Bad news for the trac/ misfire

[Sp0rtTr4c]

My truck started to sputter pulling in to the driveway today. Code reads cylinder 4 misfire and will barely run. One of my family members had the same problem with a ranger 4.0 and my dad tried everything but the truck needed a rebuilt motor so I am expecting the worse. Anybody else on here had this problem? I cleaned everything with electronic parts cleaner, checked the iac and that was clean, no leaks anywhere, gets spark, and I tried a new coil with no luck, tomorrow I am going to check compression and go from there.

 

[MidnightRebel07]

That sucks man. Check compression and see where things go from there. Hopefully its something as simple as a bad spark plug wire or fouled plug.

 

[boominXplorer]

That sucks man. Check compression and see where things go from there. Hopefully its something as simple as a bad spark plug wire or fouled plug.

I would start there. A common missfire issue with the SOHC could be a broken valve spring. I worked on a 04 sport trac that snapped the intake valve spring on #5 , only had 105k mi on it too.

 

[Sp0rtTr4c]

It is the valve. Cylinder 4 reads 0 on compression tester. My dad is a mechanic so he knows all the details but I am looking in to just rebuilding it or a long block. we have the valve cover off and the valve is visibly lower and the little top thing is loose. (Sorry I don't know all the terminology). Once we get the head off we will know the full extent of the problem but I don't have much for tools so I need to get some together and we are going to dig into it next weekend. Working 50 hr weeks right now so there isn't really any time during the week and my dad lives a little ways away so I am stuck with wrenching on the weekends. Luckily my boss is letting me use the company truck but I don't know how long I can keep it.

 

[Sp0rtTr4c]

I am at 123,000 miles btw. So really not very high, was not expecting a problem like this to ever happen with this motor. The only problem I have ever had is a dead battery with this truck til now.

 

[Sp0rtTr4c]

It is the valve. Cylinder 4 reads 0 on compression tester. My dad is a mechanic so he knows all the details but I am looking in to just rebuilding it or a long block. we have the valve cover off and the valve is visibly lower and the little top thing is loose. (Sorry I don't know all the terminology). Once we get the head off we will know the full extent of the problem but I don't have much for tools so I need to get some together and we are going to dig into it next weekend. Working 50 hr weeks right now so there isn't really any time during the week and my dad lives a little ways away so I am stuck with wrenching on the weekends. Luckily my boss is letting me use the company truck but I don't know how long I can keep it.

Quote from my dad- "you dropped a valve" heard the term before but not exactly sure what it means. But either way thats what happened.

 

[mustang6878]

Before you get too carried away, just make sure you did not just break a valve spring. ( The valve spring holds the valve closed from the topside, a broken one would let the valve fall down and the cylinder would be "open", which would cause your zero compression reading)

Is a worse case, you broke the valve off, the piston crushed it as it came up into the cylinder and you are toast.

Be careful of just popping the heads off and doing a valve job, a motor with that many miles will have a fair amount of wear on the "bottom side" ( the rings on the pistons seal the bottom of the block) and by sealing the top side, you could blow past the piston rings and basically waste the cost of a valve job. It happened to me 30 years ago on my '69 Bronco.

 

[boominXplorer]

Just fill the cylinder with compressed air and use a OHC valve spring compressor to swap out the spring. I bet the valve is fine. I did one not too long ago in about 4 hours with great success and didn't pull the head off.

 

[Sp0rtTr4c]

I will post up next weekend what we find. He thinks it is going to be bad though because of how it sounded when it ran. Sounded like the piston was hitting the valve so we are expecting the worse but hoping for the best. I am thinking about knocking out my v8 swap now while it is down. Going to be doing a lot of researching over the next couple weeks to figure what the best option is.

 

[boominXplorer]

Put the compression tester on it and instead of putting the gauge on hook an air line up and charge the cylinder. Lift the valve up and it should seal and hold itself up, if so its good to go.

The truck I did felt like it had a bent rod, it ran very crappy. After a new valve spring It registered 185 psi, which is like new.