Oil pressure drops as it warms up?

[TraumaTruck1]

I'm not sure what a sending unit does when it goes out, but I wouldn't think so because the pressure is dropping as the oil warms up. I would think a bad sending unit would just show low all of the time.

I would start with changing the filter and topping the oil off.

If that doesn't work I would move up to a higher weight oil. If that does work, your bearings are wearing down. The higher weight oil will probably last a while though. Racing engines and the older engines were built loose. That's why they have a higher weight oil to begin with.





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[Big Roller]

Sitting at a red light today, oil pressure dropped to zero... I immediately put it in neutral and revved it up to get oil pressure back up. I'm leaning toward a new oil pump... The truck is my only vehicle so I'm worried about burning the motor up.

I've read about checking bearings or something like that while the oil pan is off -- what am I looking for?

 

[ezdaar]

Melling high volume, high pressure pump. don't install a oem rep.
Make sure you get the Aluminum reinforced one piece oil pan gasket from felpro.
It resists "squishing" along the sides of the oil pan which causes leaks.
And as always, make sure your oil pan gasket surface is straight, smooth and not dented up.
Be sure to clean the block and oil pan gasket surfaces with 90% alcohol.
Good Luck.

Bad bearing

 

[Big Roller]

http://www.autozone.com/autozone/parts/Melling-Oil-Pump/1999-Chevrolet-Tahoe-2WD/_/N-jd17lZ8zn8y?itemIdentifier=430280_729183_4697_


Is this the right pump? Says it comes with a screen as well.

 

[Big Roller]

Well, running short on funds this week... So I'm just gonna try switching to heavier oil and ACdelco filter along with Lucas Oil Stabilizer... Hoping for the best!

 

[Big Roller]

Changed the oil to 10w40 and used a quart of Lucas and ACdelco filter, and so far I'm running 20psi at idle and about 50 at 2000rpms... I will never use anything else but ACdelco ever again! We'll see if that fixed the problem... If not, I guess it'll be time for an oil pump.

 

[mattluttrell]

Changed the oil to 10w40 and used a quart of Lucas and ACdelco filter, and so far I'm running 20psi at idle and about 50 at 2000rpms... I will never use anything else but ACdelco ever again! We'll see if that fixed the problem... If not, I guess it'll be time for an oil pump.

That's good. You could even go a little heavier with the oil. I've done that in old 350s.

 

[SunlitComet]

changing to a high volume pump will not help a whole lot. ion fact it may leave you with a broken pump shaft or oil starvation in the pan if it keeping most of the oil in the block more then in the pan. and on that if a pump fails then replace it but if your oil pressure is changing with different viscosity then look at you filter or bearings as the issue. would dump the lucas stuff as well it really just thickens the oil.

 

[ezdaar]

Absolutely wrong.
Millions of 350's are running fine with high volume pumps for hundreds of thousands of miles with NO problems.

 

[Big Roller]

A week later and still no more pressure issues. I really think it was the crappy quality oil filter that caused my oil pressure to drop so low. Running at 60mph on the highway, my oil pressure sits at 40-45psi. Even goes up to 50+ if I jump on it. At idle I'm sitting at 20psi. I think I'm gonna run 10w40 for the rest of its' life. Maybe switch to 30 weight in winter if the 40 doesn't want to flow well.