Reasons for excessive oil usage ??

[Harold]

A few months I had my 22R engine redone, bearings, rings etc.
The engine was OK – not using any oil except that a pressure test revealed that compression on one cylinder was low, As I had already done 300,000 I decided to redo the engine.

Now the oil usage is now excessive.

Took the vehicle back to the guy that did it, a private garage with an excellent reputation, they checked it out.

Results are:
Compression test - excellent.
No oil leaks.
No smoke.
Plugs clean.

This proving to be a mystery. Anyone have any ideas what the problem could be?

[CasKru]

How clean is the underside of your bakkie? Is it not leaking out at your crankshaft seal either side of the motor?

[Harold]

Underside clean. No sign of oil anywhere, top or bottom.

I got my wife with to stand at the bottom of a steep mountain descent and ran the vehicle down at speed against compression, then floored the pedal; - not even a puff of smoke.

Must also mention that overall performance is also OK.

That's the mystery - where is the oil disappearing?
I'm talking of almost a litre in 3000 km.

[CasKru]

Is the oil clean? No water or any other debris....?

[CasKru]

Is it not maybe leaking at the back of the engine where the halfmoon rubber gromet is below the tapped cover?

1. Halve moon grommet
2. Some sort of plate with gasket where oil could also leak out
3. Gearbox

http://yotatech.com/f115/22r-freakin-oil-leak-108708/

[Mr_B]

Have you checked the PCV(positive crank ventilation) circuit? It's possible that there is a bit too much sump compression, or the PCV valve is faulty... and the oil is being "leaked" via the PCV circuit and burnt during the normal combustion process... if this is the case you won't see much in the way of tail pipe smoke, but the oil will magically disappear...

The PCV circuit consists of 2 pipes to and from the carb(I'm referring to the 4Y, but I'm pretty sure the 22R is the same)... one supplies clean air into the tappet cover, the other allows the combustion gases in the crank case to be drawn into the carb to be burnt up... you can try disconnecting the one that supplies the combustion gas back to the carb, on the carb side, and stick it into a plastic bottle, mounted somewhere in the engine bay... drive the vehicle for about 1000+ km and see how much oil builds up in the container... if it's alot, then either the PCV valve is stoofed and there is too much sump compression...

Just a hunch!

mr b

[Harold]

The engine is clean front, back and sides – no sign of oil.

No leaks on garage floor.

Oil looks OK, no sign of water or any impurities.

Cold start instantaneous; running temperature normal; radiator water clean; engine sounds smooth and performance OK.

Will certainly check PCV circuit. Have done just checked the pipe from the crank – used and ear-bud to swab the pipe – it looks OK, but I’ll follow up on this lead.

[Harold]

Feed back on the oil usage issue:

Fellow who did my engine overhaul made a number of enquiries with various experts, including Toyota. Then finally suggested I bring in the vehicle. He stripped down the motor removing the pistons and called in Toyota to inspect.

Result:
The oil rings had ‘glazed’ as well as the cylinder bore. Toyota accepted that the rings were faulty. The rings were replaced by Toyota, the cylinders were buffed to remove the glaze, and new big end bearings were replaced.

This kind of problem apparently happens once in a ‘blue’ moon. For the technical experts – I hope you understand what this is all about , ‘cause I don’t.

Other than the price for the head gasket, fuel filter and oil – there was no charge.

So now I have to do 1000km; been advised to drive normally; occasionally push revs to 4000+ for a short period but not strain the motor. After 1000km he will re-torque the head, change oil, reset tappets and timing. Lets hope the oil usage problem will be over.

[Mud Dog]

Harrold, I'm glad that you have been able to get to the bottom of the problem and that TSA came to the party and bore most of the cost. That is how service should be.

IRO the actual problem ... it is indeed almost unheard of. Let's put it this way .... if your brake or clutch linings become 'glazed', they no longer bite / grip very well, right? So with a glazed oil ring it's only different in that the metal has become 'glazed' and no longer performs it's primary task properly any more in that it still holds oil and lubricates by depositing but cannot bite sufficiently to 'scrape' the excess oil off the cylinder walls. The wall and compression ring surfaces become so highly polished after 'running in' that there is not much friction and only a very fine film of oil (an almost microscopic layer) is all that is required for lubrication. Excessive oil deposit left behind is burned during combustion and lost.

How much is excessive?

I cannot quantify, but if we take your example, you say you were using about a litre per 3000km. Just roughly, disregarding the higher revs of stop/starts and gear changes let's say that travelling at 100km/h your motor might be doing about 3000 rpm. 3000km @ 100km/h would take 30 hours at 3000rpm which = approx. 5400000 revolutions of the motor. 1 litre (1000ml) are burned over these 5400000 revolutions so only 0.0001852 ml are burned per revolution but are burned on power strokes only. On a 4 cyl motor there are 2 power strokes per revolution, so per individual power stroke that would make a tiny 0.000093 ml that goes out through the exhaust. That's not even enough oil to coat your fingertip, so it gives you an idea of how little an error in tolerances or efficiency is required to produce that kind of oil consumption. Scary!

[Mr_B]

I had a similar experience when my 4Y engine was professionally(not) rebuilt... I followed there advised run-in process to a T... almost right away the engine used oil... I had a many issues with this rebuild, including the valve timing being out 2 teeth, a rookie error... on one 600km trip it used over 1 litre of oil... after fighting with the so called pro's for 2 months, I decided to rebuild the engine myself... I found to rings were installed incorrectly(ring gaps were all lined up, they must be on opposite sides of the piston), and the bore had glazed badly... this because the engine couldn't break-in properly with the valve timing out... an engine needs decent compression from the word go for the rings to seat properly... also 90% of the ring seating is achieved in the first few minutes after first start...

I followed this break-in procedure with excellent results:
http://www.mototuneusa.com/break_in_secrets.htm" onclick="window.open(this.href);return false;

Mr B

[Family_Dog]

Sheesh Andy, I don't know about Harold, but now I understand even less what the problem was...! You really put on your thinking cap with that reply.

Mr B, what can I say? I told you at the time (on the historic ASPW forum) to rather buy a Ching-Chong motor... would have saved you lots of lolly afterwards.


-F_D

[Mr_B]

All those big sums Andy... sho! How many cups of coffee before you attempted that

Oh and what do you have for breakfast You got it all this morning :!:

Mr B

[zepplin]

....... but if we take your example, you say you were using about a litre per 3000km. Just roughly, disregarding the higher revs of stop/starts and gear changes let's say that travelling at 100km/h your motor might be doing about 3000 rpm. 3000km @ 100km/h would take 30 hours at 3000rpm which = approx. 5400000 revolutions of the motor. 1 litre (1000ml) are burned over these 5400000 revolutions so only 0.0001852 ml are burned per revolution but are burned on power strokes only. On a 4 cyl motor there are 2 power strokes per revolution, so per individual power stroke that would make a tiny 0.000093 ml that goes out through the exhaust. That's not even enough oil to coat your fingertip, so it gives you an idea of how little an error in tolerances or efficiency is required to produce that kind of oil consumption. Scary!

James May would be so proud of you Andy

[King Rat]

With the old types of engines I re-build quite regularly (I drive Alfa's ) I use only mineral oil for the first 5000kms or so otherwise I also get this glazing of the bores and oil rings everytime. Afterwards,once the engine is nicely bedded in, I'll replace the oil with proper semi-synthetic.

[Mr_B]

Mr Rat... I do the same, monograde 30 or 40W mineral oil...


Maybe u should help Thys with his Chev rebuild... else it may never be completed...

[Mud Dog]

Ok rag me all you will .... I was just trying to illustrate how something so seemingly insignificant can lead to the volume of oil consumption mentioned.

.....James May, hey! ......

[zepplin]

Yes................but have you seen his haircut????????

[King Rat]

Mr Rat... I do the same, monograde 30 or 40W mineral oil...


Maybe u should help Thys with his Chev rebuild... else it may never be completed...

Nah, I leave the proper engines to the experts

[Mud Dog]

Yes................but have you seen his haircut????????

What haircut!??? I don't think it's seen a barber in over 30 yrs .... looks like he just lets it grow till it falls out and is replaced.

[cprinsloo]

Feed back on the oil usage issue:

Fellow who did my engine overhaul made a number of enquiries with various experts, including Toyota. Then finally suggested I bring in the vehicle. He stripped down the motor removing the pistons and called in Toyota to inspect.

Result:
The oil rings had ‘glazed’ as well as the cylinder bore. Toyota accepted that the rings were faulty. The rings were replaced by Toyota, the cylinders were buffed to remove the glaze, and new big end bearings were replaced.

This kind of problem apparently happens once in a ‘blue’ moon. For the technical experts – I hope you understand what this is all about , ‘cause I don’t.

Other than the price for the head gasket, fuel filter and oil – there was no charge.

So now I have to do 1000km; been advised to drive normally; occasionally push revs to 4000+ for a short period but not strain the motor. After 1000km he will re-torque the head, change oil, reset tappets and timing. Lets hope the oil usage problem will be over.

Last year I gave mine a "mini" overhaul, but it also used oil afterwards and it got worse. Plugs had a brown, crisp deposit.

So, decided to take off the head again: sleeves felt like glass! Last year I replaced the rings but didn't hone the sleeves, lesson learned!

I'll also remember the running in procedure this time!

C

[cprinsloo]

Info update: cost of a ring set from Alert: R120 (Hastings)

Had a look at there web site, very good info.

http://www.hastingsmfg.com/ContentData. ... ntentid=82" onclick="window.open(this.href);return false;

C