HELP!!! NEW ENGINE REBUILD; LOW OIL PSI

[celouden]

OKay, Ive got a 1.3L 86 sami.  I just rebuilt engine, crank bearings, rings, oil pump, head, etc....Upon initial start up, I was idling @40-60psi psi oil pressure.  After my test drives and about 30 miles, my oil psi is in trouble.  At cold start, idle is 2000rpms, Im getting 40psi.  Driving at 3000rpm, I get @25-30psi.  At warm idle (800rpms) I get 10-15psi.  I idle up to 1100rpm to achieve 20psi.  I put 10w-30 castrol oil, oil is clean, no fuel or water.  Engine is pulling @14in/pds of vaccum.  Truck runs pretty good, but at 800rpms, it wants to die.   


HELP!!!!!!!!!!!!!!

[zuk1972]

 Ive seen posts where the rocker shaft screws missing could cause a pressure loss?Also did you have oil pressure issues before the rebuild ?

[rangerscott]

did you install the head gasket right???     There's that one little hole that can be blocked if put on wrong.

[celouden]

No oil problems before rebuild.  Blew a head gasket.  I replaced the head with a new one and installed the gasket in the only way I thought would work.  One hole is partially blocked, the one on the front intake side corner.  ( in #1 intake side)  When cold start, or even warm, pressure goes right to 50-60psi and if left idling, it just gradually drops down and down and down to about 15.  If you give it throttle it climbs up to 40 but drops with rpms.  on the road at 3000rpm's I can not get more than 35psi. 

I removed the valve cover and checked the "cap" screws, they were tight.  Valve cover leaks a little, timming is 10' vacum pulls 22

I installed the new pump, but did not check the relief valve.

my thoughts;

the pick-up tube o-ring MAY have fit a little loose, would it be sucking air?  This would be more appearant when cold, right?

relief valve on pump stuck open?

trash in oil pan restricting flow?





Also, what should this little truck rev?  I have owned diesels for 10 years, and keep shifting at 2200rpms, but tonight I ran the gears out to @ 3500 and got a lot more power, it will only run 55-60mph, max.  I put a header on the engine, but when the motor torques, it hits the frame, any fixes for this?

[hargraves]

on my efi engine the rev limiter is around 6500. If have seen a carbed turn 8 grand before.
on my truck with the low r@p gears i shift between 4000 and the rev limiter. But i run it around 3500 just driving around town. It's a 1.3 it likes rpm's

[wheresmyhat]

I know long ago when my Dad rebuild my 1.3 he took his time with it then when his friend came over, he was in a hurry and
missed one little step. Prime the oil pump. Either by packing with petroleum jelly or running a drill with whatever you need to turn the
gear in the dizzy housing. When oil comes up through to the head then it is primmed. I had a nice rod nock a couple days later. And then no
more fresh rebuild 1.3l.

It sat in the back for two years. 

Just a thought.

[SamiAK]

I just went through this last year. According to the guy I bought it from it had been rebuilt 20k miles before. I changed the oil 5-30 and the oil light would come on warmed up at idle. I could also hear some rattle on the bottom end. I decided not to let it beat it elf to death and broke it down, the crank and bearings were shot. There was about a cup full of heavy sludge in the bottom on the pan. I don't know if it was dirt or bearing material. There was evidence the crank had been reground and it had been rebored .30 over, the oil pump had not been replaced. I put in a crank kit and oil pump from Hawk. Now it runs great.

I would recommend you tear it down. It isn't worth throwing a rod. The oil pump is marginal in capacity IMHO making clean oil very important.  The only way to prime the pump is to turn the engine over (with spark plugs removed). loosen the pressure gage and have some one watch for oil. Use assembly lube heavily and fill all the passages you can with oil.

Samiak

[jaredsamurai]

How much moly did you put on the cam. You should always change your filter right after cam break in. Assembly lube is like mud in your filter and causes it to go into bypass mode. Is the pressure sending unit before or after the filter (I can't remember). If after, the bypass valve in the filter might lower oil pressure? Putting the head gasket on wrong should cause a restriction and therefore an increase in pressure I would think. What are your rod and main clearances. If those are a little loose (between .002 and .003) you might consider running 40w or 50w. If relief valve is set wrong than it should  never get up to 50-60 psi.

[zuk1972]

  If the pickup tube was sucking air it wiuld prolly have lower pressure at cold idle too?Id say that you could ve had some extra clearance issues possibly on the crank-bearings did you have them mic-ed?Maybe you recieved wrong bearings ?
  I would seem to think if you had head gasket wrong if it restricts [oil hole]it would help your oil pressure [instead of loosing oil pressure]but then you would starve the cam and rocker arms...

[tdspence]

My Samurai does the same thing and i sent an e-mail to one of friends that builds lots of engines and different types. Here is his response.

Oil is wierd. When it's cold the viscosity of a 10w30 is heavier than when it's warm.  A straight 30 weight oil is going to stay about the same pressure at most temps. As your engine RPM increases, the oil pump turns faster, pumping more oil. The clearances in your bearings don't change with RPM so oil pressure don't bleed off any faster, making it rise with RPM. Scroggin Dickey recommends about 7 pounds of pressure for every 1000RPM on hot rod motors, any more is just a waste. I used to put high volume/high pressure pumps in my motors and they ran just fine. As soon as I learned about how oil works I started putting stock pumps back in and believe it or not I get more power and fuel economy now. It takes a lot of effort to pump that stuff. A contaminated(old) oil will lose its viscosity propertys and oil pressure will go down also. I'd say change the oil, keep an eye on the pressure, and don't worry about it untill it goes way down.