Temp and oil guages?

[btoscano]

Hello,



I drove the '90 D250 home on Saturday (this truck is new to me) and have a few questions on the guages.



The oil pressure and temperature gauges don't have any numbers on them, just a "way" left and right, and some hash marks in between.



My oil pressure reads at the right hash mark (not the WAY right hash mark) when I'm driving along the road, or the 2nd from right at idle.



My coolant temp guage reads between the 2nd and 3rd marks (not including te WAY left or right marks) (actually swings between them) . What temp is this? From what I've read, its probably running higher than normal? I plan to flush the cooling system and replace with a new Cummins t-stat. I can't find any more information in the owners manual.



Thanks for your help in advance.



Brian Toscano

 

[BushWakr - RIP]

Hi Brian,



Your description of the oil pressure sounds pretty much right on the money. On mine the needle never drops out of that center range. Most of the time I am running about midway between the two center 'hash marks'. When cold the pressure is at the right hand "hash mark".



The engine temp is another story. There is some variation on this.

On my truck at operating temp, the needle just clears the left "hash mark" enough that I can just make out that line. I have never had the needle climb any further than 2/3 of the way to the right 'hash mark', before it starts to open the T-stat fully and cool down.

Our trucks generally run a bit too cool. You want an operating temp between 180-190*F roughly.

Some members have a fairly wide needle swing like you mention while others, like me and my brother (92CTD) have a much tighter swing range.

If you're going to flush your rad, you may as well pressure test your intercooler too. You can use a short rubber boot with one end capped. That capped end has a press. guage and an air fitting. The other end slips over the turbo inlet and uses a couple good hose clamps to secure it.

Do not run any more than about 20 psi because the boot can shoot off the turbo inlet and damage the back of the alternator.

A tiny bit of leakdown is normal because you could be pushing some of the test airpressure past a partially open valve.



Bob.

 

[btoscano]

BushWakr,



I think some of the differences are in the guages themselves in the different model years. Instead of saying "WAY" I'll say "VERY".



So, my oil pressure has a "very low" and a "very high" and also four hash marks. Its the right two of these these that the oil pressure stays in between.



My coolant has maybe 4 hash marks inside "very low" and "very high" and it generally cycles between the 2nd and 3rd whether is 70 or 50 F outside.



The 1990 models don't have intercoolers.



Thanks,

Brian

 

[BushWakr - RIP]

Brian,



"... The 1990 models don't have intercoolers... . " OOPS I missed that, sorry..... that's a 2 RWHP deduction for me too... . rats



Bob.