Gas in the crankcase

[mankins]

Hi all-

I have a 1973 Series III 88" that I bought back in the summer. It has run since I've had it but not really that well. It has the bad carb kind of symptoms: it chokes, it gags, I feather the accelerator, I mess with the choke...

So a few weeks ago, I pull the carb (a Zenith 36IV) and just clean it up and give it a once over. It looked pretty good if that means anything. Carbs have been a mystery to me for 30 years: I can remove them, install them, adjust them a bit but I still feel like an amateur when I mess with one.

Anyway, new gaskets then I put it back on. Before starting, I do the normal checks and in checking the oil, I notice that its thin and smells like gasoline.

So, my initial thought is that maybe the carb is the source of this problem as well. Could it be dumping fuel? If so, what's my next move? Could the fuel pump be playing a part?

Any advice toward getting on to smoother running engine would be much appreciated.

Thanks in advance, Phil

Richmond, Va

[I Leak Oil]

Your zenith carb is known for having warping issues. The symptoms you describe fit the bill for this. Search the web on it and you'll find a ton of info about it and how to fix it. My personal fix has been not to use a zenith but that's just me.

[mearstrae]

An over-rich carb will cause all sorts of problems, but an over-rich carb on an engine with the plugs not all firing causes more. Fuel that's un burned washes down the cylinder bores and ends up in the oil pan and washes all the oil off of things as it goes, if left in circulation with the oil it will cause bearing failure and/or cylinder failure and/or cam failure, etc. A fuel pump attached to the block can leak fuel into an engine resulting in the same lack of lubrication troubles (and also cause carb adjustment problems). I've had fuel leaks that actually caused explosions in the crankcase with interesting results.

'95 R.R. Classic LWB
'76 Sreis III Hybrid 109
'70 Rover 3500S

[TeriAnn]

An over-rich carb will cause all sorts of problems, but an over-rich carb on an engine with the plugs not all firing causes more. Fuel that's un burned washes down the cylinder bores and ends up in the oil pan and washes all the oil off of things as it goes, if left in circulation with the oil it will cause bearing failure and/or cylinder failure and/or cam failure, etc. A fuel pump attached to the block can leak fuel into an engine resulting in the same lack of lubrication troubles (and also cause carb adjustment problems).

Not having seen the vehicle in question, my first guess would be seal/diaphragm failure in the fuel pump allowing the pump to leak fuel into the crank case.

If the car was running rich enough to have large amounts of excess fuel flow down past the rings I would expect a noticeably black exhaust and black sooty plugs that would be fouling. Unless your rings were already shot and you are overdue for a rebuild.

[bmohan55]

To determine if it's fuel pump or carb dumping in the fuel I'd suggest by-passing the fuel pump with an electric one from NAPA ($50). Added benifit is that you will never worry about vapor lock again.

[TeriAnn]

To determine if it's fuel pump or carb dumping in the fuel I'd suggest by-passing the fuel pump with an electric one from NAPA ($50). Added benifit is that you will never worry about vapor lock again.

I won't bore you with my tales of woe sitting on the side of a trail in 100+ degree weather with an electric pump fed system in vapor lock (pump near a rear fuel tank). Thankfully I carry books in the truck whenever on a trip.

But if you do get an electric fuel pump, get a high volume low pressure one. The carbs like about 3lbs pressure. Too much and you will push fuel past the float valve and insure excess fuel in the cylinders. Facet makes some pumps that work between 2 & 3.5lbs that would be about right. Electric fuel pumps like to be placed near the fuel tank and about at the level of the bottom of the tank. And you want to soft mount them with rubber standoffs becuase they tend to be noisy.

[mankins]

Hey All-

Thanks for the insight and tips. I'm off work tomorrow, I wish you could all come over and play cars but it looks like it will just be me. Anyway, I'll start plugging away and let you know what I find.

Thanks again, Phil