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Help with 94 4.0 liter "valve clatter" and "ignition misfire/exhaust popping" noise fix

Hey everyone,

My 1994 Limited has an interesting problem/problems.

1) It sounds like there is noise in the valvetrain, cylinder 4 (drivers side, closest to radiator). A "metallic clatter" sound can be heard all the time (startup, driving, highway speed, etc.). At this point I do not know if it might be a collapsed lifter, or a problem with a pushrod or rocker arm. The motor runs "fine", but is very lacking in power, and does not have a smooth idle or operation

2) The exhaust "pops" like a cylinder is misfiring, and the sound coincides with the metallic sounds coming from the engine (i.e. the sounds occur with the same timing and frequency).

3) The truck shudders quite a bit with "light throttle" at highway speeds. Either backing off or accelerating harder reduces the amount of shudder considerably (back to the "background vibration" that occurs even at idle). I do not notice this at speeds less than 50k. It does seem to go away if I shift from OD to Drive....but I don't know if that relates to the RPM of the motor, or if it suggests a transmission issue. The car also "clunks" into reverse, and I have read that U-joints may be the problem. Could that relate to the shudder at highway speeds as well?

So far I have done the following:

-replaced spark plug wires and plugs (and yes, I wired the plugs correctly, taking into account the weird order on the coil)

-removed, tested, and cleaned all fuel injectors to ensure fuel delivery is occurring (replaced upper and lower fuel rail gasket at the same time)

-tested for spark (spark is very strong from wire to plug) in questionable cylinder

-I have also cleaned the MAF and IAC a couple of times now to ensure they are working properly.

-changed oil, ran 2 cans of "valve/lifter quieter" additive, then changed oil 350 kms later and used 20w50 oil (no change in problems)

-had all tires rebalanced (they are quite new tires on all 4 wheels)

So I think that I have a valvetrain problem, and am wondering if improperly opening valves is causing a misfire-like condition.

As far as I can tell (running engine with #4 spark plug removed) gas is entering the combustion chamber (the air being expelled from the spark plug hole reeked of fuel), and there is definitely adequate spark.

Sooooo.....the question is what to do next. I am thinking about pulling the valve cover to see if something obvious is broken (I picked up a used rocker shaft set and pushrods from a scrapyard just in case).

If the lifter is collapsed, I presume there will be lots of play between the rocker arm and pushrod? If this is the case, can someone tell me definitively if I have to pull the head or not to replace the lifter? The AutoZone web manuals say no, but an article I read on a Ford website said yes.

And any suggestions on cheap replacement lifters? Apparently they are $70-90 EACH!!

I was told that "the lifters have a teflon cap that can fall out with age, causing valve clatter, but this is just to be expected".....however even if that is true (can anyone verify?) why does my motor run poorly and exhibit a misfire condition?

Thanks in advance for any suggestions. And if I am way off....please point me in the right direction.

Chris

Reply to
Chris
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Wow. And I was going to write a post called "Wierd Rattle." I have not quite isolated the rattle on my '92 EB yet. It comes and goes. It sounds like it's coming from under the valve cover above the #5(?) cylinder (middle, driver side) or somewhere at the front of the engine. Mine sounds like something metallic is hitting something that's going around. It is not steady or rythmic. I was thinking it might be something that rotates (water pump, AC pump, power steering pump etc) failing. Or maybe the timing chain is coming apart or loose. I was (kinda) hoping that it was a broken spark plug bouncing around in the cylinder and I could just get it out with a magnet or something. My rattle occurs sometimes when it's idleling. It's actually my wife's car and she said that it seemed to be running poorly as though it was not running on all cylinders. The idle speed also seems to be a bit low, or at least lower than it used to be.

Another possibility is that a mouse dragged something such as a screw under the hood (yea, they build nests there) and it's just bouncing around. But I'm never that lucky.

I also suspect the engine has a slight head gasket leak. It loses coolant through the reservoir. It overfills the reservoir even though it is filled to the proper level when cold. I replaced all of the hoses and the heater core and had the radiator taken apart and cleaned. The intake manifold gasket does not seem to be leaking. Can anyone tell me if a bad head gasket can cause this?

The car has about 265K miles on it so I guess it's not unreasonable to expect to have to start taking apart the engine about now.

Reply to
Ulysses

I just spent another couple of hours trying to isolate the rattle. I stuck a length of garden hose up to my ear and listened all over the engine. It seems to be loudest around that middle cylinder on the driver's side (#5?). It was difficult to pin it down because it would stop sometimes. It didn't seem to matter if the car was in gear or not, the brake on or not, or if it was going uphill or downhill. It seemed to rattler more if I sped up the engine but I couldn't tell for sure if it was rattling faster.

So, what might cause a sound like this? In my mind it sounds like perhaps some 1/8" thick steel hitting against another chunk of steel and resonating slightly. Broken valve stem maybe?

I just want to have some more clues before I go taking stuff apart.

Thanks.

Reply to
Ulysses

Did you try a new radiator cap? Sounds like when the engine is cooling off it's not sucking the coolant from the overlfow jug back into the engine/radiator.

Reply to
JaWise

Thanks. Yes, I replaced the radiator cap and cleaned where it goes to make sure it was sealing properly.

Reply to
Ulysses

Who was driving while you were in the engine compartment listening with the hose? Was the hood up or down? :-)

Bill Funk Change "g" to "a"

Reply to
Big Bill

About halfway down. I was also driving it. I'm very flexible.

Reply to
Ulysses

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