Just finished the rebuild on the '98 4.2 after the mandatory lower intake gasket leak...this was a COMPLETE tear down, clean up rebuild.

She started up fine, seems to idle smooth, but I noticed on the maiden voyage, when accelerating, theres an obnoxious clatter from the pass. side. Is it common for some lifter clatter at first? I spun it sans plugs to build the oil pressure, it shows good pressure when running, and the clatter only comes with moderate to heavy acceleration. light accelerating and idling it goes away.

Don't think its a valve, since wouldn't that be a more constant noise?

Grrr. All this time and money, I gotta get this thing right. And I'd HATE to have to pull the damn intake to get at the lifters again.

Ideas?

 

Shouldn't be lifter clatter, those things have roller lifters in them. Any chance that the cam position sensor is off a little bit?

 

Don't think so. I made dang sure to get that in right. Used the positioning cap, TDC, even busted out the angle finder...perfect 54 degrees from centerline. I've read online that some clatter or "pinging" as its been called is normal. Now, the truck did sound like a semi before rebuilding, but I don't remember any clatter like this. If need be I'll just pull the valve cover this weekend and see...cause that one is SO easy to get to. Thanks alot Ford engineers!

 

LOL, gotcha. One thing you might check is the engine lift hooks that came bolted to the manifolds. Does that new motor still have those? They nuts/studs frequently break and they will rattle around.

 

Nope, took em off after getting the engine back in. The manifolds were hard enough to get bolted back on without them... I used washers to take up the space from the missing hooks. But I'll double check the bolts just to be sure.

**I totally forgot they were roller lifters, D'oh!

 

ANY chance it is a catalytic converter?

They have been known to break apart inside and rattle. Long shot? Maybe. But something to be aware of.

 

I know this thread is over a year old, but was the problem ever solved? I have the exact same problem with my 4.2 rebuild. Heads redone, new lifters, push rods, rings, crank and bearings, and timing set. My symptoms are identical.