Chev 216 Oil Pressure
 

Hi, My 216 engine has been completely reconditioned, assembled and painted. I have just fitted the external oil piping to the bypass oil filter etc. Thought it would be a good time to check for leaks and also ensuring there was oil to the rockers. I made up a drive to operate the oil pump with an electric drill down through the distributor mount in the block. I am alarmed that at 900 RPM input to the pump there is 40 PSI on the test gauge (used two gauges same reading). Increasing the RPM to 1500 I get 42 PSI. and I assume the relief valve has opened. Max RPM of a 216 is 3200 RPM giving 1600 RPM at the pump. Normal maximum engine RPM would be about 2000 RPM again giving pump RPM at 1000
Now the max. setting of the relief valve is 15 PSI at 2000 RPM according to the manuals.
I have a new Melling pump fitted. Is it possible that this pump could be set up for a later series engine with higher oil pressure requirements?
Of course my other thoughts are that the relief valve is working but stuck up or restricted some how. As any investigation of the relief valve means dropping the sump - new gaskets etc, I thought I would run this past you folks for your opinions.

I can't speak with experience on the Chev oil system in a dipper engine, but my thoughts on seeing that sort of pressure in an engine that has been recently "reconditioned, assembled and painted" would give rise to suspicions that the block was not properly cleaned (ie some sludge or crud remaining in an oil gallery), or not properly assembled (ie misalignment of a feed hole in a bearing, wrong gasket covering a port).

But before you get too worried, can you get a second person to rotate the engine by hand, or even crank the engine on the starter while you "drill" the pump and observe the gauge. It could just be a tight tolerance or something needing to bed in to open up a clearance somewhere to improve flow to relieve pressure.

Thanks Tony. I can assure you the block and oil galleries are clean. The relief valve is on the pump itself and therefore if it was working correctly the 40 PSI could not be generated.

Ok. Well, I think you've answered your own question. The problem must lie in the relief valve.

So the question then becomes "Is 42psi going to be a problem, can I live with that"?

Ken

30-40 PSI is not unusual on start up for a 216 with a cold engine particularly a tight reconditioned one. It will drift back steadily as the engine warms to the desired 12-14 PSI at a sedate cruise speed (they seem to run just fine on as little as 5PSI at cruise though a bit disconcerting for the driver).

What oil are you using? This makes quite a difference. Most people have marched on from the old straight 30 and I believe 10W30 or 20W40 is all the go now.

Some good mechanics might chime in with more ideas.

Lang

I should have mentioned that I am using 15-40 running in oil. The thought of extra pressure on the rear crankcase oil seal bothers me. Note to Tony's answer above.

Remember oil pump is turn by camshaft
 

Hi Ken

Are you taking into account the camshaft turns at a lower speed than crankshaft, if I remember correctly. Don't have manual handy to confirm the difference.

Now as to oil pressure on 216 after rebuild I'll check my notes but the 40 psi sounds correct for drill prelube. Cranking the engine while using the drill is a good idea to be sure the engine is fully lubricated.

Did you use the heavy assembly lube as you put the engine together? If so that will increase oil pressure until it is washed out by the engine oil.

The splash/spray lubrication is a very high volume pump and the nozzles on the crank sprays will take care of most over pressure situations like a stuck pressure relief valve. My concern would be is the spray branch is blocked. If I remember correctly the spray can be confirmed by removing the fuel pump and looking in while priming with drill.

Please keep us posted on your progress.

Cheers Phil

Hi Phil, the speed of the camshaft and distributor is half the crankshaft speed and I allowed for this. I cannot understand that the relief valve can't limit the pressure to 15 PSI for whatever reason. I can only assume that for some reason the tightness of the bearings etc is causing some kind of pressure behind the valve ( I have seen this in other types of motors). I will push on for the time being until I have rebuilt the starter motor & then turn over the motor at the same time as spinning the pump. I will check the dipper sprays through the fuel pump mount. Will keep you all posted.

I don't fully understand what you are asking. How does the oil get past the camshaft? Often there is a cut out in the cam journal (or a hole through it) and this limits the flow to the valve gear. If the cam is in a certain position there is full flow, and in another position, no flow. The overall effect is a lower psi to the rocker gear (the rotation of the cam being a regulating device)

I am not sure what model Chev motor or oiling system you are referring to. I am referring to the output PSI of the oil pump and this PSI is determined by the relief valve which is integral to it and is irrelevant to anything further down the oil lines i.e. nothing can happen further down the lines to increase the pressure. It would seem that I either have a faulty relief valve OR as has been noted in this thread and is discussed in other Chev club pages etc. that a 216 motor with a new oil pump, ground crankshaft and cam shaft and all new bearings (all slippers, so the clearances should be correct) will give a PSI of 30 to 40 with a drill test driving the pump and even in an on road test. This decreases as the motor warms and "runs in". It appears to be understood that the "tightness" of the motor i.e. causing restriction to oil flow through the bearings, overcomes the flow capacity of the relief valve and it cannot bypass the volume of oil so that the PSI rises from 15 to 30+. Adding to this the crankshaft is not rotating in the drill test and is probably contributing to the lack of oil flow.
I will leave it now until I can fire up the motor, I should mention that the bypass filter filled nicely and there is flow to the rockers. The oil jets work well.