Low oil pressure at the tappets.

[jimavati]

Hi all, I have just started up my 138 grey for the first time since the rebuild. The tappets where very noisy but so happy it started first time.I removed the cover to readjust the tappets and found that i only had oil on 3 tappets. I have 40psi pressure on my oil gauge but the oil pressure coming out of the oil pipe at the head is very little. Is this normal or do i have a problem somewhere ?? Is there some way of checking the pressue at the head. Any advice would be greatly appreciated. Cheers Jim.

[Jolls]

Hi Jim,

Firtstly welcome to the forum.

On a Holden grey motor, it’s quite possible to see around 40 psi on the gauge yet have little or no visible oil at the rocker gear. Pressure and flow are related but not the same thing, and the grey motor oiling system has a few well-known choke points. The other thing to be aware of is excessive bearing clearance. This sounds odd; but, large bearing clearances can lead to oil being dumped back into the sump instead of being forced up the head (course of least resistance). Both of these problerms will result in the gauge seeing pressure but no volume to the top end. The pressure reading does not reflect flow â€" just how much pressure there is as it exits on the feed side of the oil pump. 

As you are aware the oil gets to the rockers from the oil pump up through the head via the oil feed line to the rocker shaft feeder, then along the rocker shaft and out through small drillings in each rocker. Anything that restricts that flow path can show good pressure at the gauge but poor flow at the rocker gear, or there is a less restrictive path for the oil to take (excessive bearing clearance). It is a matter of checking pressure at all of the points along the way to determine the cause.

The most likely cause is a blocked or restricted oil feed between the pump and the head. This could be sludge, gasket debris, silicone, or swarf and result in a partially blocked feed line → pressure still reads OK, but flow volume is tiny
I would start by removing the feed line and blowing it clear with compressed air. Once you are satisfied that it is clear refit the oil line but do not fit it to the rocker gear.

Then set the motor up to pass oil from the gallery to the top-end. There is a groove in the second-from-rear camshaft journal, but it doesn't go all the way around the journal.  You need to set the engine at TDC on the compression stroke for number 5 cylinder. Remove the dizzy then use a shaft (old dizzy shaft works best) to drive the oil pump with a drill. You should see the oil come up to the rocker gear in only a few seconds. If you don’t, the problem is before the oil line and you will probably need to remove the sump and inspect the oil pump, the galleries and bearing clearances.

If the oil flows, reconnect the line to the rocker gear and spin up the oil pump and look for even flow to the rockers â€" flow to one side or the other probably indicates a blockage in the one of the rocker tubes. Oil not getting to isolated rockers probably indicates a blocked rocker. Either way if the oil is up to the head in good quantity and is not passing to the rocker gear it is probably time to strip it all down and give it a thorough clean. While you are there check to see if there has been a modification of the rocker connecting nut/union to "improve" flow to therockers by installing a self-tapper or a split pin. If the oil pump is healthy this mod should not be required.

“Normal” rocker oiling should look like:
•   Not a flood.
•   At idle: oil beads forming and slowly running along shaft.
•   At fast idle: steady weeping from each rocker.
•   Oil should reach the far end rockers, not just the first two.

Another consideration (probably not likely) is very thick or very old/contaminated oil. This simply doesn’t flow when it is cold.

I trust this helps

Cheers n Beers
Jolls

[my8thholden]

Jolls has covered it , your rocker shaft is two pieces , one for the rear cylinders , one for the front , have to be right way most important ..brass union between the two where the oil feed line goes in has hole in it , if flow is excessive there block the hole to ensure oil gets to where it should ...Vern

[jimavati]

Hi Jolls and Vern,
Thankyou for all the information. What i did not say on my previous post and i should have is that i have rebuild the motor from scratch. Eveything was cleaned and refurbished.All lines where throughly cleaned. All new bearings  and journals where fitted by the machine shop and i doubled checked the journals and they seemed to be in the correct position. I did the screw driver thing on the oil pump before i fitted the motor into the car and all seemed to work ok. Joll i will definitively do as you have suggested. I am using 20W-60 oil. Is that to thin or is it ok ?? And secondly the brass connecter between the two rocker shafts has a big hole on one side and a small hole on the other, does it matter which way it goes?? Thank you guys for the help i do really appreciate it. I was so excited to get the engine running and now i am back at the drawing board. I will get to drive my FC one day. So Close. Jim.

[jimavati]

Hi Jolls and Vern, I did all as you guys suggested and no luck with oil getting to the head. I set up an old block and camshaft to see how it works and now have a firm understanding off the system. Unfortunatley as i said spinning the oil pump with the drill and no oil at all coming out off the union that goes to the head, so I thought either a faulty pump or as the journals are new and have been fitted by the engineering shop it has been blocked or incorrectly fitted. To test the pump i removed the oil gauge and spun the pump and have plenty of oil coming out so the pump is good. Next step out comes the engine and inspect the journal.
So disappointed. If you guys have any suggestions before i start to take out the engine i would be very very gratefull. Cheers Jim.

[my8thholden]

did you have the cam tunnel bearings replaced ?

[jimavati]

Yes the cam tunnel bearings where replaced as well. Jim

[ardiesse]

Here's something to try before you take the engine out -

Take the rocker cover and sideplate off.  Remove the rocker assembly oil feed pipe and the brass fitting in the block.  Set the engine to firing instant on number 5 (I think that's the right position for the groove in the camshaft journal) and drive the oil pump.  If the camshaft bearing has been installed correctly, oil should start to run out almost immediately.

If no oil, then get a short length of coathanger wire with one end rounded off and put it down into the oil feed hole.  Have somebody else turn the engine over very slowly while you put a finger on the end of the wire.  You should feel the wire rise and fall as the end of the wire drops into the groove in the journal.  If you can't feel anything move under the wire as the engine is turned over, it's a pretty sure sign that the camshaft bearing's been installed wrong.

If there's no oil flow, but yet the hole at the top of the camshaft bearing is clear, that may mean that the passage leading to the oil galley is blocked (camshaft bearing installed so the second hole is on the outer side of the tunnel, not lined up with the the passage leading to the main oil gallery).

Both of these conditions will mean an engine-out, camshaft out, sump off, remove and replace rear intermediate camshaft bearing.

Rob

(I have a newly reconditioned grey motor with the same problem.  I'll need to do this same diagnosis myself . . .)

[my8thholden]

How can engine recon shops get that wrong ?

[Jolls]

You have to wonder how they could get this wrong - but I guess a lack of experience with grey motors and the intracacies of the oil system and its flow has caught more than one out.

That was part of the reason I built the test bed so I can ensure all is good before it goes in. I have tested it (to the best of my knowledge as I have progressed the build in order to try and catch these sorts of problems.