Oil pressure up then down - The 1947 - Present Chevrolet & GMC Truck Message Board Network

vtwinsport · 04-15-2010, 08:54 AM

Hey all,
recently my engine psi has been up around 50 psi from normal 20 at idle. Doesn't seem to make a difference if its warm or cold, been parked or been running.
motor only has 6000 miles on it. rebuilt by a shop tied to 350 turbo that seems to be working fine.
Any ideas what's going on? Something about to break?

Jonboy · 04-15-2010, 08:56 AM

I would try another gauge before you start pulling everything apart. Maybe try a cheap aftermarket gauge just to confirm.

**old Rusty C10** · 04-15-2010, 09:17 AM

could be the sender unit too those go bad far more often than the guages.. is it electrical or is it mechanical?

Jonboy · 04-15-2010, 10:20 AM

76 is still a mechanical gauge.

vtwinsport · 04-15-2010, 12:08 PM

thanks guys- good ideas
I actually have a mechanical Autometer in there. Guage is 1 year old. Me thinks it could be the sender now that you'll brought it up.

Colesnsty68 · 04-15-2010, 08:07 PM

is it bad that mines done that since the day i put it in? seems to run fine, jw.

harnalien · 04-15-2010, 09:00 PM

Quote:

Originally Posted by Colesnsty68

is it bad that mines done that since the day i put it in? seems to run fine, jw.

Mine too!!

Colesnsty68 · 04-17-2010, 02:21 PM

It only does it at lights, just at a lower rpm so i figure its just the pump aint pumpin so fast, any other ideas? i know its not bad, just would like to know.

Hoods69BadBowTie · 04-17-2010, 04:22 PM

Quote:

Originally Posted by vtwinsport

thanks guys- good ideas
I actually have a mechanical Autometer in there. Guage is 1 year old. Me thinks it could be the sender now that you'll brought it up.

Yea that's what I was thinking as well.

Panelman55 · 04-17-2010, 07:15 PM

When did you last change the oil??? What oil are you using??

Colesnsty68 · 04-17-2010, 07:17 PM

About three weeks ago, its always done, castrol gtx 10w 40.

LONGHAIR · 04-17-2010, 08:09 PM

A pressure increase is odd.
Filter failure?
Pressure regulator stuck? I wouldn't think so at idle, but?
Spin a cam bearing?
Is the top-end still oiling ok?

Colesnsty68 · 04-17-2010, 08:40 PM

oh yah everythings just fine, it runs great, so who knows.

spinem · 04-18-2010, 03:09 AM

if its electrical id check all grounds. did you use sensor safe selant on the sensor? (not all "sensor safe" sealants conduct.)

LONGHAIR · 04-18-2010, 07:03 AM

Colesnsty68, this thread is the exact reason that it is against the rules to "Hi-jack" someone elses thread. You jumped in after the last response of the original poster and have continued to answer and give details....confusing the heck out of this thread.
Unless a responder "knows" the OP pretty well, it goes unnoticed that the person asking questions and giving details has changed.

vtwinsport · 04-23-2010, 08:52 AM

thanks longhair. I was thinking about that.

Anyway, checked my lines and fittings, no leaks, checked oil level, checked top end under valve covers- all appears fine but I'm no 20 year mechanic.
Oil pump, guage, lines and sending unit are 1 year old.

It is still doing it, though I think the high pressure at idle is related to core block temperature- like metal temperature. I have noticed that after 20 minutes of driving the pressure started behaving normally- 20 psi at idle, 60 at hwy speeds.

Is this indicative of a bearing issue since the oil pressure drops after the journals and good and warm or an oil type- pump issue? I'm running 10w-30 & penzoil filter. I guess I'll try a new sender and an oil/ filter change first as it cost so little and see what happens.
thanks in advance

raws67 · 04-23-2010, 10:27 AM

If its a mechanical gauge it shouldnt have a sending unit should it? Another thing to look at may be crud in the line or gauge itself maybee some thread tape or something like that.

vtwinsport · 04-23-2010, 11:54 AM

I was thinking of the brass fitting that threads into the block. I guess its not really a sending unit.
That's agood suggestion as well, remove the lines and fittings and clear them with compressed air.

Colesnsty68 · 04-23-2010, 11:02 PM

Quote:

Originally Posted by LONGHAIR

Colesnsty68, this thread is the exact reason that it is against the rules to "Hi-jack" someone elses thread. You jumped in after the last response of the original poster and have continued to answer and give details....confusing the heck out of this thread.
Unless a responder "knows" the OP pretty well, it goes unnoticed that the person asking questions and giving details has changed.

My MF'in bad.

Colesnsty68 · 04-23-2010, 11:03 PM

Also, Vtwinsport, my deepest apologies for Hi-jackin yalls thread.

vtwinsport · 04-25-2010, 09:10 PM

No problem Colesnsty68,
It happens. I've caught myself a few times doing the same.

Cleaned the oil lines and brass connection at block with air. Will take it for a test run and see if did anything later.

staggerd86c-10 · 04-25-2010, 09:57 PM

As far as i know its normal for the oil pressure to rise and lower at different rpms, it builds up pressure as the motor revs. as long as it doesnt stay low im pretty sure youre alright.

04-15-2010, 08:54 AM	#1
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Oil pressure up then down Hey all, recently my engine psi has been up around 50 psi from normal 20 at idle. Doesn't seem to make a difference if its warm or cold, been parked or been running. motor only has 6000 miles on it. rebuilt by a shop tied to 350 turbo that seems to be working fine. Any ideas what's going on? Something about to break? __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/

04-15-2010, 08:56 AM	#2
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: Oil pressure up then down I would try another gauge before you start pulling everything apart. Maybe try a cheap aftermarket gauge just to confirm. __________________ 1974 Jimmy- 5.3/4L80e/NP241

04-15-2010, 09:17 AM	#3
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,286	Re: Oil pressure up then down could be the sender unit too those go bad far more often than the guages.. is it electrical or is it mechanical? __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

04-15-2010, 10:20 AM	#4
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: Oil pressure up then down 76 is still a mechanical gauge. __________________ 1974 Jimmy- 5.3/4L80e/NP241

04-15-2010, 12:08 PM	#5
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Re: Oil pressure up then down thanks guys- good ideas I actually have a mechanical Autometer in there. Guage is 1 year old. Me thinks it could be the sender now that you'll brought it up. __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/

04-15-2010, 08:07 PM	#6
Colesnsty68 Registered User Join Date: Jun 2009 Location: Arvada, Colorado Posts: 210	Re: Oil pressure up then down is it bad that mines done that since the day i put it in? seems to run fine, jw. __________________ 1970 Chevrolet custom camper 20 2000 F@$d F250 Powerjoke "And i still like bologna on white bread now and then" -Alan Jackson

04-17-2010, 02:21 PM	#8
Colesnsty68 Registered User Join Date: Jun 2009 Location: Arvada, Colorado Posts: 210	Re: Oil pressure up then down It only does it at lights, just at a lower rpm so i figure its just the pump aint pumpin so fast, any other ideas? i know its not bad, just would like to know. __________________ 1970 Chevrolet custom camper 20 2000 F@$d F250 Powerjoke "And i still like bologna on white bread now and then" -Alan Jackson

04-17-2010, 07:15 PM	#10
Panelman55 Registered User Join Date: Dec 2009 Location: Winston, Ga. Posts: 240	Re: Oil pressure up then down When did you last change the oil??? What oil are you using?? __________________ In God We trust!!!

04-17-2010, 07:17 PM	#11
Colesnsty68 Registered User Join Date: Jun 2009 Location: Arvada, Colorado Posts: 210	Re: Oil pressure up then down About three weeks ago, its always done, castrol gtx 10w 40. __________________ 1970 Chevrolet custom camper 20 2000 F@$d F250 Powerjoke "And i still like bologna on white bread now and then" -Alan Jackson

04-17-2010, 08:40 PM	#13
Colesnsty68 Registered User Join Date: Jun 2009 Location: Arvada, Colorado Posts: 210	Re: Oil pressure up then down oh yah everythings just fine, it runs great, so who knows. __________________ 1970 Chevrolet custom camper 20 2000 F@$d F250 Powerjoke "And i still like bologna on white bread now and then" -Alan Jackson

04-18-2010, 03:09 AM	#14
spinem haha, ford guys... Join Date: Feb 2007 Location: Visalia, CA Posts: 576	Re: Oil pressure up then down if its electrical id check all grounds. did you use sensor safe selant on the sensor? (not all "sensor safe" sealants conduct.)

04-23-2010, 08:52 AM	#16
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Re: Oil pressure up then down thanks longhair. I was thinking about that. Anyway, checked my lines and fittings, no leaks, checked oil level, checked top end under valve covers- all appears fine but I'm no 20 year mechanic. Oil pump, guage, lines and sending unit are 1 year old. It is still doing it, though I think the high pressure at idle is related to core block temperature- like metal temperature. I have noticed that after 20 minutes of driving the pressure started behaving normally- 20 psi at idle, 60 at hwy speeds. Is this indicative of a bearing issue since the oil pressure drops after the journals and good and warm or an oil type- pump issue? I'm running 10w-30 & penzoil filter. I guess I'll try a new sender and an oil/ filter change first as it cost so little and see what happens. thanks in advance __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/ Last edited by vtwinsport; 04-23-2010 at 08:55 AM.

04-23-2010, 10:27 AM	#17
raws67 Registered User Join Date: Jun 2007 Location: lemoore ca Posts: 126	Re: Oil pressure up then down If its a mechanical gauge it shouldnt have a sending unit should it? Another thing to look at may be crud in the line or gauge itself maybee some thread tape or something like that.

04-23-2010, 11:54 AM	#18
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Re: Oil pressure up then down I was thinking of the brass fitting that threads into the block. I guess its not really a sending unit. That's agood suggestion as well, remove the lines and fittings and clear them with compressed air. __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/

04-23-2010, 11:03 PM	#20
Colesnsty68 Registered User Join Date: Jun 2009 Location: Arvada, Colorado Posts: 210	Re: Oil pressure up then down Also, Vtwinsport, my deepest apologies for Hi-jackin yalls thread. __________________ 1970 Chevrolet custom camper 20 2000 F@$d F250 Powerjoke "And i still like bologna on white bread now and then" -Alan Jackson



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04-25-2010, 09:10 PM	#21
vtwinsport Registered User Join Date: Nov 2008 Location: edmonton, alberta Posts: 293	Re: Oil pressure up then down No problem Colesnsty68, It happens. I've caught myself a few times doing the same. Cleaned the oil lines and brass connection at block with air. Will take it for a test run and see if did anything later. __________________ 76 Silverado, 2wd, long box, 350/th350, 3.42 posi, edelbrock performer 64cc heads, edelbrock 1405, 2101 intake, Hedman Headers, Comp Cam XE262 http://beerbreadbike.wordpress.com/

04-25-2010, 09:57 PM	#22
staggerd86c-10 Squarebody Aficionado Join Date: May 2008 Location: Miami, FL Posts: 713	Re: Oil pressure up then down As far as i know its normal for the oil pressure to rise and lower at different rpms, it builds up pressure as the motor revs. as long as it doesnt stay low im pretty sure youre alright.

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