5 month cold start - oil pressure rise time

JHZR2

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This is my 1982 Mercedes 300CD. Parked it in October, just got it out today. Totally cold start, first touch.



AC kicked on perfect too. I’m surprised because I know there’s a slight leak at the expansion valve that I need to attend to.

Just thought it was interesting to watch the oil pressure rise on a real mechanical gauge (oil line comes up into the cluster), after sitting that long. Especially with the thread that @OVERKILL made with the pressure data.

Fired beautifully though first time. A little bit of whitish smoke when idling at the start, so perhaps I need to look into something about that… these old engines don’t have afterglow like my newer ones do.
 

JHZR2

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Thinking you meant "glow plugs"
Afterglow may refer to something not car related.
No. All the MB 61x and 60x (the series that was made next) have glow plugs. You can see the glow plugs come on in my video.

Later 60x series engines added a timer to the glow plug relay to keep the glow plugs on after the engine started. This is called “afterglow”. Earlier engines did it for 60 seconds (depending upon engine temperature, no afterglow if the engine is over 40C); later 60x engines did afterglow for up to 3 mins.
 

OVERKILL

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What was the ambient temp and what was in the pan? That's a solid delay there! Neat that it pegged the gauge too. I had a mechanical gauge on my old foxbody and I remember a similar phenomenon, it would come up and go right to the relief pressure with 0w-40 in it at high idle, but would come off it once the idle started to come down. It didn't take as long to get oil pressure though, it was always pretty close to instant.
 
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Does that gauge have a fluid filled line running to the dash like old mechanical gauges? IF so the oil pressure probably came up faster than what was shown. Oil over time may have drained from the line and it took a bit to fill back to the gauge in a small diameter line.
 
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Does that gauge have a fluid filled line running to the dash like old mechanical gauges? IF so the oil pressure probably came up faster than what was shown. Oil over time may have drained from the line and it took a bit to fill back to the gauge in a small diameter line.
That's probably the case, especially since it sat for 5 months, it did seem to take a while to get pressure.
 

OVERKILL

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Does that gauge have a fluid filled line running to the dash like old mechanical gauges? IF so the oil pressure probably came up faster than what was shown. Oil over time may have drained from the line and it took a bit to fill back to the gauge in a small diameter line.
He said in the OP that "oil comes up into the cluster" so it sounds like a plumbed gauge to me, similar to the Autometer I had on my Mustang (had a copper line).
 

JHZR2

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What was the ambient temp and what was in the pan? That's a solid delay there! Neat that it pegged the gauge too. I had a mechanical gauge on my old foxbody and I remember a similar phenomenon, it would come up and go right to the relief pressure with 0w-40 in it at high idle, but would come off it once the idle started to come down. It didn't take as long to get oil pressure though, it was always pretty close to instant.

36F and a mix of Rotella 5w-40 and Rotella SAE30 (had a few gallons on hand thst I needed to use)…

Normally it is instant, this car has been sitting untouched for five months. It will be instant until it sits for months again…

Does that gauge have a fluid filled line running to the dash like old mechanical gauges? IF so the oil pressure probably came up faster than what was shown. Oil over time may have drained from the line and it took a bit to fill back to the gauge in a small diameter line.
yes, a fluid filled nylon line right up to the cluster. Very plausible what you mention… sure hope it came up faster!
 
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JHZR2 said:
A little bit of whitish smoke when idling at the start

Probably from worn injector nozzles. Whitish smoke is typically unburnt diesel on cold engine. If it has sat for months, I'd run it and get it up to temp, boiling off any condensation that may have accumulated in the oil.

Oil pressure will come down when idling once the oil warms up to operating temp, otherwise it typically pegs the gauge under load.

We had several of the older MB diesels, my Dad loved them. Sold the last one with 326k miles on it.
 
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