Tweet
Help - I just went to start my '63 340 and had quite a surprise. There was a terrific backfire and white smoke started to roll out from under the hood. There was no fire, but once the smoke had cleared, the drivers side valve cover was blown clean off and the passenger side gasket under the cover was blown off. I had just ran the car for 30 minutes and parked it to clean up things under the hood. The car had run great and was at the normal temp -180- when I parked it. The engine had been completely rebuilt 2 years ago and now this engine has about 200 miles on it. I just pushed the car back into the garage and am looking forward to some advice. Thanks !
-
-
Re: Valve cover blown off
See if the fuel pump leaked into the engine. -
Re: Valve cover blown off
Is it possible you used an intake without a breather and valve covers without breathers? If that's not the case, I defer to the more knowledgable engine guys.
LarryComment
-
Re: Valve cover blown off
PCV system in place and functioning?Comment
-
Re: Valve cover blown off
AFB was probably dumpimg raw fuel, it accumulated in theoil pan/lifter valey as fumes and when you restarted, the fumes ignited. that's my guess. check out mr afb. good luck, mikeComment
-
Re: Valve cover blown off
I agree. I think that sounds like the crank case got filled with gas from a bad fuel pump and then ignited. TerryComment
-
Re: Valve cover blown off
Sounnds like you had a crankcase explosion. Check the condition of the oil pan, too.
The likely causes have been listed. I'd be interested to know if the PCV system is still to original spec with a properly functioning valve including anti-back flow feature.
DukeComment
-
Re: Valve cover blown off
Peter,
Yes, you have gas in the oil pan. It either came from the AFB or the fuel pump but you may have another problem. Usually the oil pan is damaged or completely ruined when the little explosion occurs. Check it out carefully.
Your engine will probably be OK as moly rings will reseat if they are as new as yours should be with the rebuilt.
Make sure you know the source of the leaking gas before you hit the ignition switch again. It WILL happen again if not diagnosed and repaired properly.
Keep us posted,
JRComment
-
Re: Valve cover blown off
The same thing occured to me about 2 months ago. The fuel pump on a friend's motor had failed and filled the crankcase with fuel. I replaced the pump and changed the oil. I never thought about accumulated gasoline fumes under the valve covers. I had the engine cover off and was sitting right next to the engine when I cranked it over and the driver's side valve cover blew off. It scared the you know what out of me. I feel luck that I wasn't injured.
I was lucky that the other valve cover and the pan were both fine.Comment
-
Re: Valve cover blown off /add. ?'s
Thanks to all on replies. It looks like afb is coming off, oil change and pan inspection. My question is how can a defective fuel pump lead to this problem? I always thought pumps fail due to too low of a flow.Comment
-
Re: Valve cover blown off /add. ?'s
the fuel pump diaphgram ruptures and allows gasoline to enter the oil pan thru the oil drain back hole in the block below the fuel pump pushrod.Comment
-
Re: Valve cover blown off /add. ?'s
Peter,
The fuel pump can fail for a number of reasons. There are a number of springs, diaphragms, and the valves within the fuel pump assembly. It is quite typical for the main diaphragm to tear or rupture. When this occurs, fuel is free to bypass and head for the crankcase. The manufacture provides a small weep hole on top of the pump body to relieve back pressure on the diaphragm and also to let out some of the by-passing fuel , should the diaphragm fail. Under normal conditions, if the diaphragm were to fail, you would have a small amount of fuel dripping from the pump body weep hole. This would alert you to a failing pump. That is if you parked on concrete where you would notice a wet spot under the car. Or you would be alerted by the smell of gasoline, unless your sense of smell was dull or you have other fuel system problems that make your car constantly smell like fuel and you've trained your sense of smell to ignor the fuel smell as 'normal'.
Many times this hole may be plugged with dirt and grime, and the problem goes un-noticed until a sufficient amount of fuel has accummulated in the pan to cause serious problems.Comment
Comment