I have been installing a 1974 Mercedes 240d engine and trans into my car. I got to the point where I hooked up an oil pressure gauge, and it buried the needle on an 80 lb gauge. I then tried a 100lb gauge with the same results. I now have installed a 200lb autometer super comp gauge and off idle and in about the mid range of rpm it is reading past 200lbs and I am guessing from the needle position that it is maxing out around 230 lbs. This does not seem right to me.

 

I don't know the specs on You particular Engine but on My Year and model the Manual has that the Oil Pressure Relief Valve inside of the Oil Pump opens at 110 psi. So that is the max possible Oil Pressure on Mine.

when actually measured the Max Oil Pressure I could get hot or cold was about 97 psi.

When I first start the Car the Gauge peges at the top even at idle speed. After the Engine is hot it drops down to about 2 bar (about 29 psi) but when you get on the Accelerator Pedal the Pressure quickly shoots up and maxes out the Gage at 3 bar althoug it goes higher than that.

 

On a 1977 616 Engine it has the Oil Pump Relief Valve opening at 8 or 7 Bar ( That is about 116 psi-102 psi). So that should be the max Oil Pressure Possible.

It might be of benifit to remove the Oil Pressure Relief Valve in the Oil Pump to see if it is stuck.

Also are you runing the Stock Mercedes Oil Fiter?

 

I will have to pull the oil pan and see if I can access the relieve valve for inspection with out removing the entire aluminum upper oil pan. I just installed a brand new oil filter and cleaned the pre filter screen and replaced the oil with new 15-40 shell rotella