Hey guys,
I am brand spankin here...Just got my first project an 89 E350 cutaway with a 7.3 IDI in it....it knocks like hell when first cranked, and the oil pressure gauge is sittin on its rearend... I have looked into an aftermarket gauge from az. If you ladies and gents would be so kind as to help this novice, where can I find the sending unit to make sure this gauge is compatible?
Thank ya in advance
Wayne

 

The oil pressure sending unit is on the very back side of the engine, a little to the passenger side. On the E series, if you take the dog house cover off you will be able to get to it very easy.

 

its a little tower looking thing lol....

 

I believe the gauge in these trucks is not a oil-pressure gauge but a oil-flow gauge- somebody correct me if wrong...

BTW when I first got mine it also knocked loudly at startup.
My OP also sat at it's lowest...
I thought it was a lifter, valve, rod, something....turns out it may have been an injector.

After replacing my fuel lines the knock went away!?

After replacing OEM oil filter with FL1995 Stroker filter and changing from Rotella 15w-40 to Delo 400 15w-40 the OP gauge now usually sits right near the "N".

I think in some way fuel starvation to a cylinder(s) can cause knocking, wonder what knocks??

Most common issues with these trucks are air-intrusion/fuel leaks, broken pick-up tubes in tanks, bad glow plugs/relay and/or cheap glow-plugs (only use Motorcraft ZD9's), and of course dirty filters, the CDR valve, Cavitation, and worn out IP/injectors or lift-pump.

If you haven't replaced pick-up tubes best to do it soon and clean tank as well (mine had metal shavings, gravel, dirt, black goo, and water in them both).
I also had a small air-leak where the return line hooked to the front tank.

also make sure you have ZD9 glow plugs or you may end up with a burst glow-plug as I had Autolites in mine and one of them burst and went who knows where...
if the cheap glow-plugs swell but dont burst you may have to remove head....not worth the trouble or expense!

drain/flush coolant and replace with coolant with SCA's in it to avoid cavitation.

look carefully at all return fuel lines on top of engine, if any look "wet" then you have an air-intrusion/fuel leak.

If your fuel filter is ever half-full or similar then you have a air-intrusion/fuel leak somewhere from the filter to the tanks.