PCV valve dilemna, What would you do?

[JohnD1956]

Foolishly ( in retrospect) I pulled out the PCV valve on the 78 Wagon ( Buick 350, "X" motor) and the grommet came out with it. I got a new valve and grommet, but now I can't get both back into the engine. I can either get the grommet in the engine but then not the PCV valve, or the PCV valve into the grommet but not into the engine. Further, in the process of trying to get this in, one grommet popped into the valley under the intake manifold.

I tried engine oil as lubricant and then Dilectric Grease as lubricant on the 2nd grommet. But this PVC Valve will not go into the grommet once the grommet is in the intake manifold?

Anyway, I'm thinking of pulling the intake to find the grommet that popped in, and then installing the parts while the manifold is off the car. But does anyone know a trick to getting this thing in? I even tried cutting the tapered end off the old valve just to see if it would slide into the grommet when it is in the manifold, and that won't go in either???

First time I've come across this. Any ideas out there?

[Smartin]

Replace the grommet with a good rubber one from TA Performance. You might be able to match one up at the HELP! section at the parts store, but I have never had luck looking there. They're only a few bucks at TA, I believe.

A little motor oil on the grommet itself and the PCV valve should work well. Most of the grommets I've seen are very hard, and can hardly get the old PCV valve out....let alone a new one in. I have bent several in the past trying to hammer them in. I usually just end up plucking the old grommet out and getting a new one.

[JohnD1956]

Hi Adam. Thanks for the response. But do you think the ones from TA performance are softer than the ones on the Help Board?

Actually, the two that I have purchased for this are listed in the NAPA books as intended for this application. I did not get them off the Help Board. They both appeared pliable enough, and went into the manifold easily. Too easily in the case of the first one that dropped in. It just seemes that once in the manifold, the hole for the PCV valve closes up slightly and then it's a major chore to push in the new valve.

I also believe in divine intervention, in that; something touted as a regular maintenance procedure should not be so hard. Because (in this case) it is so hard, something else must be wrong underneath that manifold. I'm wondering if the grommet that fell in somehow went past the valley pan part of the intake gasket and is resting against the cam or a lifter waiting to cause more damage if I try to start it.

Any way, I've now decided I'm pulling the intake as soon as I get a new gasket and while the manifold is out I'll install the new pcv and grommet. This way I can hold the grommet in on the underside and if it pops out again I'll be able to retrieve it. However, I understand that the PCV valve could have also been placed in the valve cover on this engine. So I'm toying with the idea of permamently blocking the intake hole and drilling a new hole in the valve cover for the PCV valve.

Do you think I'd get the same scavaging effect from the valve cover as from the intake location?

[Guest simplyconnected]

At the expense of ranting like a fool, I'd like to say this about PCV's. I got into a nasty argument on another board about this:

PCV's are a check valve in one direction, preventing backfire mixture from entering your crankcase. They can suck engine gasses from your valley cover or your rocker cover, but most covers have a PCV baffle underneath to separate oil (as much as they can).

Jiggling is NOT an indication of a good PCV, as the spring inside might be broken (particularly if it's old). PCV's may mount to the intake or the carb plate and are hosed to the valley or rocker cover. PCV's may also mount to the valley or rocker cover and are hosed to the carb or intake manifold. The most important thing is to get a correct direction PCV, that blocks toward the engine but passes toward the intake. Some have arrows but if not, you can blow through the end to detect the 'blocked' direction.

Sorry your grommet fell into your intake manifold. I would be surprised if GM would allow clear passage for a grommet to reach an intake valve.

The seal between PCV and manifold must be tight (many are threaded), or you will have a vacuum leak. If the rubber is correct, you may try a THIN coat of RTV because it is so slippery and it sets-up in fifteen minutes. If the PCV valve still won't go in, use a Dremmel tool with a small sanding drum on the inside of your rubber grommet.

Hope this helps, John.

- Dave Dare

[JohnD1956]

.. I would be surprised if GM would allow clear passage for a grommet to reach an intake valve. ( mine is in the intake manifold, so I'm concerned about getting into the camshaft or lifter valley)

The seal between PCV and manifold must be tight (many are threaded), or you will have a vacuum leak. If the rubber is correct, you may try a THIN coat of RTV because it is so slippery and it sets-up in fifteen minutes. If the PCV valve still won't go in, use a Dremmel tool with a small sanding drum on the inside of your rubber grommet.

Hope this helps, John.

- Dave Dare

Great idea on sanding the inside of the grommet with the dremel.

[D Yaros]

Simply coat the 2 parts with STP. You may be amazed at how easily they then go together!

[NTX5467]

From the early days of pcv diagnosis, "the rattle" was seen as a good thing as it proved that the spring inside, which helps modulate flow through the valve, was free and working. If you take a used valve, spray some carb cleaner into it, with the outlet blocked, then shake it, you'll hear "the rattle" become freer and easier and louder as the residual oil deposits on the spring are cleaned away. Similarly, if you put the cleaner into the valve with the outlet blocked, then close the inlet, shake the valve for a while, the resultant cleaner will be more oil-colored as it comes out. I have not known many, if any, pcv valves to fail due to internal spring issues. I suspect that if the internal spring did fail, it would minimize flow through the orifices internal to the valve and make the engine more prone to oil leaks from crankcase pressure buildup. It might well be that "the rattle" with a good spring would be different than one with a failed/broken spring?

It could well be that the pcv valve has capabilities to stop engine backfire gasses from getting to the crankcase. The baffle under the pcv valve, typically, is there to keep oily vapors/mist from being sucked into the pcv system and engine ... more than they should be. The absense or poor functioning of the baffle can be an oil consumption contributor.

Just some thoughts,

NTX5467

[JohnD1956]

Thanks for all the replies everyone. Today I pulled the intake, and the drivers side valve cover. I discovered that the broken piece of the old grommet had passed the valley pan gasket and was resting just over the top of the camshaft. The one new grommet that punched inside had also come to rest between the valley pan gasket and the rear of the block. Probably would have never been a problem to leave them but I feel better that I got them out.

While I had the intake out I installed one of the new grommets and then ran one of my 3/8th extensions around inside the hole just to make sure the grommet was fully seated. Then I followed D Yaros' advice and coated the new PCV valve and gromet with STP. That worked great. The pcv slipped in and maintained a very tight fit.

Unfortunately reinstalling the intake I managed to pinch the bracket for a metal vacuum line between the intake and the head. I did not even notice it till the intake was torqued. Then I had to release the entire manifold to pull the offending bracket out. Not having another intake gasket I retorqued the intake again and figured I had nothing to lose by trying. And it seems I may have gotten lucky after all. The car ran good with a slight roughness which I am sure is now a matter of changing the vacuum hoses and spark plugs. I don't see any antifreeze leaks but I will keep an eye on it for a week or so. If it drops at all I'll redo the intake gasket again and chalk it up to experience. I just hope I don't have to re do it, that intake manifold is heavy...

Anyway, thanks again for all your replies and assistance.

[Guest simplyconnected]

John, just to test for a vac leak, use an UN-lit propane torch. Turn it on and slowly wave it around your intake gaskets and carb base while the engine idles. If RPM's go up, fix the leak you just found.

I'm glad to hear you retrieved your grommet parts (I know you were concerned about that). Now you have piece of mind knowing they won't be munched and clog something. Glad to hear your PCV is good again, too.

- Dave

[JohnD1956]

Thanks for that idea Dave. First thing this AM I checked the vacuum line to the transmission. As I suspected I did not have it seated properly. That cleared up a lot of the concerns I have.

Today I took the car out for a long ride. Up to 45 MPH the car is so smooth it's scary. 46-55 MPH I had an intermitent miss. Now this could be plugs. The day before I got into this mess with the PCV valve, I had to change the pick-up coil in the distributor. Before confirming that diagnosis I pulled all the plugs and determined that they could be cleaned and regapped but two of them ( at least ) had rounded edges on the electrode. So before I tear anything else apart again, I plan to put in new plugs early next week and see if that eliminates the greater than 46 MPH miss.

Other than that the first three times I drove the car I smelled anitfreeze occasionally. Three trips and smelling antifreeze at least once per tells me I still have an issue. The problem is I don't see any physical leakage from anywhere, and it is not a consistent smell. I just replaced the radiator cap last week, and the radiator itself was replaced back in December . So somewhere along the way I'll need to do a pressure test to see if it was just coincidence or if I have another issue to fix.

[JohnD1956]

Update, This car is gonna get killed. That's right, I'm gonna beat it to death with a ball peen hammer.

Today when I started it, it had a awful miss, and it is still missing. I went over all the vacuum hoses, all the distributor things, all the wires, and added dry gas just in case that was the problem. I even sprayed all the distributor internal parts with WD 40 and nothing has stopped that miss.

It does not miss at idle, but even a little bit of a load has it "poop poopingh ".

It feels like the pick up coil miss but that's just two weeks old. I took the spark control module to NAPA where they ran a diagnostic test and it passed with flying green colors. But it's still missing.

I haven't picked up the spark plugs yet and now it's supposed to rain the next few days anyway. Sheesh, this is frustrating!

[Guest simplyconnected]

Check distributor for loose grounds and re-seat your connections. No missing at idle, and intermittant missing at ~45 usually means a weak electrical connection somewhere around your distributor, coil, etc. Remember, two wires make the path. Many times it's simply a ground connecton or weak pin in a connector. Check pins for witness marks of heat (melting). Coils tend to show signs of failure at high rpm before they give out.

[NTX5467]

I can't think what would be really different in below 45mph and 46-55mph, in the way of carb operation, engine load, etc. The increase in engine rpm would be very modest, so that particular speed break seems unusual.

If there were any index points on the ignition part you replaced, did you get the new one indexed at the same place? What might be happening is that if the index point was not correct, it might be acting like a set of points that's set with insufficient point dwell . . . which would mean "weak spark" as the vacuum advance moves the breaker plate and/or the advance weights do similar with small increases in engine rpm. Just a stray thought . . . but what about the ignition module (which controls what we used to call "dwell")?

Can you "drive through" the random miss with more throttle input? Just another stray thought, but anything that might have a vacuum leak or is controlled by vacuum and is not working correctly should be causing issues well below that rpm/speed range. Can the condition be found if you lock the trans in 2nd gear and hit the same rpm levels?

What about the plug wires? When were they changed last? Putting new plugs, or cleaning and gapping the existing ones, will lower the energy required for the spark to jump the gap, which might mask a wire issue until the plugs get some wear/miles on them. If that's one of the engines that had a spec plug gap of .060"+, you might try them at .045", which will also lower the voltage requirement to jump the gap a little.

What about the inside of the cap and the rotor? Deposits on the rotor end and plug wire terminals inside the cap? Just tryning to think of things, which are somewhat normal "wear" issues, which might cause issues when a "build tolerance stack" situation might happen.

NTX5467

[JohnD1956]

Thanks guys, for those good ideas. Last night I checked for arcing wires after dark. While at idle I didn't observe any leaks. I raised the idle while in park to almost 1700 or so RPM and no arcing. Then I had my son put it in drive and raise the idle just enough that it started to miss. At that point I could see the arcing on cylinders one and three just around the edge of the plug boot.

I'm back to the plugs being the root cause of these problems however, if this does not fully fix it I'm going for a new coil next. Then it's off to a competent mechanic for further testing. I got new plugs today but the rain stopped me from putting them in.

Couple of things I just wanted to mention.

I rechecked all the connections yesterday when I reinstalled the spark control module after having it tested. There is no evidence any of the connections have failed or overheated.

And the pickup coil can only be installed one way. There is a pin hole for the vacuum advance hook up and if you don't put the coil in the right way this won't align. I think this negates the theory about the dwell being misinterpreted.

However I do think the theory about the weak spark is correct, and the possibility of a failing coil is right up there. It ran pretty good when I got it six months ago but it is 31 years old.

Eventually we'll get this figured out. I put the ball peen hammer back in it's place.

[Guest simplyconnected]

...Then I had my son put it in drive and raise the idle just enough that it started to miss. At that point I could see the arcing on cylinders one and three just around the edge of the plug boot...

Good job, John! By George, I think you got it. A shunted arc is certainly a low voltage condition at the plug gap.

[Smartin]

Make sure your distributor shaft doesn't have any side-to-side play. I chased an intermittent miss for 2 months before I found that problem. I could "drive through" it, but it progressively got worse, as the distributor shaft bushing ovalled out.

[JohnD1956]

Hey Adam, thanks for that tip. How odd that problem. How did you figure that one out?

Meanwhile, let me be clear that I am not saying the car is definately fixed. I learned that particular lesson. However I replaced the plugs today and the miss is gone. I hope it stays that way but I want to put a few hundred miles on it before I'll feel comfortable with sayings it's fixed.

Meanwhile at the risk of embarassing myself I should mention that I made a mistake when I cleaned and regapped the old plugs. The #2 plug which is under the compressor was not tight. It appears I hit the bracket for the compressor with the ratchet and I must have thought the plug was fully seated. I'm lucky the thing did not blow out of the head.

Anyway I made sure all the plugs are now fully tight, and put fresh grease on the boots and the engine feels good. Now I' just gotta see if it lasts.