Oil psi

1BigAmerican · 02-28-2009, 06:57 AM

Hey guys. I have an 88 Pickup with a 305ci v8. I have a tricky one here:

So my oil PSI gauge shows the when I accelerate or idle my psi keeps bouncing up an down. Variations are small when the engine is cold, but when it's at operating temp it normally jump up and down between 10 psi. So for example when it's idling it bounces between about 30 and 40 psi. However, when I decelerate or if I put it in neutral when I idle the psi is completely normal. So maybe this is a tranny problem instead of an oil pump? Thanks for any help!

bradrhale · 02-28-2009, 07:06 AM

you are going to have oil pressure fluctuations. the faster the engine turns, the more pressure you are going to have. as long as this does not bottom out, you are going to be ok. you did mention 10psi. i am assuming that this is at a dead stop with the truck in gear?? how many miles is on the engine??

wild bill · 02-28-2009, 07:20 AM

if it's wildly bouncing i would check the sending unit .it's normal to change with rpm and temperature .but should remain relatively constant .

1BigAmerican · 02-28-2009, 11:08 AM

Quote:

Originally Posted by bradrhale

you are going to have oil pressure fluctuations. the faster the engine turns, the more pressure you are going to have. as long as this does not bottom out, you are going to be ok. you did mention 10psi. i am assuming that this is at a dead stop with the truck in gear?? how many miles is on the engine??

It's never this eradic though. PSI will gradually increase with the RPM, but right now it's bouncing within that 10 psi range. When the truck is at a dead stop in gear it normally idles at 30psi, but it constantly jumps from 30 to about 40. 76k miles on a rebuilt engine 225k on the truck. I use 10w-30 just so I can split it between my truck and my fiances, I'll usually add an oil thickener to mine. This time around I used STP.

Quote:

Originally Posted by wild bill

if it's wildly bouncing i would check the sending unit .it's normal to change with rpm and temperature .but should remain relatively constant .

Thanks. I'll try that.

leolkfrm · 02-28-2009, 01:40 PM

Why are you using an "oil thickener"? All you need is a good quality oil and it will be fine. if the variance bothers you I too would suggest trying the sending unit first, but it does not sound necessary

crabtruck · 02-28-2009, 04:40 PM

Could also just be a loose plug on sender.

98k1500 · 02-28-2009, 06:33 PM

if youre dumping snake oil into your engine be ready for problems, that junk doesnt work, I however use Lucas oil stabilizer, yeah im splitting a hair here but the point is me and dad use it in everything, trucks tractors combine, just helps keep from having dry startups and with Kansas weather helps oil survive dramatic climate changes every five seconds.

I ONLY recommend LUCAS... Its the only stuff that works, all the other is like dumping gear oil into your crankcase. it doesnt help psi or anything.

joe dirt · 03-01-2009, 09:27 AM

My 90 carries 55 psi and 89 caries 5 psi
but they still run good

chevyguy · 03-01-2009, 07:27 PM

Dont use mechainc in jar, It never does anything except cause problems. I suspect you have a faulty gauge or sending unit, Get a direct reading gauge and see what your pressure is really doing.

silverChevy79 · 03-04-2009, 09:23 AM

get a nice oil pressure gauge and see if it does it again. i have a napa mechanical gauge in my truck. it works fine and i would buy the copper line kit because i blew two ferrils or whatever they are called in my truck. completely blew the line up and i lost 2 quarts of oil the first time and 4 the second. im lucky i have a 5 quart pan and didnt blow the engine. sad thing is i wasnt even running it hard either time.

02-28-2009, 06:57 AM	#1
1BigAmerican Junior Member Join Date: Oct 2008 Posts: 8	Oil psi Hey guys. I have an 88 Pickup with a 305ci v8. I have a tricky one here: So my oil PSI gauge shows the when I accelerate or idle my psi keeps bouncing up an down. Variations are small when the engine is cold, but when it's at operating temp it normally jump up and down between 10 psi. So for example when it's idling it bounces between about 30 and 40 psi. However, when I decelerate or if I put it in neutral when I idle the psi is completely normal. So maybe this is a tranny problem instead of an oil pump? Thanks for any help!

02-28-2009, 07:20 AM	#3
wild bill Senior Member Join Date: Jul 2008 Location: davenport iowa 52806 Posts: 277	pressure if it's wildly bouncing i would check the sending unit .it's normal to change with rpm and temperature .but should remain relatively constant .

02-28-2009, 01:40 PM	#5
leolkfrm Senior Member Join Date: Mar 2008 Location: N.Y. Posts: 4,904	Why are you using an "oil thickener"? All you need is a good quality oil and it will be fine. if the variance bothers you I too would suggest trying the sending unit first, but it does not sound necessary __________________ 4 wheels move the body 2 wheels move the soul B.W.A.I

02-28-2009, 06:33 PM	#7
98k1500 Senior Member Join Date: Jan 2008 Location: Manhattan,Kansas Posts: 322	if youre dumping snake oil into your engine be ready for problems, that junk doesnt work, I however use Lucas oil stabilizer, yeah im splitting a hair here but the point is me and dad use it in everything, trucks tractors combine, just helps keep from having dry startups and with Kansas weather helps oil survive dramatic climate changes every five seconds. I ONLY recommend LUCAS... Its the only stuff that works, all the other is like dumping gear oil into your crankcase. it doesnt help psi or anything. __________________ GOD BLESS CHRIS LEDOUX!!!

03-01-2009, 07:27 PM	#9
chevyguy Senior Member Join Date: Sep 2005 Location: ALABAMA Posts: 3,555	Dont use mechainc in jar, It never does anything except cause problems. I suspect you have a faulty gauge or sending unit, Get a direct reading gauge and see what your pressure is really doing. __________________ Some people are like slinkies, Basically useless, But fun to watch when you push them down the stairs.

02-28-2009, 07:06 AM	#2
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 9,512	you are going to have oil pressure fluctuations. the faster the engine turns, the more pressure you are going to have. as long as this does not bottom out, you are going to be ok. you did mention 10psi. i am assuming that this is at a dead stop with the truck in gear?? how many miles is on the engine??

02-28-2009, 04:40 PM	#6
crabtruck Senior Member Join Date: Jul 2007 Posts: 4,106	Could also just be a loose plug on sender.

03-01-2009, 09:27 AM	#8
joe dirt Full Member Join Date: Jan 2009 Posts: 10	My 90 carries 55 psi and 89 caries 5 psi but they still run good

03-04-2009, 09:23 AM	#10
silverChevy79 Senior Member Join Date: Feb 2009 Location: Cody, Wyoming Posts: 99	get a nice oil pressure gauge and see if it does it again. i have a napa mechanical gauge in my truck. it works fine and i would buy the copper line kit because i blew two ferrils or whatever they are called in my truck. completely blew the line up and i lost 2 quarts of oil the first time and 4 the second. im lucky i have a 5 quart pan and didnt blow the engine. sad thing is i wasnt even running it hard either time.

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