Thanks BREWSKI.

Yes, and I also have that confirmed from a PDF of a Clark service manual (finally found the page that has oil pressure specs)

For anyone interested the manual reads: "1. Oil Pressure Indicator. The oil pressure should be approximately 5-15 pounds at idle (500-550 rpm)."

That is about right. These engines used a high volume low pressure oiling system.

Hey guys, I am working on my forklift (very similar unit) C500-45 with D-155G engine. Do any of you know what I should be getting for oil pressure out of this engine? My oil pressure gauge read roughly 15 psi, climbing to just under 20psi at full throttle. I took out the sender and plumbed in my mechanical gauge and confirmed that is the pressure she is putting out. Is this a normal pressure for this engine? Seems a little low to me... I am going to be pulling this engine as I found my crank to have some end play so it is coming out for a rebuild in the next couple weeks. I am going to start a separate thread for my resto. Thanks

Actually only 10% of the oil flow is constantly filtered. The Waukeshaw engine has a high flow oil pump. The entire oil sump is filtered in just a few minutes, once the oil is warmed up. Running any engine without a filter results in zero filtration. This is why I said I would not run any engine without a filter.

Call Atlanta Lifttruck Salvage.800-999-9866. They can get you a used set up.

Brewski, with all due respect, most engine oil filters are full flow, filtering 100% of engine oil. The Waukashaw engines, along with older Continental engines, use a by-pass style filtering system. If a full flow oil filter set up is installed on a by- pass style engine, a complete loss of oil pressure will result.

The by-pass style filter has a restrictor inside which limits oil flow, keeping 70% or so of oil flow going thru the engine unfiltered. This type of oil system allows almost instant oil flow at start-up to the critical points in the engine.

If engine oil is kept clean by a tightly controlled maintenance program then a filter is really not needed.

Alright then can anyone point me in the right direction for finding a remote oil filter setup for this ol girl?
Thanks and sorry about the back and forth questioning.

These are bypass type filters. They do not bypass until pressure exceeds 35 lbs. This is so the engine will not starve for oil during extreme cold starts or if the filter element becomes plugged. Most all automotive filters function this way. Not using a filter is a quick way to destroy an engine. I would not run it without a filter.

I was actually thinking about that and opted out of putting a filter back on the system. Just like you said ill just keep tabs on oil changes.
Thank you

That type of oil filter system is called a "bypass" filtration system. It only filters about 30% of the oil on a complete circulation cycle. If you change your oil every 100 hours (about 3000 miles), you should be fine without it.

If you do install a filter assy, make sure it's not a full flow type of filter as you'll loose oil pressure. The correct filter has a restriction orifice in it to retain oil pressure

Yea im seeing that the previous owner came across under the oil pan with a bypass hose and plugged it in to that juntion box near the governor. Now i just have to find a 1/8 npt remote filter setup.
Thanks again gents!

One goes in next to the governor housing. The other is connected on the side of the block. You should see the fittings.

The previous owner must of ripped it off and bypassed it then because there is really nothing else besides the tranny spin on and the huge hydraulic cartridge filter. Ill have to find a remote oil filter setup i guess and plumb it back through the oil galleys. Any chance you guys know where the original supply and returns went?
Thanks for the year and part numbers that will help very much!

This series of truck used a remote mount filter. Depending on the vintage it could be in two locations. Both locations are in the engine compartment. Look for the filter with the small oil lines coming from the block. The other spin on is for the transmission. It has large hoses running to the base. The oem number for the engine oil filter is 990936. The trans filter is 990937. This truck is a 1973-74 vintage.

Nothing on carburetor side there seems to be an unmachined boss on the block where maybe a filter mount should of been? Unless the oil filter was remote only? Where do these lines come from and end at? How can i send pictures on this **** forum!
Thanks