There was a problem in my wife's '97 Chrysler LHS. We kept smelling gasoline while driving the car, but I could not find any leaks under the hood, or under the car. I checked the entire fuel system from the tank, all the way to the injectors and could not find any dripping gas anywhere...
While I was under the car, I noticed that there was oil seepage in several places. I thought that oil smelled as if it had gas in it. I checked the oil on the dipstick, and it was water thin and smelled of gas.
So, I had somehow gotten gasoline in the crankcase. The car had been starting and running fine, so I couldn't figure this out initially.
I immediately changed the oil with some house brand 10W40, and put on a new oil filter. But I knew I'd have to solve the problem with the gas getting into the crankcase soon.
I remembered that the car had been loping a bit at idle for the last 1000 to 2000 miles. It would run fine when accelerating, and while going down the road... it just loped a bit at idle.
I decided that perhaps I had a bad plug wire that was grounding out, and firing well only when the engine's RPM's were up a bit. I figured that if I had a non-firing plug, that could have been the reason that gas was going unburned, and then seeping down past the rings into the crankcase.
I changed the plug wires and that seemed to help the loping idle problem... but after two days the gas smell had not gone away. It would come and go, generally after the engine was warm and I ran the heater, you could smell the gas smell in the interior. So the plug wires did not fix the problem.
I checked the OBD system and it had coded (the check engine light had been on for a couple weeks), indicating a faulty EGR valve. I think that was the source of the sloppy idle, and unrelated to the gas in the oil. I cleaned the EGR valve and the loping idle improved, but it still isn't perfect. I need a new EGR valve, I'm sure...
I ran the car about 25 miles on the new oil and filter without fixing the gas in the crankcase problem.
I asked a friend of mine who is a mechanic about the problem, and he said check the fuel pressure regulator valve. He said when that valve goes bad, it will cause gasoline to accumulate in the crankcase.
I didn't really understand the Haynes manual as to how to check that valve, but I decided to go on and buy a new one (fifty bucks
)... and I removed the intake plenum and replaced the valve.
That seems to have solved the problem. No more gas smell.
I believe what was happening was that gasoline was getting into the oil, and when the oil got hot enough the gasoline was vaporizing and escaping from the engine, and that's when it would give off the odor.
Here's the thing: We drove the car about 25 miles on the new oil before fixing the problem, but I don't think the oil is harmed enough to worry about changing it again. Do you guys agree or disagree?
And I don't know how much (there must be at least some) damage I did to the engine running it for 100 to 300 miles (a guess) with severely fuel diluted oil. I guess the engine should be flushed out pretty well though!
Anyway, the fuel diluted oil really found its way past some of the gaskets in the engine. I put a pint of engine oil stop leak (CD-2 brand, I believe) in there when I changed the oil. Good idea or bad idea?
I'm hoping the gaskets will swell and re-seal the engine. It's got 162,000 miles on it, so I'm hoping to just get by with it for as long as possible without any major mechanical work.
I guess my main question is whether there would be a good reason to change the oil again soon, or just treat this as a normal OCI and forget about it.
How does high fuel pressure cause gas to leak into the crankcase? Anybody know?
One last question: I found a LOT of carbon in the intake plenum, and the two steel tubes that run from the back of it down to the exhaust (don't know what they're called)
... What might clean that stuff out of there?
Thanks for the read,
Dan
While I was under the car, I noticed that there was oil seepage in several places. I thought that oil smelled as if it had gas in it. I checked the oil on the dipstick, and it was water thin and smelled of gas.
So, I had somehow gotten gasoline in the crankcase. The car had been starting and running fine, so I couldn't figure this out initially.
I immediately changed the oil with some house brand 10W40, and put on a new oil filter. But I knew I'd have to solve the problem with the gas getting into the crankcase soon.
I remembered that the car had been loping a bit at idle for the last 1000 to 2000 miles. It would run fine when accelerating, and while going down the road... it just loped a bit at idle.
I decided that perhaps I had a bad plug wire that was grounding out, and firing well only when the engine's RPM's were up a bit. I figured that if I had a non-firing plug, that could have been the reason that gas was going unburned, and then seeping down past the rings into the crankcase.
I changed the plug wires and that seemed to help the loping idle problem... but after two days the gas smell had not gone away. It would come and go, generally after the engine was warm and I ran the heater, you could smell the gas smell in the interior. So the plug wires did not fix the problem.
I checked the OBD system and it had coded (the check engine light had been on for a couple weeks), indicating a faulty EGR valve. I think that was the source of the sloppy idle, and unrelated to the gas in the oil. I cleaned the EGR valve and the loping idle improved, but it still isn't perfect. I need a new EGR valve, I'm sure...
I ran the car about 25 miles on the new oil and filter without fixing the gas in the crankcase problem.
I asked a friend of mine who is a mechanic about the problem, and he said check the fuel pressure regulator valve. He said when that valve goes bad, it will cause gasoline to accumulate in the crankcase.
I didn't really understand the Haynes manual as to how to check that valve, but I decided to go on and buy a new one (fifty bucks
That seems to have solved the problem. No more gas smell.
I believe what was happening was that gasoline was getting into the oil, and when the oil got hot enough the gasoline was vaporizing and escaping from the engine, and that's when it would give off the odor.
Here's the thing: We drove the car about 25 miles on the new oil before fixing the problem, but I don't think the oil is harmed enough to worry about changing it again. Do you guys agree or disagree?
And I don't know how much (there must be at least some) damage I did to the engine running it for 100 to 300 miles (a guess) with severely fuel diluted oil. I guess the engine should be flushed out pretty well though!
Anyway, the fuel diluted oil really found its way past some of the gaskets in the engine. I put a pint of engine oil stop leak (CD-2 brand, I believe) in there when I changed the oil. Good idea or bad idea?
I'm hoping the gaskets will swell and re-seal the engine. It's got 162,000 miles on it, so I'm hoping to just get by with it for as long as possible without any major mechanical work.
I guess my main question is whether there would be a good reason to change the oil again soon, or just treat this as a normal OCI and forget about it.
How does high fuel pressure cause gas to leak into the crankcase? Anybody know?
One last question: I found a LOT of carbon in the intake plenum, and the two steel tubes that run from the back of it down to the exhaust (don't know what they're called)
Thanks for the read,
Dan
