MP Lafer: Fuel additive thinning oil?

[Mauricio]

Thanks in advance for reading this. My Lafer had been sitting at my parents’ garage for years and I finally got it started with the help of a mechanic.

To make a long story short, the mechanic got it started after changing the spark plugs, fuel filter, gas pump and carburator.

The first thing I did when I got the car back was to add a bottle of fuel additive to give an octane boost to old gasoline.

The car ran OK for a little while, but this weekend, it started backfiring a bit and I noticed the oil had thinned out and smelled a bit like gas (the Oil I use is Castrol high mileage 20w50). Could the fuel additive be affecting my oil?

I haven’t checked the spark plugs, but I did hear a bang in the engine compartment. I hope the mechanic did not damage the threads and a plug was ejected as a result.

Any ideas? Thanks much.

[Rich]

 A couple small things to check is the choke open all the way 2 are you flooding and having gas wash by rings.3has oil level gone up 4 Is breathing tube plug for crank case I would start with that. Rich

[Mauricio]

Thanks Rich, but what you just said is like Mandarin to me.  I am not much of a mechanic. I can change the oil and that is about it.

Someone just mentioned this to me: The diaphragm may have ruptured which decreases it’s ability to pump fuel and also dumps gas into your oil. What would cause the diaphragm to rupture? It is after all, a brand new gas pump. Is ethanol in current gas bad for the car? Could the fuel additive have caused this?

Also, the fuel pump is sealed (I think) and I would not able to open it. Or is there a way?  Thanks.

 

[edward ericson]

Fuel pump diaphragm bursts? really? Hadn’t heard that one but if Greg
(Wolfgang on the Samba) says it’s so than maybe it is. He built his
Speedster engine 20 years ago and has yet to fire it up, though, so
then again maybe it’s not.

Whatever, the oil smells like gas because unburned fuel is getting into the crank case. Besides that bad fuel pump, which i hereby endorse, there are three other ways that can happen. 1. your rings are shot. Rings are the things that go around your pistons that fill the gap between them and the cylinder walls. They help your pistons make compression, which makes power. They sometimes wear out, sometimes break. Could be that, but probably not. Usually bad rings make you burn more oil, but don’t portend much gas in the oil, unless you’re alo running very rich.

2. Valve seals. Usually this also makes you burn oil (exhaust smells like oil instead of dipstick smells like gas), but if you’re running especially rich, you can get some oil in a fouled cylinder and have it end up in your crank case with the extra unburned fuel.

3. Someone dumps gas directly into your crank case. This could be a prank or it could be you/your mechanic/the blokes in China who made your new Solex PICT 34 carb. That’s why the question about the choke opening all the way. You might have a rich condition (too much gas flooding through your carbs into your intake manifolds). There’s supposed to be only atomized air/fuel mixture in there, which is the good stuff that burns inside your cylinders and makes all that raw power you need to push the car forward. But if the carb was adjusted wrong, or just got out of tune somehow (it happens), you might end up with liquid gasoline in there and a rich-running engine. That would give you a gassy smell when it’s running, plus hesitation, and that backfire thing too. Sometimes a rich-running engine snuffs out one of your spark plugs. (Same principle as this: you can actually throw a lit cigarette into a full tank of gas; 99 times out of 100 the cig will just go out, drowned by the liquid…not saying you should try it though; trust me). Then the engine pulls unburned liquid fuel into that dead cylinder and pumps it back (some, anyway) into your muffler pipes, where it sometimes ignites from the heat of the others, which will all be working extra hard now that one’s shirking. A lot of the rest of that unburned gas makes its way into your oil.

So. Pull that fuel pump and look, see if it’s gassy/oily on the underside. If so, replace. If not . . .

Take a careful look at the carb. Are all the thingies and doohickies therein moving freely? When the motor is running, and warmed up, is that butterfly valve on the top standing straight up and down, letting all the air that’s possible into the carb and thereby the engine? If not, get that fixed.

And is there gas, maybe, dripping down the inside of the carb into the manifold? If so, get that fixed. It might be as simple as rapping the side of the thing so needle valve comes unstuck and the float settles down. But I’m not about to advise you on that, especially since you got a mechanic. And by the way, where’s he (or she?) at?

edsnova40665.9181828704

[Dale Schumacher]

Had a problem w/ mine once – filled the crankcase w/ fuel – the carb inlet

valve was stuck open and it siphoned all my fuel out of the tank. One way

to tell if this is the problem – remove the top of the carb and turn it

upside down and blow in the inlet – if you can blow through the little

valve needs to be replaced ( 4.00 – 10.00 part ) – if you can’t blow

through it is OK and not your problem. As an insurance I added a small

plastic fuel shut off in line by the tank ( 4.00 part at the lawnmower

section at Autozone/advance auto ) and shut the fuel off if the car is

going to sit longer then a few minutes. The added bonus is nobody will

get farther then 1/4 mile If they try to steal your car. If there is fuel in the

oil – you can smell it – do not run it like that – fix the problem and

replace the oil.

How far up the oil stick is the oil level – you should be able to tell by that

as well.

Dale

[Mauricio]

Wow! Thank you guys! Amazing responses and I now know a heck of a lot more about my problem. 

Ed, my mechanic is just a general mechanic in Miami.  He changed the parts I supplied for him and manually adjusted the carb.

I will look for a VW bug mechanice in Miami. If you know of anyone, please let me know.

Thanks again for your valuable help!  Have a great day!

[Mark Hendrickson]

Old gasoline is just that…old gasoline. All the fuel additives in the world won’t bring it back to life. You should have drained it, flushed the tank and started with fresh fuel. If the carb/pump/filter were replaced, they all just got contaminated with the bad gas because the tank was not drained and flushed.

Also, it may just be a stuck piston ring/s. It sat for a loooong time. In cases like this I use a squirt bottle full of Marvel Mystery Oil to lube the cylinders (through the spark plug holes). I let it sit a couple days, turn it 90 degrees by hand and repeat the process. I do this until I’ve turned it over by hand 360 degrees. It takes a week or so.

After this, I turn the engine over with the starter to blow out the excess Marvel and do a compression/leakdown test on the cylinders.

After it’s running, at fast idle, I’ll slowly pour a pint of Marvel Mystery Oil into the carb. That will decarbon and free up the rings too. Plus, you won’t have a mosquito within 100 yards for months Then I do another compression/leakdown test.

Good Luck,

Mark H.

 

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