I have a 98 F150 with a 4.6 V8 with 82,000 miles.

The engine started misfiring, code indcated that it was cylinder #5 which is the front driver side plug.

I picked up some plugs and when I pulled the plug wire for number 5 it was wet with antifrezee. The plug is recessed and there was antifreeze around the plug. Actually the antifreeze was up to the top of the plug.

All the plugs, including #5, were in good condition for 82,000 miles. It ran fine with new plugs.

I want to know where the antifreeze came from. Could this be a problem with the intake manifold gasket? I thought about putting some barrs stop leak to see if this would cure the leak.

 

most see a coolant hose that drips down into the plug from above causing a repeat misfire after replacing the plug and wire

 

Bentwrench

The coolant covered the spark plug as if it was poured into the recessed area. The area where the coolant the found is sealed by the plug wire boot. I looked for evidence of a leak but can not see any. So the coolant didnt leak down from above.

Has anyone taken a 4.6 apart that can tell me if this could be a gasket problem aloowing coolant to get under the spark plug boot.

 

Justfishing, are the plug wires the stock ones or OEM? If so, then it may in fact be a coolant leak from above, and the cylinders behind that one have a good seal, and that one is the only one that actually allowed coolant to leak down into the plug well. I haven't heard of any issues of any coolant leaking from anywhere else, but that is definitely what I would do is change the hose clamps on any hoses above the engine, there was a TSB on it. You wouldn't notice the leak, either, it's a slow leak, but it builds up in the plug wells.
Let us know what you find out.

 

Pickupman

I looked for signs of a leak but coudnt find any traces of coolant other than under the boot in the spark plug well. I am going to flush the cooling system and put some barrs stop leak in.

There are so many tubes/wires etc that it hard to see. The intake manifold is close. I am wondering if the gasket sprung a leak. That seems like the only place it could come from other than a cracked head.

The plugs in this engine are completing recessed, you have to look down in the hole to see the plug at all. The boot seals the all mositure out. Becuase of that I dont think it is geeting in from above. That is why I am thinking it is a intake manifold gasket. Dont think it coud be a head gasket...at leak I hope not.

 

Justfishing, it would be uncommon for the hoses to leak down onto that side of the engine, and it very well could be the gasket leaking. The OEM boots seal very well, but if the antifreeze got down around the boots and that was the only one that wasn't sealed perfectly, then it would have moisture. You won't see any evidence of the hoses leaking other than this. I have a 97 4.6, I understand how the plug wells are, but I am thinking that the leaky clamps are on the passenger side, usually plugs 3 & 4. I am not sure, but I don't think that any hoses run over the driver's side, so in your case, you may be right, but if the plug boot is sealed completely, then it would have to be leaking under where the boot seals, and I hope not, because that would be a headache. On cylinder # 5, though, I am not sure where any anti-freeze would be coming from other than a leaky gasket. Are you extremely low on anti-freeze? I had this problem, and it didn't look like it was very low, but like I said, I was on cylinder #4. If it is anything other than this, I would hope that it is an intake manifold, because that would be a whole lot easier to deal with than a cracked head, not to mention a whole lot cheaper. When I had the leak, there was no evidence anywhere of any leak at all, except for the tip of the plug boot having anti-freeze on it. It evaporated from everywhere but there, but that is an area that is dark and not ventilated at all (ideally), so the moisture will hold in the plug wells, and they foul the plugs, because they are sitting in liquid when they fire. Are you sure that it is anti-freeze? Here is what my plug wires looked like when I pulled them out.






That's a hard plug to get to, too, it takes a couple of small extensions put together, and you have to get the socket onto the plug and the extensions in place before you can put the ratchet on. I would change that plug clean everything around the entire area (hoses and all), then try to see if you can find any stains of where the anti-freeze is coming from. Definitely don't want to overlook the intake gasket or a possible leaky head, but don't discount that it could be coming from somewhere else, either. Let us know what you find out, and good luck!

 

Pickupman

That what it looks like. Mine is on the drivers side front plug...#5.
The coolant completely covered the plug so it would be shorting out. Blew out the coolant and replaced the plug and it ran fine for 2 days. Started misfiring again so I pulled the boot this morning and it was dry.


It time for plug wire anyway so I am going to replace them. If it continues then I guess its either a coil or fuel injector.

 

maybe you could pull the boots and pump up the cooling system with a pressure tester. then maybe it would be easier to see where it is comming from.

 

misfire was from dirty connectors for the fuel injectors. The shop pulled the connectors and found corrision. Cleaned and lubed the connectors and she is running again.

 

Go to www.leakingfords.com

They describe the coolant leak condition which results in fluid buildup in the cylinder. Prevents the piston from compressing and can result in broken or bent rods. Speaking from experience - I'm having to replace or rebuild because of what happened. If you're having coolant leak into that cylinder, it may be escaping as steam. But because it is pressurized, it will eventually fill an intake valve that is open if the gasket is broken. When that happens and you try to start the engine, you run the risk of having to replace. The website tells you all about it.

 

That problem referenced on leakingfords.com is indiegenous to 4.2L six cylinders. Not the 4.6L V8. Im having the same problem. I have replaced the wires, plugs, and did the coil pack swap, only to realize that a small micro sized jet of water will drip down and coat the plug and wire causing the misfires.