1993 Sc300 Oil Burn And Coolant Loss

[whh333]

I recently purchased a 1993 SC300 showing 77,000 miles and the seller claimed that was accurate. It is a great car and the only quirk I have noticed in a couple of thousand miles of driving is some transient shudder on about half the morning startups.

My question is that it has burned about 1/3 quart of oil in the past 1500 miles and lost 1 or 2 pints of coolant. I cannot find external oil leaks, and there is no smoke according to someone following the car on the road. The tailpipes have only dry dark soot. I will try to look for external coolant leaks some more and tailpipes have no coolant smell. I switched oil to Mobil 1 10W30 when I changed it 1500 miles ago and the coolant is Red Line. I know this is not much consumption, but my wife's 1.8 liter Celica with 120,000 miles does not loose any fluid at all. Probably would not be asking these questions if the car did not have a Toyota engine.

I did not know whether the higher compression engine on my car might account for the oil burn, or whether there is something I need to check. Also, whether others might have ideas on coolant leaks.

Thanks for any ideas. ;)

Bill Harrison

[K9crew]

I've never been a fan of the plastic/aluminum radiators that come in many import and domestic vehicles since a common problem is that coolant seeps out at the interface between the plastic tanks and the aluminum core. I had that problem with my '98 Jeep Wrangler so I installed a three-row copper/steel unit from radiators.com. Now I have no coolant leaks and no coolant smell when the engine gets hot. Anyway, that could be the source of the leak. Other causes of coolant loss include a failed head gasket, a cracked head or block or anything that causes the coolant to get too hot e.g. a lack of sufficient pressure in the cooling system, debris on the front of the condenser blocking air flow to the radiator, a water pump failure etc.

As for the oil consumption ... 1/3 QT in 1500 miles doesn't sound that bad for a six cylinder engine although I just changed my oil (Mobil 1 10W-30) and I didn't have to add any in 4900 miles ( the engine has 51K on it now). Do you always check the oil when the engine is cold and in the same place each time such as your garage or driveway? These may sound like simple questions but it's important to compare apples to apples. If the conditions under which you check the oil each time are the same then we can assume that your engine is consuming or losing oil. The oil could be leaking out somewhere but you already checked for external leaks and didn't find any so it's probably getting past the rings and being burned with the fuel. I don't know if the repair manual provides oil consumption specs (I doubt they do) but you could perform a compression test to see if one or more of your cylinders are out of spec.

:)

[AWJ]

welcome ;)

[whh333]

Many thanks for the ideas and encouragement. After some closer looks, I did find oil running down the front left side of the engine behind the distributor and other front accessories. I have cleaned the area several times, experimented with finding the source and it appears to be loose valve cover gasket bolts allowing seepage on the front area of the left valve cover. The car had a new timing belt a few thousand miles ago, before I bought it, and it looks like the bolts were torqued to some spec that allowed leaking. Possibly the sealant was not renewed in the front areas or maybe the gaskets were reused. It seems the leak has stopped for now with heavier torque, but I will keep some valve cover gaskets on hand in case this is temporary cure.

As for the coolant, it is coming out of the drain tube below the nylon petcock. I put a cap on the tube to see if this slows it down, but a new radiator is probably imminent.

I think these are the sources of the problems, and I am still hoping this is not a head gasket or worn rings. Only a few hundred more miles will tell for sure.

Thanks again.

Bill Harrison

[JPI]

Bill,

You need to change your distributor O-ring and valve cover gaskets. Also, the inline six does consume a little bit of oil. To fix this problem you will need to replace your valve steam seals. It will run about $1,500-$2000 at the dealership.

JPI