So my stepfathers late 1993, (OBD1) Corolla DX Auto Trans with 265K miles started throwing Check engine lights. It is CA registered, so a CEL is a problem to transfer, and Smog, but otherwise it runs fine, with a *solid* 33-35 MPG, on regular gas. No knocks, no pings and runs cooler than any other car I own.
Ran CEL diagnostic routines, and EGR system was the culprit., with a 71 error code. I reset the code several times, and it would send the repeat code, (typically) after about 300 miles of driving at highway speeds. There is also a auto trans ECM code present, but that is another issue...
For those not familar this particular EGR valve, is one of those parts, where I truly hate that we have child labor laws.. .because my 8 year old's hands, are perfectly sized, for the EGR Remove and Replace, where mine are kinda of a nightmare.
The EGR is towards the Rear of the engine, almost against the firewall. After much swearing and even contemplating cutting a wrench in half to try and fit it between the bottom (25mm?) nut and the fire wall, we ended up taking the EGR *and* its (exhaust Manifold) riser pipe off, as one unit. Less swearing, less drama. Once the EGR was off, here is where the fun began.
Upon manually applying positive air pressure to the vacuum diaphragm (read: Take hose in mouth and blow), *water* came out of the other end of the 2nd hose on the Diaphragm hose *only*. Slightly rusty, and about 2/3 of the volume of the diaphragm space itself. I.E. "enough to make the valve not actuate--- probably, or worse "sometimes". Note this only happened with the diaphragm was upside down. I had applied vacuum and positive air several times when it was in the car... no fluid expelled. to quote a phrase: FRACK!
Once I spent an hour or two soaking the entire assembly in brake cleaner, (except the diaphragm of course), the valve started to work normally with "manual vacuum applied". (read: Suck on one hose, plug the other). Gave the N2 sensor a solid cleaning and scrub brushing, and pushed Q-tip sticks into the various narrow diameter pipes and hose connections. (Also spent about 5 minutes manually sucking the broken Q-tip end *out* of a vacuum hose connection with a shop vac...). Lesson learned, right tool, right job. Shot gun cleaning brushes worked fine by the way, for the larger bore pipes.
The vacuum control unit filter was *totally* clogged, but water free, (washed, rinsed, dried, re-installed). The hoses were dry, to and from the diaphragm.
The car is located in a moist climate where fog, is common.
Is it possible that over the course of 16 years, that enough water vapor collected in the diaphragm space, that eventually it actually became a pool of water? Even more weird is it possible that there was not enough engine heat, to actually boil off the water captured in the EGR diaphragm space?
No other part of the system is throwing water, and (to be frank) I plan on selling the car shortly, so a 167 dollar new EGR valve is not a good investment. Once the water was removed (and *much* air was blown through the actuator), it works perfectly normally "out of the car"..
My labor cost is free. I needed the help of a neighbor master mechanic, for one particularly nasty reach.
So, unless I hear a suggestion otherwise, I will re-install the unit tonight and see if the system throws another CEL, over the course of a week. I will probably force the computer into diagnostic mode *first* just to see if I can convince it to throw another CEL.. saving much drive time.
Suggestions? Did I miss something?
Thanks in advance.