Very Low Oil Pressure in New Engine

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toolmanmike said:
Just to clarify, does anyone have a diagram as to where the 3 gaskets go? tmm
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There is a gasket under the head of the ported bolt and another on the ported bolt between the block and the adapter. The last one is the large diameter one between the block and the adapter.

Found my notebook, in the glovebox. Who would have thought?

Measuring the the bearings in the rods/mains with a bore gauge and a micrometer on the crank I got:

Mains
1 - .0028
2 - .0028
3 - .0026 - Trust clearance was .0065
4 - .0030
5 - .0027

Rods
1 - .002 2 - .0018 side - .014
3 - .0018 4 - .0019 side - .015
5 - .0021 6 - .002 side - .013
7 - .0017 8 - .0018 side - .014

Using plastigauge for the final assembly and rods read between .0015 and .002, the mains between .002 and .003.

The pick up sits a 1/2 inch off the bottom of the pan and is very parallel.

Being that the oil is clear and the filter wasn't full of bearing material I would bet that if I pulled it and tear it down I'll find nothing wrong with the bearings.

I don't buy that I have two bad gauges, but if I never looked at the gauge I wouldn't know anything is wrong. There are no other symptoms. Everything was fine until the gauge dropped.

I am going to attempt to pull the pan with the engine in the car, but I don't think that is possible.

Any other ideas?
 
make you sure you dont have kink in the oil pressure line to the gauge somewhere.what was your operating temp when the pressure was low? the only thing i can really think of is an oil galley either has some crap in it or a cam bearing has moved. or there is still something going on with oil pump. idk....
 
I'd have the pan down before I ran it much more! Something changed.

Given your clearances, I would expect the hot idle oil pressure to drop to 20-25, but with a HV pump it should pick up to whatever the bypass spring is set at by 1500 - 2000 RPM or so.

If I were a betting man, I would put money on something keeping the bypass valve from completely closing since oil pressure is rising with RPM (should come up to normal and level off by 3000 RPM or so). Sadly, Melling's quality control isn't what it once was and their pumps should be disassembled and inspected before installing. Sort of a trust but verify thing (like Eddy float levels).

I believe you CAN remove the pan in-chassis on an early A, shouldn't be much harder than removing engine completely (you will have to lift it off it's mounts).
 
"I'd have the pan down before I ran it much more! Something changed.

Given your clearances, I would expect the hot idle oil pressure to drop to 20-25, but with a HV pump it should pick up to whatever the bypass spring is set at by 1500 - 2000 RPM or so.

If I were a betting man, I would put money on something keeping the bypass valve from completely closing since oil pressure is rising with RPM (should come up to normal and level off by 3000 RPM or so). Sadly, Melling's quality control isn't what it once was and their pumps should be disassembled and inspected before installing. Sort of a trust but verify thing (like Eddy float levels)."


All x2...
 
It's solved!


  • I am the luckiest guy I know
  • Anyone in the Maryland area would like to come by and kick me in the balls, please feel free
  • You CAN pull the pan in an early A with Doug's headers and it's not that big of a job


The god damn oil pump was about to fall off! I swear I torqued it, I know I checked that the bolts weren't too long and I made sure it was seated before put the bolts in, but apparently I missed something.


There is no more crap in the pan than was in the filter. Judging by the oil dripping from the rods some pressure was getting everywhere.


I don't post a ton on here and you guys don't know me, but I am way too anal about this stuff. I guess I'm getting older, but it seems I'm getting luckier too. I feel like such an idiot!


On the plus side the centerlink was hitting the pan and it would have eventually made a mess. Now that it's out I get to mod that.



Thanks to everyone that posted!
 

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I've been watching this thread, and I have a new Melling oil pump for my new motor. I will take it apart before I finish assembling the motor.
 
Good news meathead. Just kidding ya. We all make mistakes. Glad to see you paid attention and found the problem.
 
This is embarrassing, but not nearly as embarrassing as getting stuck on the side of the road.
 
Good job. I'm thinking that you didn't miss it, it's that type of flat washer that helped it to loosen.
 
Glad you found it. Might not be a bad idea since you've got the pan down to pull a few bearing caps for an inspection just to make sure it didn't hurt the bearings. I use a little locktite on the pump bolts so they won't rattle loose.
 
Everyone's human. At least you caught it. I would second the pulling of the caps just to make sure there's no damage there. Now is the time if it did score a couple bearings.
 
I hate it when that happens! j/k man. Like Fishy, I use locktite on the oil pump bolts as well.

Sometimes we get distracted... The dog is chasing the neighbors cat, the phone rings, the wife sends you on an errand, etc. Stuff happens but you caught it, that's what counts.
 
The problem was the washers on the bolts. I use red locktight and lock washers on the bolts(no washers!) so this never happens again.
 
Glad to hear you found it. Good thing you were smart enough to stop running the engine when you did. You just saved yourself a ton of money. I would pull a couple of caps and if everything looks good button it back up.
 
Just thought I'd let you know, I pulled my Melling pump apart today and it was clean. I flushed it anyway and filled it with assembly lube before closing it up. I did loc-tight all the bolts. Maybe you saved more then one motor!
 
Thanks again everyone, last update...

Hot, Idle, Pressure - life is good!

I pulled #2 main and #4 rod, the bearings looked like they did when I put it together. Got 75 PSI with the drill, put it together and it was 80 PSI cold at about 1500.

I used no washers and red loctite.
 

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Robbie2734 said:
Just thought I'd let you know, I pulled my Melling pump apart today and it was clean. I flushed it anyway and filled it with assembly lube before closing it up. I did loc-tight all the bolts. Maybe you saved more then one motor!
Click to expand...

That's good stuff!
 
thats a damn good feeling isnt it !!!!! glad you didnt hurt anything ! it pays to shut it off when in doubt !
 
Been watching this post too. I had a similar problem on initial start up with my 273 but found a bad oil filter without a drain back valve. Good to know. I plan to take my engine out in the fall to get the car ready for paint. I want to pull the pan and double check everything just in case. Glad to hear your good news.
tmm
 
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