Bad Positive Crankcase Vent Valve?

[Administrator]

Tom:

Any chance the bright, clear stuff is 100 per cent water?

Been there, done that....

Bill

[thatch]

"Condensation?"

TomG,
Before going any farther, I would like to get Dave Neptune's opinion on this situation. He is better educated on the goings on in these carburators than anyone I know. I do know however, that in some race engines that I have delt with, it is not unusual for condensation to build up because of a combination of high vaccum and "fat" air. As to weather the PCV valve is involved in this scenario, is also up to speculation. You might try removing it from the system again to see what the results are.
Tom T

[Dave Neptune]

Condensation?

Good point TomT! I doubt there could possibly be enough condensate to cause wet plugs even if the crankcase was full of steam. Tom got to play with an experimental duel fueled turbo motor 1800HP, interesting thing is they're using the hot 210 degree water to HEAT the turbo charger "intercoolers", yes heating the air. At 27 PSI and almost dry air the intake runners would ice closed and that was on the salt at Bonneville. It's an amazing power package and street legal.

TomG. I think you may of found your idle fluctuation and indeed hope it is not the issue. I'm betting that the water is coming from the intake manifold. They tend to rust out over time and a rusting water jacket often rusts it's way into an intake passage. Time to preasure check the manifold or perhaps your lucky and a gasket is all that failed. I've had that happen, I limped home with a sputtering A-4, replacing the manifold fixed it. Are all the plugs wet or just a couple?

Dave Neptune

[TomG]

Lately it occurs to me...

...what a long, strange trip it's been.

EPILOGUE:

Went the boat today. Rainy here on the Chesapeake, so I was able to get a lot done without the usual interruptions from slip mates.

Drained fuel from Racor water separator. No water.

Removed, disassembled, cleaned, and replaced carb.

Purged fuel lines. No water.

Sampled tank with siphon off the bottom. No water.

Hooked everything back up. Ran fine for 10 minutes maybe then a sputtering shutdown. Drained Racor. No water. Drained carb fuel bowl. Water. I'm not kidding.

Pondered the meaning of life and internal combustion engines. Came to terms with my existential angst.

Removed Racor fuel/water filter. Discovered that I had not inserted the .10 cent O-ring around the bottom of the filter element. Congratulated myself on having discovered my own stupidity. Installed new Racor filer (with O-ring this time) and new polishing filter.

Started the mighty A-4. She roared approvingly at my choice of straight gasoline and rewarded me with running beautifully for 30 minutes.

Installed new PCV valve. Adjusted carb idle screw in to 3/4 of turn out. Set idle at 800rpms.

Enjoyed the melodious sounds of a low idle.

AFTERMATH: I think the water was simply residual from my water intrusion issue several weeks ago. I replaced the Racor filter then, but without the O-ring it simply held the water in the filter. As I would clean up the system downstream, small amounts of water would leech out of the Racor filter and find its way into the carb.

The first PCV valve was bad. The new one runs as designed. Engine idles nicely at 800 rpm.

Thanks for everyone's suggestions and ideas. I really appreciate having this forum to run problems by you all.

[Dave Neptune]

Excellent

Tom, a Monty Burns comment for you. Lucky you found the 10 cent culprit, certainly beats the cost of a gasket or manifold. A lot less work too .

Dave Neptune

[thatch]

"Congrat's"

TomG,
Much of what I know about engines has been learned while chasing an illusive bug. I will assume that you are more familiar with the workings of your A4 than before, and I feel that we have all benefitted from this excercise.
Tom T

[TomG]

I will assume that you are more familiar with the workings of your A4 than before, and I feel that we have all benefitted from this excercise.
Tom T

Am I ever.... I can remove, tear down, clean, reassemble, and mount the carb with my eyes closed! Chasing down two simultaneous but unrelated issues has been challenging, but I do think I've learned quite a bit. Especially about O-rings!

[Administrator]

Way to go, Tom!

There is a variation on the "no gasket" theme which can be equally troublesome. In that scenario, the gasket remains behind when you remove the old filter, giving you two when you install the new one.

Don't ask me how I know.

Bill