Smoking From Under The Hood, Help Please?

August 21, 2015

A little introduction, since I'm new to this forum. I'm Jordan from North Carolina, USA. I drive a 95 Toyota Celica GT convertible 5 speed 2.2 that I recently received from a lady about 2 months ago. It has 293xxx miles on it, single owner, dealership maintenance ever since she bought it brand new in 1995. The car's in seems to be in excellent shape running-wise and the body/interior is awesome.

The issue - Ever since about 2 or 3 weeks ago, if I drive for more than 20 minutes it will pour smoke from under the hood seemingly from under the engine. I replaced the valve cover gasket and spark plug rings today and after my test drive (in town and on the highway, one trip) the same thing happens. I don't know if it was residual oil on the motor burning off, or if I fixed what wasn't broken. I've always heard that stop-leak chemicals are not the best thing to put in your car and I would like to fix it right instead of pour that stuff in my car, but if I have to I will. Any help would be very much appreciated. Thanks!

August 21, 2015

Hello Jordan and welcome to the board. I take it your car has the 5S-FE14 engine but no matter which engine, that kind of mileage means general wear, especially of the cylinder bores and rings which will result in “heavy breathing” ie increased crankcase pressure. If you have something wrong with your crankcase breather system (eg blocked or disconnected hoses) then you might see this as smoke rising in front of the car when stopped – especially at night with the headlights on. The increased crankcase pressure can also blow oil and fumes past the front and rear crankshaft oil seals.

Oil can also leak from the valve cover and sump (oil pan) gaskets and various other points eg the oil drain plug or even the oil pressure switch and find its way on to the exhaust – even a little oil can mean a lot of smoke.

You might want to power wash the engine top and underneath (cover up the electrics first) and after it’s dried leave some clean sheets of newspaper underneath over night to give you an idea of where any leaks are coming from. Always check the highest gaskets first.

A word of warning about Stop Leak products – don’t use them. I had an engine a while ago that was leaking oil from the rear crankshaft rubber oil seal and poured in a can of Stop Leak. It shredded the seal and left the leak twice as bad as before. It’s meant to work on rubber seals that have become dried out and hard, a variation on the old car dealers trick of pouring a can of used brake fluid into the engine but that was usually just for cars that had been laid up for years and not run.

August 22, 2015

Thanks Tom. I was pretty sure I shouldn't put any stop leak products in there. I'm a little embarrassed to say that I ignored checking my PCV when I changed the valve cover gasket and sure enough, the valve was gunked up and the grommet was non-existent (melted away). Took a trip to my local auto-parts store this morning and changed the valve and grommet out in the parking lot. Now, the smoke was still coming out when I got home but the amount was noticeably less and the duration which it came out was maybe 45 seconds as opposed to 3-5 minutes. How likely would it be that running the car with the PCV valve as it was (I've been driving it like this for a few weeks) that it blew some more gaskets in the oil system due to over-pressurizing the system? Also, I don't seem to be losing oil anymore, but I haven't really driven it enough to tell for sure.