Oil pump-need advice

[jpcrzy]

I have a 78 401 with 150,000 miles on it. The oil pressure is great on cold startup with 40lbs. When it warms up to temp the pressure drops to 5lbs at idle and 10psi at highway speed. It also has tappet noise. I use castrol 20w50 with stp oil treatment to help noise problem. I have read some threads on rebuilding the oil pump. Will this solve my problem, or do I just need to rebuild motor and replace timing cover/oil pump at same time

[ September 07, 2003, 07:04 PM: Message edited by: jpcrzy ]

[amx390]

The quickest thing to try is rebuilding the oil pump, parts are available. Once you have the gears out of the housing you can check the timing cover & replace if worn or grooved as this would let oil past your gear & cause low oil pressure.See a shop manuel for specs on the gear bores. If after rebuilding the oil pump you still have low oil pressure your main and or rod bearing may have worn enough to cause the oil pressure to be lower than normal.
PS if you replace the timing cover check the timing chain and replace if needed.

[jpcrzy]

Hey, thanks for the sound advice smile.gif Do you think BJ's is the best place for the kit?

[wy_white_wolf]

Oil pressures that low with 20-50 sounds like the mains, rod, and or cam bearing are really louse. If they were tight, they would have spun after the engine after warmed-up.

How is the engine otherwise?

[letank]

do you trust your oil pressure gauge?

the CVR in your gas gauge may be on its way out..... yes you have a tappet noise..... all of them.....

do you know how to test you oil pressure gauge.....

it was answered before....

78 to 68 ohms for 0, 25 to 21 ohms for 40 and about 13 to 7 for 80 psi ( i used fixed resistor of 78, 25 and 10) ..... engine has to be at operating temp. Just connect that know resistance between the oil presure sender wire and a good ground..... if values are way off your cvt is toast, replace your gas gauge

if values are correct.... then either your sender is bad or your engine needs rebuilt.... arrrrrrgh... or may be your crank bearing are a bit off

Michel

[brent]

I absolutely second the above advice: "do you really trust your oil guage?"
Get an ohmeter for piece of mind. At least you'll be positive.
The only guage that works accurately on my FSJ is the temp sender and that's only 'cause I replaced it myself when I revamped the cooling sys.
Flucatuations like you described, with no visible affect on power, seem like typical FSJ.
But even Wyoming said there could be loose stuff. A few factors to consider before pronouncing it unreliable/dead.---Brent, 2cents

[quikclimber]

even better, you could thread a pressure gauge into the oil pressure sender to see what the actuall oil pressure is. i thought i had low oil pressure for a long time, then after my rebuild the guage still read low, so i tested the actual pressure, which runs betweem 40and 60 now. Anyone know how to fix the stupid guage in the dash..any way to adjust it... or just find a new one?