Very Low Oil Pressure in New Engine

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fzmax

fzmax

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The engine is a 71 318, RHS X-Heads, KB pistons, a Lunati cam, Hughes rockers, Melling HV oil pump, Kevoco Pan and pickup. The typical machine work was done and every clearance was checked when I assembled it. All the rods and mains were between .0015 and .002, but I don’t remember the side clearance or trust clearance off the top of my head and my notebook is MIA.

The oil pressure was about 60 PSI primed with an electric drill, and during the cam break-in it was almost 90 at 3K. Hot, the pressure was between 30 and 40 at idle.

After break-in (Lucas 30w break-in oil), the oil was changed (still Lucas 30) and I started to put some miles on it. I’ve laid into it a bit, but no full throttle and no crazy RPM. Everything has been peachy for about two weeks.

Two days ago I notice the oil pressure was low when idling at a red light (15 PSI), but came up as soon as I touched the throttle. The next day the pressure was even lower (between 5 and 10), still came up with RPM, but I stopped using the car. It had about 100 miles on it.

Today, I changed the oil to GTX 20w 50, but the idle pressure is still low and does not change with RPM. Priming it with the drill yields no more than 20 PSI. I removed the valve covers and no oil was making it to the rockers using the drill. I removed the rockers and nothing is coming out of the feedhole, though the gauge still makes it up to 20.

Since the engine is in an early A, pulling the pan is out. Before I do pull the engine to get to it I’m looking for something I may have missed. This is not my first engine, I’ve been playing with this stuff for 35 years but I am still stumped. Maybe I’m too close to see the obvious.

Any ideas?
 
sounds like the cam bearings ..or ur pick up on oil pump fell off..next time tac weld it so that dose t happen dont ask me why i know that..lol
 
what kind of pump are u running no need 20-50 oil 10-40 works fine
 
was it making noise? any metal in the pan? sounds like it may have been the oil pump going south. if it were me, i would put a new pump in it and see if you get good pressure again. if it doesnt , then i would yank it out and check all your clearances. then go from there.
 
Maybe a cam bearing spun a little in its bore, blocking off the hole that feeds the rockers??

Or, If I remember correctly there was something about the HV pumps in GuitarJones oil galley thread about the pressure plug being in there backwards causing some weird things to happen. I'm gonna read through it now.
 
I never had any luck with melling pumps.I'd check the barings and pull the pump apart and mybe strich the spring a little or find a mopar hv pump...........Artie
 
Okay, it was opposite with the plug in backwards,

"OK, I've recently been made aware of an issue with the Melling high volume oil pumps. It would appear that the cup plug for the pressure relief spring has been installed backwards in some pumps. The cup portion should face the spring and be pressed in just far enough to install the cotter pin. My pump came with the plug pressed in with the cup facing outward towards the cotter pin. mshred installed his back in the same way (as did I) and he ended up with over 150 psi of oil pressure just priming his engine. "
 
I trust you have ruled out the gauge/sending unit. Or better yet hooked up a good mechanical gauge. If so....You could cut open the oil filter and look real close. If it's real clean inside then It may be something simple like a bad oil pump. Or maybe the dreaded plug came loose & fell out. The one in the back of the block that leaks internally when it's forgotten during the build.
Sounds like pulling the pan is next on the list.
 
Thanks for all the replies.

Motopsycho said:
what kind of pump are u running no need 20-50 oil 10-40 works fine
Click to expand...

Melling High Volume. I tried 20-50 grasping at straws.

73AbodEE said:
was it making noise? any metal in the pan? sounds like it may have been the oil pump going south. if it were me, i would put a new pump in it and see if you get good pressure again. if it doesnt , then i would yank it out and check all your clearances. then go from there.
Click to expand...

No noise at all, sounded great. The rockers were tapping, but it is a solid cam. If I could get the pan out in the car it would be out already, but I am hoping to avoid that.

When I changed the oil I ran it through a coffee filter. It was clean enough that I could have put it back in the bottles. No metal under the valve covers at all.

64 SRT8 Dart said:
Maybe a cam bearing spun a little in its bore, blocking off the hole that feeds the rockers??

Or, If I remember correctly there was something about the HV pumps in GuitarJones oil galley thread about the pressure plug being in there backwards causing some weird things to happen. I'm gonna read through it now.
Click to expand...

Cam bearings lined up before it went together. But even if it spun I don't think that would cause the gauge to read low. Cam bearing clearance is the only thing I didn't check. I don't have a bore gauge that small and since I've never run into that problem before...

bignasty123 said:
sounds like the cam bearings ..or ur pick up on oil pump fell off..next time tac weld it so that dose t happen dont ask me why i know that..lol
Click to expand...

The pick up threads in so it would have had to break as it couldn't unwind. But since I still have some pressure I think that rules that out.

64 SRT8 Dart said:
Okay, it was opposite with the plug in backwards,

"OK, I've recently been made aware of an issue with the Melling high volume oil pumps. It would appear that the cup plug for the pressure relief spring has been installed backwards in some pumps. The cup portion should face the spring and be pressed in just far enough to install the cotter pin. My pump came with the plug pressed in with the cup facing outward towards the cotter pin. mshred installed his back in the same way (as did I) and he ended up with over 150 psi of oil pressure just priming his engine. "
Click to expand...

I think I'm good there too as if it were backwards the pressure would be too high.

OwdKasd said:
I trust you have ruled out the gauge/sending unit. Or better yet hooked up a good mechanical gauge. If so....You could cut open the oil filter and look real close. If it's real clean inside then It may be something simple like a bad oil pump. Or maybe the dreaded plug came loose & fell out. The one in the back of the block that leaks internally when it's forgotten during the build.
Sounds like pulling the pan is next on the list.
Click to expand...

We think alike. It has a mechanical gauge and I did try another. It reads a few PSI higher, but still way low.

There was nothing in the oil, but I'll cut apart the filter and see if there is anything in there.

The plug on the end of the lifter bore feed is (well it was) in place when I put the motor together. I guess I could pull the intake and see, but I can't imagine that coming loose.

Anything on the right angle filter adapter that could be hosed up? This engine didn't have one, but needed on to clear the headers.

Thanks again for all the replies. I'll keep update this when I find the problem.
 
solid lifters?

you did not use the dumb bell looking solid lifters?....
 
waggin said:
makes me wonder if the cam retainer plate has gotten loose?????
Click to expand...

I wonder if the cam could walk far enough to uncover the hole in the cam bearing? I guess it would leak enough pressure even if it moved just a little.

70aarcuda said:
solid lifters?

you did not use the dumb bell looking solid lifters?....
Click to expand...

Nope. I've only seen those once, odd things and I assume would require the same oiling mods as a roller.
 
So with the magic of iPhone I was able to get its camera in the distributor hole and snap a few pictures. In one you can see the plug is still in place, but it also appears that a piece of the block may have gone missing.

I don't have another block handy to go look at, but I am missing the final bridge between the two sides? If so, where the hell is it?
 

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maybe its in your pickup screen. how bizarre, i dont have an intake off any of my motors for comparison, but im pretty sure something is supposed to be there ?...great pics by the way..
 
I just went out to the garage and checked a 1970 and a 1982 318 block and they look like yours, there is no bridge in the rear.
 
any of these help?
 

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73AbodEE said:
maybe its in your pickup screen. how bizarre, i dont have an intake off any of my motors for comparison, but im pretty sure something is supposed to be there ?...great pics by the way..
Click to expand...

It's possible, but the pickup was new (as was the pump and pan) and I did clean it anyway.

Damn phone takes better pictures than any camera I've owned. If only it could diagnose oiling issues...

SGBARRACUDA said:
I just went out to the garage and checked a 1970 and a 1982 318 block and they look like yours, there is no bridge in the rear.
Click to expand...

Thanks, I just found this pic from the assembly. Phew!
 

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lol, what a relief huh ? funny , i just had my intake off the other day and i never noticed that there is no bridge there. thats one less worry...
 
You have to have the engine turned to exactly the right spot for oil to come out of the holes that feed the rocker arms and it's a different spot for each side. It doesn't come out continuously so ignore that as a problem. Did you cut open the oil filter for an inspection yet? That'll tell you if it's a major problem or not. If there's metal crap in it you know something catastrophic happened. If not it's possible the oil pump relief valve stuck open. Your mention that the oil pressure reached nearly 90 psi during break-in doesn't sound right because the relief valve should not have ever let that happen. Did you disassemble the oil pump for a cleaning and inspection before installing it? You should always do that cause you wouldn't believe the lousy quality control in some factories. Do it as fast as possible so they can sell another seems to be the motto of today.
 
I have a rule - If oil pressure changes drastically after breaking it in, pull it and inspect everything. You will catch problems in most cases before they really get expensive and all it costs is time, gaskets, and oil/filter. The rods - if they are .0015" they were tight. If the side clearance was not checked they may have been tight. If the thrust clearance has changed at all, tear the lower end apart very carfeully and inpsect.
Some hints:
Always always always always take the new oil pumps apart, pull the cotter pin, and remove the relief valve so you can clean and blow out the passages.
Always always always keep the notebook where you can get it quickly.
Always always make sure the bores and oil galleys are spotless clean when you're washing the block before final assembly.
Always verify by backlighting and looking down each passage that the cam bearings are positioned to allow for full oil to the top end.
Always triple check the oil galley plugs during assembly - I place a check mark in my assembly notes to verify I did it - Once after the cam breaings are in, once after the crank/pistons are in, and once before bolting on the tin and intake. You might be surprised how often you find one missing somewhere just before the intake goes on...lol
 
fishy68 said:
You have to have the engine turned to exactly the right spot for oil to come out of the holes that feed the rocker arms and it's a different spot for each side. It doesn't come out continuously so ignore that as a problem. Did you cut open the oil filter for an inspection yet? That'll tell you if it's a major problem or not. If there's metal crap in it you know something catastrophic happened. If not it's possible the oil pump relief valve stuck open. Your mention that the oil pressure reached nearly 90 psi during break-in doesn't sound right because the relief valve should not have ever let that happen. Did you disassemble the oil pump for a cleaning and inspection before installing it? You should always do that cause you wouldn't believe the lousy quality control in some factories. Do it as fast as possible so they can sell another seems to be the motto of today.
Click to expand...

Good point on the upper end oiling. I was assuming some would get past the cam bearing, but it's not grooved so I guess not.

Took apart the filter this morning. No chunks of bearing material with a readable part number. There was a little metal in the canister, but nothing I would get excited about with a fresh engine.

I had a picture of the gauge as it was quite high, but I can't find it now. Got to go to work...

moper said:
Some hints:
Always always always always take the new oil pumps apart, pull the cotter pin, and remove the relief valve so you can clean and blow out the passages.
Always always always keep the notebook where you can get it quickly.
Always always make sure the bores and oil galleys are spotless clean when you're washing the block before final assembly.
Always verify by backlighting and looking down each passage that the cam bearings are positioned to allow for full oil to the top end.
Always triple check the oil galley plugs during assembly - I place a check mark in my assembly notes to verify I did it - Once after the cam breaings are in, once after the crank/pistons are in, and once before bolting on the tin and intake. You might be surprised how often you find one missing somewhere just before the intake goes on...lol
Click to expand...

Check all that. Well except for my notebook.
 

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