowby, they make a high flow PCV valve tha t usually will help.
To test for blowby, remove the oil filler cap and put a piece of paper on i t, you should feel vacuum, NOT PRESSURE. Pressure means the rings are worn or there is an internal engine fault such as a slightly leaky gasket or som ething of that nature. That causes the pressure in the crankcase to exceed the vacuum the PCV allows. (volume actually)
Generally, if you are high on HC but not CO, the mixture is on the lean sid e and you're getting a lean misfire. If both HC and CO are high you usually have an ignition problem or an internal engine fault.
For it to be on the lean side and not throw a check engine light there is u sually a vacuum leak right near the intake valve of one (or more) cylinder( s). That is the only way the O2 sensor can be satisfied with a lean mixture . A leaky EGR valve can also cause it but those are usually easy to fix. Us ually a piece of dirt gets caught in there and won't allow the valve to ful ly close, which is very similar to a regular vacuum leak. One engine we had was so gunked up from never being punched that when you did hit the gas ha rd there was another piece of dirt and it would run funny. Eventually we we nt to a head shop and bought a pipe screen and that fixed it for good. If y ou have alot of miles you might have to do that.
To reiterate in case you missed the thread - to check for a vacuum leak :
Disconnect the IAC (idle air control). Spray either ether or propane at sus pected areas and watch for the RPM to rise.
Disconnecting the IAC keeps the computer out of the idle speed control. The control may be so precise you can't tell because it is compensated so fast .
This will set a code so you will need a scanner to reset it in most cars. M ost people know at least one person who has such a scanner. Buy them a few beers and let them plug in and push the button. Most of them like their toy and don't get enough chances to use it.
One thing that's easy & may help: make sure you have "new" oil, as in just changed, before you submit to the posterior probing. Possible a grade thicker than spec if you are worried. The Japanese engines tend to have soft rings, I see a lot of hi-milers running around here (near the Mx border), some of them really smokey, but running just fine. Don't know how they get away with that...
Thanks, I didn't know that was possible but it seems it is.
Where'd they get spewed to? I also always wondered what could possibly fume with oil other than miniscule amounts of gas that might seep past the rings on old engines.
In the olden days that was all simpler. My 16-horse Citroen had a rubber "fart device" to let go of any crank case flatulence.
It is 21 years old but only around 50k miles.
I read about misfires but the spark plugs are clean and the engine runs very smoothly. It also never burns any oil.
I'll let the shop handle that if it fails HC at 15mph. Got too much work right now. A client just threw me three board designs.
The weird thing is that is passes HC at 25mph with great margin, as well as everything else.
That I will do anyhow. Got the new filter waiting here on the table.
I use 5W30 which is quite thin but cars start easier in winter and my wife mostly drives short distances where thinner opil is better. Still our cars never consume any oil. I change every 3k miles at the lastest or before smog wichever comes first. I never have to add oil inbetween.
The engine is old (21 years) but low mileage (around 50k).
That's the clue that it is the old PCV... flow restriction. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at
formatting link
| 1962 | It's what you learn, after you know it all, that counts.
I am sure hoping so. Last time it passed with 61ppm out of 61 allowed. Whew. Since those things do not tend to become better with time by themselves I am also going on a couple of long rides with Lucas cleaner added to the tank and giving it a fresh oil & filter change right before the test.
Strange thing is I did not notice any restrictions in the plunger movement in the old PCV valve versus the new one. Also, at lower power the PCV valve is supposed to reduce flow and not increase it. It is supposed to open at high power, see middle of page:
formatting link
One of the issues with my wife's car is that it is used almost exclusively for 2-3 mile trips. Grocery, church, local nursing home visits. The cat and engine never really warm up except for the few times I use the car.
We're more "boony"... 5 miles to the _closest_ grocery ;-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| STV, Queen Creek, AZ 85142 Skype: skypeanalog | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
It's what you learn, after you know it all, that counts.
My brewing supply store is 15mi away. When I run out of something and people find out I go there by bicycle the usual reaction is "WHAT?". To make it a good exercise it's up and down and on the way back a net
1200ft altitude difference has to be recouped. Same when I need electrical stuff because the big stores are all down there in the flatlands.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.