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85impala 07-26-2012 12:09 PM

Oil smells like gas 85 Impala
 
Hey guys, I have a 85 Impala with a 305 and cc-qjet. I recently changed my oil about a week ago because it smelled like gas, and now it smells like gas again just not as strong as before.

I have an innovate a/f gauge that's reading around 15 so I know its not too rich. I also replaced a leaking mechanical fuel pump with the airtex brand for 16$.

What would cause the gas to mix with my oil?

Thanks,
Clint

delawarebill 07-26-2012 12:14 PM

fuel n oil don't mix well
 
well u really only have 2 places.. either the new pump is no good or your carb is leaking down and running into manif and into cyl and past the rings.. a pain, but maybe a compression test might say something..

85impala 07-26-2012 12:41 PM

Thanks for the reply
I actually did a compression test about 2 weeks ago and the whole driver side was the same @ 135psi and the passenger side was @135psi except #2 was 140.

I also can hear a faint drip right when I shut the car off, could the float bowl leak that fast after I turn the car off?

boothboy 07-26-2012 12:45 PM

1 Attachment(s)
Q-jets are notorious for the well plugs leaking. Get the engine hot, remove the air cleaner, shut down the engine, hold the throttle full open and wait. After a little while you'll probably see a white vapor cloud coming from the carb. Leaking well plugs. Time for a rebuild.A lot of mechanics epoxy the existing well plugs but I never had any luck. They always leaked again. Here is where you can get o-ringed replacement plugs. Call them with your carb #. There is two sized plugs.
Carburetor Parts for Rochester Quadrajet, 4G, 2G & Carter AFB, AVS, Thermo-Quad Carburetors

85impala 07-26-2012 01:07 PM

Quote:

Originally Posted by boothboy (Post 1577299)
Q-jets are notorious for the well plugs leaking. Get the engine hot, remove the air cleaner, shut down the engine, hold the throttle full open and wait. After a little while you'll probably see a white vapor cloud coming from the carb. Leaking well plugs. Time for a rebuild.A lot of mechanics epoxy the existing well plugs but I never had any luck. They always leaked again. Here is where you can get o-ringed replacement plugs. Call them with your carb #. There is two sized plugs.
Carburetor Parts for Rochester Quadrajet, 4G, 2G & Carter AFB, AVS, Thermo-Quad Carburetors

Wow thanks for the info, I'll try that soon and post back here with my results.
:thumbup:

DoubleVision 07-26-2012 01:20 PM

More than likely it's the fuel pump. While yes Quadrajets do leak down the majority of it evaporates when it hits the hot intake so not much makes it into the oil. In my experience in almost every case it's the fuel pump.
When you replace the pump make sure you pack the pump cavity with moly or break in lube, this will assure the pump is lubed and will do so until oil can make it's way down to the pump. After you change pumps you'll have to change the oil and filter again as if you leave it then it won't be long before it'll cause excessive wear and it'll be rebuild time.

85impala 07-26-2012 01:29 PM

Quote:

Originally Posted by DoubleVision (Post 1577309)
More than likely it's the fuel pump. While yes Quadrajets do leak down the majority of it evaporates when it hits the hot intake so not much makes it into the oil. In my experience in almost every case it's the fuel pump.
When you replace the pump make sure you pack the pump cavity with moly or break in lube, this will assure the pump is lubed and will do so until oil can make it's way down to the pump. After you change pumps you'll have to change the oil and filter again as if you leave it then it won't be long before it'll cause excessive wear and it'll be rebuild time.

Cool, is there anyway to see if its the fuel pump?
Maybe unhook the inlet and wait for a drip?

DoubleVision 07-26-2012 02:08 PM

Not really, when the fuel pump gets ruptured it just drains down and follows the curves into the oil pan. It cost about $15 for a new fuel pump so even if I'm wrong and I don't think I am your still not out much by replacing it.

85impala 07-26-2012 02:16 PM

Ok cool thanks for the help

cobalt327 07-26-2012 11:44 PM

Quote:

Originally Posted by 85impala (Post 1577302)
Wow thanks for the info, I'll try that soon and post back here with my results.
:thumbup:

The newer Q-jets almost never leak at the well plugs. If they ARE leaking, the engine will either take a lot of cranking before it starts or will start then immediately stall until it's cranked or run enough for the float bowl to refill.

Below is what epoxy looks like after a brief exposure to gasoline. Marine Tex epoxy is supposed to last better but I've never used it to say first hand, and there are several types- Ruggles has info on Marine Tex if you ever wanted to try it (click on image for article on rebuilding a Q-jet):
http://www.crankshaftcoalition.com/w...y_on_Wells.jpg

And here's those cheesy little pads the rebuild kits include, before and after being installed for a while. Utterly useless:
http://www.hotrodders.com/gallery/da...ELL_PLUG_1.jpg

The method that has the best track record for staying fixed (no rubber o-rings or epoxy) is to tap the plug holes for a threaded plug as shown below:

http://www.mre-books.com/quadrajet/i...leakrepair.gif

There's a chance the fuel pump diaphragm is bad as DV said. Or that the fuel pressure is too high (you need ~4-5 psi). There's also a chance the needle and seat isn't shutting off the flow. Or that the float has become fuel logged and that is causing the float level to be too high. One thing that will sometimes help is to use a carb filter (the one that's inside the fuel inlet housing that the fuel line attaches to) with the spring loaded check valve on it, not the type w/o the check valve- either will fit.

In any event, if the carb is allowing fuel to get into the engine when it's shut off, I'd want to be real sure this wasn't also happening as you are driving- if it is, the excess fuel will wash the oil from the cylinder walls and that leads to rapid ring and bore wear. You might want to pull a couple plugs to check them for having black dry deposits- meaning a too-rich mixture.

DoubleVision 07-26-2012 11:54 PM

I just took the SMI Quadrajet back off my truck's 4.3 V6 so I could fix the main wells. All I did was the same as I always do, remove the base plate and give each one a good smack with a hammer. Then I'll lay the carb on top of a bucket, fill the bowl with fuel then peek in to see if any fuel is dripping out. In every case I've did this thus far it's solved the problem. The SMI Quadrajet I have had the main wells epoxied but they still leaked so I used a wire brush to remove it then gave'em a smack with a hammer to seal them off.

85impala 07-27-2012 11:26 AM

Quote:

Originally Posted by cobalt327 (Post 1577482)
The newer Q-jets almost never leak at the well plugs. If they ARE leaking, the engine will either take a lot of cranking before it starts or will start then immediately stall until it's cranked or run enough for the float bowl to refill.

Below is what epoxy looks like after a brief exposure to gasoline. Marine Tex epoxy is supposed to last better but I've never used it to say first hand, and there are several types- Ruggles has info on Marine Tex if you ever wanted to try it (click on image for article on rebuilding a Q-jet):
http://www.crankshaftcoalition.com/w...y_on_Wells.jpg

And here's those cheesy little pads the rebuild kits include, before and after being installed for a while. Utterly useless:
http://www.hotrodders.com/gallery/da...ELL_PLUG_1.jpg

The method that has the best track record for staying fixed (no rubber o-rings or epoxy) is to tap the plug holes for a threaded plug as shown below:

http://www.mre-books.com/quadrajet/i...leakrepair.gif

There's a chance the fuel pump diaphragm is bad as DV said. Or that the fuel pressure is too high (you need ~4-5 psi). There's also a chance the needle and seat isn't shutting off the flow. Or that the float has become fuel logged and that is causing the float level to be too high. One thing that will sometimes help is to use a carb filter (the one that's inside the fuel inlet housing that the fuel line attaches to) with the spring loaded check valve on it, not the type w/o the check valve- either will fit.

In any event, if the carb is allowing fuel to get into the engine when it's shut off, I'd want to be real sure this wasn't also happening as you are driving- if it is, the excess fuel will wash the oil from the cylinder walls and that leads to rapid ring and bore wear. You might want to pull a couple plugs to check them for having black dry deposits- meaning a too-rich mixture.

Thanks, all that info helps greatly.
Im almost positive its not happening while its running because the air fuel ratio gauge is around 14>15 so almost all the fuel is being burned.

The car does crank for a little while before it wants to start, I hit the gas a little and it fires right up so I'm thinking its the float, those plugs or the pump.

I haven't had a chance to check anything out yet but hopefully I'll get a chance today

85impala 07-27-2012 11:30 AM

Quote:

Originally Posted by DoubleVision (Post 1577486)
I just took the SMI Quadrajet back off my truck's 4.3 V6 so I could fix the main wells. All I did was the same as I always do, remove the base plate and give each one a good smack with a hammer. Then I'll lay the carb on top of a bucket, fill the bowl with fuel then peek in to see if any fuel is dripping out. In every case I've did this thus far it's solved the problem. The SMI Quadrajet I have had the main wells epoxied but they still leaked so I used a wire brush to remove it then gave'em a smack with a hammer to seal them off.

That's a few good ideas
Thanks I'll definitely try that
:D

85impala 07-27-2012 02:28 PM

Ok so I have a 86 olds cc-qjet I found in the garage, I'm going to do a quick rebuild, make sure everything is sealed up real nice then grab a banjo inlet and switch out the base plates because the throttle linkage is different.

Hopefully this will work but it's going to be a week or so before the banjo inlet and air horn gasket arrive in the mail :(

85impala 08-03-2012 03:26 PM

I got everything in the mail and switched the carb.. when I pulled the carb the intake seemed dry and so did the fuel line and inlet. What was weird is the float bowl was dry and the needle was seated but I could still blow a tiny tiny bit of air through the inlet.(on the old carb)

Now I have to do an oil change and bend the fuel line so it can reach the banjo inlet

Thanks again everybody for all your help, I'll update soon once she's running :D


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