Lingering fuel smell in oil

[SD_R/T]

First noticed the smell of gas in the oil a few weeks ago. Went ahead and replaced the fuel pump since I'd learned the diaphragms can leak into the crankcase (no record of when the PO last changed it so it seemed like a reasonable place to start). Changed the oil and filter. Didn't notice any significant increase in the oil level on the dipstick.

Fast forward to now: I've got this lingering fuel smell in the oil. The smell isn't as potent as before. Perhaps my nostrils are just being overly sensitive since I know that the diluted oil could be the death knell for the slant?

I have not done any real tuning to the carburetor since I got the car (I know, I know. I need to get to that). I suppose it's possible it could be dumping fuel in the intake, however I haven't noticed horrible mileage, the car fires up with ease in the morning, and there is no sign of black smoke out the tailpipe.

Anything else I should be looking at???

Car is a 68 Valiant (based on the engine color I'm thinking it's been replaced with a 69 slant at some point). Single bbl, no headers, basically stock. Doesn't get driven a huge amount, but when it does get driven it's generally fairly short trips.

 

[wjajr]

Check for carburetordribbling raw fuel into intake manifold after shut down. Summer heat sometimes causes excessivepressure build up in fuel bowl and or boiling of fuel in fuel bowl forcing rawfuel be purged eventually ending up in crankcase.

 

[67Dart273]

There is that "rare" possibility that the new pump could be leaking!!!

 

[SD_R/T]

Check for carburetordribbling raw fuel into intake manifold after shut down. Summer heat sometimes causes excessivepressure build up in fuel bowl and or boiling of fuel in fuel bowl forcing rawfuel be purged eventually ending up in crankcase.

Question: could this occur even though I generally only take short trips where the engine often barely gets up to temp? I'm also in san diego, so rarely does she get driven in anything over 80 degrees. Regardless, I'll have to peek in there after the next shut down as you suggest.

There is that "rare" possibility that the new pump could be leaking!!!

No, no, no :angry7: That's what I was hoping not to hear! I hope that's not the case. They're not all that expensive I suppose. Is there a way to check them beforehand? I didn't notice any obvious visual issues on the old one that I took out, but perhaps it's not something obvious.

So I'm safe to assume this is generally either a fuel pump issue or carb issue, right?

The oil still feels 'oily' and it's not rising on the dipstick at this point-in-time. Luckily.

 

[jos51700]

Mine does that, and I don't even have a mechanical pump. Hmmm...

 

[67Dart273]

I notice you said "fairly short trips." I can't imagine trips being terribly short in San Diego (was 1977 last time I was there!!!) and this time of year, but short trips will certainly make this problem worse.

Also make sure the choke isn't too rich. Of course you've looked at the plugs

How is the engine condition? leakdown? compression?

 

[SD_R/T]

I notice you said "fairly short trips." I can't imagine trips being terribly short in San Diego (was 1977 last time I was there!!!) and this time of year, but short trips will certainly make this problem worse.

Good point; the Valiant is just a 'putt-ing around' car, though (for now). Occasionally take it a mile or two down the road to work, etc. Thus the short trips. Slowly working on her and hope to have her 'roadtrip' worthy at some point.

Also make sure the choke isn't too rich. Of course you've looked at the plugs

Haven't looked at the choke in a while but will put that on my list. Same with the plugs (although when I replaced them about 100 miles ago everything looked good).

How is the engine condition? leakdown? compression?

Good question. Haven't done either yet. Also on my list. Although she feels to have plenty of 'pep'. Valve adjustment done in the last 100 miles.

 

[67Dart273]

A mile or two might be exactly what's causing this, depending on "run time." If you don't get the engine fully warmed to evaporate condensation, etc, that alone might explain it.

 

[Charrlie_S]

Check the pcv system, to make sure it is working properly.

 

[discharger1332]

thosse 1 bbl carbs are famous for going bad. mine would leak the fuel from the bowl into the crankcase if it sat for more than a day. found a new ont(not rebuilt) and did a good tune when changeing carb. all is good.

 

[SD_R/T]

Thanks for the input guys. Got a few more things to look at, it appears.

Drove it into work today, taking the 'long' route so she could get up to temp. Had a few minutes so I pulled the PCV. Clean (had replaced it not long ago) with good suction. Shut her down and peeked into the carb to see if I had some dribbling, but unfortunately the sunlight angle was wrong and couldn't see much (no flashlight with me). Will try again later....

I'm in the process of collecting parts for the super six upgrade, so if it ends up being the carb maybe this will give me the kick in the pants I need to get moving on that.

 

[wjajr]

After seeingshort trips, never fully up to operating temperature, I suspect this is theproblem.



Some rawfuel always finds its way to the oil pan at cold start up, and accelerator pumpshoots before manifold is fully heated contribute to the problem as well as allthe fuel won’t stay in suspension on its trip to combustion. As stated previously, get her up to operatingtemperature, and drive it long enough to evaporate all the moisture and rawfuel from sump. An additional benefit offull warm up is the moisture in exhaust system will be driven out lengtheningits life.

 

[Oldmanmopar]

Put a fuel filter on with a return off of a 1987 dodge truck . last year before injection. And the first years of this ethanol fuel. The fuel dead ending at the carb will pressurize when shut down. A return can be added with a 70 back fill tube with vent tube . Or installed in the top front of the tank

 

[67Dart273]

Put a fuel filter on with a return off of a 1987 dodge truck . last year before injection. And the first years of this ethanol fuel. The fuel dead ending at the carb will pressurize when shut down. A return can be added with a 70 back fill tube with vent tube . Or installed in the top front of the tank

You can use Wix (or equiv) 33040 --5/16-- or 33041 --3/8-- filters as well.

 

[BillGrissom]

Check all the spark plugs. If one is totally clean, that cylinder may not be firing, so raw, unburned gas is flowing thru and could flow down past the rings.