26 replies to this topic

[SomethingNew71]

Hey everyone!

 

I have been encountering a pretty large drop in oil pressure on my motor the past couple weeks.  Normally my car runs at a solid 80-100 PSI depending on the load however recently its been idling at around 25-30psi and maxing out at 60-65psi.  I have removed the relief valve and cleaned it multiple times as well as changed the oil and filter in the car twice.  I am still seeing the very low (in my opnion) pressures and its really concerning me.  I have noticed under throttle load the pressure is lower than when I am at speed(lets say 45-50) and I am in gear with no throttle.  When I and just coasting down the road in gear I have a higher pressure.  

 

Now I have talked with Jedduh on this forum who is a friend of mine outside the forum and who's opinion I trust very much.  He suggested perhaps the oil pressure sender line is blocked in some way or perhaps there is just a lot of crap in the oil system.  I did want to open the question to everyone else here as well though.  Anyone have any additional ideas?  Oil pump is about a year old and all the engine(cam, crank, etc) bearings were replaced during a fast cam upgrade about 1.5 years ago. 

 

[Cooperman]

As a rough guide a healthy A-Series engine will have the following pressure ranges when the oil is hot:

 

1000 rpm                                10 to 20 psi

3000 rpm                                40 to 50 psi

5000 rpm                                55 to 65 psi

 

You don't need anything higher than this and a running pressure of 100 psi is far to high, even when the engine/oil is cold. The other risk with ultra-high oil pressure is the possibility of pushing out the oil gallery core plugs.

[Spider]

I agree with Coopermans post ^ and even at 80 PSI, that's way too high.

 

What type of Oil Pressure Relief Valve are you running? If the the Ball Bearing one, that'll do just what you're describing, they are bad news in my opinion. Fit a stock one with a new spring.

 

Try dropping the pressure to the number's Cooperman has posted and changing the Oil, it will be cooked to death by now from the high pressures.

 

<Edit: What Oil Pump are you running? >

Edited by Moke Spider, 01 January 2016 - 06:02 PM.

[carbon]

Have you changed make / grade of oil recently? This also makes a big difference.

 

The bit which seems odd is the change in oil pressure depending on engine load.

 

Were there any other changes made when you fitted fast road cam, such as uprated clutch?

[Rob Gavin]

What pump was fitted when the cam was done?

[Cooperman]

If you have 65 psi at 5000 rpm I really wouldn't worry about it.

As 'Moke...' says, do an oil change using top quality 20w50 mineral oil, fit a new plunger if you currently have a ball bearing as a relief valve, or even just fit a new plunger anyway as it can do no harm, and enjoy driving it.

[SomethingNew71]

As a rough guide a healthy A-Series engine will have the following pressure ranges when the oil is hot:

 

1000 rpm                                10 to 20 psi

3000 rpm                                40 to 50 psi

5000 rpm                                55 to 65 psi

 

You don't need anything higher than this and a running pressure of 100 psi is far to high, even when the engine/oil is cold. The other risk with ultra-high oil pressure is the possibility of pushing out the oil gallery core plugs.

 

 

80psi constant was about the first 6 months after a complete engine rebuild.  I just assumed that was because of all the new tight bearings and everything.  Currently it is matching the chart you wrote above.  I am probably worrying for naught.  Just from the replies I am reading.

 

 

I agree with Coopermans post ^ and even at 80 PSI, that's way too high.

 

What type of Oil Pressure Relief Valve are you running? If the the Ball Bearing one, that'll do just what you're describing, they are bad news in my opinion. Fit a stock one with a new spring.

 

Try dropping the pressure to the number's Cooperman has posted and changing the Oil, it will be cooked to death by now from the high pressures.

 

<Edit: What Oil Pump are you running? >

 

See above it currently isnt running 80psi that was just right after the motor was rebult.  The pressure release I have now is the spring type with the "semi-cone" shaped thingy.  It's bone stock original system.  I just changed the oil 2 days ago though in an attempt to bring pressure back up. Although it sounds like I don't need to be worrying about the pressures I have.

 

Have you changed make / grade of oil recently? This also makes a big difference.

 

The bit which seems odd is the change in oil pressure depending on engine load.

 

Were there any other changes made when you fitted fast road cam, such as uprated clutch?

 

Same grade oil as before 20w50 standard dino oil.    The clutch is standard.  We ported the head, did a big valve swap, but the oil pump was just a stock replacement that matched the pattern of the cam.  

 

What pump was fitted when the cam was done?

 

I cant remember the exact one but it was a standard stock pump to match the cam I put in.  I think it was a spider drive.

 

If you have 65 psi at 5000 rpm I really wouldn't worry about it.

As 'Moke...' says, do an oil change using top quality 20w50 mineral oil, fit a new plunger if you currently have a ball bearing as a relief valve, or even just fit a new plunger anyway as it can do no harm, and enjoy driving it.

 

Yeah from what I am reading it sounds like I am in normal pressure ranges.  I use the plunger type relief valve and 20w50 in now just changed.  Sounds like I need to stop worrying so much.  

[SomethingNew71]

Hey everyone,

 

I know I am kinda bringing this back from the dead but I had some new issues and didn't feel like I should start a new thread. 

 

I was driving yesterday and under load my cars pressure dropped down to 10psi maximum.  The engine sounded pretty rough as well.  I naturally pulled off the road and checked my bypass valve to make sure it was operating correctly and could not find any obstruction.  Well I managed to get it to 10-20psi under a tiny load and gimped my way back home(about a mile or 2).  I pulled apart the bypass again and flushed it out as best I could with the engine in the car and couldn't find anything.  I then tried car again and still can't get above 10-15psi even when revving the engine.  When the engine is revved as well it sounds ROUGH so I am trying not to do that for fear of damaging it.

 

I dumped the oil out and then with the drain plug out and the bypass open I shot high pressure wd-40 in there to try and flush any gunk out and down the bottom of the car.  I think I saw a pretty sizable metal flake come out but it slide down in my drain pan never to be seen again.  :-/ 

I have just filled the car up with new oil and tried to get pressure again, and I am getting 40psi at cold start idle.  I am kind of afraid to drive it right now hahaha.  Is the ball bearing replacement a worthwhile upgrade instead of that plunger?

[nicklouse]

if it sounds bad I would say the bearings have gone.

 

need pulling.

[SomethingNew71]

if it sounds bad I would say the bearings have gone.

 

need pulling.

 

I just put brand new bearings and rebuilt the motor about 11 months ago.  With the oil pressure back up now it sounds fine.  Think with the low oil it was just getting rough in there between the metals.  

[Cooperman]

It is very likely the bearing shells are fubar and you do need to strip and inspect bearings and crank journals.

Edited by Cooperman, 29 February 2016 - 07:26 PM.

[nicklouse]

oil pressure is the result of oil not getting past the bearings.

 

your lack of pressure and the comments about it sounding rough and that sliver of metal........

 

pull it out.

[SomethingNew71]

It is very likely the bearing shells arrange fubar and you do need to strip and inspect bearings and crank journals.

 

 

 

oil pressure is the result of oil not getting past the bearings.

 

your lack of pressure and the comments about it sounding rough and that sliver of metal........

 

pull it out.

 

 

Well dammit.....

[MRA]

Do not strip it out until you have checked for contaminants in the oil...... 

 

Drain the oil in to a clean (only clean if you would eat off it) drain pan, then take a good look at the sludge if any in your oil if there is no silvery flecks in your oil then you have NOT destroyed your engine bearings.

 

so what is next.....  did you also notice a slight increase in the water temperature ?   when you built the engine did you get it to a rolling road ?  then you need to get it to a Mini based rolling road as I suspect you have retarded ignition.

 

However if you find lots of flecks and you didn;t get a slight increase in your water temperature then yes you will have to strip it out for a rebuild as stated above.

Edited by MRA, 29 February 2016 - 04:35 PM.

[MRA]

 

if it sounds bad I would say the bearings have gone.

 

need pulling.

 

I just put brand new bearings and rebuilt the motor about 11 months ago.  With the oil pressure back up now it sounds fine.  Think with the low oil it was just getting rough in there between the metals.  

 

 

"rough in there between the metals" ?  eeeeeek !  I hope it is ok, as it can be very costly if you have damaged the crank etc...

 

Oil pressure is also a function of the following..

 

Crank journal / bearing wear / damage

Camshaft journal / bearing wear / damage

Camshaft follower and their bores, damaged or worn.

Rocker shaft, rocker post, rocker damaged or worn

PRV valve and / or seat worn or damaged

 

In my opinion and experience most of the above are ignored or forgotten about during an engine rebuild.