Help - 216 no oil pressure!
 

Just started my C15A up after doing the valves and I'm not getting any oil pressure. This is the first valve adjustment after rebuild (pump was good and all bearings/shafts measured well in tolerances). It had 25-30psi cold at idle and 5-10 hot when idling.

I pulled the valve gear off to retighten the head and it all went back on fine. After starting it and running for 15 seconds twice, still no pressure. I pulled the valve cover off to check if I'd put the rocker oil delivery pipe on properly and that's fine, but oviously no oil being delivered up there. I started it for a couple more seconds with that pipe off and nothing's coming out.

Could it be when I took the rocker gear off all oil drained back and it needs to be pumped back up and this takes time? Would've thought two bursts of running for 15 seconds would do this though. How long can I run safely with no pressure in a 216?

Just curious, did you at any time try the trick of chucking a flat screwdriver bit in a drill, removing the distributor and driving the oil pump with the drill to spread oil around? Also, is it possible that the distributor isn't seated quite deep enough in the block for the tang on the distributor shaft to engage the oil pump shaft? Since the engine ran, the distributor is engaging the camshaft but this doesn't guarantee that it is also driving the oil pump. Oil pressure should be visible when turning the motor over with the starter (particularly if the system has been primed at some time with a drill).
I would be reluctant to run any more without knowing you have oil pressure but is the gauge "known good". You could check with air if you turn the regulator on the compressor down, start at near zero and work up (looking more for a progression of pressure than absolute values).

The screwdriver on the drill is the answer. I wouldn't run the engine again until you verify oil pressure. When you turn the pump, you will feel the resistance when it starts pumping. With the valve cover off, you will see oil coming out the rockers and the drain tube.

It is possible that the relief valve in the pump is stuck open, or that the relief valve spring has broken. Not common on a chevy, but I saw it many times on the perkins diesels.

Thanks guys. When I first reassembled it I did the screw driver trick. It actually took quite a long time to get oil pressure like that but it did in the end. So could this be it - opening that pipe opened the system and it needs repriming? I actually just tried to remove the dizzy but seemed like something was holding the shaft in - had about 2mm of up/down then stops (yes I removed the clamp bolt!), is there a trick? I was in a rush so didn't keep pursuing it, should read the manual really...

The thing is I've run it quite a bit, probably about 2-3 hours overall. Oil pressure has always been good so the shaft is obiously mating well and the gauge is good (it's a manual one out of a dodge d5n).

So drill/screwdriver it is.

Harry, As Grant has stated, about the dizzy.
When you drop in the dizzy, the gear on the bottom meshes with the cam shaft, but the dog teeth on the bottom don't always line up with the pump slot. You have to turn the pump with a screw driver to line up with the dog, which doesn't happen easily, because the gear on the dizzy turns going in. It might take a few goes to get it in.
You shouldn't need a drill to turn the pump as it will only take a couple of turns of a suitable screwdriver to feel the resistance of the oil pressure(you had pressure before?)when you turn the pump in the correct direction.
Your oil pressure to the valve gear is only low pressure, and low volume. It is fed from a cam bearing and regulated by machined cuts in the camshaft, so this is not the reason for the sudden loss of all your oil pressure.
Good luck!

Harry,

You have a seriously good 216 oil pressure with 5-10psi at hot idle. With 14 psi as the book running pressure and "indicating" as the book idle pressure your jigger looks in top condition. Most people would not stress if the needle dropped to zero on hot idle.

Lang

I doubt very much that opening the tube to the top would lose the prime. Not unless it was over a very long time.

The distributor should come straight up. You may be on to something there. Perhaps there is some problem in the belly of the beast.

The reason why I suggested the drill over simply turning the screwdriver is so that you can see the oil run up to the top end. If the system is dumping the oil somewhere else it is better to figure that out with the drill than with the engine running.

had is the word :( Yeah i did some research and found that, makes it all the more frustrating now

I remember it being a pain to get in, took me several attempts. Yes I had oil pressure before, but as I now don't I'm guessing it will take more than a few... So with the rocker oil line disconnected it should still be reaching good pressure?

That's not what I wanted to hear! Even if something more serious is up (what else down there could be stopping the dizzy coming up?), surely it's too much of a coincidence to drive in with great oil pressure, remove and replace the rocker gear (with nothing else touched) then have no oil pressure?

Either way, so my first move is to get the pump going with a drill. Then if no pressure comes up, what then? Can I pull that little pressed plate off above where the filter lines go - will anything in there tell me anything?

Harry, yes it should still generate oil pressure with the rocker gear line dis connected. Depending on how the cam is sitting oil may or may or may not come up through the pipe, when you turn the pump. You will feel the resistance and hear the noises when pressure comes up.
It may be that the distributor wasn't right home from the start, and it has only just started not driving the pump.

mid repair update - pulled the dizzy off and hit the oil pump with a drill. 5-10 secs (18v cordless on hi) and good oil pressure came up. Put the dizzy back in and hit the starter and it's straight up to 5psi while cranking.

Now I'm having a fight getting it retimed... Was in a bit of a stress pulling the dizzy out I must've knocked the shaft and timing's off. Got it to the timing mark on the flywheel and thought I had the dizzy in right and it runs like shit (ran sweet as this morning with no oil pressure) - rich, backfiring etc. obviously timing is way off. Rotate the dizzy with the bottom bolt with the graduations and rotated and it improves but still crap. I thought taking it out and rotating one tooth puts it way too far out. I could loosen the main clamp and rotate but I shouldn't have to if it was fine before right?

Following the method in the book (test light between ground and primary terminal - is this where the coil comes in? So it's across the points?) and I have to rotate it way way off to get it to just light at the timing mark... Is this method right? Maybe I should try pulling it out and trying another tooth again

Hmmm
 

Sounds like the old "180 degrees out trick" to me Harry.

Worth a try anyway...

you mean I've got it at no 6 instead of no 1? Got the valve cover off no 1 is definitely at compression. I've almost got it - can get the dizzy to mesh in the right spot but then it won't go that extra 3mm or so for the oil pump. It'll only engage the oil pump on the cam teeth one before and after this - whenever I get the oil pump to mesh the timing is ALWAYS wrong... I can get it right by undoing the clamp and rotating the body I guess but then I shouldn't need to seeing as it was correct.

Gee I wish I'd never touched the bloody rocker gear. But there's no way to get to the central no1 head bolt otherwise is there?

OK she's all good now. I just loosened the clamp and rotated the body 'till the ohmeter just stopped beeping. Started right up and running sweet with great oil pressure - sometimes you really take those things for granted...

It just pisses me off I couldn't get the dizzy body back into its original position. I just put it down to a female nature

Oil pressure diagnostic seminar
 

Hi Harry

Thanks for hosting one of the best diagnostic seminars I read. With loss of oil pressure as topic a very clear discussion of causes took place ending with the solution.

You got to love MLU in what looks like 10 hours elapse time a problem was posted and the correct solution was found.

Cheers Phil

Thanks Phil,
I do like to add an ending to these sort of posts, and I wish everyone would. I've learned two things from this - don't open the oil system unless you have to (and remove the dizzy to reprime if you do), and when reinstalling the dizzy don't try and get it in the same tooth spot, just adjust with the clamp.
I agree MLU has some very knowledgable and useful people on it

Harry, there is a bit of a trick to it. Having set the engine on its timing marks (noting which cylinder is firing -No.1 or number 6)you can then remove the dizzy.
You have to picture where the tooth will end up, and turn the gear back enough so that when the distributor is in, the points are just about to open for the correct cylinder. Wiggling the rotor back and forward as the dizzy goes in can help to align the oil pump drive that you have hopefully pre aligned.
I have done a Chev, but it is much the same for the G.M based inline six engines. (Bedford, Holden etc)
If you are a tooth out, the cylinder fires but the rotor arm is effectively not lined up with the terminal inside the cap.

Yeah worked out where the arm should point, and could get it in like that but not also when meshing with the oil pump. I could get it to mesh with the oil pump one tooth before and one tooth after the correct position. No matter where I put the oil pump slot (believe me, I tried them all - an hour of dizzy in and out while moving the oil pump a fraction at a time).