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Discussion Starter #1
Freshly rebui;t 351W. This is my second oil pump. I cannot get oil up to my rocker arms and such. There has to be a pressure problem. My guage reads 5PSI at idle and about 20-25 at 2,000 RPM, but still not getting oil to my rocker arms. I have the oil pan off. The oil pump is stock. I rebuilt this engine. Did I do something wrong? The engine runs fine but the lack of oil pressure worries me. I have ensured that the pick-up is clear of any blockage. The oil filter is getting oil past that I am not sure where the oil goes. What is going on here! HELP!!!!
 

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Without going into a lot of questions,I'm going to assume that bearings and everything else are ok,since it was just rebuilt.Pull the timing cover and check the oil galley plugs behind the cam gear.I remember a few situations when the machine shop forgot to put the plugs in.There are three cup plugs,two further back in the cavity behind the gear and one that the cam retainer plate holds in place.If they are missing make sure you stake them into place with a punch to make certain they don't pop out.If these plugs aren't missing,pull the intake and check the cup plug at the rear of the block,where the end seal goes.Missing plugs in any of these locations will cause the symptoms you describe,but will not leak oil externally.Let us know what you find....
 

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Is it possible that one of the front gallery plugs is leaking or missing...

Do you have hydraulic lifters, and, if so, are you getting lifter clatter?

You could try removing the distributor and having a friend pressuize the oiling system with a drill motor driving the oil pump (CCW rotation) while you look for obvious areas of leakage. Oil supply can be from a container of clean oil placed in contact with the pickup. It'll be messy (use a drain tray to catch the falling oil) but it might give you some clues.

Do you note lack of oil to both banks of rocker arms...?? There's a transfer passage at the back of the block with terminates in a freeze plug at the top...

Another possibility is that you have a .010 under crank but put in standard bearings, which would give excessive crank oil clearance...easy to check..

Try a few things and get back to us with your observations...
 

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Discussion Starter #4
Yes, I am getting lifter clatter.
 

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The clatter means the lifters are likely getting inadequate pressure to pump up properly.....the stock oiling system IME is biased towards the lifter galleries (hence my many mods to the system in the race car)...

Check the things mentioned in my first post and get back to us with what you find.....with a pressure test, excessive oil coming from the front of the engine will indicate where to look next, wheras high flow from all areas may mean there is a combination of problems...

I work on hydraulics for a living and can tell you with assurance that the oil doesn't lie..*G*

Lastly, there is a remote possibilty of a failed oil pump or pressure relief...only a dynamic test or close inspection by someone with experience with oil pumps will yield answers to that quandry. I've been using stock or HV stock pumps for years and have never had one fail.. ¿
 

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Discussion Starter #6
What exectly am I looking for when I do this oil test? Where should the oil be coming from?
 

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Discussion Starter #7
I know that they are all there. I had the timing cover and intake off last week.
All the bearing are new and are proper to the rebuild.
Any other suggestions???
 

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If you have checked and are sure about the things mentioned above then you may have a bad oil pump. If you feel that it is ok then its time to plasti-gauge the bearings. How about the cam bearings? Are they installed properly? Are your rockers new? I have seen worn rockers not oil properly but dont believe this is the case due to your lifter noise. Like said in previous posts, the oiling system is just a bunch of passages and if there is a leak (bearings, plugs, etc) you will have low pressure.
 

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So you have spun the oil pump (CCW) from the drive shaft where the distributer goes? Does it get resistance? It should get very hard to turn with a speed wrench. You should be able to see the oil pump out of the lifters at the pushrods if everything is OK. When I pre-oil an engine I spin the oil pump until I get oil in each rocker fulcrum. At the same time you can check that there is no oil bypassing back from a missing plug. Speaking of bypassing, it could be possible for your relief valve to be stuck open so that the oil pump is just pumping oil back to the crankcase - not likely though, since you have had two oil pumps.
 

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If the gallery plugs are leaking or missing, you'll see a lot of oil coming from the front, timing chain area, of the engine, much more so than from the main and rod clearances...

You can always visually inspect all areas, but this will mean removing the timing cover....and a couple of main and rod caps.

If you're darn sure the oil pump is up to snuff, there's got to be a leak in the oil system somewhere.

Maybe you'll get some further suggestions of things I might have missed...
 

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Other than mismatched bearing/journal sizes,as mentioned earlier,there has to be a leak preventing the oil flow from reaching sufficient pressure.Irregardless of whether the plugs were in place,I would have to say one popped out and/or is leaking.If the pan is still off,use the test procedures Pat mentioned and let us know what happens...
 

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While this will not explain the low oil pressure, if you were given lifters for a big block, you will not get any oil to the rockers. The lifters are the same bore, but slightly shorter and no hole in the pushrod cup.

Some Plasti-guage may help to check clearances.
 

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Discussion Starter #13
I took the main caps off and checked the bearings they all look ok. I will try the oil pump thing tonight. Where should I be expecting oil to come from and vise versa.
Everything is new in this engine. I didn't reuse anything except for the rods. .10 over Forged pistons, crank is .10 and .20 over, rebuilt heads with 1.90 and 1.63 valves, mild cam. It drove great, has some power, but I am getting really pissed off with this oiling problem. If I can't figure it out by this weekend I am pulling the engine and taking it to a machine shop (my wife isn't going to like that).
I will report back after I do the test.

Thanks guys!!
 

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I took the main caps off and checked the bearings they all look ok

I'm glad to hear they looked OK but what did they measure? You said the crank went 10/20 but what are the bearings? They should be stamped on the back or you can measure the clearance with plastiguage.
I measure all these clearances (with inside and outside micrometers) as part of the blueprintng process when I build an engine. Parts makers can stamp bearings wrong and crank grinders can grind cranks wrong....we're all human. It's just that once you've put the engine together (if you did the work), then it's your baby and they take no responsibility normally...

If you had a shop build the engine, definitely take it back if you find something amiss...

Good luck and keep us posted!
 

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In addition to all of the prior posts, have you checked the accuracy of your oil pressure guage? If the guage isn't reading accurately, your engine could be just fine and the guage is the problem. Good luck.
 

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Discussion Starter #16
It is a brand new guage and like I said I have taken off the valve covers while the engine was running and there is no oil.
It is in a 67 GT 390. I just got it from a lady and I had a 351W lying around. It doesn't have any of its orginal driveline, 4 speed and 9" are gone, but it has everything else and looks hlfway decent. I hope I can get it on the road soon!
 

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Discussion Starter #17
OK I think this is getting a little to complicated for me. I am just going to pull the engine and have a professional find out what is going on.

Thanks!
I will tell you what the machinist says when I find out.

Mike
 

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Discussion Starter #18
OK... I pulled the engine. I was told by a mechanic that there is a top and a bottom for the main bearings. I took it a part and found that they are not different. They are what the machinist who did the work on the engine told me, 10/20. I also found out that the passenger side rocker arms were getting oil. I should have done the pressure test but.... The galley plugs behind the cam gear are installed and are not leaking.
I haven't taken off the intake but I think I will tomorrow. What should I do? Is it best for me to take it to a machinist? or what?
Please help!!!!
 

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On semi-grooved mains, the grooved shell with the slit goes in the block...

The fact that the bearings are marked is encouraging, but it is not final. Only a meaurement of the clearance, either with plastiguage or with precision instruments, will tell you what your clearance is. Bearings can be made wrong and cranks can be ground wrong, although both occurances are not common.

Glad to hear the plugs are in place...and, if the passenger rockers are getting oil, that means there is a clear passageway across the transfer at the back of the block, although we don't as yet know if it is restricted...

I wish I had a bare block in front of me...I could walk you through the oiling system step by step...

Have we ruled out a faulty oil pump (pressure relief most likely) as a culprit? Was a gasket installed between the oil pump and the block? Are you confident that the oil pressure guage is correct?

I know I'm beating the obvious to death but I've done a fair amount of overlooking in that department on occasion here..*G*

Anything else to note from your observations? I'd love to see a picture of the bearing surfaces...
 

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Discussion Starter #20
both sides have the grove and are identical.
I will try to send pictures tomorrow.
Could have been 2 faulty pumps in a row? the first did the same thing. Yes I installed the gasket.
I have no idea how to measure the crank and stuff.
What else can I do?
 
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