gas smell in engine oil in 300

gregamorton · Post by **gregamorton** » Mon Sep 14, 2009 8:53 pm

Guys I got me a 75 f500{has the 67-72 body} with a 300 six this last weekend. After tinkering with the truck a little I got it to start. The carb runs ruff over idle but smooth as silk at idle. There is a lot of trash in filter right before the carb and it doesn't have one before the pump. The truck has set up for several years and the motor is not the original because it doesn't have the heavy duty manifold on it. I got the truck in shop and running it sounded like I could here the lifters or rockers clicking. My thinking is that there was a little gas getting in around the pump due to the trash. I heard that happens sometimes on the pumps with the old trashy gas. I dumped the oil out of engine and it was super thin and it did smell like old gas. I am going to change to a new fuel pump and put a filter before it to be on the safe side. My question to yall is due you think it will be alright after I change oil and pump or could it be the carb dumping to much fuel with old rings? I also checked and it didnt have a thermostat so I will be putting in a 195 tomorrow. I have never had a 300six and I think I could build up a neat old truck with some advise.

fordman · Post by **fordman** » Mon Sep 14, 2009 9:18 pm

it could be gas past the rings.

Blue Cloud · Post by **Blue Cloud** » Mon Sep 14, 2009 9:25 pm

It might have flooded when you were trying to start it. I'd try adjusting the carb and watch it close for a few days to see if you have any more gas smell in the oil. Also changing the fuel filters is a good idea. Watch your water pump for a couple of weeks, they usually go out after sitting a long time.

Post by **70_F100** » Mon Sep 14, 2009 9:35 pm

It's very possible there is a leaking diaphragm in the fuel pump if your oil smelled like gas.

Go ahead and replace the pump. For the small cost, it's good insurance.

gregamorton · Post by **gregamorton** » Mon Sep 14, 2009 9:44 pm

I hope it is just the fuel pump. I would think the carb needs a rebuild after sitting. The guy that had it quit using truck because the carb was having fits. When I first got it running, it was pouring gas out of the 2nd base gasket(what it looked liked to me). The next day it didnt run out so I assumed the gasket had sealed off. The truck has a 16ft bed on it and if I get running good I might build me a car hauler out of it. Do any of yall know how the brakes work with a vacuum booster under the truck? That is a first for me also.

Post by **70_F100** » Mon Sep 14, 2009 10:17 pm

That's called a hydrovac.

Basically, it's a remote-controlled booster. The master cylinder operates a slave cylinder on the booster unit.

fordman · Post by **fordman** » Mon Sep 14, 2009 10:19 pm

i missed that it was a F500.

Post by **70_F100** » Mon Sep 14, 2009 10:21 pm

fordman, that shouldn't matter on the engine, just on the brakes.

Your diagnosis could apply to both.

fordman · Post by **fordman** » Mon Sep 14, 2009 10:24 pm

i know . i was just thougth it was funny when he said the booster was under the body until i looked at his first post again. i once worked on a international that had the booster on the frame. and it had air brakes too. i dont knwo what kind of deal he had going there. but the brakes never would come around. he didnt want to spend any more money on them. it needed a master cylinder.

gregamorton · Post by **gregamorton** » Wed Sep 16, 2009 6:23 pm

guys I looked in my books and it didnt show if my 300 has adjustable rockers or not. My engine has very loud ticking but I have never been around a engine with a problem of any knocks or whatever. I changed to new 10/30 oil with one quart of lucas and it still has the ticking and it gets louder as I rev the engine. Does this sound like lifters or rockers or could it be the rods?

JMcTurnan · Post by **JMcTurnan** » Wed Sep 16, 2009 8:56 pm

Ok, well I got a good idea. Same thing that happened to me, if its carburetred than yes. My gas leaked out my my carb into my oil, when it was off it just slowly drained, and burnt my bearings out. So I had knocks from piston bearings. But I ended up putting a knew crank kit in.

NM5K · Post by **NM5K** » Fri Sep 18, 2009 4:25 am

gregamorton wrote:guys I looked in my books and it didnt show if my 300 has adjustable rockers or not. My engine has very loud ticking but I have never been around a engine with a problem of any knocks or whatever. I changed to new 10/30 oil with one quart of lucas and it still has the ticking and it gets louder as I rev the engine. Does this sound like lifters or rockers or could it be the rods?

Ticking is usually the valve train. Knocks are usually bearings, etc.
The rockers on the 70's 300 are generally considered non adjustable due to
the design of the rockers and studs. They were designed to be tightened down
all the way down with push rods that are the right length.
But there is a way to convert them to adjustable. Add a 2nd nut on top
of the regular adjusting nut. But invert the top nut, and use it only to lock
down the lower adjusting nut. When I adjust valves, I prefer to do it with
the engine running. If you slightly loosen one, it will start to clack.
If you tighten it back up, there will be a point where the noise quits.
That is "zero lash". When I adjust them, I'll get to zero lash where the ticking
stops, and then I'll tighten down about 1/4 to 1/2 turn farther and lock it down.

Steve75 · Post by **Steve75** » Thu Oct 08, 2009 12:05 pm

gregamorton wrote:Guys I got me a 75 f500{has the 67-72 body} with a 300 six this last weekend. After tinkering with the truck a little I got it to start. The carb runs ruff over idle but smooth as silk at idle. There is a lot of trash in filter right before the carb and it doesn't have one before the pump. The truck has set up for several years and the motor is not the original because it doesn't have the heavy duty manifold on it. I got the truck in shop and running it sounded like I could here the lifters or rockers clicking. My thinking is that there was a little gas getting in around the pump due to the trash. I heard that happens sometimes on the pumps with the old trashy gas. I dumped the oil out of engine and it was super thin and it did smell like old gas. I am going to change to a new fuel pump and put a filter before it to be on the safe side. My question to yall is due you think it will be alright after I change oil and pump or could it be the carb dumping to much fuel with old rings? I also checked and it didnt have a thermostat so I will be putting in a 195 tomorrow. I have never had a 300six and I think I could build up a neat old truck with some advise.

The fact that the truck has been parked for so long cuases a lot of issues. The clicking noise is difinitely coming from the valve train. I experienced the same problem with my V-8. Sticky lifters. After while they gummed up. I believe my Dad put some CD-2 oil detergent in it and it took care of the problem. As to the gas smell in the oil I would look at the carburetor. Before getting to carried away turning wrenches check your timing and make sure that the vacuum advance is working. Pull the distributor cap and hook up a hand vacuum pump and test the advance make sure everything is moving freely. Also check the plugs they may need replacing. Bascially do a complete tune up of the ignition system. If this does not cure the problem then move onto the carb.

Clean and rebuild the carb that will cure the issue with rough running engine above idle. Replacing the fuel pump is something that would be done at a reasonable price, so if you think that might solve it try it. Also at some point you might want to run a compression check on the engine.

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gas smell in engine oil in 300

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