Tap,Tap...Tap?

[blkman9]

My 91 ford Explr 4.0L sounds like someone is rollin dice under the hood!The valves will tap for awhile then go away,Then start up again.Oil level is good, pressure seems to be ok,thats if my gauge is correct.I can sure use some help on this.I,m pretty good with the tools ( about a six,from 1-10)

 

[jimbo74]

have you adjusted the valaves?

 

[sloxploder]

I had an 87 Ranger with a 2.9l that did that after i ran it through some deep water Every time i changed the oil, it didnt do it for like a week, and then it started again. I sold it to my dad and he puts a quart of lucas oil treatment every time he changes the oil and now it doesnt do it anymore. The 2.9 and 4.0 are both in the Cologne V6 family, so... my theory: similar engine, similar problem, similar remedy.

 

[amessie]

Try AutoRx followed by Prolong. Bobistheoilguy.com

 

[righthooks]

sounds like your heads are messed up....try getting the compression tested somewhere...see if all cylinders are firing correctly...its probably a lifter or something of that sort.

 

[JDraper]

Some strange advice above.....

First, the oil gauge on your dash is just a glorified idiot light not a true gauge. It's really a switch with a needle on it instead of a light. It can't be relied upon to tell you that the oil pressure is ok. Since the noise fades in and out, it seems to me that it has a lot to do with either oil viscosity or oil pressure.

What you're probably hearing is the pushrods rattling on either the lifters or the rockers.

Here are some possibile causes of the noise:

Oil pump going out. There were some issues with the '91-'92 oil pumps where the return spring in the pump would break and cause a low pressure issue. This can cause clattering, as the lifters are hydraulic. It will eventually toast the motor. (This is what killed my mother-in-law's Explorer motor)

Lifters collapsing. If the lifters are shot, they won't hold pressure, and will let the pushrods rattle.

Worn pushrods/rockers. There are a few threads on the site about this. Apparently it's not that uncommon in high mileage 4.0's

Whatever the problem is, putting addatives in will only mask the problem, not cure it.

BTW, what grade oil are you running? On higher mileage motors that haven't been run on synthetic most of their lives, there may be some wear. If you're still running 5W30, it might be time to switch to 10W30. If the lifters are weak, changing oil grade may help them last a little longer.

 

[Heavymentill]

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