Burning carbon deposits...

[mcowden]

Originally Posted by Caddy-O

I bought a beautiful Black Cherry 96 Seville SLS a few months ago with 105,000 miles and love it. After about 1000 miles I started getting a Service Engine Soon light, an O2 Sensor fault code, and a Service Emission System" light and I also have a a/c compressor seal leak. I do mostly just stop and go around town and drive about 100 miles a week averaging about 18 mph between 0 and 45mph. (no snickering please). I had an ocassion to drive my son to work recently and did about 70 mph for about 20 minutes each way. Lo and behold All the warning lights went out and All the associated annoyance. I think a WOT run would do the engine and exhaust system a world of good. However, I`m a little reluctant to do it for fear of breaking something expensive like a head gasket, etc. considering the milage on the engine and the amount of driving I do. What do you guys think about it?

The WOT isn't going to break anything expensive. Continuing to baby it and driving it with the SES light on and O2 codes, however, will break something expensive. Open up the throttle and get those codes fixed.

[rfishing]

Just leave yourself room on highway to cool down the engine afterwards. Keep moving forward at a good speed until engine is cooled down. You dont want to do a red line and stop suddenly. Sudden stop might blow a gasket?

If you find an old school mechanic, they might be able to blow it out with water down the throttle body. On older engines, I used to watch mechanics put brake fluid down the throttle body with high rpms to burn off carbon. Not sure about these Norstar engines.

Dealership in San Diego told me about an acid they would put inside the cylinder to burn off the carbon. Was about 200 bucks, I relocated before doing it, and dealership in my new area does not know anything about it.

[Ranger]

Water down the carb is an old trick that does work, so I am told (not sure about brake fluid and would never try acid.) I have done it many years ago. Never really saw a before and after to confirm that it does work I must say. The problem with todays engines is that the manifold is different. There is a possibilty that water will pool in one of the runners and then all of a sudden injest a slug of water and hydrolock. Too much of a russian roulette game for me.

[swimmster]

that's why you use a spray bottle with water in it.. avoids any sort of pooling..

[Ranger]

I hear what you are saying but that is not a guarantee. If the water droplet hits any part of the intake during its trip to the intake port it will no longer be airborne and will likely cling to the intake until there is unough vacuum to draw it out. If it happens to be in an area where it can pool, then there is the possibility of hydrolock. Still a risky proposition when you consider the posibilities and consequences.

[fartman]

I hate to interject, but what is a hydrolock?

[Ranger]

Hydrolock is when a cylinder gets enough liquid in it that it occupies more space than there is in the cylinder when the piston is at TDC. Air is compressable, liquid is not. You can imagine what happens at that point. The piston abruptly stops and something has to give. Usually a connecting rod. Not pretty.

[swimmster]

Not being critical here, but... using a spray bottle, and running the engine at the required RPM of at least 2000, there is ZERO chance of causing any sort of hydrolock condition first , due to the fact that the droplets are way too small, and second, if a droplet DOES hit the intake and become non airborne, 2 things will cause this droplet to disappear.. the amount of air moving thrut he intake will evaporate it along with the heat output from the engine.. the droplet would not last but a second inside the intake by itself.. if you happen to DUMP a bottle of water into the engine, then you would definitly run the risk of hydrolocking.. even if you put the spray bottle on "Stream", you would not hydrolock the engine.. the heat of combustion would evaporate too much of the water to cause hydrolocking.. I've only seen hydrolock occur in 2 occasions.. both of which were blown head gaskets into the cooling passage and having a cyllinder fill up with coolant overnight after cooldown and having that cylinder on the compression stroke. If the motor was very hot, any coiolant leaking in after shutdown would evaporate after hitting the inside of the hot combustion chamber. until the chamber is sufficiently cooled down and if there is enough coolant still able to pass thru AND the gap between the head, head gasket and block is not closed up doe to shrinking metal on cool down, you could then risk hydrolock.. how would you ever KNOW your cylinder is full of fluid? You'll find out when you crank the engine..


If your heads are ever removed, MAKE SURE THEY ARE RETORQUED after a couple of good driving sessions!!.. CHEAP insurance against needing new heads or chancing hydrolock. My first encounter with this was on a car we bought with a rebuilt chevy LT1 engine. The heads were never retorqued. after the first night of taking it out on a saturday night, we brought it home, parked it, and went to bed.. the car ran flawlessly all night.. next morning, treied to start, BANG BANG BANG BANG!!!!!..... opened hood, opened transmission cover, nothing.. did compression check.. one cylinder was a tiny bit lower than the rest.. kept playing with a few different things and checking.. nothing out of the ordinary.. yanked the motor.. found MOST of the head bolts could come out with slightly more than finger pressure... got the oil pan off and found the problem.. bent connecting rod.. caused piston skirt to hit the crankshaft counterweight.. why?? coolant leaked into the cylinder overnight.. the hi-torque mini starter just cranked right onto the connecting rod and forced it to bend.. also bent that part of the crank.. so.. make SURE your heads get retorqued..