Today I started up my 454 getting ready to break in the cam when I noticed that the oil pressure slowly dropped from 20 to 0 after it warmed up and never came back up. I am using Rotella Diesel 14w30 and pan is full. I stopped the engine and first check my oil pressure gauge line that is tapped into the oil filter housing, no kinks everything looks good, then I removed the gauge and tested it. Gauge tested OK. Then I decided to remove the distributor and everything was intact. Next thing I did was remove a valve cover and see if the pushrods were getting any oil. Once I fired up the car there was no oil coming out of the pushrods, I promptly shut the motor off and I am now stumped. The oil pump is brand new and installed correct as it was working previously and randomly quit. Only thing I can think of is that the oil pickup may have fallen off but that just seems unlikely due to the fact I tack welded it on. Any suggestions? Thank you in advance.

Any suggestions?

i'd pull the distributor and put the priming tool back in there to sort it out first. make sure you've got oil pressure. maybe try another guage as well. that's a starting point before tearing back into it. if it's an electronic guage,, and you didn't start to hear it knocking after the oil pressure went to zero,, then maybe it's a faulty guage or sending unit. doesn't take long to start knocking with no oil pressure. i've even heard some engines knock pretty badly even getting re-primed after a basic oil change till they get pumped back up. andy

edit: oh yeah,,, welcome sean

if the pressure started out at 20#'s,, maybe it has the wrong bearings on the crank. like .010 bearings on a .020 crank. just thoughts.

if the pressure started out at 20#'s,, maybe it has the wrong bearings on the crank. like .010 bearings on a .020 crank. just thoughts.

That was my first thought also,, mis ordered, or mis-boxed bearings. Plastigauge a couple of rods and mains. Might tell you the whole story. I know,,,,, that means pulling the motor back out. But that's where your headed anyways. Just do it and get to the root of the trouble. Oil pressure dropping to nill is either bearings, or oil pump pickup tube. Either way the motor is coming out. I wouldn't do anything else till the motor is out, on a stand and being inspected before you do any more damage.

Another area to look is at the rear cam bearing as we have seen other shops not getting them in far enough towards the back of the cam tunnel exposing the groove.

2 other things I can think of:

Did you install the plug in the oil passage above the rear main cap?
Certain the pickup is at the right height above the pan sump floor?

Either way I'd put the oil pump primer on it and see what I get and make sure the guage isn't bad. Just to be sure I'd cut open the filter and check for signs of bearing damage too. You will have to pull the engine though if it ain't the guage at fault.

2 other things I can think of:

Did you install the plug in the oil passage above the rear main cap?
Certain the pickup is at the right height above the pan sump floor?

Either way I'd put the oil pump primer on it and see what I get and make sure the guage isn't bad. Just to be sure I'd cut open the filter and check for signs of bearing damage too. You will have to pull the engine though if it ain't the guage at fault.

BBC don't have that plug under the cap like the SBC

BBC don't have that plug under the cap like the SBC

Durp :screwup:

Perhaps the pickup is clogged?

Oil filter plugged with break in lube? 20 is low to start with.

If it only got up to 20 on intial start, I would think a clog in the circulation or the bearings are completely off like Marv and Rat said.

Although I have seen crap filters twice clog from Clevitte bearing lube.

Only thing I can think of is that the oil pickup may have fallen off but that just seems unlikely due to the fact I tack welded it on. Any suggestions? Thank you in advance.


Mine was welded on too, and it still fell off (long story), but you will still have oil psi. at least more than zero.

the thing that put mine down last time was not the welded pickup tube falling out of the pump,, but the screen came un-welded/unbrazed and broke loose from the pickup tube. it floated arround to a position where it wouldn't allow it to pick up enough oil. there went my mains. that was my last go round with this current block,, that's just now back together. andy

There is no right oil pressure at idle. All Chevy engine oil pressure specs are at a higher RPM. For example a stock small block is 35 psi at 1500 rpms.

It worries me too that you didn't have any oil up through the pushrods. I think you need to pull the distributor and put an oil pump primer on it. That way you should be able to see good oil pressure AND oil coming out the pushrods.

You are in my prayers with this one. There are many BAD things that can cause the problems that you are having and I'm praying it isn't ANY of them.

So today I used a priming tool and noticed that I could build roughly 15psi at full drill speed which is somewhere around 2000rpm. I relocated the oil pressure tap to the oil tap towards the timing cover instead of the oil filter housing and pressure went to 19psi but the heads are still not getting any oil. We only primed for about 20 mins. Everything seems to point towards a stuck open pressure relief valve. Any other suggestions before I pull the engine again. Also the oil seems heavily saturated with molylube, could this have any correlation with my problem?

sean,, are you using a straight priming shaft going down to the pump? just to check,, the proper type to use is the type that blocks off/completes the oil passage in the lower distributor hole to make the oil pressure build and send oil to the passenger side lifter oil galley. if not blocked off at the lower part,, it'll just pour a stream back into the oil pan @ the distributor hole passage. about a 1/2" stream and no pressure. an old distributor with the weight advance mechanism knocked off works well to connect the drill to up top where the advance mech. was. will only show pressure like you're saying with a straight shaft to the pump. you can take your current distributor shaft out of your dist. and insert the straight priming shaft in place of it without having to knock off any advance mech,, and use your current dist. housing.

just making sure you're using the proper device for priming that completes that oil passage in the lower dist. hole in the block. make sure to be sure of that first. hope it helps. andy.

i used the straight one at first and got 20 psi/ then i ripped apart an old dist. and conncted it to the drill it would only build 20-25psi. at full drill speed. and still nothing coming out the pushrods, would no oil be going to the pushrods becuase the lifters arent pumping

Assuming this isn't the 1st engine you assembled.....have you pulled the oil filter off yet? I've seen brand new engines' oil filters become clogged with lent from shop rags that were used during assembly. What kind of oil pump are you using? Does a BBC have an oil filter by-pass? (I've never built a BBC) Did you plug it or leave it open?

i just replaced thefilter and it still only has 20 psi on full drill speed

What brand of filter? Please tell me that it is a AC Delco or Purolator and not a Fram.

is it a hydraulic cam?

bleed the line and still can only build 20psi. Its a microguard filter.

Its a mechanical hydraulic cam.

ok,, now you know it's got to come apart somewhat. maybe a front oil galley plug (behind the timing chain/cam gear) isn't there/popped out/forgot/something....... and is leaking back internally into the oil pan. seen that show/make low pressure like your saying. if not that,, then probably wrong bearings for the crank size.

bbc uses the same spin on oil filter adapter that the small block uses.
good luck with it,,
andy