Blocked oil filter

[ShivaYash]

Dear all,

On my 1983 S123 230TE auto, I've begun flushing the engine prior to oil changes. This was mainly because of very loud lifters. The flushes have really helped and the lifter noise has nearly disappeared.

However, during the oil change, I did the flush (Liquid Moly proline) and drained off the oil. New oil and filter as usual. Within 60 miles or so, the engine has very low oil pressure. I removed the oil filter and fired the engine, oil pressure was back to normal. I concluded blocked a filter, replaced it, and now again, 700 miles later, I have the same issue. Oil pressure is low, 2 bar at cold, just under 1 bar when warm. On revs, the gauge only reaches 2.5 bar and not 3 as it did previously.

I previously used 10w40 high mileage oil, from Liquid Moly, and Mahle Knecht Ox 33d filters. Now I've begun using Mannol Classic 10w40. Both oils are MB spec.

My solution: while it is wasteful, I will drop the oil and do a filter change. I suspect the current filter is blocked, with carbon from the engine flush.

Comments welcome. I cannot continue to change filters every 700 miles!

Greetings from Berlin.

 

[alexanderfoti]

It does sound like it's incredibly sludged up to be blocking oil filters.

When you cut the old filter open, what is stuck inside? You may want a more aggressive flush like bg109 or berryman b12

 

[ShivaYash]

It does sound like it's incredibly sludged up to be blocking oil filters.

When you cut the old filter open, what is stuck inside? You may want a more aggressive flush like bg109 or berryman b12

The old filter looks used but not really different to a filter that has been in for 6000 km.
The LM flush is pretty powerful: https://www.liqui-moly.com/en/pro-line-engine-flush-p000065.html#2427
Pressure seemed restored with fresh oil and filter... will monitor.

 

[alexanderfoti]

I tend to stick with flushes that have PEA, which LM flush does seem to. I know bg109 can be very aggressive so many contain more. In any case, I'd run another flush just before changing the oil.

 

[Steve@Avantgarde]

I'd say you have a failing oil pump which is losing pressure.

 

[DREAMER NO2]

We dont know how long you have owned the W123 ..Could it be that previous owner used an engine oil additive ?

 

[ShivaYash]

We dont know how long you have owned the W123 ..Could it be that previous owner used an engine oil additive ?

Unsure about the previous owner. She had the car around 12-years and all oil changes were done annually by the same mechanic. When I got the car, the oil change tag stated Shell 10w40, no mention of an additive.

 

[ShivaYash]

I'd say you have a failing oil pump which is losing pressure.

What makes you say that, a new filter immediately resolved the low pressure issue. If the pump was failing, wouldn't that show low pressure even with a new filter?
The car pulls very well and the issue is new, since I started using Mannol 10w40. But it within spec.

 

[ShivaYash]

Would a slightly thicker oil, say 15w40 be worth considering? Or compared to 10w40, it would not make a noticeable difference?
I suspect temperates will drop to around -10 degree Celsius this winter, which is still tolerable for 15w40.

 

[DREAMER NO2]

I used 10x40 in the 6 pot engine ..thicker the oil,the longer it takes to cerculate the engine

 

[Steve@Avantgarde]

What makes you say that, a new filter immediately resolved the low pressure issue. If the pump was failing, wouldn't that show low pressure even with a new filter?
The car pulls very well and the issue is new, since I started using Mannol 10w40. But it within spec.

Because of this comment below:

The old filter looks used but not really different to a filter that has been in for 6000 km.
The LM flush is pretty powerful: https://www.liqui-moly.com/en/pro-line-engine-flush-p000065.html#2427
Pressure seemed restored with fresh oil and filter... will monitor.

The filter hasnt picked up any particles to say it was blocked and its only 700km old. I've never known an oil filter to cause an oil pressure fault and the viscosity of the oil hasnt changed, just the mineral additives.

What causes an oil pressure loss is usually a blockage in the oil system which could be a main gallery sludged or a pipe restriction (not on this model), and if the engine is that sludged then I'd be lifting the rocker cover off to inspect just how much sludge has affected the top end.

Given that the oil pressure is low but there is no sign of debris in the filter, then a failing oil pump would be the logical suspect. You could do an oil pressure test with a gauge to confirm or rule it out of course.

 

[ShivaYash]

Because of this comment below:


The filter hasnt picked up any particles to say it was blocked and its only 700km old. I've never known an oil filter to cause an oil pressure fault and the viscosity of the oil hasnt changed, just the mineral additives.

What causes an oil pressure loss is usually a blockage in the oil system which could be a main gallery sludged or a pipe restriction (not on this model), and if the engine is that sludged then I'd be lifting the rocker cover off to inspect just how much sludge has affected the top end.

Given that the oil pressure is low but there is no sign of debris in the filter, then a failing oil pump would be the logical suspect. You could do an oil pressure test with a gauge to confirm or rule it out of course.

Makes sense. I’ve got a new rocker cover to fit and will inspect the top end next week.

Agreed, this behaviour is usual. A friend suggested 15w40 to mask the low oil pressure issue. But I don’t think this is the way to proceed.

In the meantime I’ll ask my usual parts man to reserve an oil pump for me.

Will update this thread.

 

[ShivaYash]

Thanks to those who have replied to me. Here is my update.

Today I flushed the engine again, I had a single dose of Liqui Moly Proline Engine flush. The oil was pretty dark upon draining. The oil filter looked ok, I will take it apart tomorrow and inspect under good lighting.

Fresh oil and a new filter. Oil pressure is spot on again. I used approximately 4.5 litres of oil for the change. I got approximately 4 litres out… but with the engine flush, that means only 3.5 litres of oil was in the engine! The dipstick was just above the mid point when I checked it last week.

So this is pretty much the situation I had 700km ago. Low oil pressure, which I resolved by dropping in a fresh filter.

I will ask my local mechanic to check the oil pressure properly with a gauge… and perhaps I do need a new oil pump at some point in the near future.

 

[ioweddie]

might be dodgy filters...change brand.....might do the trick...or run it a while without a filter to see what happens

 

[Steve@Avantgarde]

Thanks to those who have replied to me. Here is my update.

Today I flushed the engine again, I had a single dose of Liqui Moly Proline Engine flush. The oil was pretty dark upon draining. The oil filter looked ok, I will take it apart tomorrow and inspect under good lighting.

Fresh oil and a new filter. Oil pressure is spot on again. I used approximately 4.5 litres of oil for the change. I got approximately 4 litres out… but with the engine flush, that means only 3.5 litres of oil was in the engine! The dipstick was just above the mid point when I checked it last week.

So this is pretty much the situation I had 700km ago. Low oil pressure, which I resolved by dropping in a fresh filter.

I will ask my local mechanic to check the oil pressure properly with a gauge… and perhaps I do need a new oil pump at some point in the near future.

So if you put 4.5L of oil in 700km ago and you have drained out approx 3.5L of oil excluding additives, that suggests you are burning a litre of oil every 500 miles or so, which is very high even for a 292k mile vehicle.

Either you have a hurrendous oil leak or could it be you are burning oil and thats also causing your oil pressure drop? Perhaps worn piston rings?

Something not adding up here.

 

[ajlsl600]

Worn rings will not in my view effect oil press. Previous owner not changing or using cheap shxte oil might. When I build diesels I mix half oil half diesel for initial 3 min run. Then I interview oil filter for debris, none seen drop oil diesel mix. Refill, new oil filter. Worked without issue 35 yrs. Worn rings will add combustion gas deris to ur oil and prematurely pollute ur oil filter. But wud hav to be pretty grim to block ur oil filter in 700 miles
Do not run ur motor without ur oil filter. U cud also check if ur by pass valve spring is weak, tho I doubt it if not previously tampered with.

 

[ShivaYash]

Appreciate the replies.

So I made a mistake. Just looked properly at the used oil. I think got around 4.5 L out of the engine. Meaning 1L ish used in 1050km. See the Sharpie pen mark on the left hand side bottle.

Still a bit high? The scale on these bottles is rubbish. Will try and measure more accurately tomorrow.

 

[Silver_Star]

After throwing all the various flushes in, have you checked the oil pickup strainer?

IMO, flushes are always risky on older higher mile engines.

 

[mioba]

Stick with 10w40. Use a genuine MB filter.

For a petrol car thats done 1k km that oil looks pretty dirty.

 

[ShivaYash]

Stick with 10w40. Use a genuine MB filter.

For a petrol car thats done 1k km that oil looks pretty dirty.

I prefer Mahle or Hengst to be honest, they are made in Germany. The 'original' MB filter is from Mann and made in Bosnia and Herzegovina. But I think they are all pretty good quality.
Currently using 10w40 and will continue to monitor the situation.