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240 Gas smell in oil.

Pappy325

New member
Joined
Oct 28, 2015
Location
Corydon, IN
Have a 91 240. That has a smell of gas in the oil. Oil is fresh changed and still had the smell. Outside of that I'm pretty lost on troubleshooting or fault checking. Any ideas where I can start or a part path to take to start replacing starting with cheapest and then to most expensive.
 
Make sure when you drive your car it's getting to full operating temperature each and every time. Frequent short trips causes vapor buildup in the oil and that's bad. Remember that clearances are wider on cold internals, and the engine runs more rich on cold starts.

Once everything warms up and expands, the engine should seal properly. Also check your pcv system.
 
Make sure when you drive your car it's getting to full operating temperature each and every time. Frequent short trips causes vapor buildup in the oil and that's bad. Remember that clearances are wider on cold internals, and the engine runs more rich on cold starts.

Once everything warms up and expands, the engine should seal properly. Also check your pcv system.

Maybe that is part of it. It never seems to go above 1/4 to 1/3 of the heat gauge. Never to 1/2 as I am used to on other cars. Even on long hauls. But I only drive 120 miles a week that are highway. And only short trips less than a mile other than that. As I work from home. What else could it be?
 
It could be a sign that the rings are a little tired? All my 240's have had some degree of gas odor in the oil but they have all been 200k or more mile motors. I just change oil frequently - usually based on time, not mileage.
 
How is your fuel economy? Recently was down to 13mpg, stinky exhaust, gas in oil, and just poor running. Performed trouble shooting with O2 sensor, MAF, temp sensors, injectors etc. Just turned out to be faulty fuel pressure regulator. If this goes out, this might cause your injectors to dump too much fuel and cause very rich mixture.
 
Check Thermostat. Squeeze upper hose. If you can feel coolant pushing back into the engine it's stuck open.

It's amazing how rich some EFI cars run when cold
 
Yeah sounds like your not getting to operating temp and it's staying in warmup enrichment and running real rich. New thermostat should fix you up but you might just want to accompany it with a new o2 sensor too.
 
You may also have an injector that is sticking open. To test, pull the complete fuel rail and jumper fuses 4 and 6 to energize the fuel pumps. Observe the fuel injectors to see if they are dripping when the car isn't running but the pumps are. Be very careful when doing this and don't do anything that could generate a spark. Keep the ignition off, etc.

Do you have any codes?
 
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I'm going to try the thermostat as I need to replace the hoses anyways and do a coolant flush. If that doesn't correct I will then do the PCV and then the injectors. Trying to go cheapest to most expensive. If none of those work would we be left to an issue with the rings or pistons?
 
I would pull the rubber vacuum line off of the fuel pressure regulator and see if there is any gasoline in the vacuum line. If the regulator diaphram gets a hole in it, the regulator can dump gas directly into the engine intake. It has happened before.
 
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