Thread: 3.9 v8 oil pressure

Indeed, and even better was that I didn't have to get the 45/70.

And it's back to the same trick again.

I'm going to have to try a different timing cover. Before that I'll check the tension on the cover bolts. I was absolutely fastidious over the preparation of the surfaces and the gasket.

When I have it apart I'm going to pressure test the oil gallery on the suction side of the block. I can't discount the possibility that the ()*#&$%(*&#$% machinists damaged something doing the resleeve work.

Very, very )(#*$%_)#$% annoyed.

I removed my oil pump cover, does this look acceptable? Ordered a new gear set + uprated spring from Rimmer Bros, should give me an extra 10psi

That looks fairly badly worn to me. Is the top of gear chamber similarly scored? Can you feel much wear across the surface or is it mostly superficial?

How did the old gears look? I ordered a new set which didn't mesh nicely, replaced them with another set only slightly better (which are now sitting in on the shelf ) and resorted back to my original gears.

When you reassemble it all, DO check the protrusion of the gears below the timing housing and DO use the thinnest gasket you can find. I found going to a gasket just over 0.22mm thick made the world of difference to the idle pressure and if you have excessive clearance within the pump nothing will lift the pressure. Be aware that the uprated spring is not likely to make any difference to idle since at low crank speeds the pump is working at low output. The relief spring comes into effect once the pump is supplying more oil than the clearances in all the moving parts can flow, so you will notice that pressure will be up for engine speeds above 1500-2000 RPM.

The pic looks bad but I cant really feel the score. Only one part I can just notice a very minute difference. The old gears still look good, no chips/scoring but I'm replacing them anyways for good measure. Didn't see any marks/scoring with the timing cover part of housing. Hopefully the new gears + uprated spring will help.

Running 15/40 oil made the initial start up oil pressure to be quicker but hot idle oil pressure 16-18 psi, 27psi @ 2700rpm. Oil pressure won't get much higher than 30 psi. 20/50 oil I always had 18-22psi hot idle, still wouldn't get more than 35psi when engine revved. I would like to see 45 psi @ 4k. Been told by a landy mechanic that anything over 7psi at idle is okay and that the relief should keep oil pressure under 40psi. He was happy with what I was getting but Im not willing to rev it past 3.5k until I get 40psi. I know that anything past 60 is putting strain with distributor drive.

Although oil light takes about 4 sec to go out, I never hear any noises whilst the light is on.

I did notice when ordering the gears the option for the earlier shaft gears as well as the earlier idler gear. Perhaps you got the wrong idler gear Macman? Would love a new housing but I bet they are non existent now.

Cheers

You'll almost certainly be happy with the increase at 2700 then. Let us know how you go.

I would say that oil pump cover is stuffed. It doesn't seem to take much to affect the oil pressure - worn gears, worn timing cover, and an oil pump cover like that with gear marks on it will all be bad.

New covers are available. I've found a couple by trawling the Internet. You need a part number and then you look around regularly until you've ruined your eyesight!

Still on the hunt for a new pump housing but I put the new gears in + uprated spring in the old housing for now. Cold oil pressure is 30 psi which is much better but hot idle 18 to 20 no change. Getting 27psi @ 1500 rpm hot now and get 40 psi @ 3500 rpm which is much better. Still takes 4 to 5 secs for light to go out but there are no noises. Oil is 15 w 40 pentrite. No doubt 20w 50 would give me higher reading. Uprated spring has done the trick though I still want to replace oil pump housing. 4 seconds still a bit high but anyways.