95 blazer LS oil pressure / pinging issue

[phuz]

just got my blazer back a few weeks ago from the shop after having a new engine put in after the old one overheated.

it ran fine for about two weeks and then i noticed last week driving home one night that the oil pressure dropped to zero. i gave it a little bit of throttle and the pressure came back up to 40psi. i have parked it since then. the oil level was low so i added 1.5 qt. the following day i started it up fine, and the pressure right away was about 50psi at cold idle. i drove it around the block as it warmed up and the pressure started to drop as it got warmer. it would fall into the red zone numerous times. under throttle i also noticed intense pinging from the engine, however at idle, everything sounds normal.

the only thing i noticed that the shop did:

i have a cone filter installed and i had to remove the one line which connects to the crankcase breather. they had capped it so it was blocked completely. the passenger side valve cover has a vacuum line connected to the vacuum side of the throttle so the crank was under a lot of vacuum with the other end blocked. i first noticed this when i went to check the oil and had trouble loosening the cap. when i pulled it off, a huge in-rush of air entered the tube. could that extreme vacuum in the case cause a problem as im describing?

matt

[flatire]

uncap that line and see how everything goes,keep us posted


flatire

[Mikado14]

Originally Posted by phuz

just got my blazer back a few weeks ago from the shop after having a new engine put in after the old one overheated.

it ran fine for about two weeks and then i noticed last week driving home one night that the oil pressure dropped to zero. i gave it a little bit of throttle and the pressure came back up to 40psi. i have parked it since then. the oil level was low so i added 1.5 qt. the following day i started it up fine, and the pressure right away was about 50psi at cold idle. i drove it around the block as it warmed up and the pressure started to drop as it got warmer. it would fall into the red zone numerous times. under throttle i also noticed intense pinging from the engine, however at idle, everything sounds normal.

the only thing i noticed that the shop did:

i have a cone filter installed and i had to remove the one line which connects to the crankcase breather. they had capped it so it was blocked completely. the passenger side valve cover has a vacuum line connected to the vacuum side of the throttle so the crank was under a lot of vacuum with the other end blocked. i first noticed this when i went to check the oil and had trouble loosening the cap. when i pulled it off, a huge in-rush of air entered the tube. could that extreme vacuum in the case cause a problem as im describing?

matt

When the gauge reads that low, do you hear any tapping as if the lifters are not getting enough oil? These senders are not that reliable and I am sure if you had either a short or long block installed, the old sender was reused. They are cheap enough, just swap it out.

Now as to your other question. Am I to understand that the line from the PCV is still connected to the throttle body BUT someone capped off the other line to the breather on the other valve cover? If that is the case, better uncap it, the crankcase needs to breath. It is also a wonder that the vacuum wasn't sucking more oil out and through the engine.