Slow oil pressure 406 / 419

[Pinsandpitons]

On my FLU419 the oil pressure takes about 11 seconds to register on the gage. This is consistent every time the engine is started after sitting overnight. It occurs to me now that I haven't confirmed how long it lags after a few minutes off with the engine warm, but not long. As you might imagine I'm reluctant to start the engine and find out. I can't confirm with the documents I have where (or whether there is) a check valve or anti backflow system in the oil filter filtration but I suspect there is and that's what needs attention. Any input from those more familiar with the OM352?

Edit:
The pressure rises quickly ( 0.5 sec ) after the lag and is strong in the 70psi range at idle.

 

[tennmogger]

I have three 406 mogs with OM-352 engines. They all take many seconds to show gauge pressure. 11 seconds seems like longer than mine though, but that time is dependent on idle speed. I think you are seeing normal operation. I have 70's model 406's so you need comparisons to later model SEEs.

When the engines sit for a while, like days, the oil pan level increases indicting the oil has drained out of the engine/ That might be true especially on the newer model OM352 engines with upside down oil filters (like the SEEs?). Oil remains in the bearings though (tight Mercedes tolerances) and lubrication has not been a problem. That's why oil level should be checked just after shutdown.

Bob

 

[The FLU farm]

The slow reaction of the gauge is normal, unfortunately. Never did get around to check if there's an actual lack of pressure, or just a delayed gauge. It doesn't sound like they're running without pressure...to me anyway.

Oh, and the filter on a FLU is positioned correctly, tennmogger, so that's probably not the reason for the "eternal" wait. I hate it, but keeping the rpm low until the gauge registers full pressure is about all I can do.

 

[Pinsandpitons]

Copy those responses. Thank you. I did check today by cranking the engine with the throttle off until pressure registered, that took a while, but as soon as I open the throttle and started the engine the pressure rose immediately. The take-home is the engine is definitely tight, there’s no low oil pressure, it just takes a while to build which made me think maybe the filter or pump was draining as that’s happened in other engines I’ve worked on. Also, if you shut down for 2min or 2hrs the pressure rises more or less immediately when starting it back up.

 

[RayJH]

Thanks. My 419 takes 15 seconds after being off for days.

 

[joeblack5]

Thanks. My 419 takes 15 seconds after being off for days.

Started mine yesterday after 10 months... pressurized the system with the hand pump . Oil level was 3 fingers high on the dipstick above max. I was worried that coolant had leaked in the oil but the coolant level was normal.
started with first turn. About 30 sec before pressure registered.

Later J

 

[CMPPhil]

Important point

The slow reaction of the gauge is normal, unfortunately.....
...... I hate it, but keeping the rpm low until the gauge registers full pressure is about all I can do.

Hi

You make, to me, a very important point, don't Rev the engine to get the oil pressure up quicker. I hate it when I hear engines racing as they start.

It doesn't matter to me if it's a Unimog or a Honda Civic, let the oil get around to all the bearings and start flowing.

Cheers Phil

 

[The FLU farm]

Phil, it may be taking it to the extreme, but I don't cold start an engine if I can help it. I'll push, pull, tow, whatever it takes, if a vehicle needs to be moved.

If it gets started, it'll get driven until the fluids are up to temp. That's different from letting it idle for 15 minutes, obviously. I don't like idling vehicles, either.

Now, I wish that the trans, axles, etc., could also be brought up to temp on a regular basis, but that unfortunately won't happen when driving 1/4 mile at 5 mph and then running the backhoe for an hour. But at least I'm trying to be nice to my vehicles.

 

[Pinsandpitons]

I also hate engines idling unnecessarily, especially diesels. I always shake my head a little bit when I see some stupid person’s ridiculous, loud, lifted diesel truck idling in the grocery store parking lot for who knows how long. I’m not sure where that wives tale came from but engine slobber is a real thing brought on by long idle sessions, not to mention soot. Now that’s not to say letting the turbo cool down as a bad thing, of course that’s true.

On the oil pressure thing, I did some looking a while ago and found that there is a check valve in the oil filter that is supposed to prevent drain back. My guess is that that ball and seal is not a tight fit in most of these engines.

 

[The FLU farm]

I think the common idling of diesels is due to over-the-road trucker idling during the night in years past, either to run the heater or the A/C.

Can't remember how bad it is for them, but at least on OTR tractors the rings aren't even meant to seal at idle. That's a lot of fuel and crap going into the crank case.

 

[frank8003]

......and the reason cop cars last like they do is because they run all the time at operating temperature and get the oil changes as to recommendations. You are all correct, the lube oil must get up to operating temperature to "boil Off" the nasties.