Took a trip over the weekend and had a hard time getting up a mountain. Got a P0304 misfire on cylinder 4. Later on I got a misfire on cylinder 2. I made it home OK but today while driving I noticed steam out of my exhaust pipe and smelled antifreeze. The temperature gauge never got hot and I made it home. The reservoir was filled to the top with boiling water. Any ideas?

The only code I had before this was P0304 which I had for years. Replacing EGR valves and DPFE both twice and checking all tubing and hoses only <cite>temporarily fixed the problem.
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Blown head gasket maybe, what engine & year model do you have????
Edit: Pull the engine oil dipstick & look for signs of moisture on it, or a milkshake look to the oil on the dipstick. Look under the oil fill cap & down into the valve cover too.

 

Blown head gasket

 

Checked the dipstick and it was normal. No milkshake when I checked it after running it. Oil was dark but it is about time for an oil change. I will check the oil cap tomorrow. This is a 1996 3.0 liter.

 

OK, good feedback.

The 3.0L is known for cracked, or warped heads, especially after over heating, so did this problem begin after such an event????

Maybe pull the radiator cap & start the engine & look for exhaust bubbles in the coolant.

If you find bubbles in the coolant, pull the spark plugs on the two cyl's you have codes for & look for signs of coolant on the plugs, or for spark plugs that look like they've been steam cleaned.

You might also consider doing a compression test on those two cyl's.

Keep us posted on what you find.

 

After the engine warms up it expands, this lets compression gasses into the cooling system, hence the symptoms. When the engine is cold it hasn't expanded and the compression gasses are contained.

+1 on the radiator check for bubbles, it works better when there is no thermostat in the cooling system.

 

Also if coolant is getting into the combustion chamber & being conumed, the exhaust should have a sweet odor.

If the head is cracked around the combustion chamber, or the block around the cylinder, exhaust gasses can be pushed into the cooling system & overheat it & thus the exhaust gasses/bubbles should show themselves in the coolant at the removed radiator cap location & the plugs in the suspect cyl's you have misfire codes for may show signs of coolant in those cyl's.

If enough coolant is getting into those two cyl's to clean the plugs, the oil cap, or dipstick may show signs of moisture, even though the oil isn't a milkshake color.

 

I did notice signs of coolant on the oil cap. Hours after coming home I opened the radiator cap and heard bubbling in the overflow reservoir.

Hear is a history of this truck. Early last summer I ran the air conditioner and soon after the truck stalled while driving. I kept starting and driving about 100 feet until it stalled again. It did this all the way home. The next day it was fine and never did it since.
Six months ago my check engine light starting flashing and my truck was running like crap. I pulled code P0306 missfire in number six. I shut it off and started it up and it ran fine and I never got the code again.
Two months ago I started it up and it ran like crap. Shut it off and started it again and it ran fine. It didn't give me any codes.
Now the long trip over the weekend getting missfire in 2 and 4.

What caused these misfires? And does this normally blow head gaskets or crack heads?
If I decide fix it, I still have to deal with this misfire issue. Thanks for the input so far.

 

Still a bunch of unknowns.

We don't know where you are on All past & present due scheduled maintenance, like spark plugs & wires, which could have been playing a part in your past misfire codes.

Thermostats, radiator caps, belts, hoses & coolant need attention on a scheduled basis too, so coolant thats been ignored can become acidic & get after head gaskets & metal & can cause them to leak, or blow under pressure.

Bad coolant can corrode the cooling system metal & cause it to not conduct heat well & the engine to develope hot spots, which can cause cavatation that'll mess with the block, water pump impeller & that & acidic coolant can erode it & cause a loss of coolant flow, further messing with the coolant systems ability to do it's thing.

An acting out radiator cap can mess with cooling system operating pressure & that can affect the coolant boiling point.

Anyway you get the idea, many things may be in play here, so we need to get some maintenance background history on this engine & you need to do some more diagnostics, to try & ascertain the root cause of your misfire codes & coolant system acting out, the coolant boiling & coolant signs on the oil fill cap.

Have the coolant system pressure tested, most autoparts stores will do it at no cost.

If thats ok do a compression test on the cylinders with the misfire codes & maybe do a blow down test on those cylinders too.

If you're not sure of the test results, but think you have coolant showing on the oil filler cap, pull an oil sample at the next change & have Blackstone Labs do a UOA & look for coolant in the oil.

Does it seem to be using coolant, such that you have to top off the recovery tank on a regular basis????

By then you should have a fairly good idea whats going on with your engine.

More thoughts for pondering.
Let us know what you find.

 

Spark plugs and wire where replaced last summer. I never replaced the coolant. I do have to add coolant once in a while to fill the radiator and reservoir. I am not driving the truck until I get it fixed. If I drive it now, won't it damage it more?

 

Well if it has coolant in the oil it sure won't do things any good, the bearings can be damaged just sitting there if there is lots of coolant in the oil.

So if it's been using coolant & you can't see any external leaks, with the symptoms you've posted, an internal coolant leak problem belongs high on your suspect list & if your going to let it sit, pull an oil sample for analisis as it can confirm coolant in the oil & how much engine wear it's causing.

Then change the oil while it sits & you figure out how your going to trouble shoot your problem/s, yup, you may have more than one & as such they may confuse your trouble shoot, so keep an open mind & go about it systematically so you get definitive results.

When last was the coolant changed & what kind of shape is it in now????

A coolant leak into a cylinder can cause a misfre, so keep that in mind.

I'd first try & run down the recovery tank boiling scenario you posted about & I'd probably begin with a coolant system & radiator cap pressure test, then move on to a compression & maybe a blow down test, at least in the cyl's you have misfire codes on.

By then you should have an idea whats going on & if you need to tear into the top end of the engine.

Still lots of unknowns, so we're doing a lot of guessing at this point. Do some trouble shooting & post the results.

 

I had a nice day to check the compressions.
1: 130 psi
2: 35 psi
3: 137 psi
4: between 120 and 130 psi because I forgot to write it down
5: didn't check
6: 120 psi
I cranked the starter for about 6-7 seconds and didn't push the gas peddle. Spark plug in number 2 had the center missing and was black and oily. I mean down below the white part in the middle. And it was wet and number 1 was a little wet also. The rest where dry for the most part. Weird because number 4 appeared OK but I got a P0304 code.

A mechanic said a bad thermostat could have caused part of my problem. Could this be true?

Another weird thing is that I checked my 1984 302 F150 and I had almost the same results. Number 2 only had 30 psi while the rest had 120 to 150 psi.

I am about to take a number 2 on both these trucks.

Any advice on either truck? The F150 overheated and backed up in the reservoir too today.

 

Does anyone have any advice? Someone on another post mentioned Sea Foam. Could this help?

 

The #4 cylinder may look clean because the water in the coolant can steam clean it. I would consider its clean condition to indicate a problem. #4 and #6 are lower pressure than the other cylinders. Is #2 really 35 psi or did you mean 135?

 

Yes #2 is 35 psi and had the plug with the missing center. The bent over tab part is intact and not smashed. #4 wasn't clean but looked like it should...gray in color.