1998 4Runner smokes only when oil is low Symptom: visible blue smoke came out of tail pipe; checked
oil level (very low); added oil (added 1 qt 5W-30 along with Motor Honey); and
no more smoke (at least for now) 02/28/2009. I changed the PCV valve on 03/01/2009 but it looks like the old one I replaced is still in pretty good shape.
Background: I brought this 1998 4Runner on 02/20/2009. It
passed emission without any problem. No leaks on the ground. I changed the
engine oil and added gas treatment. 185 miles later, the above symptom
occurred. When the oil is at the proper
level, no visible smoke comes out of the tailpipe.But when the oil is low, smoke comes
out.Any idea what can be wrong? Any
help would be highly appreciated.
One more piece of detail to add... I also find oil inside
the air filter compartment. Can just a bad PVC valve cause this? Thanks.
Yes a crappy PVC valve can cause some of your problems but not necessarily all of them, they are cheap, I always replace it to start. The air cleaner housing being full of oil is like how the oil is being consumed. In addition to a PVC valve, there may also be a blow-by hose running into the housing. check to see what other hoses go into the housing & which ones have oil coming from them. I'm not familiar with the "Motor Honey" you mentioned but I rarely add additives to my Engine oil, especially if they are thickeners. The only stuff I recommend is a Quaker state or similar "High Mileage Oil". These semi-synthetic oils have additives to swell old rubber & cork seals in older engines and can help reduce oil consumption & leakage. Again, it may not be a total solution, but it couldn't hurt to drain out all of the existing oil & replace with a high mileage type & also change the filter at the same time. Never mix it with other oils, despite the manufacturer telling you it may be safe to do so.
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The most common cause of blue exhaust smoke is oil leaking past engine seals and into the cylinders where it then mixes and burns with the fuel. This is most frequently seen in older or high mileage cars with worn seals and gaskets. It only requires a very small amount of oil leaking into the cylinders to cause excessive blue exhaust smoke.
Blue exhaust smoke only at start-up can indicate worn piston seals or damaged or worn valve guides which may also cause a rattling noise. An external engine oil leak can drip onto hot engine and exhaust parts causing what appears to be blue exhaust smoke. Other possible causes of blue exhaust smoke include: piston wear, worn valve seals, a dirty or non-functioning PCV valve, worn piston rings, an intake manifold gasket leak, worn engine oil seals and possibly even head gasket failure.
Oil leaking into the cylinders can cause a rough idle, misfire and fouled spark plugs. In addition, a reduction in power and oil loss can be indicators that the blue exhaust smoke is caused by an internal engine oil leak. Internal engine oil leaks can also allow fuel to mix with the oil in the crankcase which will degrade the oil and prevent it from adequately protecting the engine.
Operating a car with a severely dirty oil filter, air filter or improperly functioning PCV valve can also sometimes result in engine oil blow-by, oil loss and blue exhaust smoke. Periodically checking the engine oil level with the oil dip stick will indicate if there is excessive oil consumption. Higher viscosity engine oil can sometimes temporarily reduce the amount of blow-by; however, this is not generally recommended. Excessive blue exhaust smoke indicates a possible internal engine oil leak that should be inspected by an ASE certified mechanic.
just about everyone does with either an old car or a new car with high mileage.how excessive? is oil consumption.well first thing is to check for oil leaks either underneath the motor or any oil lines feed into the motor .any major leaks would be pretty noticeable.if none are present then one would assume that your motor is burning the oil through the exhaust system .check to see what color smoke is coming threw the tail pipe.blue or black smoke indicates oil burning white will indicate engine coolant burning.in any case some color smoke is normal just depends on how much.so lets say your exhaust smoke is normal still could be burning oil just not a noticeable amount.on average you shouldnt have to add anymore than 2 quarts a month or every 1000 miles .depending on your driving conditions if you are having to add more than this there would be a leak some where or heavy color smoke.keep up on oil changes and always add lucas oil usually 1 quart its alot thicker than conventional oil so it reduces engine wear and will handle any small leaks in the engine components like the pistons and rings.if problem still present get to a dealer or certified mechanic as soon as possible good luck.
WHITE smoke? Or BLUE smoke? White smoke is usually caused by burning antifreeze (possible blown head gasket). Engine oil burning causes a bluish colored smoke.
Changing the oil two months ago means absolutely nothing to me. I have customers that travel 6000 miles or more in a month. Oil consumption is measured in volume over miles, not volume over months. It is normal for most 4 cylinder engines to use a little less than 1/2 quart in 1000 miles (even more than that for 6 cylinder and 8 cylinder engines).
I just bought a 2005 envoy too. I read in the manual that the 4.6 6 cyl engine needs 7 qts total. 2 Over the normal oil change. Is it possible it wasn't low to start? I noticed when Walmart changed the oil they charged extra for the change because it needed the two extra qts. However my dip stick has oil over the full mark. Seemed strange but I haven't had any leaks and after 3k mile no change in level. Make sure you had the correct about the first time.
At 40K miles it shouldn't burn that much oil, unless the motor has been abused or overheated. With no signs of oil leaks, the engine must be burning it via the exhaust,
Change the oil (use a good quality oil) and then observe oil consumption.
If it still uses excessive oil check further as below:-
1) if it blows blue smoke on steady accelleration (pistons or ring wear),
2) only blows blue smoke on initial accelleration after a period of steady coasting or de-celleration (faulty valve stem oil seals).
A quart /1000 miles is on the high side for that mileage- something abnormal is causing it.
1) Ensure any motor oil leaks are fixed to ensure they are not contributing to the oil loss.
2) Observe if any blue smoke from exhaust on downhill coast/deceleration - if present it indicates worn valve stem oil seals (these can be replaced relatively cheaply).
3) If blue smoke from exhaust on acceleration the piston rings may be worn- (costly repair).
pan gasket on bottom of intake manifold may be leaking internally and causing oil consumption..remove air cleaner housing and open throttle plates and look for oil pooling inside manifold..if so..intakw ill have to be removed and all gaskets replaced
Oil consumption can be when the piston rings worn out, also valve gaides worn out.
means engine oil passes through the combustion chamber, you cant see smoke sometimes.but when condition of the piston ring is wost you can see smoke behind the exhaust.