Just picked up this ugly and beat up 85 4x4 with manual trans winch... and Roto max turbo? only problem so far is that the oil pressure tanks at idle after its warmed up a bit, seems to run fine no funny noises and as soon as you get over 1500rpm the pressure climbs back to normal (well the far side of R in normal...).

Guy I bought it from claimed a fresh rebuild 75k ago, and new heads. There is permatex all over it so I'm inclined to think he wasn't completely lying, Runs strong, and starts easy.
I'm hoping its the oil pump, or that booster thing hanging of the left side (can'r remember the name...maybe the oil cooler), No obvious leaks and it don't seem to use any oil. I just hope its not the crank bearings...

Any Ideas?

 

pull the old sending unit and install a manual guage .... these sending units over time become lazy and give BS signals .... replaced mine after the same thing ... found mine to have 20psi @ idle hot ... and 45 @idle cold on fast idle in mornigs

 

20 idle 45 while running is where my beat up '84 6.9L is at - is this acceptable?

 

I'll try a new sending unit first, its the cheapest...

many of the gauges are a little on the wonky side, when cold the speedo almost works, but when it warms up I could be in 4th gear at 2k rpm and the speedo says I'm only doing 20...
then the tach will quit... so I have to guestimate how fast i'm going. The oil pressure gauge is pretty dependable though, so I'll try the sending unit first.

 

Yeah .... 20/45 are good numbers .... my engine is fresh ....about 100k ... the previous owner swapped out the 6.9 and installed a fresh 7.3...... but he used factory HG's .... that's why I'm now having to redo them...
Either the sending unit or the guage ..... check the wiring ...... I would suggest a manual guage ... cheeper and more accurate .... you will get an actual number you can hang ur hat on .... imho

 

Swapped out the factory sending unit, better now but still a little low at idle, but it does have pressure.

Also discovered that 3 glow plugs where not plugged in, and the home made turbo has a funky drilled plate for the aircleaner, turns out without all that crud on there it gets closer to 5-7 pounds of boost instead of maybe 3-4 on a hill..., now to figure out a new air cleaner system...

 

look in to AFE .... they will pretty much fit anything and anywhere