another oil pressure question.. - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by:

Reply
 
 
 
LinkBack Thread Tools Search this Thread
Old 02-28-2011, 07:08 PM   #1
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default another oil pressure question..

so i tried searching, but didnt find exactly what i was looking for so i thought i would ask.

I recently rebuilt my engine, using a donor crankshaft from another motor (my cranknose failed) so i had to swap over the oil pump too. now im idling at about 15psi (which according to m.net is ok, but if it gets any lower is bad news) so im wondering if low oil pressure has anything to do with the engine still being in the break in stage? will it change once the engine has some miles on it, or should i start looking for a new oil pump? all seals were replaced so it shouldn't be a leak.

any insight would be appreciated

Thanks,
Chad
rigidbigelsworth is offline   Reply With Quote
Old 02-28-2011, 08:19 PM   #2
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

and i guess more importantly, where the **** can i get a 1990 oil pump? i cant find one anywhere. if they are only a couple hundred dollars, ill just replace it for piece of mind/prevent worse damage
rigidbigelsworth is offline   Reply With Quote
Old 02-28-2011, 08:30 PM   #3
I'm Miserable!
 
Join Date: Jun 2009
Location: albany, ga
Posts: 1,869
Total Cats: 3
Default

Techsalvager is offline   Reply With Quote
Old 02-28-2011, 08:34 PM   #4
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default



01+ motors have no more than 55-60psi tops and like 5-15 at idle. How much do you have at redline?
Faeflora is offline   Reply With Quote
Old 02-28-2011, 09:06 PM   #5
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

checked rockauto already, no luck. i havent taken it to redline yet, im trying to stay under 4k for the first couple hundred miles. (im only up to 150 miles so far)

i wouldnt be that worried about it, but the engine i stole the crankshaft from (short nose) was replacing my big nose, so i had to swap the oil pump. the donor engine literally had a melted rod bearing(see pic ), the #3 rod turned black from the heat so im thinking the cause might have been from lack of oil. that, or the fact that the previous owner tried rebuilding that engine, and LEFT OUT THREE MAIN BEARINGS. so it may or may not have been due to the pump. it had good pressure upon initial startup, and the first few miles. i then drove it for about an hour on the highway (i know that might be a no-no but i had to get from my parents house back to school). i noticed driving around today that it was idling around 15 and if i remember correctly, pre-rebuild i was idling at 30, crusing at 60. now i idle at 15, cruise at 30. also,im sure its unrelated, but it wasnt idling very well either. i shot the ISCV with some carb cleaner and that seemed to help.

im ok with replacing it if its not super expensive, but i guess ill have to call mazda in the morning to see how much they wanna rape my wallet for one if noone else has a source online for one?

thanks,
Chad
Attached Thumbnails
another oil pressure question..-02192104.jpg  
rigidbigelsworth is offline   Reply With Quote
Old 02-28-2011, 11:58 PM   #6
Elite Member
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

not super expensive but requires pulling the motor to replace

10psi per 1k rpm hot is generally accepted as being sufficient.
fooger03 is offline   Reply With Quote
Old 03-01-2011, 12:45 AM   #7
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

oh so i should be ok then it sounds like. idling (750 rpm) yields 15 psi, cruising (around 3k) is about 30 psi. guess i wont worry about it unless the pressure gets lower. if the oil pump is bad, will it get worse exponentially? or will it just gradually get worse over time?

Thanks,
Chad
rigidbigelsworth is offline   Reply With Quote
Old 03-01-2011, 02:04 AM   #8
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

uhhh

hmm your oil pressure is probably ok. flow not pressure!
Faeflora is offline   Reply With Quote
Old 03-01-2011, 02:16 AM   #9
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Stop being a fuckign ***** and rev your bitch to 7000 RPM once and tell us what the oil pressure is.
Faeflora is offline   Reply With Quote
Old 03-01-2011, 03:01 AM   #10
Elite Member
iTrader: (13)
 
Join Date: Dec 2009
Location: Fraser Valley, British Columbia
Posts: 2,502
Total Cats: 13
Default

My brand new motor with 400kms on it running the Maruha oil pump idles at 800RPM with 17-20PSI. Highest I see it is 60-62PSI with a current RPM limit of 5000RPM.
falcon is offline   Reply With Quote
Old 03-01-2011, 03:14 AM   #11
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,366
Total Cats: 1,326
Default

Quote:
Originally Posted by falcon View Post
current RPM limit of 5000RPM.
What reasons were given for this RPM limit?
Savington is online now   Reply With Quote
Old 03-01-2011, 04:49 AM   #12
Elite Member
iTrader: (13)
 
Join Date: Dec 2009
Location: Fraser Valley, British Columbia
Posts: 2,502
Total Cats: 13
Default

No specific reason other than I don't want to beat the **** out of a new motor. I've been driving it hard, just not high in the RPMS. Once I hit 500kms I'll bump it up some more. Once I hit 750-800 I'll be using it all.

Same way I've broken in all my motorcycles and I have never had an issue with ring seal or blowby with any of them.
falcon is offline   Reply With Quote
Old 03-01-2011, 08:36 AM   #13
Elite Member
iTrader: (2)
 
fooger03's Avatar
 
Join Date: Jan 2009
Location: Columbus, OH
Posts: 4,132
Total Cats: 187
Default

Quote:
Originally Posted by falcon View Post
No specific reason other than I don't want to beat the **** out of a new motor. I've been driving it hard, just not high in the RPMS. Once I hit 500kms I'll bump it up some more. Once I hit 750-800 I'll be using it all.

Same way I've broken in all my motorcycles and I have never had an issue with ring seal or blowby with any of them.
You're doing it wrong
fooger03 is offline   Reply With Quote
Old 03-01-2011, 10:01 AM   #14
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

what is your suggested break in method fooger? i have heard everything from limp wrist it around the block, to wail on it once its warmed up. im trying to take the center road and drive it average for a few hundred miles then beat on it. but ill check max oil pressure on my way to work and report back.
rigidbigelsworth is offline   Reply With Quote
Old 03-01-2011, 02:18 PM   #15
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

at 7k my oil is about 60psi. which seems kinda low to me. it used to peak around 90
rigidbigelsworth is offline   Reply With Quote
Old 03-01-2011, 02:45 PM   #16
Boost Pope
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Delicious and Moist.
Posts: 26,323
Total Cats: 1,920
Default

Quote:
Originally Posted by rigidbigelsworth View Post
it used to peak around 90
To me, that suggests that the pressure relief valve in your old oil pump may have been sticking.

There is a spring-loaded plunger in the oil pump which opens to bypass oil directly back to the crankcase when pressure exceeds a certain threshold, as would be the case when the oil is cold or at very high RPM. My recollection is that the target pressure is in the neighborhood of 60 PSI.
Joe Perez is offline   Reply With Quote
Old 03-01-2011, 02:54 PM   #17
Junior Member
Thread Starter
iTrader: (3)
 
Join Date: Apr 2010
Location: Cary, NC
Posts: 494
Total Cats: 6
Default

by target im guessing you mean target max pressure? if so, that is awesome news. so instead of installing a worse pump, i fixed a problem i didn't even know i was having! haha

thanks for the help everyone
rigidbigelsworth is offline   Reply With Quote
Old 03-01-2011, 04:26 PM   #18
Elite Member
iTrader: (13)
 
Join Date: Dec 2009
Location: Fraser Valley, British Columbia
Posts: 2,502
Total Cats: 13
Default

Quote:
Originally Posted by fooger03 View Post
You're doing it wrong
cool.
falcon is offline   Reply With Quote
Old 03-01-2011, 04:50 PM   #19
Elite Member
iTrader: (12)
 
Join Date: Nov 2009
Location: Harpers Ferry WV
Posts: 1,521
Total Cats: 20
Default

If it bothers you that bad buy a set of billet oil pump gears and shim the relief valve spring .030 and your oil pressure will be back up in no time. I shimmed my last pump and it would hold around 25 psi. at idle and 80psi at 7000k. On the other had my shimmed honda pump on my daily idles at 110-12 psi and maxes out around 75psi not that that matters for your mazda just a side not because that car has a donor crank in it as well.
Sean is offline   Reply With Quote
Old 03-04-2011, 11:41 AM   #20
Senior Member
iTrader: (1)
 
Join Date: Oct 2008
Location: Trailer County
Posts: 530
Total Cats: -9
Default

15 psi at idle is not bad, and 60 psi at redline is acceptable.
mazpr is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Moroso Air Oil Separator Catch Can Aroundcorner Miata parts for sale/trade 2 10-01-2015 04:20 PM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:31 AM.