Chattanoah

I'll start off by saying I believe my 1992 SC300 has clogged/leaky injectors OR a top-end oil leak. Here's why. Keep in mind it still runs extremely well; I'm treating the issue as preventative but attention-worthy.

From the start, even after replacing the MAF sensor, the exhaust has a noticeable (but not excessive) gasoline smell. I eventually checked the oil for smell as well, and it's there, too. Shortly after starting, for the first .25-1 miles, she feels a bit sluggish and just kind of meh. Thus far, I've run 2 cycles of injector cleaner and a full Sea Foam treatment. There's still a good bit in the tank. I, of course, changed the oil + oil filter. The car seems to run better, but the smells persist, as well as the sub-par performance right after start up. I log my MPG's for diagnosing purposes and curiosity, seems perfectly fine.

leaky/clogged injectors?: gas is not being efficiently burned due to imperfect spray pattern (exhaust smell); gas is also pooling into the cylinders when the engine is off, causing run down into the oil (oil smell); pooled up gas in cylinders needs time to burn off, explaining the occasional rough starts and poor initial performance. I do not think it's EGR because no CEL.

Top-end oil leak?: oil leak has fouled the plugs, causing incomplete burning, yada yada yada see above explanation. I also keep on seeing a splatter on top of my fuse box that reappears from time to time after being cleaned. On the valve/engine cover right by the oil cap, I sometimes see oil, and yesterday there was fresh gold oil. I don't know if this is run off from changes/top offs or if it's an actual leak. Pops thinks there may be some sort of drainage clog under the valve covers, causing them to become pressurized and therefore leak.


What are your opinions on this, oh blessed CL members? What would you suggest as course of action? I'd like to have someone do a full injector cleaning (the kind where they run cleaner through the fuel rail test port... do these cars have fuel rail test ports? ) and if that doesn't work, take off the throttle body and spark plug cover, check for oil leaks/pools and check the plugs, and heck do a compression test while I'm at it.

I'm not worried. There aren't really any indications that something major is going wrong, but I love taking care of this car, and if/when I sell/trade, I don't want to be selling a heap. Which it isn't, but... you get the point. Thanks guys.

-Noah

Chattanoah

One more thing (somehow got lost while posting): I removed the top valve cover (4 allen screws), didn't find any leaks. If anything, a little run off from the oil fill cap when I topped off mid summer without a funnel. Pulled plug connectors 1 & 2 and peaked down. 2 looked good, 1 seemed to have a bit of oil on it. I wonder if I caused it foul up, and i just need to replace plug #1. The car got brand-new NGK's in May so I don't think replacing 1 plug would be too bad a thing to try.

Again, I'm not worried here, just a very thorough and detailed person.

RXRodger

iTrader: (2)

No codes flash when you check the OBD1 codes? Check timing, it may show you something? Bad knock sensor really effects performance and will cause the fuel smell you describe but usually effects fuel mileage. Would show up as a code 54 or 55 if I recall correctly.

Ali SC3

iTrader: (10)

its common as the injectors age for them to leak after you shut the car down and it will depressurize the rail into the cylinders for whichever ones are leaking. generally they will still inject fine but they don't hold that pressure till the next start like they are supposed to, that could be one explanation. you can send them in for a simple rebuild there are lots of injector places that can do that service, I have had it done before on older injectors many times, its not something most people notice. I dunno if it would cause it to run rough for a quarter mile it would usually clear out in a matter of seconds when running but it would for sure cause a gas smell in the exhaust and the oil

I don't think there is a way for oil to get where you are saying unless the cap is cracked or bad. its probably just a spill had that happen before. make sure the top of the plugs are clean, no need to replace newish plugs. if there is oil on the top it will short the spark out to ground and you get an incomplete burn and you might get more gas smell as you describe. anytime you have a non spark event that gas can also wash down the cylinders and get into the oil, lots of ways to get that oil smell not just leaky injectors.

its possible to have a coolant temp sensor issue but I would think when those go it will be rich when warmed up, or lean when cold and give you hard starts, not the way you are describing.

Chattanoah

Thanks for the response! Definitely good input.

I have checked the OBD1 multiple times and never get anything. Have not tried checking timing, but a free loaner from autozone would make quick work of that, the belt is really easy to see on these guys. Also, unless I'm just a total scrub, I'm absolutely positive there is no knocking.

A single plug is cheap enough that I think that's worth a shot. I'll check timing if that doesn't work. I'll look into injector work after that and after I replace the fuel filter.

Thanks again guys. Anyone else reading this with input, it's still welcome. I've had a blast learning about this car and even something small like this affords a lot more opportunities.