Oil Fouling Rear Plug, Gas in Oil, leaking from plug

[1964FLDUO]

Hi guys, I have been having some problems with my 1964 Panhead fouling the rear cylinder's spark plug and thought you might be of assistance. The problem is the rear plug is fouling to the point of completely failing to fire when riding around town or in traffic. It is also smoking out the rear cylinders exhaust pipe when coasting down hills, but not so much while under throttle. When I would stop and pull the spark plug after the bike died it was black and wet, so I assumed it was oil fouling, but upon further inspection I have determined that the oil in my oil bag smells like gas. I still believe it is oil because of all the oil around the outside of the sparkplug hole. I know an intake leak can cause fouling problems so I decided to test the manifold for leaks using an adaptor plate on the intake and a bubble test. After bubble testing I determined there is no intake leak, but air is leaking from around the rear spark plug hole quite significantly even with only 10 psi. I tried putting a different plug in and think that there is some damage to the crush washer surface as you will see in the pictures I have attached. Could this be causing my problems, I'm sure it is at least causing extremely low compression while running as there is oil all over the around the plug hole. You will notice there are two blemishes on the surface of the plug hole insert, I was told I should replace the insert as this is where it seems to be leaking from. Oh, and I almost forgot, I had the heads rebuilt twice this year and they have new guides valves etc. And thanks to Cotten for the info.

Rear Head

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Front Head

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Front Plug

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[nmaineron]

I would try some teflon thread tape on your plugs to see if this changes things.But I really doubt that this is your problem,I would pull that head and check for valve depth and guide fit in the head and on the valve.Sounds to me that you are sucking oil into the cylinder.

[Hog54]

My plugs actually fit loose because my threads are worn and I dont get that.You shouldnt have any oil in the combustion chamber to even push out the plug holes unless your rings arent seating right or something.And why did you need your heads rebuilt twice in one year?

[1964FLDUO]

To make a long story short, the whole reason I pulled the head was because the plug was oil fouling. I also pulled the cylinders and replaced rings and honed the cylinders, even though the compression test results were fine. So I take it to a guy who "specializes in antique motorcycle" and I tell him all of the problems and tell him to go through it and fix everything that needs fixing. He talks me into pulling the front head also so they both get done and I wont have to worry about it so I bring the front head to him. He goes through the heads tells me all the guides and intake valves are fine, but the exhaust valves are galled and need replacing (this is the point I should have started questioning him or when he tried to "clean up the galling" on a wire wheel). How valve stems can be galled and guides not damage I don't know, but I let him replace the valves and he also sent them out to get the seats cut. So, $700 later, I put them back on and go through break-in procedure because the rings are also new after about 300 miles the rear plug is still oil fouling, so I call him and tell him and he says bring it by. I bring it by and he performs some various tests: compression, squirts oil in and performs compression test again; same results. I even let him road test it around the neighborhood, he comes to the conclusion that I need to pull the heads to figure out what is wrong. Thinking he is going to make it right I pull the heads and take them to him. He says he'll get right on it so I leave them with him thinking its going to be fine. So I tend to periodically check in when someone has my stuff and after five days I give him a call to see whats up. He tells me the guides need to be replaced and the intake valves since it wasn't done before (see red font) So I even go pick them up from the supplier and hand deliver them to the guy to speed the process up. After I deliver those I start playing the waiting game, one week goes by and I call him, no answer. I decide I'll try him the next day, no answer; So now I'm thinking this guy is messing with me, so I start doing some door knocking. I go and knock on his door for three days in row and wait for 30 minutes each time and he still isn't answering. I leave him notes at his door, and he still wont call me, so now another week has passed and I am pretty much thinking the worst now and getting pissed. So I go knock on his door and knock and knock and after 30 minutes or so he finally answers the door. He ends up telling me some bull shit story that he went on vacation, and he didn't know he was going on vacation. So by now I know this guy is a total bull shitter, so I cut to the chase and ask where my heads are and he tells me that he sent them out to get new seats cut and its going to be $100 to get the new seats cut, when its his fault it wasn't done right the first time. He tells me that he will call the guy to see if they are done. He calls and says the guy isn't there and he will call later and let me know. He calls me at about 7PM and tells me that he called the guy and that they will be ready in the morning. So I was in the area the next morning so I just stopped by and he says its $125 more; 25 for the guides that I PICKED UP, and 100 because of all the work he had to do assembling them, he even has the nerve to say its not his fault I'm having problems its because "I didn't want to spend a lot the first time around"(see blue font),

And believe me that was the short version of it. I'll never deal with this son of a bitch again.

[Hog54]

Well I would have them checked again by somebody else because he forgot something.Maybe seals.All I know is I get no oil leakage and my plugs are really loose and I dont get any smoke and mine were done 15 years ago.Im using the same plugs too! Autolite platinum plugs are good for a 100,000 miles you know.

[Panacea]

Sounds like a bummer, sadly it sounds like you'll have to find a qualified shop or ship the head to headHog. Look on the bright side, It's Winter!

[indianut]

Am I the only one that sees the crack?

[58flh]

I think Indianut hit it & that coil set was shot during installation--liitle off center with the tool----but like flathed said You could run even iff your sparkplug holes are fubared,& not look like that plug.The gas is just unburned fuel mixing in with the oil.If the head pic was cleaner in that spot you would see it more but its a snakey long crack.from the looks on my 15year old moniter.----58flh

[Hog54]

I have a good monitor and I dont see a crack?

[indianut]

I have a good monitor and I dont see a crack?

Then maybe you need Glasses. In fact the more I look at it the more cracking I see. I'll bet the oil Feed is pumping oil Directly into the CC and fouling the plug. May be fixable, but this is typical of one of the reasons I tend to shy away from top end work on Pans. And Knuckles. And Shovels.
FLATHEADS RULE! Except I am currently dealing with a multiply cracked Sport Scout cylinder!

[58flh]

HOG54---Look at the pic with the arrow on it. ,bottom right side of plughole, thats just the tailend--indianut spoted that quick ----Richie

[Cotten]

Folks,

First, we all know that gas in the oil is a petcock problem.

Ordinarily an airleak would make a cylinder burn lean, so if the plug fouling is indeed oil that does not dry sooty, and we dismiss the fresh rings (modern rings do not "break in" by the way...), then we are left with three common points of entry to the combustion chamber: Through an intake guide, around an intake guide, or at the drain hole in the head gasket.

The airleak at the plug may well have elevated temperatures to the point of warping the head enough to allow the headgasket to breach inward. Naturally all heads should be ground flat as part of an overhaul, and even torque upon re-installation is critical.

An oversized seal washer may alleviate the plug leak, but the damage has been done.

....Cotten

[1964FLDUO]

Also I forgot to say that the last time I pulled the rear head oil started leaking out the head bolt hole nearest to the rear left of the bike. Upon inspection there was no crack, so it had to leak from the drain hole to the bolt hole somehow, why there was still that much oil in the head after sitting I don't know. I checked to make sure the passages weren't clogged.

It sounds like I'm going to have to pulled it no matter at this point, oh and the "crack" you all see wasn't on my head before the guy who worked on em touched them, upon inquiring as to what happened he replied that " I should keep an eye on that, and that it was only cosmetic" I will post pictures of where I believe it originated.

Notice the two marks where it appears something was dropped on the head or something hit the head and the crack right next to the marks (wouldn't suprise me since they were sitting on the floor when I went to see them)

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[Huck]

Just a thought. I just went through a puzzle with my rear head, I was looking for an oil leak. Turns out my head is cracked. Looking at your pic it starts just to the right of the non pointer end of the arrow and continues under the fin. It leaks oil out. I did all the normal compression and leak down tests prior to finding this leak, all was good. Clean the area well. Put the spark plug in. Add some snoop remove the timing plug and gently add air to the crank case and see if you’re leaking. Mine leaks oil out right under the fin, you really have to get your nose in there and look, it's coming from the oil galley return. Maybe yours is leaking out and also into the combustion camber? Nobody cares about that head more than you, you'll figure it out! Good luck and let us know.

[cosmiccowboy]

both my heads have those same semi circle marks on them so i don't think thats the culprit. I too have air leaking out my sparkplug hole but no oil fouling. someone mentioned earlier in this thread to use teflon tape. will that stand up to the heat or was that just a method to eliminate the threads as the source of the leak and remove befor running. I don't see a crack in my head but I haven't pulled them for close inspection yet. I suspicious that the threads are leaking and if teflon tape is the answer I would like to try it. cc