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alvin

High Oil Usage

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Guest parkerstnc

I have a 99 Corolla 1zzfe with 158,000 miles that is burning about 1.5 quarts of oil per 300 miles. I did a compression check and all 4 cylinders read 180 psi and held it. There is no sign of any leaking. There is a lot of soot on the car around the tailpipe. From reading this forum, it seems it would be an oil ring or the valve seals. The question is does the good compression test rule out the valve seals as the problem??

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trap

Worn, hardened or cracked valve seals will have no effect on compression but worn valve guides which are in the same neighborhood could. So, if the guides were a sloppy fit to the valve stem, they probably could affect the performance of the valve seals.

 

Watch to see if blue smoke comes out your tailpipe when starting after the car has sat for a while. Generally this is when you will see smoke caused by valve seal failures. Blue smoke during hard deceleration can also be a sign of valve seal failures.

 

 

 

.........The question is does the good compression test rule out the valve seals as the problem??
Edited by TRCar54

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Specs have compression for the 1ZZ-FE engine between 218PSI to minimum 145PSI with no more than 15PSI difference between cylinders. Sounds like yours is OK. Assume that this was done on a fully warmed up engine.

 

Couple things to check - compression test is easy enough to do and you can do a simple leakdown test by checking to see if the cylinder is holding pressure. But they can sometimes give you false readings or cannot capture a slow, persistent leak. A better way to do a leakdown test is to use pressurizes your cylinder with compressed air - old school method, at least I believe it is old school since I've done it for years and my dad has done it before me.

 

Basically, the test is done by setting the cylinder of interest at TDC. Connect a screw-in adapter that T's to a pressure guage and has a nipple for compressed air line to be connected. Then listen to specific areas to pick up potential problems.

 

- Crankcase

Remove oil filler cap and see if you can hear / feel compressed air through the opening. If you can, most likely it is leaking past the rings.

 

- Intake

Disconnect the intake / airbox connection to your throttle body and see if you can hear / feel compressed air through the opening. If you can, most likely it is a leak from the intake valves / valve seals.

 

- Exhaust

Disconnect the downpipe or if your exhaust is in good shape, see if you can hear / feel compressed air through the opening. If you can, most likely it is a leak from the exhaust valves / valve seals.

 

- Headgasket

If the tests above do not show anything out of the ordinary, try taking the radiator cap off and watching the level of coolant and see if there are any changes in height or bubbles forming. If you can, most likely it is a blown headgasket. A chemical test will confirm that.

 

QUICK TIP: Do cylinders #1 and #4 or #2 and #3 together - as they are in the paired at TDC. Halves your diagnostic time.

 

At the rate you are consuming oil - pretty hard to believe that the compression is still good on all cylinders. Could be a combination of a slighly leaky rings and valve seals taht is causing the oil consumption issue. Let us know what you find out - Good Luck.

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I usually top off the oil about 1/5qt every two weeks which is around 1/3qt every month or every 1k miles. Back when I first got the car I never checked the oil not knowing the engine ran that hot and I discovered before one oil change at the dealer that my level was down to half full, so I knew I'd been driving like that for months. Needless to say I had varnish buildup so ever since then Ive been diligent about topping the oil off and running seafoam through the crankcase around every 20k miles to keep the varnish out. I used b12 in it the first go around and Ive since learned that b12 is stronger than seafoam so I'll probably use it from now on.

Edited by 01loadedLE

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