Weird Smell When Revved

[Mike 92 XLT]

92 XLT, 127,600 miles. Recently I noticed that the car has been smelling a little strange. When idling in park for a few minutes a smell starts to creep into the car. Today when I parked at my house, I opened the door while the engine was idling (in Park) to see if I could smell it outside the car. I couldn't until I revved the engine up, then it smelled horrible. The thing is, once you let off the gas, the smell goes away immediately. I *think* it's coolant, because it has a sweet odor to it, but I don't know for sure. It's definitly not a burning oil smell. I don't think it's my heater core, because you can't really smell it inside the car, even when driving, and my heat works fine. The overflow tank hasn't dropped at all since I topped it off (up to the Cold Fill line) a couple of weeks ago. The truck still runs and drives fine, and gas mileage is the same. If anything, the engine has started to sound a little louder and a little more coarse than before when accelerating, and in general, the truck doesn't seem to drive as smoothly as it used to. I know this is a little vague, but does anyone have any ideas?

peace

Mike

 

[Mike 92 XLT]

bump

 

[SteveVB]

What does it smell like?

Hard to tell does it smell like sulfur? or rotten eggs? Since you ruled out the coolant smell I would guess it may be an excess fuel or O2 problem. If it smells like rotton eggs check the fuel system and the o2 sensors( how long since they were changed).

Run a quick test and see what comes up- hard to tell just by "it smells strange"

Good luck

 

[Mike 92 XLT]

Yeah, I know it's hard to tell by my description, sorry for being so vague. I didn't completely rule the coolant smell out, just the possibility of the heater core. It definitely doesn't smell like rotten eggs, so it's not the cat. It's also definitely coming from the engine, not the exhaust. The O2 sensor(s) (I think the 92s only had one) have, I think, never been changed. Never had any codes from the computer relating to the O2 sensor, but it's going to be one of my summer projects anyway. I just took a look at my overflow tank, it looks like my coolant level is down about 1/2 an inch from the Cold Fill line. So I'm thinking I have a small leak somewhere in the system and it's burning off before it makes it to the ground. I've never seen any drops on the ground. Would a leak like this show up on a pressure test?

peace

Mike

 

[TDG]

Mike,
My 92 does the same thing and it is coolant. Depending on age and type coolant can smell like a lot of different stuff. If I pop the hood in the right light and rev the engine I can see a very fine mist blowing back. Since the radiator is 3 months new I suspect that the water pump seal might have a small leak that is spraying close to the fan. Since I'm working on a new engine which is going to have a new water pump I havent bothered to fix it. It uses water mostly because of the cracked cylinder head but I suspect that this is also a prob. (this thing does have 257000 miles and counting)

Tim