ok i have a oil pressure question. when i crank my blazer it is fine and drives perfect. but the gauge says that when i am at idle there is NO oil pressure and the check gauge light comes on. it has never died when it says no pressure and it does this at an idle of 500 RPM. and if i take it to just 1000 RPM it is fine and goes to 20 oil pressure and once i drive it 40mph + it goes to 40oil pressure and every thing is good. the only thing i have done to make it maybe change is i gave it an oil change and did not use synthetic(witch i had in there first).
but i have to say it drives fine and i dont think any thing is wrong but i want to know


thanks and please ask any thing to diagnose the problem.

 

Factory gauges are horribly inaccurate. If you really want to know what you have for oil pressure, you need to put a "T" in the port where the factory sensor is and install a mechanical gauge.

 

ok thanks.but what is a "T"? thanks for the quick reply!

 

Exactly that... It is a fitting that has three ports. It can be used to take one input and split it into two.

 

A tee like a T shaped piece you add into the current lines. Then you can connect to that and test off of it. It does kind of sound like your gauge is probably off by like 20ish, unless of course your engine is knocking when it says 0 or you oil is really thick or low.

 

well i just got an oil change and so the oil is new less than 100 miles and i listened to it for 30min. and it did nothing strange or crazy. it still drives GREAT and i really don't think there is any thing wrong but i just needed to make sure so i don't kill my only thing to drive

 

well some more info for you all.

1. the engine runs great at idle
2. it does not ping or clank or any noises.
3. once you crank the car the gauge will say 0 and then you go to go and it does stutter for like 3 seconds and then it goes and the pressure goes up to. i think related.
4. the oil is new

thanks for your info and help.

P.S. where and how much would a compression test cost?
thanks

 

Why would you do a compression test? Compression has nothing to do with oil pressure...

 

well sorry. some one told me that i might have bad compression hence the stutter/ oil pressure. but i guess that is true. but do you think i have a bad problem or no?

thanks again

EDIT: i just noticed that when the car has just been cranked the gauge works fine(it shows oil pressure at 20) and it is good for a good while. but after you drive it it goes to 0 oil pressure at idle and then goes to 40 oil pressure for normal drive. but i have listened to the engine when the gauge says 0 oil pressure it still does not sound strange or have any strange noise.

 

it sounds like it is the pressure sender or the gauge than. If you truely had 0psi then you would definetly get some knock if it stayed at 0 for more than like a minute.