A specific question about the old "dipstick popping out" issue

[Huskymaniac]

So I noticed one day that the dipstick was out. I pushed back in and drove the car a few times and it didn't pop out. After a couple of weeks, it was out again. I noticed it when I went to work on the hood squeak.

I know the two issues are the rubber o-ring and the PCV valve. I know that a new o-ring usually solves the problem. My concern is what if it is the PCV valve? Getting a better seal on that dipstick would only cause the pressures to rise and there might not be any other immediate symptoms of a stuck PCV valve. Assuming that were the case, what damage could be done by not replacing a bad PCV because either one doesn't know about it or one saw a symptom but fixed that symptom another way and assumed the PCV valve was OK?

Normally I would just replace the o-ring and not worry too much about it but I have another symptom that might point to the PCV valve in an indirect way. When the weather got cold my idle would bounce immediately after starting the car. It would jump up to a normal RPM first. Then it would drop very low and nearly stall. Then it would bounce back to the normal cold RPM again. Then it would drop again but not as low. This repeats and the "undershoot" is less each time until the car finally settles on the normal RPM for a cold idle. It takes all of about 5 seconds for this to happen.

From what I have read, it sounds like this could be due to a stuck AACV and the AACV could be stuck due to oil being pushed out which in turn could be due to the stuck PCV valve. However, this bouncy idle seems to be getting better with time since I replaced the O2 sensor. Sometimes it doesn't bounce at all. Maybe the AACV is OK and the bouncy idle was due to the O2 sensor. And the underside of the car looks pretty dry right now. I get zero drips of oil on the driveway. So maybe the PCV isn't stuck after all.

But the bottom line is, what damage can be done by a stuck PCV valve?

[Cam]

If the pressures in the crank case are high enough you could potentially start leaking from your cam, crank, valve cover and/or rear main seals.

[Coan]

I've had the same issue with the dipstick popping out and replaced the o-ring to get it to stop. I also planned to replace the PCV valve at the same time, but after 3 failed attempts I still haven't been able to get it out. I'm going to try once more with a different tool before I take the manifold off and do it the hard way. But yeah, the pressure has to go somewhere, it's best if it goes where it was designed to go.

I've also had the same issue with the idle during start-up. I've never looked into because I usually forget about it by the time I get back home lol.

[Huskymaniac]

Originally Posted by Coan

I've had the same issue with the dipstick popping out and replaced the o-ring to get it to stop. I also planned to replace the PCV valve at the same time, but after 3 failed attempts I still haven't been able to get it out. I'm going to try once more with a different tool before I take the manifold off and do it the hard way. But yeah, the pressure has to go somewhere, it's best if it goes where it was designed to go.

I've also had the same issue with the idle during start-up. I've never looked into because I usually forget about it by the time I get back home lol.

Yeah, the cold idle is a weird one. It was doing it consistently so I was convinced that I was going to have to remove and clean the AACV at some point. It didn't stop immediately after replacing the O2 sensor but now, suddenly, it occasionally will start in the morning with no bouncing. Someone had mentioned that the computer may just be taking its time settling on correct air/fuel mixtures.

[NikFu S.]

Originally Posted by Huskymaniac

Someone had mentioned that the computer may just be taking its time settling on correct air/fuel mixtures.

On this note it could be temperature related.

All summer long I had the dipstick popping out, but as winter rolled in that has stopped and now I have vicious bouncy idle which kicks in right after I pull out of my garage.

I have had PVC issues in the past, but there is something else causing the fouling of the valve. I know Harvey explained it to us once but damned if I can remember.

[Huskymaniac]

Originally Posted by NikFu S.

On this note it could be temperature related.

All summer long I had the dipstick popping out, but as winter rolled in that has stopped and now I have vicious bouncy idle which kicks in right after I pull out of my garage.

I have had PVC issues in the past, but there is something else causing the fouling of the valve. I know Harvey explained it to us once but damned if I can remember.

It doesn't happen when you start it but when you pull out of the garage? If that is the case, I would suspect IACV which, from my understanding, is what takes over when the engine warms up versus when the car has just been started and is still very cold.

[ensteele]

My thought was that vibration was the reason that the dipstick moved out. With the o-ring being replaced, the dipstick may not be able to vibrate out, and pressure may not be increased at all. Just a thought.

[Huskymaniac]

Originally Posted by ensteele

My thought was that vibration was the reason that the dipstick moved out. With the o-ring being replaced, the dipstick may not be able to vibrate out, and pressure may not be increased at all. Just a thought.

Yeah, that's my hope but I am concerned that the PCV may be causing it and I was just wondering what damage that could cause. I got a good answer to that. It sounds like you think the PCV is not what causes the dipstick to pop out and it is always the o-ring plus vibration. If that is true, I would be happy to hear that. The o-ring I can replace. The PCV involves issues that I am not sure I trust myself to deal with. I depend on this car daily so I don't want to mess it up to the point where I can't drive it for several days. If I had time to go nice and slow I may feel good about something on the level of the PCV and maybe even taking the intake manifold off to get a better look at the AACV. But my next few weekends will be taken up with putting up xmas lights and coaching basketball. It would be great to just take care of the o-ring and keep an eye on the bouncy idle to see where that goes.

My son informed me today that he would like to modify cars. Looks like I may need to keep an eye out for a project. I probably should have jumped at that 1997 SVX in PA last week.

[1986nate]

When your PCV valve is really bad, you piss oil out of all seals as well as popping up the dipstick and oil in all of the intake tubes... Oh, about 3 quarts get lost in a 200 mile drive with 4.44's and cruising at 75 mph...
Ask me how i know...

[dcarrb]

Replacing the PCV valve on both of my cars (I should say, having the PCV valves replaced by a nimble mechanic with small hands) instantly and completely cured dipstick pop-up. Old Subarus suck lots of oil and crank gases though the intake. That's not a problem unless you're losing quarts between changes or leaving a cloud of blue smoke in your wake. I'd change the PCV.

My silver SVX has always had an odd bouncy idle when warm, ONLY when rolling to a stop. This is most noticeable in stop-and-go traffic. Sitting still at idle, it's so smooth and quiet I glance at the gauges to be sure it's running. So long as she doesn't stall, I can live with it.

dcb

[NikFu S.]

I checked again last night, I guess my idle is bouncy even before I leave the garage. Strange, though, it was rough all the way to the store, park for 40 minutes, then it's smooth and steady all the way back.

[SoCal LS-L]

Originally Posted by NikFu S.

I checked again last night, I guess my idle is bouncy even before I leave the garage. Strange, though, it was rough all the way to the store, park for 40 minutes, then it's smooth and steady all the way back.

My guess is the gunk thats slowing your AACV warms up and thins after the engine heat permeates to the throttle body. Our intake gunk is very viscous when its hot but turns to tar when it cools.

[Huskymaniac]

Originally Posted by dcarrb

Replacing the PCV valve on both of my cars (I should say, having the PCV valves replaced by a nimble mechanic with small hands) instantly and completely cured dipstick pop-up. Old Subarus suck lots of oil and crank gases though the intake. That's not a problem unless you're losing quarts between changes or leaving a cloud of blue smoke in your wake. I'd change the PCV.

My silver SVX has always had an odd bouncy idle when warm, ONLY when rolling to a stop. This is most noticeable in stop-and-go traffic. Sitting still at idle, it's so smooth and quiet I glance at the gauges to be sure it's running. So long as she doesn't stall, I can live with it.

dcb

My idle is only bouncy when cold and only for a few seconds immediately after starting the car.

I don't see blue smoke so I guess that is good. Would you expect a bad PCV to pop the dipstick even if the dipstick has a new o-ring?

If I am getting oil pushed into the wrong places due to a PCV, wouldn't I see some in the end of the black air "snorkle" which is clamped to the intake manifold?

[Cam]

Originally Posted by Huskymaniac

My idle is only bouncy when cold and only for a few seconds immediately after starting the car.

I don't see blue smoke so I guess that is good. Would you expect a bad PCV to pop the dipstick even if the dipstick has a new o-ring?

If I am getting oil pushed into the wrong places due to a PCV, wouldn't I see some in the end of the black air "snorkle" which is clamped to the intake manifold?

1) Your dipstick may not pop out with a new o-ring, especially if it is installed well and is a good fit. This would simply mask the problem. PCV valves are CHEAP! i suggest spending a weekend with a crows-foot and replacing it.

2) You may see some at the end of the snorkle, or it may just be in the intake manifold. Depends on the pressures your crank case is seeing.

[LetItSnow]

I used a right-angle ratcheting wrench to remove my PCV valve... one... click... at... a... time.