I have a 304 engine

ANDREW1985

MEMBER
1976 JEEP CJ5
200,000 MILES

I have a 304 engine. When it starts up it will have 55 pounds of oil pressure, when it warms up it has about 20 to 25 pounds of pressure. Which I know is normal for this motor, but when u idle it up cold or hot the pressure will drop to zero. Sometimes it rises back to 10 to 20 and other times it dont. It has a new bottom end in the motor. Which is the crank and bearings. What might be causing this?

Sunday, October 28th, 2012 AT 10:26 PM

5 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Did you replace the pump?

There are cam bearings too that can wear out and cause low pressure

before jumping to conclusion, have the pressure checked manually before assuming anything.

Roy

Was this

answer

helpful?

Yes

Sunday, October 28th, 2012 AT 10:31 PM

ANDREW1985

MEMBER
3 POSTS

I have changed the oil pump and it has a manual gauge installed

Was this

answer

helpful?

Yes

Sunday, October 28th, 2012 AT 10:36 PM

ASEMASTER6371

MECHANIC
52,796 POSTS

Ok, god chance you have excessive clearance in the cam bearings.

What did you set the mains and rod clearances at?

Roy

Was this

answer

helpful?

Yes

Sunday, October 28th, 2012 AT 10:38 PM

ANDREW1985

MEMBER
3 POSTS

I just bought a stock replacement crank with bearings. I put it in and torqued it to specified torqued settings. I really dont know the clearance of the bearings

Was this

answer

helpful?

Yes

Sunday, October 28th, 2012 AT 10:56 PM

CJ MEDEVAC

MECHANIC
11,004 POSTS

SEE THIS ONE

https://www.2carpros.com/questions/1994-ford-thunderbird-oil-pressure-drops-comes

BOTH GAUGES ON MY JEEPS ARE MECHANICAL.....I WOULDN'T HAVE IT ANY OTHER WAY

IT'S POSSIBLE THAT THE ENGINE HEAT HAS MESSED UP YOUR SENDER

THE SENDER IS PRETTY CHEAP

THE MEDIC

Images (Click to make bigger)