Low Oil Pressure Issue

[mnetwork]

Before I rebuilt this motor (and on the first rebuild) I was having low oil pressure readings (on the stock gauge). I know it isn't the best thing to look at, but here is what was happening. At idle the gauge would read lower than it always used to (even lower than my old stock motor did). While driving pressure would climb and at around 3300k it would start to drop. The higher you went after 3300k the lower the gauge would drop and as you came down the pressure would rise again. When the first build motor was originally build the gauge read very high (which was expected because of the BSE). After 2-3 months I started getting weird readings. The motor was rebuilt, everything was tightned to spec, rods were reconditioned and re rounded. The block was bored and I bought .020 overbore pistons because the shop said the bore on the block was too big for for the standard size pistons when they looked at it before they bored it. The rods were reconditioned because when checking roundness they realized they weren't in spec and every rod had the wrong cap on it. I thought this all could have led to my oil pressure issues. I did my first initial start yesterday (after priming) and I expected the oil pressure gauge to read all the way to the top like it used to, but it read a little above halfway. I hooked up a mechanical gauge at the housing and I believe I saw it reading around 80-90, but I have to recheck this. If the mechanical gauge was reading this high and the stock gauge was reading low, could this be the sender? If so, what would cause a sender to start reading lower and lower after 3300k? Also, if it was the motor causing the gauge to read low on the previous build, how could the oil pressure drop after 3300k???

Also, on a new motor with new oil pump and a BSE kit and no relief porting, wouldn't 80ish PSI be low for a cold start?

 

[kidtsi]

Before I rebuilt this motor (and on the first rebuild) I was having low oil pressure readings (on the stock gauge). I know it isn't the best thing to look at, but here is what was happening. At idle the gauge would read lower than it always used to (even lower than my old stock motor did). While driving pressure would climb and at around 3300k it would start to drop. The higher you went after 3300k the lower the gauge would drop and as you came down the pressure would rise again. When the first build motor was originally build the gauge read very high (which was expected because of the BSE). After 2-3 months I started getting weird readings. The motor was rebuilt, everything was tightned to spec, rods were reconditioned and re rounded. The block was bored and I bought .020 overbore pistons because the shop said the bore on the block was too big for for the standard size pistons when they looked at it before they bored it. The rods were reconditioned because when checking roundness they realized they weren't in spec and every rod had the wrong cap on it. I thought this all could have led to my oil pressure issues. I did my first initial start yesterday (after priming) and I expected the oil pressure gauge to read all the way to the top like it used to, but it read a little above halfway. I hooked up a mechanical gauge at the housing and I believe I saw it reading around 80-90, but I have to recheck this. If the mechanical gauge was reading this high and the stock gauge was reading low, could this be the sender? If so, what would cause a sender to start reading lower and lower after 3300k? Also, if it was the motor causing the gauge to read low on the previous build, how could the oil pressure drop after 3300k???

Also, on a new motor with new oil pump and a BSE kit and no relief porting, wouldn't 80ish PSI be low for a cold start?

oil press should be 30 or 40 psi on idle and 80psi when wot.

 

[mnetwork]

oil press should be 30 or 40 psi on idle and 80psi when wot.

Isn't oil pressure much higher on a motor with BSE and no relief port on a cold motor? Also, on the previous motor (if the sender wasn't causing it) what could possibly cause oil pressure to drop at 3300k and drop lower and lower as the rpms go higher... One thought I had was maybe the sender is messed up and reading lower to begin with and then at a certain psi it would just start dropping... Not sure if that is possible, I've never had/seen a bad sender before.

 

[DSMnoobsause]

replace the sender or just install a good oil pressure gauge. senders give a certain resistance depending on the pressure its reading. if the diafram in the sender goes bad usually it leaks oil or fills up with oil and gives false resistance readings.

 

[mnetwork]

replace the sender or just install a good oil pressure gauge. senders give a certain resistance depending on the pressure its reading. if the diafram in the sender goes bad usually it leaks oil or fills up with oil and gives false resistance readings.

That makes sense, I didn't know how they worked internally. Well having some fueling issues that should be fixed now. I reinstalled the mechanical gauage at the filter housing and I am going to pay close attention to it next start.

What should I be looking for oil pressure wise during a cold start on a brand new motor with BSE and no relief port...

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Ok just fixed my fuel issues car runs fine now (although I have to investigate a possible tick, not sure..) THe mechanical gauge was flicking between 75 and 85 on the cold start.. dropped down to 40's 50's after at operating temperature.. If I would rev it into the 2's it would jump right back up, so the sender MUST be bad because the mechanical gauge is reading high, right?

 

[DSMnoobsause]

i think you would be correct in your conclusion