Real Fiero Tech

Okay, today my neighbor called me over to look at his '97 Chevy Venture minivan that he just got for free. He thought it might have an oil leak, and it did. But I couldn't believe what I found. On the block, just above the starter, and just "behind" the dipstick, ( if it was installed in a longitudinal setup ) there is an oil pressure sensor. It was threaded in straight and tight, it was plugged into it's wiring, but oil was coming through the sensor, at the rate of 3 drops per second with the engine idling. I replaced it, and that solved the problem. Made me sad, because the engine had 180,000 miles on it, and I thought it would be nice to get for future use in one of my Fieros.

The plastic film diaphragm at the base of the sensor had to have ruptured. The sensor is essentially generic. I wouldn't put down the 3400 altogether because of it.

My last 3.4 DOHC OPS failed in a similar manner, I was about 99% sure my pan gasket never sealed correctly and was spraying oil mist from crank windage at high RPM. there was oil mist sprayed all over everywhere on the front of the engine. I changed it out at the insistence of Chris West when I was over there one day (resealing/retorque never worked), and the front of the engine dried right up and the problem went away.

The 60's era technology one screwed into my 2.5 on my other car failed the same way as well. I changed out all sorts of stuff trying to stem the loss of oil, after I pulled the dipstick one day and it came out dry from how much oil it was leaking. I decided to start the car and crawl under carefully to have a look... You can imagine my surprise of seeing a runny stream of oil flowing out of the harness plug onto the ground... That poor Duke... I'm positive I've run the pan down to the last PINT (not quart) at freeway speeds during the 20 minute drive to work, and it still runs. Didn't they say that there's at least 3 quarts of oil in the engine itself at freeway speed?

Emc209i wrote:The plastic film diaphragm at the base of the sensor had to have ruptured. The sensor is essentially generic. I wouldn't put down the 3400 altogether because of it.

I wasn't bashing the 3400, I was baffled and amazed at that much oil coming through the sensor. The 3400SFI is on the long list of engines I'd be willing to tolerate in a Fiero. On the long list, it's right below the N/A 3800-II, and just above the 4G63T. It's just not on the short list.

I recently took a OPS off my 3.4 DOHC that had the same problem, though not nearly that much oil.