4.0 sohc will not start!

[boody78]

Hi,

I have a 2000 explorer with 150k, It has a 4L sohc that cranks, but will not start. My fiance was driving home the other day, she says it made a very loud "pop", stalled out and coasted to the side of the road. I have not been able to get it started since.

It has fuel pressure 60psi at the rail.
It seems to be getting spark, I pulled a plug it was wet and sparking.
I replaced the coil, and the crank position sensor.
The theft light does not blink when cranking.
The Check engine light comes on with the key and off while cranking.

The funny thing is, if it sits for a day or so, it will ALMOST start, but doesn't, and then it just cranks with nothing happening until you let it sit again.

I'm at a loss, anyone have this happen to them? I searched this thread and found 1 post that was similar, but it had no result.

 

[scdix50]

Sounds Like something broke in the timing chains area. You should pull both valve/cam covers, look at the chains & guides. There are a good number of photos here of what to look for. good luck

 

[vroomzoomboom]

or even easier, do a compression check. if you have a few dead cylinders, chances are, you have broke the timing chain, and also did valve damage.

 

[boody78]

Would a broken timing chain cause an "almost" start after the trucks been sitting for a while? This is the most confusing thing for me. The truck will do nothing but turn over unless you let it sit for an hour or so, then it will "catch" on the first attempt, but stalls immediately. It will NOT catch again unless you let it sit for another hour? It does this every time without fail? What would cause this?

 

[yavapaires]

Would a broken timing chain cause an "almost" start after the trucks been sitting for a while? This is the most confusing thing for me. The truck will do nothing but turn over unless you let it sit for an hour or so, then it will "catch" on the first attempt, but stalls immediately. It will NOT catch again unless you let it sit for another hour? It does this every time without fail? What would cause this?

You said the plugs were wet when you pulled them out. Did they smell like gas? Did they smell like coolant? Do you hear any odd noises when the engine cranks? Did you pull a valve cover to check for valve action? Pull #1 spark plug, rotate engine to TDC. Are both valves closed?

 

[boody78]

no weird noises, haven't removed the valve cover yet, I didn't notice a coolant smell but I wasn't looking for it either, I'll have to recheck that.

 

[2000StreetRod]

compression test

or even easier, do a compression check. if you have a few dead cylinders, chances are, you have broke the timing chain, and also did valve damage.

I agree that you should perform a compression test since you appear to have fuel pressure, ignition and apparently no DTCs.

 

[budwich]

"almost start"... is likely a "loss of compression" ... :-( I think "broken timing chain" might be a little "harsh"... you might have lost a "degree of timing" due to "slipped links" which I think people have seen with this particular engine (sohc). Compression test will quickly determine if you have "mechanical sanity" in your engine. IF so, then you can move on to other things. IF NOT, you can then head for the "engine tear down".