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Ford Explorer Community - Maintenance - Modifications - Performance Upgrades - Problem Solving - Off-Road - Street
Explorer Forum Covers the Explorer ST, Explorer Sport, Explorer Sport Trac, Lincoln Aviator, Mercury Mountaineer, Mazda Navajo, Ford Ranger, Mazda Pickups, and the Ford Aerostar
Hey guys - and gals! I'm a newbie here. I drive my dad's old 94 Ranger. (less than 100K on it) I notice when going up hills in particular, that my engine makes a lot of "clicking" noise. I was told by a mechanic once that I'll need a valve job. I once had the mass air flow sensor replaced and that seemed to help but it's back. If I do have the valves done, I'm concerned because the heads on the bolts on one side of the valve cover have pretty much disintegrated and will have to be drilled out. My questions are does this sound usually indicate that, and also, does anyone have an idea what a valve job having to drill out at least 2 bolts will run me?
Valve clattering noise under load on the OHV 4.0L is usually the result of worn rocker arms. The metal they used was too soft and so the valve contact points wear into the rocker arms. Fix is new rocker arms ($10-20/ea x 12) or you can still get complete rocker arm shaft assemblies from Ford for just $80 ea, so $160.
If the valve covers are in that bad of shape you should remove and refurb them soon anyway, otherwise they will rust out and oil will leak all over the place. It's also a good chance to replace the valve cover gaskets which are known to leak as well.
Agreed with Anime on the above points. In certain states especially, the stock valve covers are often in poor condition (corroded), and warped around the bolt holes due to previous owners reefing down the bolts. You may be able to remove the bolts using a vice grips to grab the heads, or a bolt extractor set which grabs the head and latches onto it while turning it out. On one of my Explorers, the stock valve covers were corroded and the mounting points were bent due to fastener abuse. I got a fresher set from a junkyard (newer year OHVs will work), straightened the metal out and sanded the mounting surfaces until they were perfectly flat.
The 4.0 valve covers are known to weep oil commonly, but this is usually due to damage from the fasteners being over-tightened combined with soft cork gaskets. I recommend using a Fel-Pro Perma-Dry Plus gasket set instead of cork. It is a reusable rubber and metal or plastic gasket that is very strong, and resistant to damage caused by over-tightening the bolts. It requires that you fix your valve covers if they are warped around the bolt holes, but if you do, it will seal far better than the cork gaskets.
As for the clicking noise, is it only under a heavy load or up hills? More like a rattle? I had that once for a while and only premium fuel made it go away. Eventually I switched back to regular gas and the noise had disappeared on its own. Guessing it was carbon deposits or something? Anyways, see if you can pinpoint where the noise is coming from, if premium fuel has no effect. Try using a mechanic's stethoscope to check under the hood, and see if the noise is coming from the valvetrain. You may be able to use a screwdriver instead, by touching the tip to the valve cover and the handle end to your ear. Valvetrain noise is not uncommon on the 4.0 due to reasons Anime stated, but it won't typically self destruct and can run for a loooong time even with the noise.
Lifters can get gummed up as well. I have on occasion experience similar noise so I would do the usual cleaned my MAS, IAC, IAT, o2 and checked the FPR and reset the battery connections to the CPU to varying success. It was recently while I was working on my front and rear ends, that I decided to deep clean the engine. This was upon recommendation from an retired heavy engine mechanic. So I drained my engine oil with the used filter in place and added fresh transmission fluid to the engine 5 quarts. I started the engine and let it warm up a bit to circulate the fluid well. Then I let it sit for the week or so I was finishing up the driveline project. When I was ready to drive again, I replaced the oil and filter with fresh oil and a new filter and started it up again allowed it to warm up to full temp. Immediately upon driving away I noticed the ticking and knocking went away, particularly under load going up a grade. I have since totally eliminated the noise. There is a slight ticking noise that I am certain is valve train wear that is always present. So,I do feel that the valve train is getting worn and it will be replaced when a complete rebuild comes next year or so, but until then, this was an easy way to get rid of the knocking noise, when I knew I had clean, working sensors and no other issues.
This issue can be very annoying and irritating to resolve at times, but once resolved it tends to stay that way for a good while. Hope this of help to your situation.
I have what I thought was valve clatter. I have since decided that it is an exhaust leak. It started out only under serious load it would kind of tap, and the best way to describe it is a typewriter. It has now gotten to the point it almost always does it. I can even hear it at idle now. It is just a very soft, pffft, pffft, pffft, at idle. Unless I'm off the gas, it almost always makes the noise when driving now. Its hard to distinguish between valve clatter, and this kind of exhaust leak because under load it is a distinctive tap, rather than a normal air leak sound. Unless the sound really bugs you, it shouldn't cause a problem. I cant even imagine the work it would take to put new exhaust headers on my Minnesota motor.
