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High oil consumption B21A

A

arcturus b

Member
Joined
Feb 27, 2025
Hi, approximately 1 ltr 500km. engine has 150,000 km. Which is most likely, worn valve seals or piston rings?
 
Look at the spark plugs, do the compression test, basic visual check for leaks, glove test for the crank case ventilation. What grade of oil are you running?
 
arcturus b said:
Hi, approximately 1 ltr 500km. engine has 150,000 km. Which is most likely, worn valve seals or piston rings?
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In addition to PCH's suggestions have someone drive behind you and look for smoke with a bluish tinge to it. With a liter every 500km I'd expect either a nasty leak or some serious oil burning.
 
PCH said:
Look at the spark plugs, do the compression test, basic visual check for leaks, glove test for the crank case ventilation. What grade of oil are you running?
Click to expand...
Useing millars cladsic pistoneeze. 20/50
Ehat's the glove test?
 
arcturus b said:
Hi, approximately 1 ltr 500km. engine has 150,000 km. Which is most likely, worn valve seals or piston rings?
Click to expand...
Translated to american measurements: 1 quart of oil every 300miles, wow!, 93K miles on B21A engine.

What's the history of the car/engine? Did it sit for a long time? Is there a pool of oil under it where parked?

I'd guess at either really gummed up rings, or ring damage from freeing up a stuck engine after long term storage. A compression test would help. Dry first, then again with a squirt of oil per cyl.
 
bobxyz said:
Translated to american measurements: 1 quart of oil every 300miles, wow!, 93K miles on B21A engine.

What's the history of the car/engine? Did it sit for a long time? Is there a pool of oil under it where parked?

I'd guess at either really gummed up rings, or ring damage from freeing up a stuck engine after long term storage. A compression test would help. Dry first, then again with a squirt of oil per cyl.
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Yes,it did sit for 4 or 5 years. Compression warm,10 bar. With oil squirt,22bar. Probably done about 1000km since re comissioned
 
arcturus b said:
Too much of the grape🤪juice
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Jack said:
Did you put the drain plug on all the way
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I'm stsrting to lean more towards valve stem seals. The car was garaged for over four years, enough time for seals to dry out. Will do one more comp' test. How much oil should i squirt in to get a good reading?
Haven't worked with ohc before. To check seals what problems or pitfalls should i look out for removing cam shaft to inspect seals? All advice appreciated.
 
arcturus b said:
I'm stsrting to lean more towards valve stem seals. The car was garaged for over four years, enough time for seals to dry out. Will do one more comp' test. How much oil should i squirt in to get a good reading?
Haven't worked with ohc before. To check seals what problems or pitfalls should i look out for removing cam shaft to inspect seals? All advice appreciated.
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I've had bad stem seals before. Those alone would not cause it to consume a liter every 300 miles. I'd be tearing down the engine pretty quick if I had to add a quart at every visit to the gas station.

arcturus b said:
How little difference in bar would indicate worn rings?
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It is hard to tell. 10 bar (145 psi) is maybe on the low end but reasonable for a B21. I don't think anyone believes that your engine is producing a compression test result of 22 bar (319 psi). That kind of compression is only normal for diesel engines. For a pretty high compression redblock (10:1 to 11:1) with fresh rings just out of break in I'd expect something around 200 psi. If there is a significant difference then I'd expect worn rings, but we need more reliable numbers.

Have you checked the spark plugs? If it is burning that much oil it should show on the plugs.

Also you haven't acknowledged whether it is blowing clouds of blue smoke out the tailpipe. I'd expect clouds of smoke if it was burning oil. You can kind of tell whether it is rings or the stem seals based on what the engine is doing when it is smoking. For instance, is it smoking while accelerating or decelerating.

Also you still haven't eliminated the possibility of a leak, which is far more likely. Can you take photos of the plugs, the gauge readings during your compression tests per cylinder, the engine bay, and the underside of the engine bay? That would help us help you considerably. We are kind of flying blind.
 
Hi, the plugs are dry. Couldn't get a decent pic of underneath but the mat under is dry appart from a small drop 1000006679.jpg.as far as smoke goes nobody has said anything and it's not obvious in mirror .nothing when i walk around. I gues that i will just have to bite the bullet and have the engine overhauled. Replace all the rings,worn seals etc. The staining on the plug if from the addative
 
arcturus b said:
Hi, the plugs are dry. Couldn't get a decent pic of underneath but the mat under is dry appart from a small drop View attachment 31962.as far as smoke goes nobody has said anything and it's not obvious in mirror .nothing when i walk around. I gues that i will just have to bite the bullet and have the engine overhauled. Replace all the rings,worn seals etc. The staining on the plug if from the addative
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Yeah, that plug looks good. I'd inspect for leaks before overhauling it. I don't buy that it is using that much and not smoking. My B20 had a bad intake valve stem seal for a bit and it smoked despite the oil not moving on the dipstick.
 
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