Clark C500 Low Oil Pressure

[Blueacre]

I recently bought a Clark C500, 5000 lb pneumatic tire model with a Waukesha gas engine. When i bought it The oil pressure and temperature gauges were not working but it runs fine. I just finished refurbishing the entire wiring harness but the oil pressure gauge was still not working so I replaced it with a mechanical gauge with a 1/8" tube from the sensor location to the gauge. Still no oil pressure. This engine has the bypass oil filter system with a short line running to the filter from a tee on the side of the block where the oil pressure sender is located. It also has a long hose running from the filter to the opposite side of the block. I disconnected the short hose from the block to the filter and ran the engine - I only get a real small dribble of oil from the hose - took 30 seconds to fill half a cup with oil.

Seems like there is almost no oil pressure at this location where the oil pressure is connected yet the engine the engine runs smoothly at all rpms with no noise I would expect to hear noise from rod bearings or rocker arms with low oil pressure.

Appreciate if anyone with knowledge of the Waukesha engines could give me some pointers on trying to figure out what the problem is.
Is there any possibility of something blocking the oil flow to the pressure gauge and filter connection location but the rest of the engine still getting oil ?
Is there another location I can check oil pressure and/or flow to see if the oil pump is working ?

 

[Blueacre]

Followup to original post - I guess my first problem is to figure out if the low oil pressure is a worn out engine or an oil pump failure or something else but not sure how to do that - If its the oil pump I see there is a repair kit available for the vane type pump in the D176 Waukesha engine - can the pump be serviced by removing the oil pan like many automobile engines ?

 

[lantraxco]

Sounds like a plugged fitting maybe. The bypass filters typically had a tiny orifice in the inlet side to regulate oil flow through the filter element, so you should get good flow up until that point. If something is obstructing the tee, there won't be enough back pressure from the filter to give a correct reading on the gauge.

Remove the tee and blow it clean, disconnect the coil wire and spin the engine on the starter, see if you get a blob of something out of the port on the block, then leave the tee out and install your gauge line direct to the block, see if you don't get a better reading.

 

[Blueacre]

Thanks for the suggestion - I did disconnect the hose at the filter and and hook a gauge up there to eliminate any flow through the filter. I will try removing the tee from the block and see what I find. Do you know if there are any other locations on the block where I could remove a plug and check for oil pressure ?

 

[lantraxco]

That's one engine I don't know the details of, sorry. But if you eliminated the filter flow, you should have gotten a correct reading after a time.

 

[Blueacre]

I only ran it for 30 seconds - I was scared to run it too long if there really was no oil pressure for fear if doing more damage to engine internals. I pull the tee and poke around in the hole in the block and see what I find.

 

[Blueacre]

I removed the oil connection at the block this morning, connected a gauge and ran the engine for 30 seconds - still no pressure. I disconnected the gauge and ran the engine again for 30 seconds - there was a good flow of oil out of the connection - it was a pulsing flow. I connected a 12 inch long hose that hung down to below the oil pan and ran the engine again - good flow but if I put my finger over the end of the hose I could stop the flow but still feel some small pressure pulses. I raised the hose up to the level of the valve cover there was only a small dribble coming out.

Seems like there is some oil flow but almost no pressure - possibly enough oil flow to keep the bearings lubricated so that is why they are not noisy but probably not enough pressure for adequate lubrication if the engine is under load.

My problem now seems to be how to figure out if the low pressure is due to excessive bearing clearance or a faulty oil pump ????

 

[lantraxco]

Or plugged suction screen. Sounds like the oil pan has to come off either way, unless the Waukesha was old enough it has an external oil pump sticking out one side, with and angled distributor on the other?

 

[Blueacre]

Yeah I figured the pan will have to come off - Good suggestion on a possible plugged pump screen - I hope I could be that lucky. I have a photocopy of the Clark manual but hard to find some of the info - There is a good blow up of the oil pump and its relationship to the distributor - also a photo of the bottom end with the pan off - see attached - looks like the oil pump mounts vertically inside block and the distributor drives off a slot in the oil pump shaft. You can see the inlet screen under the crank in the photo so the screen looks easily accessed with the pan off - the manual isnt clear if the pump can be removed without removing the crank. It is a vane type pump and looks like a repair kit is available with replacement vanes, drive gear and a few other parts.

 

[lantraxco]

Well, now you know where those pulses are coming from. I have never seen, as far as I can remember, a vane engine oil pump before, lol. cool. You'll probably have to remove the steer axle to access the pan?

 

[Blueacre]

Unusual for sure - all the pumps I have worked with are gear - They describe it as a low pressure, high volume lube system.