Code P0304, cylinder 4 misfire.

I pulled the plug wire, had koisture (coolant) on it. Used airgun to blow out spark plug hole before removing spark plug, cleaned all, put back together, and back to normal running. Before I pulled it I would have an occasional miss.

Anyways...

What is causing coolant by my plug? I have read a lot about the lines for the heater core leaking, but I sat there watching it while running for a half hour last night and not the first drop. Any ideas?


-Matt

 

Did you have the heat turned to full on? Did you rev the engine at all? I still have nightmares about that code...turned out to be a head gasket for me though. There is a test that can check for exhaust in your coolant but at the moment I cant remember what it was called. GL

 

Hydrocarbon test.....

Could be an intake gasket
How many miles, 4.6 right?
I still wouldnt rule out the hose yet though.

 

4.6L. 143k. I dont think its headgasket, as I have blown a couple of those throughout my driving years, and I have no problems with smoking, plug fouling, etc.

Yes this was with the heat on high, I drove it around as well to get it warmed up. Just seems odd that it only happens in the winter months. I had this happen last winter, I cleaned it up, and never had the issue again. Went all summer with no problem. This is what leads me to believe it has something to do with the heat. Who knows. I will keep an eye on it and see what happens.

Another idea I had, and I know it isnt the brightest ever, but maybe someone can modify the idea for me would be if there was something I could put on the connections for the heater core (something like a terry cloth, or something that would show a discoloration) if and where it leaks. I was kicking around the idea as a way to try and track down the leak since it doesnt want to come out and play when I want it to.


-Matt

 

Just a shot IIRC someone here had an issue with the rubber seal/weather strip on the hood leaking and having a simular problem. Might be worth looking at.

 

Those hoses leak when your not watching lol. Serious, -usually A short pressure burst here and there may cause it to dribble for awhile, then stop.

I'd still confirm it's not a gasket as well. Do some checkin around, - look behind your Alternator , -in the block valley. Check for coolant their as well.

You can pressure check the cooing system for leaks. If you see lots of bubbles in the degas bottle, - it's a gasket for sure.

Color of coolant okay?

 

Yea, but mother nature doesn't water the world with coolant lol. The OP found coolant in #4, not water. But yea, that seal can leak. I know what your referring to.

 

I cleaned up the motor really good before I went to work on it, just on a long shot of it being a gasket. Is there any way i can reinforce the seal on the hose with a typical hose clamp? Would this be worth my time, or just a waste? Thanks.


-Matt

 

If the coolant is in the spark plug well, how could that be caused by a head gasket? Did I miss something?

If you're worried about the heater core hoses leaking, why not just replace them? At 143k I'd say it's about time to replace ALL the hoses anyway. I just did all this on mine and iirc those two hoses cost about $60 at the stealership.

 

Guess I did leavt that open a hair.. The coolant is top side on the spark plug, not down in the cylinder. Ive been running all week with no issues, but watching it closely. I will probably do new hoses when I have time, but right now work is crazy, along with a few other things, so the truck is kinda sitting back burner. If anything else happens, Im sure I will be on here trying to figure it out.


-Matt

 

Ford hoses will out last your truck lol. They'll never burst, but they can leak at that hose clamp connection. I replaced mine solely because of that. Those two hoses are more than $60, - maybe apiece ? Well, if you can find them for that, grab them, - specially Ford hoses with the correct fittings and brass reducer that's embedded. Their not cheap, but their BETTER than ANY other supplier has to offer. Also, use expansion clamps, - specially made for heater hoses. Their solid, won't tear into the rubber and expand/contract with heat. I found those at O'Riely's/Murrays stores.

 

The ford hoses were the only ones I found that came with the fitting, which is why I was willing to pay the big bucks. One of them has a flow restrictor (on the 4.6L anyway) which also didn't come on the other ones. You may be right about the $60ea. It helps to know someone in the parts dept. I started getting deals because I was at the dealership so many times the week after I bought my truck that the guy started feeling sorry for me. There is always the option of calling Tousley Ford in Minnesota and telling them you're a member on SVTPerformance and they'll give you 10% over cost.

As for ford hoses lasting longer than the truck......well......I wish I had pics of the cracks in mine @141K.

 

You can also order from Tasca.

https://www.f150online.com/forums/20...over-cost.html

 

Well, - to whom ever ends up changing out these hoses~

If you fill it this way to begin with, it's so much easier lol. Sometimes their a PITA getting the pockets out.



Use expanding clamps on the engine side /core hoses. Their solid + they expand and contract. You just have to make sure you don't over torque them. That's what I hate about those, - it doesn't seem like enough, - I guess it is. - Mine are still on..

 

Got the same code on my '98 F150 5.4L. At 140k miles I figured it was time for a tune up anyway, and considered myself lucky to have made it that far on the original plugs. I disassembled half the electrical system to get easy access, pulled the fuel lines out for a little more room, removed the COPs, then went to blow out all the debris with compressed air before yanking the plugs.

That's when I noticed some moisture back towards cylinder 4 around the heater hose J-tube at the back of the engine. I decided to blow the standing water off with compressed air to get a better look, and as soon as I did I destroyed the gunk plug that was holding back the leak. I had been smelling a hint of coolant for some time, but as soon as this little dam burst the smell was unmistakable. Now I know why cylinder 4 is misfiring.