I had a set of Hedman shorty headers installed on my 88 305 TBI automatic last week, along with a new O2 sensor and new plugs at factory gap. Timing is set properly.


Last oil and filter change was 500 miles ago with factory recommended oil. When the oil was changed, the mechanic commented that the oil was thick and sludgey, but I find it hard to believe - in the past, even 3K miles after an oil change the dipstick shows up as honey brown with minimal oil consumption (half a quart, if any at all). Also find it hard to believe because I stopped trusting my mechanic (due to a number of issues) and actually stopped taking my car to him, period... but that's a different story lol


After the header install...

• When the car is at normal operating temperature, the oil pressure is great at cruise (45-55 psi at highway cruising speed) and pretty normal at idle out of gear (30 psi).
  
• When the car is in gear in traffic (idling around 550 rpm) at normal operating temp, the oil pressure gauge is hovering very close to or in the red - approx 3-6 psi.
  
  Note: This issue didn't exist prior to the header install. Under the same conditions (normal temp, idle in gear in traffic @ 550 rpm), the pressure guage regularly indicated in the 15-30 psi range.

I can't figure out what would cause this, other than the possibility that the pressure sending unit (which is new) may have been damaged when the engine was jacked up during the header install. Thoughts??


BTW, I'm getting the trans rebuilt this week and while the access is improved, having new motor mounts and a new oil pump installed as preventive maintenance and peace of mind since the car has 170k miles and I use it as my daily driver. Hoping this solves the problem.

 

I'm assuming there is a crossover pipe running across the oil pan. If so, check the clearance on the exhaust pipe to pan. My symptoms were a little different but the crossover pipe on mine was way too tight (on the car when I bought it). I noticed a drop in pressure at idle when the car warmed up (pipe heating the oil). I doubled up on header wrap on the crossover pipe where it crossed the oil pan and that helped a lot with mine.

 

That's a great idea, thanks man