Help with 94 exporer 4.0

[87rangerxlt]

My sister the other day she ran it out of antifreeze I don't know how long it ran low because it was somewhere within the 6 miles from work. The antifreeze leaked out of the gasket on the intake manifold. Last night I pulled it into the shop and it sounded fine outside of dripping water. Well tonight we replaced the gaskets and put it all back together and started it up and now it's knocking. Sounds like from under the valve cover. And it was leaking gas from the injector. The old o ring must of ripped. So dose anyone know if the lack of gas from the leaks be causing the knock or should I start looking for something else well I got it apart.

 

[turbo_steve]

Did you change the oil and filter? If not, do so and try drive it for a bit. Could have damaged something when it overheated or be a rod knock if coolant got in the oil.

 

[87rangerxlt]

I don't see any coolant in the oil but dad thinks it sounds like a collapsed lifter

 

[RonD]

When you removed the intake manifold and cleaned the surface some debris may have fallen into one of the lifters, they have a little cup on the top of each one where the push rod sits.

Is it a tapping or knocking sound?, tapping is more lifter/valve related, knocking leans more towards bearings or pre/post-ignition.

You mentioned fuel leaking, a stuck open injector can cause a knocking noise, it is feeding fuel into the cylinder all the time which causes a knock as it ignites on exhaust stroke.
To test for a stuck open injector unplug the wire to each injector one at a time, that cylinder should start missing, no fuel, if you unplug an injector wire and cylinder doesn't start missing then that injector is stuck open.
If it is a bad rod bearing this test would quiet the knock when that cylinder is missing, the loud knock comes from the cylinder firing and pushing the loose connecting rod down onto the crankshaft journal, without ignition its a much quieter sound.
If the noise is in the valve train it would not change even if cylinder is missing.

 

[87rangerxlt]

Thanks RonD I am hoping that the injector is the problem. Because it sounds like its spark knocking. It didn't knock when we drove it in the shop but after we tore it apart and had some trouble with them injectors. and when we put it back together it started knocking. dad and I got the whole day tomorrow to work on it. since I got it apart all ready because of the gas leak how can I check to see if the injector is stuck open?

 

[RonD]

To test for a stuck open injector unplug the wire to each injector one at a time, that cylinder should start missing, no fuel, if you unplug an injector wire and cylinder doesn't start missing then that injector is stuck open.

 

[87rangerxlt]

Thanks but she's toasted spun rod bearing or something might know by the end of the day. It was running than it quit knocking than it started knocking really loud