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100/4 Engine

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OZ_BN1

OZ_BN1

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My engine has had a rebuild and I'm getting ready for it's first start.
Cranking it over with the plugs out but not producing any oil pressure on the gauge and no sign of oil at the flexible oil pipe to the gauge.

Should I be getting oil pressure building up in the gauge line?
I have cranked it over quite a few times, getting worried!!

Cheers Graham
 
Enough oil in sump, oil pickup sucking air, oil filter still filling, bypass at pump is set right, checked oil pipe at rockers to see if oil is getting there?
Has oil level in sump dropped during trials
 
Before starting a newly rebuilt engine oil needs to be installed with pressure. I built my own pressureized tank by using a discarded propane tank. The idea is to have a supply of oil in a tank, then with an air compressor attached to the tank and about 30psi reading on the pressure gauge release the valve leading to the engine and allow the oil to be forced in. I use the oil outlet fitting where the hose to the oil pressure gauge goes in.

Lacking such a system you can remove the distributor and hook up a drill to the oil pump gear at the bottom where the distributor goes in and turn on the drill to build up pressure. Once you've built up pressure replace the distributor.

Good luck and let us know how it turns out.
 
Well....having rebuilt 3 engines, one 3000 and two corvettes. I have had no issues with disconnecting the coil and running the starter for a few seconds and getting oil pressure to the gauge.

The cylinders and bearing were well lubricated during rebuilding . On all three occasions pressure built up nicely which then allowed me to connect the coil and fire em up.

This is how I was instructed when I built the first one, the 3000. Will be interesting to get other opinions.

Pete
 
I pull the plugs, disconnect the fuel pump and crank it over for a couple of minutes until the pressure shows on the gauge.
 
"Lacking such a system you can remove the distributor and hook up a drill to the oil pump gear at the bottom where the distributor goes in and turn on the drill to build up pressure. Once you've built up pressure replace the distributor."

Sorry Johnny but you can't do that on these motors. The oil pump is not directly below the dizzy and is driven by a different gear on the cam.

Johnny's method of pressurizing is the best way IMO. You may want to ask around in your area, but in my town there is a parts store/machine shop that has converted a couple of old fire extiguishers for this purpose and loans them to anyone for initial start-up.

If you can't pre-oil as described above, at least crank it over without plugs until you have pressure and a dribble from the rockers. Running these motors without oil pressure for even a few seconds will risk damaging bearings.

I run an accusump and pre-oiling is one of the many benefits.

good luck,
Dave
 
The 4 cylinder engine with plugs out and fuel pump deactivated will usually take about 30 to 45 seconds spinning on the stock starter before oil pressure will come up on the gauge.
No priming of anything is necesssary, just wait for it.

Rich
 
Graham, are you running a modern spin-on filter? The anti-drainback valve rubber flap can provide enough resistance to flow that the pump can't push out the air and pick up oil. If so, unscrew the filter a few turns and crank er over until oil spews out all over your newly painted engine.

One very stubborn Hino truck engine did this to me and I ended up pressurising the crankcase with the air compressor to about 5psi and it was enough to push the oil up into the pump and it was away. This trick only works with the filter removed obviously.

Packing the oil pump gears with Vaseline (not grease) during reassembly will prevent the no oil pressure problem.

Andy.
 
I have oil pressure finally, but probably pushed the limits trying. I do have the modern spin on filter and it was not until I removed it and back filled the line to the pump a few times that it finally started to pump oil. I had originally filled the filter with as much oil as I could.

Andy it would appear that the modern filter was the cause.

Feeling better and will go for a start tomorrow.

Thanks
Graham
 
Graham, These guys gave you good advice. If you have a new camshaft in this rebuild, once it fires and you are sure of pressure keep it reving in the 1,500 to 2,000 range for 10 to 15 minutes to break in the cam. A new camshaft relies on the oil splash to keep it lubricated. The worst thing for a new cam is low rpm and cranking and cranking. Good luck, Bob
 
Hi

Other than a few issues with the timing, a small problem with the carbys and small oil leak. I have had the engine running all appears to be okay. Good oil pressure and sounds sweet.

Thanks for the help.

Graham
 
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