[KJHuffman]

When I start the engine, the oil pressure is running only 1-2 bars. As the oil warms up, the oil pressure drops so the idiot light comes on. Same old story right? Here's where it gets fun. The engine is a 1971 that I rebuilt a year ago and am patiently waiting to drive. I put in new main and rod bearings (the crank was fine), new seals, timing chain (timing cover off 1970), tensioner and guides. I had the head (off a 1970) rebuilt with hardened seats and valves put in, new springs, new cam bearings, cam and lifters (went with hydraulic). Basically I gave it the works. When I first started to run the engine the new lifters failed to prime. Since I used gasket sealer on it, we thought that I clogged the oil port leading to the head, so I tore the engine back down and checked all the ports in the timing cover as well as the head, and everything checked out to be fine. The gasket sealer became a problem in the system, since it broke loose and I went through a series of cleaning my sump tube as it was getting clogged by the loose particles. After reassembly, the lifters still failed to prime, so I removed them and attempted to manually prime them to no avail. I read the threads here and went after all the solutions that were mentioned to fix this problem. OGTS alerted me to check the ball check in the oil filter area and sure enough the plug was worn out and oil could slip past, so I put in the ring that OGTS sells. I also replaced the oil pump cover with a new one and reworked the spring behind the ball as OGTS suggested. I fired up the engine and the results are the same. I am going to go back into the ball check on the side of the timing cover to make sure the ball is seating properly. I cannot look inside the hole or slip a finger in there to make sure no debris is holding it open. Any suggestions on how to check or clean it out? Also, the bottom of my oil pump gears are slightly scored. they look similar to a scored brake disc. Could this affect my oil pressure to the degree that I am suffering. Can I resurface them? Should I replace them, or would that be continuing to throw money at nothing? Could there be a problem in using the 1970 parts on the 1971 engine? I'm dying in the water here. Can anybody help?

 

[tekenaar]

Low OP

Did you have the cam bearings replaced when you redid the head? If so, you need to make sure of the front bearing ports (holes) orientation (12 and 6 o'clock) as ALL OIL for the lifter gallery and for the entire head for that matter flows through these two front bearing ports. Slightly cocked installation might block off these ports (~3/16" holes). Would explain your "lifters not pumping up" problem.

Was the original OP pump cover flat, i.e. no regulator, and did you replace it with a "regulator type"? If so, you have to block of the original pressure regulator by using a very heavy spring behind the ball.

 

[KJHuffman]

Yes the cam bearings were put in by the machine shop who rebuilt the head. I did not really check that out, so I will, that will be easy. The pump cover is of the new sort that has the pressure release on it. I did fix the spring in the timing cover. However I had no way of checking inside the hole to make sure nothing was there to keep the ball from seating properly. I will be looking into that as well.

 

[anastosmotors]

just a tip for what ever is worth. when you install the cylinder head gasket
did you install the o`ring seal for the oil passage at the right front of
the engine?
pete

 

[mark gibson]

oilpress

KJH is on the right track with checking cam bearing alignment and the oil pump .

 

[nobody]

Pete that seal is for the water jacket.

The scored plate on the oil pump can't help. It can be reworked or replaced easy enough tho.

Having had the exact same thing happen, I have to ask 2 questions.
1 Did you plastiguage your rod and main bearing clearances? Looks can be decieving.

2 Where did you get your oil pump cover gasket?

3 OK one more, check the timing cover bores for excess wear and gear clearance.

 

[KJHuffman]

Yes I made sure that the O ring was installed on the timing cover before the head was installed. Would the cam bearing port cause the oil pressure to act the way it is?

 

[KJHuffman]

in response to "nobody", I purchased the new oil pump cover from Opel GT source. They suggested that I start from scratch by checking the main and rod bearing clearance. The gears do not have any sideways movement when installed, however the side wall next to the short gear seems a little worn.

 

[Gary]

2 Where did you get your oil pump cover gasket?

Nobody has a good point here. Not all cover gaskets are equal and varing a few thou in thickness can cause low oil pressure. Check the gear end clearance with a straightedge and a feeler gauge then use the correct thickness gasket to get it to specs. While you are at it check the clearance between the gears. The specs are in the Factory Service manual.

 

[baz]

the factory service manual can be found in the downloads section

 

[GTJIM (R.I.P.)]

Leaking!

The gear type oil pump as fitted to the Opel engine is capable of pumping 1,500 PSI - yes one thousand and five hundred PSI ! That is why it is fitted with a relief valve which opens at about 35 PSI.
This means that low oil pressure is caused by oil leaking out of the system somewhere. The relief valve in the timing cover is a usual candidate for this so you must be sure that it is sealing and being held closed. The other culprit is too much clearance in the oil pump itself - either across the ends of the gears ( pump gasket too thick or base plate and/or ends of gears worn ) OR aroud the outside of the gears ( housing worn ). Generally you should be able to fit a 0.002" feeler gauge between the gears and the housing but not a 0.005" feeler gauge.
The other places that oil leaks out is through loose cam bearings - some Opel cams actually have undersize bearing journals! So there should be no perceptible up and down movement between the cam and its bearings ( a maxinmum of 0.0025" of clearance). "Loose" main and rod bearings will also let too much oil pass; the clearance here should be between 0.001" and 0.0025". Wider gaps will allow more oil through and lower pressure.
Check the relief valve in the timing cover first by removing the parts and cleaning the seat then put the ball back in and tap on it with a brass or hard plastic drift to seat it ( the timing cover is alloy so a tap on the ball will deform the metal to the shape of the ball and ensure that it seats ).

HTH

 

[tekenaar]

Only OP gauge for check?

How are you checking your oil pressure? Gauges and senders are 30+ years old and, though I'm not so concerned about their physical condition themselves, you should look at their electrical connections, including their grounds. If it were me, I'd snip the connector off the sender wire and replace it with a new one.

The brass used in the originals tends to get brittle after many thousands of heat cycles and will no longer have sufficient tension to "grab" its mating terminal for a proper connection. Can't tell you how many electrical gremlins have been solved by merely replacing the connecting terminals at the end of the wires in the problem circuit!

 

[69whitegt]

*Bump* So if you install the new type oil plate with the relif valve buit in you must install a spring in the old relif where???? and what size sping do I need? Also do you need to pack that area with grease?

 

[opelwasp]

Actually I just cut a 3/8" wooden dowel to length and put it inbetween the ball and the screw cap.

 

[Opelkurt]

Don't forget....

For low oil pressure: Also remember to check the plugs above each camshaft bearing; I've had them pop out after head work and just one missing will cause a major drop in oil pressure, especially to the lifters.

-Kurt