gasoline in engine oil? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jeremy_5 · 06-29-2004, 05:57 AM

I read somewhere that if you fuel pump went bad due to a ruptured diaphram, then there could be gas in your oil. Is this true? If so how could you tell? How could gas even get into the oil sump?

Blazer1970 · 06-29-2004, 06:47 AM

Yes, it is true.

Tx Firefighter · 06-29-2004, 07:46 AM

The fuel leaks into the fuel pump cavity in the block through the busted diaphram.

You can usually smell the gas in the oil if you sniff the dipstick.

If you suspect it, just put a new fuel pump on. They are less than 20 bucks at the parts store. For me, a fuel pump is practically a maintenance item. I hate being stranded.

ChevLoRay · 06-29-2004, 08:16 AM

You can definately smell it. Besides the fuel pump entry point, the more common way is what gets past the carburetor. If (for instance) you have a Q-Jet, AND it leaks (like they're prone to do), OR you have flooded your carburetor, the excess gasoline can find it's to the crankcase. If your carb tends to run rich, it is possible, too. Doesn't always happen, just that it is possible.

I had an Edelbrock 1405, that was "jetted for performance" (brochure). It ran rich. You could tell by the odor of the exhaust. The oil smelled like gasoline, and it seemed to be thin. I changed to an Edelbrock 1901 Q-Jet, and the mixture leaned out and no more gas in the oil.

Jeremy_5 · 06-29-2004, 02:52 PM

Shouldn't the oil be changed if you smell gas in it?

Tx Firefighter I did change the fuel pump.

Do all fuel pumps have a return spring on the rocker arm, when I pulled my old one off it did, but the new one I put on didn't?

*Randy70C-10* · 06-29-2004, 07:38 PM

Quote:

Originally Posted by Tx Firefighter

If you suspect it, just put a new fuel pump on.

Yes, and also change your oil immediately!! You'll wipe out your main bearings if you haven't already.

71chevylongbed · 06-29-2004, 09:00 PM

when mine went bad it put gas in the oil and oil into the gas

franko72 · 06-29-2004, 09:09 PM

you should have gained a smelly mix of oil and gas higher on the dip stick full mark. that is an easy way to check for ruptured diaphragm in pump. do a fuel line pressure check. should be 5 to 7 psi.Or just buy one like tx firefighter said.Hey TX I am a sprinkler pipefitter here in Cincy.

06-29-2004, 05:57 AM	#1
Jeremy_5 Truck addict Join Date: Sep 2003 Location: Lincoln, California Posts: 497	gasoline in engine oil? I read somewhere that if you fuel pump went bad due to a ruptured diaphram, then there could be gas in your oil. Is this true? If so how could you tell? How could gas even get into the oil sump? __________________ 1956 Chevy Napco 1972 Cheyenne Super 1970 K20

06-29-2004, 06:47 AM	#2
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	Yes, it is true. __________________ Tim

06-29-2004, 07:46 AM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	The fuel leaks into the fuel pump cavity in the block through the busted diaphram. You can usually smell the gas in the oil if you sniff the dipstick. If you suspect it, just put a new fuel pump on. They are less than 20 bucks at the parts store. For me, a fuel pump is practically a maintenance item. I hate being stranded. __________________ I'm on the Instagram- @Gearhead_Kevin

06-29-2004, 08:16 AM	#4
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	You can definately smell it. Besides the fuel pump entry point, the more common way is what gets past the carburetor. If (for instance) you have a Q-Jet, AND it leaks (like they're prone to do), OR you have flooded your carburetor, the excess gasoline can find it's to the crankcase. If your carb tends to run rich, it is possible, too. Doesn't always happen, just that it is possible. I had an Edelbrock 1405, that was "jetted for performance" (brochure). It ran rich. You could tell by the odor of the exhaust. The oil smelled like gasoline, and it seemed to be thin. I changed to an Edelbrock 1901 Q-Jet, and the mixture leaned out and no more gas in the oil. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

06-29-2004, 02:52 PM	#5
Jeremy_5 Truck addict Join Date: Sep 2003 Location: Lincoln, California Posts: 497	Shouldn't the oil be changed if you smell gas in it? Tx Firefighter I did change the fuel pump. Do all fuel pumps have a return spring on the rocker arm, when I pulled my old one off it did, but the new one I put on didn't? __________________ 1956 Chevy Napco 1972 Cheyenne Super 1970 K20

06-29-2004, 09:00 PM	#7
71chevylongbed Got Horsepower? Join Date: Sep 2003 Location: IDAHO Posts: 406	when mine went bad it put gas in the oil and oil into the gas __________________ 2001 Dodge 2500 Cummins, 4 inch lift, 35" Toyo MT's on Ultra wheels, P-Pump Conversion, AFE intake, Fass, 5 inch exhaust, Pyro,Boost,and Fuel pressure guages, and a whole bunch of other stuff "The Money Pit" SOLD-71 Chevy C10 long bed- 2/4 drop-- 350,th400, Edelbrock performer RPM intake,Edelbrock 600 CFM carb,Crower 240 cam,port and polish,Dynomax headers,HEI ignition,dual 2.5 inch exhaust with Flowmaster 50 series mufflers

06-29-2004, 09:09 PM	#8
franko72 Franko72 Join Date: May 2004 Location: Cincinnati,Ohio Posts: 471	you should have gained a smelly mix of oil and gas higher on the dip stick full mark. that is an easy way to check for ruptured diaphragm in pump. do a fuel line pressure check. should be 5 to 7 psi.Or just buy one like tx firefighter said.Hey TX I am a sprinkler pipefitter here in Cincy. __________________ 1972 C20 cheyenne Super 402 BB/400 turbo LWB A/C Tilt, Cruise Control, Saddle tanks, Tach My Home Page Better to burn out than it is to rust



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