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Low oil pressure.............engine, sender, or filter
My grandson reported this week that the oil pressure gauge rather suddenly started reading less than 3 bars when at operating temperature and above 1500rpm. He told me that with the engine hot and idling the pressure drops to almost "0". Yikes I thought.! He said that there were no unusual noises when at low pressure and that the dipstick shows full and he has 15w40 weight Castrol GTX in the car. He arrived here today and I checked the ohm resistance on the sender after removing the wire to the gauge. Good that I have small hands! I had the granson rev the engine and the ohm reading reached a high of about 127. According to the information I found on the web the reading if at 3 bars should be in the 174-195 range so I think the gauge is fine since it reads about 2.5 bar with that reading.of 127 ohms . With the engine at idle and at operating temperature the gauge does indeed read just above "0" at idle so I don't think the engine oil pump, bearings etc. is the issue or would the engine not be damaged. I guess the next question is should I buy a new sender and if so which one. Meyle and VDO are available. Am I on the right track by changing the sender? What about the filter? Could a filter cause this? The filter is an off brand that was all I could buy when the oil was last changed. It is not my usual Mann variety that I used to get at NAPA.
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Hi Laura, I would go with the VDO, I believe it is the OE manufacturer for the oil pressure sender. Mine is still the original BTW, so I'm not 100% sure of this.
Most likely it is the sender but I assume you peeked in the oil filler cap during idling and made sure there is a healthy flow of oil to the first cam lobes.
I have to agree with Dolucasi Laura that the culprit is likely the oil sending unit and I also agree to check the oil filter to make sure it's not blocked in any way as a blocked oil filter could spell disaster. I recently had the fuel sending unit on my car start jumping around when I let my car get low on gas. It went back to normal once I got gas but I think I'm going to err on the side of caution and replace it. I think you're wise to do the same with your oil sending unit. Should the car act up again after the replacement of the oil sending unit, be sure and tell your grandson to take it seriously and pull over and check the oil level to be sure the car still has oil in it. I would also let the car sit over night and check the oil first thing in the morning before the car is started. This will give you the most accurate oil level and help to decide if the car has been using any oi that might point to a leak or other possible issues..
Thanks for your answers to my query. Well it might surprise you but the problem appears to have been the filter. I bought a filter at the local Canadian Tire store. They have a new brand of filter called OEM + (made in USA) that seems to have good reviews so that is what I bought. When I got home the oil pressure was wobbling around the "0" to slightly above at hot idle and about 2.5 at cruising speed. After I installed the new filter the pressure went to 1.5 at idle and when to the 3 bar pin at about 1000 rpm. I looked at the old filter which is a MicroGard and only had about 2000km of use. The difference that I see between the filters is that the several holes around the spin on centre are smaller on the old filter. I have always used Mann or NAPA Gold filters in the past but they are becoming difficult to find of late and require special order. Anyway it appears that the sender unit doesn't need to be replaced. I think I will replace the oil just in case the filter wasn't functioning properly.
I looked up my service records and see that the previous two filters were Microgard so something must have happened to this last one to reduce the oil pressure. It looks pretty normal but no idea what happened inside.
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Yikes! Hopefully no damage was done to the engine. They always say what is important is flow not pressure, so hopefully the flow was there.
BTW, I have never had issues with Mann. I have also used Bosch. I try and avoid auto stores for filters and go online and buy OEM filters.
Likewise with tire shops, try and avoid them if you can for things other than tires. Here is a case in point.
My friend took my car (when he had it to a reputable local tire shop for filter change. They put in some no name aftermarket fuel filter that was not even the right size.
They jammed some cardboard so it stays in place. Then proceeded to break one of the small studs that hold the plastic cover and zip tied it instead. This is the level of care that I am expecting from most tire shops unfortunately.
Top is the tire shop special with the cardboard
Middle is the OEM Mann
Bottom is OE Bosch
I know you are limited with your choices in remoteland Canada Laura.
Last edited by dolucasi; Oct 17, 2021 at 02:20 PM.
Reason: typo
Dolucasi, I realize that you are likely and understandably unfamiliar with Canadian Tire. They are ubiquitous throughout Canada and are a very large corporation that competes with box stores like Walmart and Costco. When I was a girl the stores sold primarily automotive stuff like tires, batteries and some sporting goods. Now they have expanded to being big box store selling just about everything. Almost any town of more than a couple of thousand souls has a CTC store. My local store happens to be the smallest store in the entire corporation. Their oil selection and filters selection is pretty large and probably more choice than a NAPA on a par with what I have seen and your Pep Boys and O'Riellys's etc. The nearest MB dealer to me is now over 700km away on a two lane highway. I can buy some stuff online and have in the past but shipping is very expensive and items like oil or filters is just not financially feasible. I found the OEM+ brand filter which is a new CTC houe brand on the shelf at the nearest store. Not bad for finding parts for a 1990 foreign car! I am not sure where I bought the MicroGard but probably on a trip to Minnesota. I do like Mann and Bosch and always use them when available.
190E 2.6L 1989, 190E 2.6L 1988, BMW 535dXdrive 2014, BMW 428i 2015
Got it, Canadian Tire seems to have outgrown its name in a major way. My comment was more general in nature, not just tire shops. Same goes with places like Autozone, O'riely's type auto stores in the US. I only buy oil and tools at these places. Not even light bulbs. I get led bulbs from SuperBrightLeds (online shop) because you can et the correct Color CRI index from them. There are probably other outfits in Canada. By the way you had a question out there in the other side of the World (pun intended) as to fuel system cleaners.
When I was trying to pass CA smog about 5 years ago I did some research into marginally improving the smog numbers so I can pass the smog. I was told to try BG44K by pouring it into the tank.
This is a cleaner that is actually sold by the Benz Dealer as well. So I felt safe and purchased it at the dealer. Did nothing to my smog numbers however, so I'm not sure if it is of any help but did not hurt anything. I know seafoam is used by others. I doubt you need either one of these products. My car made it to 200K miles without them.
The dealer suggested that techron is best for this system, in small concentrations in every fill-up or in concentrate.
Since the local Chevron has Techron in it they said if I only use their gas I would never develop fuel system issues. 5 years running and no issues here with techron. Because Chevron headcourters is here in Northern CA it is not necessarily expensive either. Not sure if Techron additive is sold in Canada in can form.
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