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Good day everyone. Well, since I purchased my '84 300SDT the oil pressure gauge has been a bit erratic. It never settles between the 1 and the 2 like my 300CDT; however, it also never settles. It erratically fluctuates between just below 2 and all the way up to 3 when at operating temperature idle. I have a feeling that this is electrical issue; however, I have no idea how to track this down. Or, it could be something else? I really don't know. The care runs fantastic and has ZERO oil leakage. Any help would be greatly appreciated.

Warmly,
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[amcates]

Sounds similar to my latest post except it's my tachometer that's acting up. Let me know if you figure anything out.

 

[d71889b]

well there's no way it can't be an electrical issue.

your oil line could be clogged, there is a line running from the oil filter housing to the back of the gauge cluster. also the o-rings on the oil filter cover could need replacing

the tach has nothing to do with oil pressure in any way

do a search on "oil pressure"

 

[[email protected]]

well there's no way it can't be an electrical issue.

your oil line could be clogged, there is a line running from the oil filter housing to the back of the gauge cluster. also the o-rings on the oil filter cover could need replacing

Why couldn't it be electrical? It looks there is a break in the circuit that is causing it fluctuation. However, I will certainly check to see if the oil line is clogged. I just did an oil change and the o-rings were 100%.

Does anyone know how to clean that line?

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[d71889b]

the oil pressure gauge is mechanical

 

[neex]

Replace the oil pressure switch. On your SD that part can be anywhere between $25-$85 new, depending on what brand you go with. You might be able to find a used one on eBay.

The switch sits at your oil filter housing, and takes about 10-15 minutes to swap out. If it were me, while I was at it I'd probably go ahead and do an oil and filter change, and replace the oil filter housing gaskets. Good luck. PM if you've got questions or check with the 126 guys.

 

[Guest]

the oil pressure gauge is mechanical

Not on a 300SD.

 

[Rmac58]

Not on a 300SD.

True.

 

[MBeige]

Check instrument cluster grounds. I believe they're behind the cluster...at least on a w123 they are.