Sudden complete lack of oil pressure

[Sabbot]

The preamble to this plea for suggestions is that I recently installed a 1600cc dry sump, titan 5 port oil pump, BDA with "dyno time" on it. I have been running the car around on short trips for a month or so without any issues apart from the fact that I've been gradually dialing the oil pressure back to get about 70psi cold (it started with more than 100psi at 1500rpm).

I parked up my Caterham a couple of weeks ago and I'm pretty sure it had oil pressure and no knocks. Last week I went to start and while it still had no knocks it didn't have any oil pressure according to the almost new VDO the capillary gauge. I ran it for about 10 seconds and switched it off. I checked the oil level in the 1.5 gallon tank and it was below the level of the pump pressure feed. Ah ha problem solved - just add oil …or so I thought, I added oil and still no oil pressure so I killed the engine after 5 seconds.

I figured it was either the pump or the gauge. I decided to drain the oil and see if any metal debris came out with the oil – thankfully not but I did notice that a lot (more than ½ gallon) of oil came out of the sump (seemed like the scavenger side of the pump wasn't pulling oil out of the sump). Anyway I added a gallon of oil back into the tank and tried again still no pressure. I have just pulled the pump off expecting to see a sheared shaft or at least a sheered woodruff key on either the scavenge or pressure side of the pump but there doesn’t seem to be anything wrong with it, it's all nice and clean and would support the "dyno time" claim for the engine. I also checked the gauge and it is fine (reads 20psi with the help of a bicycle pump).

Any suggestions (with the exception of refit the nice reliable crossflow) would be greatly appreciated.

Thanks,

Stewart

[Klasik-69]

If this has an adjustable relief valve, check to see if it isn't cranked out & slipped out of spring pressure range. It could be dumping oil back in if it's designed to release pressure back to the intake, or in this case the sump. You said you had dialed back the pressure which leads me to believe it has an adjustable range.

[Klasik-69]

You could also remove the oil press gauge & crank the engine to see if oil squirts out the press port. If no oil, is that passage free & clear ???? You need to determine if you have an oil pressure or oil pressure indicator problem.

[jlumba81]

Don't suppose you can take off the oil pump belt and drive the pump with an electric drill? That would test the pump and save the engine from dry starts.

[bsimon]

(seemed like the scavenger side of the pump wasn't pulling oil out of the sump)

 

Oil will accumulate in the sump with the engine off. The oil runs back through the scavenger stage(s) into the sump finding it's common level with the tank during longer periods of non-use.

 

I'm assuming that you have a distributor gear driven dry sump pump, common to Kent blocks. Since turning the pump manually is not an option, Pull the spark plugs, disconnect the coil, and only use the starter for your diagnosis experiments. This removes the loads that a running engine puts on the bearings when the cylinders fire.

[Sabbot]

Thanks for all of the suggestions. I would love to report that I fixed the problem AND I know what was wrong but for the time being I can only say that the problem is fixed but have no real idea how.

I removed, dismantled and cleaned the pump and removed and checked the gauge. Reinstalled everything and added fresh oil and now have oil pressure. Fingers crossed it stays that way...