p0304 AND Overheating

[wrldky]

Son brought the truck home today and it overheated. 2002 Discovery SD, 200K miles. Hooked up code reader and came up with a P0304 misfire cylinder 4. Engine is banging like crazy near the top of the engine passenger side. Any ideas? troubleshooting?
After it cooled down and we fired it back up without driving it and it didn't seem to overheat but I'm sure it would if we drove it.

 

[jymmiejamz]

Is it low on coolant?

 

[wrldky]

Hard to tell because by the time I got to the car my son had removed the cap off the coolant reservoir and it flowed out. I will drive it tomorrow.

 

[mlnnc]

The misfire and the overheating are almost certainly two different issues. One at a time.

First the overheating. Refill the reservoir and keep a close, close eye on it. Daily. Or twice daily. Or three times. Or more. How fast does it go down. BTW don't refill it as soon as it's down a little. Refill it only when it's down 3/4 or so. Watch it and learn from it. The speed of coolant loss can help with the diagnosis.

As for the misfire code what's the history for the plugs and wires?

And as for the "banging like crazy" can you record and post a video so we can hear what it sounds iike?

 

[jymmiejamz]

The misfire and the overheating are almost certainly two different issues. One at a time.

They often go hand in hand.

 

[K-rover]

The banging is probably the cylinders trying to compress coolant, which it doesnt do well

 

[rovercanus]

They often go hand in hand.

That was my thought as well. sounds like head gakets.
Pull number 4 spark plug and see if it's steam cleaned or if there is coolant in the cylinder.

 

[jymmiejamz]

That was my thought as well. sounds like head gakets.
Pull number 4 spark plug and see if it's steam cleaned or if there is coolant in the cylinder.

#4 would be a cracked block, not a head gasket. Coolant in cylinders 3,4,5, or 6 is a crack block or (rare) cracked head. Coolant in 1,2,7, or 8 is likely a head gasket.

 

[rovercanus]

#4 would be a cracked block, not a head gasket. Coolant in cylinders 3,4,5, or 6 is a crack block or (rare) cracked head. Coolant in 1,2,7, or 8 is likely a head gasket.

Unless the head gasket is just bad. Don't go all PT on us.

 

[distrovol]

Bump to see how this turned out.

I have coolant in cylinder 4 and misfiring a month after a head gasket job. It wasn't doing it before the job but hard to argue with JJ's logic as there are no coolant passages in that area of the gasket.

 

[distrovol]

Update: I believe the problem is in the head (cracked) as I am not getting any mixing of coolant and oil, but coolant is getting into the cylinder and coolant system was pressurizing. Not a huge amount, but enough to misfire at start up and occational rough idle. I pushed a string into the spark plug hole and it came out wet. Not having much to lose and it about killed me to do it, I put in a bottle K Seal in it per directions and believe it or not, no longer misfiring, rough idle, no white smoke, or coolant loss. I am cautiously optimistic as I love the truck and want to hang onto it a while longer. I will try and bump the thread a while down the road regarding any adverse affects from the K Seal (for posterity).

 

[jymmiejamz]

It would be very rare for a head to crack, but it is definitely possible. A crack in the block is way more likely.

 

[distrovol]

I don’t disagree and you may be correct. When I took off the plastic air plenum and looked into the throttle body I saw what looked to be coolant condensate collected inside on the inlet side of the throttle butterfly flap, like it was coming back through the air intake. It was odd considering the oil is not at all milky and is still clearish amber and zero smell of coolant. That is what makes me suspect the head, and considering this wasn’t happening before the head gasket job. I welcome the boards opinions.

 

[discostew]

I would be checking the block. You can clamp off the coolant passages in the block by clamping a piece of steel and some cork gasket sheets down onto the coolant ports at frt and rear of block. Then cap off or whatever you gotta do to hold pressure in the block. You will see it bubble out around the sleeve. Between the block and sleeve.
And if you get the head off and #4 looks like it's steam cleaned you really don't need to go any further. Because unless you have one of the only cracked heads in the country, the coolant came up from the block.