Bad Valve Seal Symptoms & Crankcase Pressure

[TripleJackInGA]

Hey All -

This is on a 99 RS 420a/ATX.

Still learning a lot about these cars, and have learned a lot reading here. I think I know the answer to this, but wanted to get opinions.

The car has 191k miles on it. Haven't had it long, but just replaced the Heater Core, and had the Timing Belt/Water Pump/Tensioner/Pulleys/Valve Cover Gasket replaced.

The car starts, runs & drives great, but like many, after you let it idle for about 5-10 minutes, it starts in with the smoke out the tailpipe.
Everything I've read on here so far tells me this is likely bad Valve Seals. I find it odd that it doesn't do it when you drive it normally, or at start-up, but that seems to be what others say as well.

I'm curious if my mystery oil leak could also be due to the Valve Seals.

I had the valve cover replaced, but after driving a bit, I still notice oil sitting on top of the valve cover.
I read that it could be the Oil Filler Cap/O-Ring, so I replaced them both. I also replaced the PCV valve, and added hose clamps to the hose going from the valve cover to the PCV valve.
I cleaned up the valve cover, drove a bit more, and more oil on the valve cover.
Looking at it after just about every time I drive it, I can see a thin sheen of oil coming from the rubber o-ring on the Driver's Side valve cover bolt, which is in the spark plug valley, but not much.
What I do see is a sheen of oil that runs from the PCV hose down to the spark plug valley. I also notice that the hose itself is slightly oily, and there is wet oil residue on the bottom side of the PCV valve itself.
Additionally, oil is leaking on the ground. It's eventually so much, that it runs down the exhaust, and drips off the cat, making a nice smell, and the obvious stains.
I got under it this AM, cleaned as much oil and grime off the bottom side as I could, started it up, and waited for a leak....nothing.
I did see that the whole back side of the block is wet, as well as part of the Alternator bracket, both the sensors in the block, etc..

What I'm thinking is that when driving, at some point, I get so much crankcase pressure, that it's shooting oil through the PCV hose, the PCV valve is shutting from the pressure of the oil, and it's simply backing up, and squirting out wherever it can.
The odd thing is that when the thing is idling, even when I'm increasing idle by hand to as much as 3kRPM under the hood, there is no blow-by noted from the oil filler cap or the dipstick.
If there's that much crankcase pressure, I would expect to see at least *some* blow-by.

I tried doing a compression test, but the tester I borrowed from Autozone isn't working. I can get it threaded into the head, but with the hose attached to it, I have no way to tighten it. I tightened it as much as I could by hand, but then the hose just starts spinning on the end. Tried it that way, but get no reading at all.
I was able to do a Cooling System Leakdown Test, to check for a potential head gasket leak. I did this in the morning, so the car was completely cold. I removed all the plugs/wires, pressurized the system, let it sit for several hours, and no pressure loss. I also had my GF start it after sitting under pressure for several hours, and saw no vapor/coolant shoot out of any of the cylinders.

This is a car I've been rehabbing for my Fiance's 16yo Daughter. It's pretty much done, and she's about to start driving it. The smoking at extended idle I can deal with for now, but the excessive oil leak/dripping off & burning off the exhaust I really need to get figured out.

All that said, is extremely high crankcase pressure another symptom of Bad Valve Seals on the 420a?
What's the correct type of compression tester to do a compression test?

Thanks for ideas.

 

[BogusSVO]

Valve seals will not have anything to do with high crank case pressure.

Bad valve seal smoke is from too much oil going past the valve seal then sucked in the air inlet tract, then burnt on the power stroke.

You should do a Leak down test, to see if you do have bad rings. but I doubt that is it.

The dripping oil leaks need to be found and fixed.
Have you checked the timing belt to see if it has oil on it? you may have bad cam seals.

Has the HG ever been replaced?

 

[TripleJackInGA]

When I had the Timing Belt and evrything on that end done, I also had the crank seal & both cam seals replaced as well. There's no sign of oil on top outside the timing belt cover, or underneath on that end of the engine. The closest it gets is a drop or two on the back side of the alternator bracket.

I just got the car a couple of months ago, and the previous owner had it since 2005. No info on the HG ever having been replaced, but the cooling system pressure/leakdown test showed no pressure loss at all.

I just sat out there with it idling in Park and raising the idle up to as high as 3k RPM slowly and snapping it, and now I can't make it leak.

I really need to do a leakdown test on this thing, but I need to get a tool to do it.

Is there a step-by-step on doing one on the 420a, or specs it should fall into? I read in general, that naturally aspirated engines can leak down 8-12%, with 4-5% variation between cylinders, and be considered normal, or within spec.

 

[BogusSVO]

I forget what years ut was but the HG would fail allowing oil to come from the block head area, there is a Factory HG to repair this issue.
The oil pass thu port from block to head is intake side, rear, last headbolt. check this corner and see if the oil/grime build up is heavest here.

Some searching on the board and you will find it, along with the specs you ask for.

Harbor Freight/Ebay will have a leak down tester for about $50

You may want to check the VC for cracks or warp, and proper bolt torque of the VC, this may explain the oil on top of the VC.

 

[TripleJackInGA]

Still frustrated by what seems like excessive crankcase pressure to me, I went to Harbor Freight today, & bought a Leak Down tester, and a decent Compression Tester. I'll be doing the Leak Down test this weekend, but I just did the Compression Test. I did the test as soon as I got home from about a 20 minute drive. I had the person cranking it let it crank until I saw the needle move 8 times (8 compression strokes).
I also read the test procedure in the Tech Articles section here, which varied from what it said in my instructions for the tester slightly. The instructions in my tester said to test it with the other 3 plugs still in the head. The tech article on here said to remove all 4. Not sure if this would affect my numbers.

Here are the results:

#1: 135
#2: 127
#3: 130
#4: 130

I read in the Tech Article section that the spec is as follows:
2G (95-99) T/E 2.0L NT 420A engine
Compression ratio 9.8:1
Standard compression 170-225 psi
Service limit 100 psi

So while I initially thought the results were low, they're still within the service limit, and vary 2%-6% across the board.
This car has 191k on it.

While I haven't nailed down the source of my leak, I highly suspect that it's the infamous head gasket. I should know more about that in the next few days. I just didn't want to even think about doing the head gasket, if the compression showed that I may have bad rings. I'll confirm this even more when I do a leak-down test.

 

[BogusSVO]

To me the compression test is not showing a blown HG, not a cyl to cyl blown one at this point.

The leak down test will show more.

 

[TripleJackInGA]

Yeah, I agree. I'll know more when I do the leakdown, but I'm thinking I just need to do the head gasket possibly due to the oil leak, and while it's off, do the valve seals.

 

[rbwtrans]

I'm going to point out that the head gaskets, revised or not, will still eventually leak. I've replaced hundreds (yes, hundreds) at the Chrysler dealership. A failing cam sensor will leak in the same spot and the valve cover gaskets have been known to leak, all in the same manner. Start from the bottom and look up. Good luck to you.

 

[TripleJackInGA]

I'm going to point out that the head gaskets, revised or not, will still eventually leak. I've replaced hundreds (yes, hundreds) at the Chrysler dealership. A failing cam sensor will leak in the same spot and the valve cover gaskets have been known to leak, all in the same manner. Start from the bottom and look up. Good luck to you.

Thanks, but I don't think it's the Cam Sensor. It's not leaking on the side or front of the engine at all. It's all over the back of the block, from the head gasket on down.
I'm going to get under there with some brake cleaner, clean it up as good as I can, then see if I can see where it's actually coming from.

 

[GSTurbo1]

I'm having the same problem!!!! I have a turbo'd gs that is having the same exact symptoms. I have been told valve seals, head gasket, and to get an oil catch can

I have the same problem except mine is turbo'd. I'm going to replace my valve seals, head-gasket, and throw an oil catch can on it.