This is my first engine rebuild. Truck is a '75. Engine is a 20R which I had bored .02 then I put in new rings, bearings, timing kit, oil pump (including housing/relief valve etc) Parts were from Engnbldr. Oil is standard valvoline, I think I got 10w-30, with lucas break-in additive, wix filter. I am reving to my best guess of 2000RPM (no tachometer)

1st run: I f-ed this one up, didn't realize I was supposed to pack to oil pump w/ grease so it was sucking air and had no oil pressure. Shut down after about 20-30 seconds. Big ˟˟˟˟ up, I know. I'm hoping the assembly lube held up.

2nd run: Primed the pump by pumping oil in where the filter goes. Started up with plenty oil pressure, then in 2-3 seconds the pressure rose until it was pegging 100 (max on the dial). I shut down after about 15 seconds.

I know that oil pressure on a cold break in is going to be high, but this seems excessive. I checked the gauge (w air compressor) and it seemed ok, maybe reading high by 5-10psi. The oil pump is brand new including the pressure relief valve so it seems unlikely that would be the issue.

Should I open the valve cover and look for oil getting to the top end while cranking the engine without spark? Will just cranking even give enough pressure to get oil to the top end? I don't have a way to spin the pump with a drill while the engine is in the truck.

Is it possible that running without oil pressure for 30 seconds chewed up enough metal grit that it clogged the oil filter? If so I guess I'm screwed anyway...

I called Todd at engnbldr and he said that high pressure on a cold break in might be normal and that I ought to run it for the break-in and see it it comes down.

Right now I'm thinking I'll change the filter, just in case, then try running it for the break-in, stopping if I hear any bad noises or if the filter starts to balloon. Is this a terrible idea? Any other tips?

 

Did you make sure the little holes in the crank bearings were in line with the holes in the crank? Sometimes if you have a bearing spin (due to oil starvation) and block one of the holes you get crazy high oil pressure. I wouldn't turn the engine over any more. Drop the pan, check the oil and cut open the filter to see if anything bad is in there. I would check all the bearings. High pressure is weird I think for break in, it's usually low at the gauge until the assembly lube is all cleaned out after a few oil changes or you find metal dust and ˟˟˟˟ from the machine shop. But by that time, it's too late and the metal has passed through your engine already. Good luck man.

 

I have a 1979 toyota pickup 4x4 I just recently bought the truck from a buddy of mine it has the 20r engine in it, every time I start it on a cold start the truck seems to over pressurized the engine and it blows the seal on the oil filter and I found that the relase value in the oil pump was stuck from the over pressurizeing of the engine so I cleaned it out and it seemed to fix the problem until I started it and it did it again is there anything I can do to stop the engine from over pressurizing.