What Causes 1.8Vvti Oil Consumption Problem ?

[paulcap]

Hi,

I have a 2002 Avensis 1.8VVTi Auto which has been a great car and I would prefer to keep. Unfortunately, at 72000 miles, it has suddenly started using oil at an incredibly high rate. Pedestrians I have driven past tell me the car stinks of burnt oil and fireworks. The car drives reasonably OK on very light throttle but if I use more, it changes down and makes a lot more noise but doesn't actually accelerate much and then the emissions warning light comes on with a Catalyst reduced efficiency code. I can clear this with my OBD device and it doesn't come back if I only use light throttle. I assume lots of oil is getting in to the catalyst and contaminating it. A compression tester says there is nothing basically wrong.

I can't afford to spend much money on it but I don't want to get rid of the car so I have to cosider doing the work myself. Can anybody tell me what actually causes the problem? Is it just oil rings stuck in their grooves or something worse? If it is sticky rings does any fuel additive or treatment poured in throught the plug holes stand a change of clearing the problem?

Thanks

Paul

[Ave I FIN]

Have a look at this document:

http://www.scribd.co...oil-consumption

[TrueBritGrit]

Hi. I had this a year ago and it's a serious problem with these engines. One of the oil drains in the engine clogs up with deposits and the oil is forced into the pistons and burnt. The engine warranty was extended on these engines but I believe only to 7 yrs. get it into Toyota quick and explain the problem and they will check it.

[igormus]

Can anybody tell me what actually causes the problem?

the main problem is each piston over heating due to initial thermal engine design fault/mistake.

the result -- an oil is being burnt converted into slag and the same blocks an oil drain holes on the skirt. what then -- an oil is simply sucked into combustion chamber but not drained in the sump.

regards

[Phil01]

Its called oval bore syndrome,

So many incorrect theories on what causes it.

basically the pistons wore the bore to an oval shape, being caused by the wrong coefficient of expansion between the steel strengthening insert in the piston skirt, this steel strip expanded too much in relation to the piston alloy and wore a nice oval shape in the cylinder wall.

Many folk will come up with their own story, but this is the correct reason

[paulcap]

Update

The oil consumption problem was first spotted when I noticed blue smoke. I checked the oil and there was none on the dipstick even though it had been topped up about 4 weeks before. I topped it up again which is when the smoke and smell got much worse and the catalyst error showed up. Now the new oils has been in for a few days the smoke and smell seem to have stopped and the error is no longer being produced. It's as if the new oil has disolved some of the crud away and the oil rings are doing thier job again. The only problem is thta the performance problem has not gone away, if anything it's getting worse. The car starts and drives perfectly providing I only use the very lightest of throttle. If I use any more, the engine note changes as if it's producing a lot more power but the acceleration is hardly noticable. If anything the engine note is a bit too loud and 'sporty' for the amount of throttle. There is also a faint hint of 'lumpyness' to the engine running, even on light throttle. The car has burnt out a couple of ignition coil pencils in the past and this lumpyness is a bit like a very toned down version of how it was when running on three cylenders. Is this symptom nothing to do with the oil problem or could it be caused by oil in the exhaust affeccting the Oxygen sensor for example?

Thanks in advance.

Paul

[Phil01]

Paul, when you replaced your coils did you also replace your spark plugs at the same time??

I have found that a heavier weight oil helps alot in the oil consumption, at one point I use to throw in the old 20/50w oil and this drastically improve oil usage.

By pure nature of a cat convertor is that it operates at such a high temp you very rarely see oil smoke out of the exhaust as the cat instantly vaporises it, if you see oil smoke from the rear that indicates to me the cat is not getting up to temperature and could be on the verge of being contaminated with burnt oil, (carbon).

Any more question then feel free to ask

[igormus]

ok

i ve seen one guy has stripped engine down due to fed up with oil burning and what di he seen? each piston oil drain holes and moreover oil scrapper rings become blocked by an oil slag as solid plug. besides -- each oil scrapper ring has lost own spring effect in the groove.

the next generation of the motors has been modified installing pistons cooling system by means of an oil jets washing pistons inside. the jet in question is taken off the oil main. it is understood MrT has also modified pistons to make them thick (burning side). besides when dismantled -- both cylinder liner wear and skirt wear were an equal without any ovals said by previous poster.

it is clear that modern engines demand respective cooling. regsrds

[Phil01]

Anyone keenly untreated in this post simply Google

1zz oval bore wear.

[Phil01]

Interested***

Silly auto correct on google

[nipponski]

Hi,

Looks like my Avensis 1.8 VVTi is headed in this direction as well. Any chance it can be repaired. I don't have the dough to buy a new car, already stretched by mortagage. Should I take to dealer even though it is more thatn 11 years old? Any comments form the seniors on this forum appreciated.

Nipponski

[Roker]

One other mod that was done and it can be done with older cars. To help the oil cooling the dipstick level has been increased by 10mm

[paulcap]

Further update -

The performance issue has rapidly got much worse. Hardly any acceleration at all particularly on a hot day. Starting off up a modestly steep hill and it doesn't get above 15mph until it gets over the top. It is no longer usable so I am going to try and fix it. I will try to take the cylinder head off and then the sump so I can undo the big end bolts and get the pistons out. I will report back on what I find.

[rockierobin]

ivce just stripped a 3zzfe same problem by service neglet easy to strip and rebuild its just remembering where the bolts go i have now fitted a replacment engine