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10 seconds to start, oil pressure slow to build...

Started by scraf, 22 December 2008, 01:22 PM


.... title says it all, I have to turn over the motor for about 10 seconds before it kicks in, but I noticed the the oil guage starts to rise at nine seconds, and when at full pressure she starts up.

When warm, she'll start immediately.

Could be many factors causing her to start slowly, starting on LPG as opposed to petrol ( broken petrol pump or line ), cold weather, damp weather, badly tuned.

I am more concerned as to why the oil pressure seems to take so long to come up to top level. ( is overfilled at the moment ) Is it a symptom of something on it's way out ?


The oel pressure sounds ok to me - as long as its above about 0.5bar at idle, and goes up as soon as you put your foot on the gas then its OK. 

My 450SE has what I would consider to be crappy oel pressure, when fully warm idle oel pressure is about 0.7bar and at 60km/h its only about 2.5bar but still according to the published literature from MB its within spec (ie. 3+ bar at 3000rpm).

If you are getting a pressure reading after about 9 seconds at cranking speed (approx 220-250 engine rpm) that I would say that you system is behaving satisfactorily.

450SEL 6.9 #5440 = V MB 690 , 450SE # 43094 = 02010 H , 190E/turbo # 31548 = AOH 68K


Sounds more like a starting problem than an oil pressure problem.

You would need to check ignition and especially make sure your plugs are OK but it sounds like you are not holding fuel pressure in the injection system.

If it only happens after being stopped for several hours but doesn't happen after only a short stop then you either have a faulty fuel pressure accumulator (Fitted above the fuel pump behind the rear axle) or a leaky injector(s).

If this is the fault you can shorten the cranking time by turning the ignition switch to start with the transmission in Drive to start the fuel pump and pressurise the system - sounds like 10 seconds in your case - before you try to start in Park or Neutral.

Just keep your foot on the brake in case you have a faulty inhibitor switch.

9 seconds would sound about right to build up oil pressure from 0 when cranking

Oil pressure in my 6.9 is 2.1 bar at 600rpm hot and about 2 bar at idle for my 450 hot.

Both go to 3 bar as soon as any revs are applied.



Then - 10 secs to start is probably normal for LPG as is your oil pressure.