Cummins 400 Oil pressure & temperature

hi bretto,
the oil pressure is still a little low.
on the side of the oil cooler housing where it bolts to the block there is a large nut (cant remember size but about 7/8 i think) facing outwards.behind that is the pressure regulator and spring.
roadside fix......undo the nut and remove the spring,then pull the plunger out (normally by inserting your finger or using internal pliers)clean the plunger then drop about a 1/4 spacer into it,insert the spring on top of the washer and put it all back in in one piece.
shld pick you up about 10lbs of pressure.
water temp in old language shld be 185F normally & allowed to go up to 195/200 in short bursts.88c is about 190 so thats ok.
cheers,
newto

Hi again newto,
I would imagine that the spring and plunger you speak of is the pressure relief spring? Correct??
If I increase that spring pressure so that it holds more pressure, then that would/should only affect maximum pressure which I believe is about 65lb and it only gets to that pressure when cold if I have to move it before it reaches normal temp. Please tell me I'm wrong in my thinking.... as I would dearly love to get a bit more pressure through her.
If, on the other hand, the valve you speak of regulates pressure at all rev ranges, then most certainly I'll give it a go!!
cheers again
Bretto

hi again back,
its not a relief spring,it controls the regulator plunger.
there are 2 pressure regulators and springs,1 in the oil pump and the other in the oil cooler head.the one in the oil cooler allows any excess pressure to dump back to the sump via an internal drilling....but....it still cotrols the pressure right across the range.shimming it shld raise both idle and max pressures.the ideal thing to do wld be to replace both regulators and springs,oil pmp and cooler.if shimming the spring raises pressure then that indicates just general wear and tear in the lube system,if it doesnt then the gremlins could be much deeper.
remember,the spec is 60lb HOT at revs,20/25lb @ idle with 15w/40 oil..your 60lb cold is probably the thicker oil.
just trying to help,
newto

Hi newto,
That clarifies it for me, I will give it a go and let you know of the result. I guess that the 1/4" spacer is to increase pressure on the valve and that makes sense to me
cheers again mate
Bretto

Newto, just to make sure we are taling the same thing, where my oil cooler bolts on there is three bolts about 9/16" AND one bolt which has a 1 5/16" head (a big bolt!). My guess is that is the one - yeah?
Bretto

hi bretto,
thats the one!....1 1/4" (or 5/16") facing out,horizontal to the ground,below where the water pipe enters.there's a cup plug and a 1/4 gas plug just below the regulator as well.
good luck!

OK, got it. Now I just gotta wait a couple days until I get the 3/4" drive socket set back (from a mate ) that has me large sockets in it
cheers newto
Bretto

hey bretto,
its been a couple of weeks,did you ever get your sockets back???
and if so have you tried the pressure regulator fix yet?

cheers,

newto

Hi Newto,
In the last weeks we have moved from Brisbane back home to the NSW Central Coast at Woy Woy.
My sockets are still with a mate in Strathpine however my son down here has a set and I get to use his sockets during this week, so will keep you in touch with the results.
cheers mate and thanks for thinking of me..
cheers,
Bretto

Hi all, well after many months of chasing the problem with reducing oil pressure, it came to a crunch on thursday.
The Turbo !
Yep, the (apparently) 30+ year old Schwitzer turbo finally gave up the ghost. On pulling it apart, she was simply worn out to the point where the seals could not hold oil pressure any more and the oil simply shot out the exhaust.
Anyway, $1885 later for a complete brand new turbo, and guess what? Oil pressure for the first time in its life is over 20lb at idle (hot) and generally runs at 50lb (hot) driving at 1600rpm. Amazing, yet so simple, in that the oil line that feeds the turbo is directly off the main oil filter housing - I didn't even think of it.
Performance, hmmm, a bit better than before (only a lot). Fuel economy - well that will come out during the next week of work.
So, in closing, the end result of 3 years of low oil pressure woes was the turbo letting the pressure down. One to remember I suppose for the future.
Thanks again to all of you who had given thoughts of what the problem was and how to fix it.
cheers all
Bretto
PS: henryox gets the prize for being the closest to the problem