Having recently fitted an oil pressure gauge and sender from JK, it reads off the dial and doesn't drop. The gauge goes up to 5 bar which suggests the oil pressure is beyond 5 bar inside the engine. The engine isn't new and hasn't had a full rebuild any further than a strip down to the block, new oil pump, additional oil capacity sump and a decent compression test on reassembly. It's a twinport 1600 B. I've check pressure regulator and relief valves. Everything looks pretty good and free moving. Worried something isn't right, that said, if the engine was building up too much pressure then the relief valve would kick in and dump the oil back into the sump? Other threads suggest 3-4 bar working pressure is normal. The bus is part reassembled so no dashboard oil pressure warning light fitted as yet. Any suggestions? Should I be worried?
What is it connected to at the other end? If you've got a combined pressure sensor and pressure switch, is the gauge connected to the right terminal? Should normally be about 3 bar or below.
Is it a higher capacity oil pump? And why the additional oil capacity sump? And dare I ask what oil are you using?
I find the oil pressure is about 5 bar when starting from cold,quickly dropping to 3 bar as the engine warms. This has been similar on 2 engines Idling when hot. The pressure drops to 1 bar
There are two senders for VDO pressure gauges, 0-5 and 0-10 bar. Have you got the right one? (To be honest I don't know if the reading would be greater or less if you got the wrong one).
The problem is either wired wrong onto the back of the guage OR mismatched sender and guage . There are 2 models of guage and if you fit an `old style` guage with a new sender it`ll go off the clock ... Ask me how i found that one out ... (Trial and error = the expensive way tuesday_wildchild)
I have seen 7 bar on a cold start recently (104psi) at -4C. After two of those the pipe popped off the external cooler on the driveway... but normally I see 5-6 bar on a cold start. It drops to about 3 bar running with hot idle about 0.5bar. Thats with a 30k mile old 26mm pump on a home built engine about 19k miles old now. And as a lazy experiment I just drove 160 miles, some quite long distances with foot hard on the floor and going up hills reaching 120C oil temperature by Hindhead going North.. With the oil about 10mm too high on the dipstick and the pressure remained the same.
Guess what I found out. 'G' means gauge not ground/earth. Drrrrrrr I had the 'wk' connected up to the guage and the 'g' connector earthed. What a div. connected properly now and getting 2.5 bar that drops to 2 once warm. Everything now ok......breath.... Thing is, now got a 5 bar guage and sender spare as I've now fitted a 10 bar guage.... Also switched servo vacuum non return valve around and now I've got decent brakes too! Believe it or not I'm usually pretty good with mechanics.
Told ya . Out of interest, why have you fitted a 10 bar gauge? Your oil pressure is never going to go above 3-4bar.
It will look scary on a 0-10bar gauge when the oil is hot and the pressure drops below 0.5 bar at idle. I’d still like to know why you changed the pump and fitted a deep sump – was there a problem? And what oil grade are you using?
I fitted a 10 bar guage because I initially thought the oil pressure was pushing the 5 bar guage beyond its limits. Now I know I wired it wrong, I'll stick the 5 bar guage back on. As for oil pump/deep sump scenario. I fitted a new oil pump as the engine was partially stripped and out on the workbench anyhow and looked fairly worn. Due diligence and all that. The deeper sump allows me to have a further 3 litre of oil to help cool the minimal oil volumes available from factory. I believe these engines had only a small volume surplus originally so taking into account a worn engine may burn oil, it would help to offset the engine looking for more oil and keeping it cool or within ideal operating parameters. Sensible addition me thinks. As for oil type, using chain saw oil. Only kidding. I didn't know if synthetic has been used previously so put synthetic back in as I couldn't risk going back to mineral. 20W50 I recall.
Adding a deep sump adds a little to the cooling but increases the capacity to store heat. If you drove two busses say 15 miles, the one with the deep sump will have a lower oil temperature. But if you then drove both of them 50 miles, the difference will be much less as all of the oil in the deep sump will be almost as hot as the oil in a stock sump. And then when you really get both engines extremely hot, the deep sump engine will stay extremely hot for longer, as the cooling system has to do more work. And if your bus is lowered, it seems a bit risky making the lowest point on the mid-line of the bus the engine sump. If you ever drive a heavily cambered road or a dirt track...
Mineral and synthetic oils don't mix well, if you're unsure of which was used always go for semi synthetic as it's compatible with either
