1990 305 TBI LO3 - no mods - 150k miles

I recently replaced timing chain. To do this on LO3, you must "remove oil pan" according to Haynes - the oil pan gasket works in conjuction with the timing chain cover. Well, I cheated - I didn't see need in total removal - just removed all bolts and let it drop in that 3/4" space above the crossmember - it was enough to get in there, get the job done, and get out.

After replacing everything, all seemed well - car ran great, and oil pressure was as before (30PSI at idle, 45 at throttle).

2 days later, I got a code - 32 - EGR Solenoid. At the same time code appeared, oil pressure dropped. The warmer car gets, the lower the pressure. Now it's 30psi when cold accelerated, 20psi when warm accelerated, 0-8 when warm and idle in Drive.

Replaced the Solenoid, code 32 now gone, but oil pressure still bad.

No visible leaks of any kind. When I replaced oil pan after timing chain job, all seemed to fit right back into place just perfectly.

Could I have messed something up when I did the timing chain job? Or just a bad sending unit maybe?

I don't understand how the oil pressure problem would be a result of the timing chain job since pressure was good for a few days afterwards.

Any help deeply appreciated!

 

I'd just change out the oil pressure gauge sending unit.... they go bad all the time, they're less than $20, and that sure beats getting stressed out over the pressure itself. I think it's just coincidence that it changed at the same time as the other work.

 

if the sending unit does'nt help you may have to drop the pan again and make sure there isn't anything in the pan blocking the oil intake (rag,paper towel,old gasket material), you get the picture.

 

agreed.

 

Well, I didn't take tha pan off far enough to get anything in there - I only dropped it about 1/2" and I didn't replace the gasket 'cause there wasn't enough space to even do that - if there is something blocking, it would have to be something that was already there before. So, I'll agree with the consensus here and try replacing the sending unit. If that's the case, you're right - big coincidence.

Thanks for the input. I love this site - I think it's great to have all these heads to bounce problems off of!

 

New Oil Pressure Sending Unit did the trick. PITA to get to.

Thanks again.