Fixing low oil pressure at start-up on the cheap help!

[bigja01cobra]

Ok finally getting around to pulling the motor out of the Cobra to figure out what is causing my low oil pressure at start-up and idle, only 7 psi at warm idle(operating temp) 40 psi at 1800 rpm.

I am guessing it is main bearings, motor has 22k miles on it since full forged balanced blueprinted shortblock install. Heads were completely gone through and ported polished, new valve train and timing components.

Is it possible for me to check the main bearings without removing the Head? for example Leave heads on with the pistons and rods in the block just remove main caps and check for wear and rough clearance check with plastigage? I do not own any of the tools to degree the cams, but plan on borrowing a set of cam holders.

Any help or tips appreciated. quoted between 6-7k for this to be sent out :nonono:. Already dropped more then that into this motor :fm:, don't want to do it again.

Thanks

 

[01yellercobra]

Turn the motor upside down and remove the oil pan. You can pull all the caps then. If you have the bolts on the mains you'll need new ones since they're TTY. Make sure the oil pump is seated properly and the o-ring on the pick up isn't damaged.

 

[bigja01cobra]

yeah I figured I could, just wasn't entirely sure on this motor. I had good compression so I don't want to pull motor completely apart and risk damaging anything. Just want to leave it as much together as possible.

It would be nice if it was as simple as that.

Ill update with pics once I get it out. Pulling it next weekend.

 

[Brutal Metal]

sounds like bearing issues with pressure that low...

 

[PONY1]

try a different gauge to confirm first.

 

[ashleyroachclip]

It seems a little low,but specs.call for 1 pound pressure per 1 hundred rpm at idle.

So at 700 rpm, that is only 7 psi. Warm

 

[Brutal Metal]

It seems a little low,but specs.call for 1 pound pressure per 1 hundred rpm at idle.

So at 700 rpm, that is only 7 psi. Warm

Where did you get this piece of info from:??:

 

[scarlett98]

I've seen that spec before to.

But really warm you should be min 20

 

[bigja01cobra]

I have a mechanical gauge installed, plus I put another on just to verify.

Regarding oil pressure. I know these mod motors need better pressure then the basic 10 psi per 1000 rpm in the lower RPM band. Think about all the moving parts in this motor with the 4 cams and tight clearances; pressure is needed to push the oil to properly lubricate.

Yeah depending on how bad the crank is will determine if I do it myself. I am hoping I can get away with just a polish and new mains.

The I guess Ill drop $200 for the cam timing tools, maybe upgrade to some adjustable cam sprockets to degree cams a little easier.

 

[MT0911]

What parts went into your rebuild? For a stock engine I like seeing a min of 18-20 psi at idle and then at the least another 10 psi per 1000 rpms. But depending on your engine build - and how you built it then it's possible to have a little lower. I've seen as low as 10 psi at idle on a pretty built engine with high boost (making over 900whp). BUT at 7k rpms - it still kicked out 70 psi which follows the rule of 10 per 1000. My engine is usually around 16-20 lbs at idle but I usually have around 35-40 psi cruising at 2k rpms and I ALWAYS have at least 10 psi per 1k rpms especially at higher rpms. I've ran mine like this for the past 3 years and I do make some healthy runs here and there - no ticking, bad noises, or anything in my oil filter.

7 psi is still pretty low and I would check it out. But keep in mind that depending on your rebuild clearances you might only have 15-20 lbs of oil at idle. Just make sure that it raises 10 psi per 1000 in all other rpms.

This is what I would do. 1. Listen to it idle - are there any bad noises, ticking, etc? 2. Try hooking up another Manual gauge just to make sure. 3. Cut open your oil filter, check through it and see if you can find any copper/gold metallic flakes similar to glitter 4. If so, definitely pull the engine - it's bearing material.

Good luck man.

 

[bigja01cobra]

Motor is a 5.1L Alumium short block from Coast High performance. Probe industry parts I do believe. I do not have the build sheet, and installer of short block has closed shop.

I checked oil previously didnt notice anything, but havent cut filter open. Only a short runtime to get to operating temp at 1500-1800 rpm (good oil pressure) on this oil. I have put a mechanical gauge plus my electronic gauge to verify oil pressures.

No noise at idle unless oil pressure dropped below 7 then it ticks. Showed 5 psi intially(2500miles on 5w20) at HOT idle factory gauge went to zero and it ticked... slight touch on throttle and oil pressure shoots up. Never had it above 2500 rpm since above. Since I changed oil and put in 5w30 no ticking or noise at idle...but I havent let it run very long at idle since I am not sure on issue.

Also takes long time to build oil pressure at startup... Have igntion disabled and turned it over to try and build pressure. Similar to when you change oil took a little bit for pressure to come up.

I am guess definitely bearings. When i get home this weekend I will cut open filter and see what I find.

 

[Lightning&Mach1]

Bump for this thread I'd like to see what you find

 

[CJK440]

What was your oil pressure readings when the motor was new?

For wear related oil pressure issues, I'd investigate the rods first then check the mains.