02 Explorer 4.0 rough idle tapping sound from valve cover

typer2k1 · 06-27-2012, 10:58 AM

Hey guys,
I've been on this site looking around and getting ideas on how to fix my father in law's Explorer. He initially had an issue with the timing chain, at first you would hear the chain rattle on start up. I told him it should be fine, the chains rarely go out(dumb me, i know). Then one day he said the noise got really bad. I went over to his house, he started the truck and it was horrible.

I towed the truck to my house, started looking for ideas what it could be. StreetRod with his informative posts really helped me out. I finally took the plunge and dove into this thing. I found the driver side tensioner and guide was destroyed, there were peices of metal under the valve cover, the chain was so loose it was slapping everywhere, not sure if it skipped a tooth or not. the front tensioner and guide had hardly any wear, the balance shaft tensioner was broken, and the rear chain guide was broken as well. Needless to say, i had to pull the motor.

I made sure the timing marks were right on, i purchased a timing tool kit from Ebay. the little nipple on the drive side cam lobe was right near the pick up sensor, the passenger side camshaft slot was parallel with the head mating surface, and the crank pully was at 0 degrees TDC. I replaced all guides, tensioners, and chains. I purchased new jackshaft front and rear bolts, new crank pulley bolts and torqued everything down to specs.

Last weekend, i had everything put back together, cranked the motor and she started, however it was running a bit rough and i could hear a tapping coming from the driver side valve cover. I thought it may have a bent valve, so i ran a compression test and got readings of 150 across the board. Now when i installed the intake manifold i didn't change the gasket, i was planning on starting the truck and spray carb cleaner around various areas to see if the engine surges this weekend, but do you think a vacuum leak could be causing the tapping sound i hear from the valve cover? I know this could be causing the idling issue. Do you think i could have bent a valve, broken a valve spring? I need to get this thing done soon, this Phoenix heat is only gonna get worse from here on. Any help and thoughts would be greatly appreciated guys, thanks!!

2002 Explorer Sport
4.0 V6 4X4

typer2k1 · 06-30-2012, 01:45 PM

Ok, so I've sprayed the engine with carb cleaner and found no vacuum leaks. I'm suspecting an issue with the rockers, hopefully. Does anyone know if a bad rocker will also cause the rough idle issue? Thanks in advance guys!

typer2k1 · 07-08-2012, 10:34 PM

Anyone have any ideas? I removed the valve cover and rotated the camshaft to relieve pressure on the valves and didnt see any obvious issues with the rockers or springs. Im going to remove the camshaft next, maybe tomorrow and inspect the valve train again. Its been over 100 degrees these last couple days and ive been using that as an excuse. Does anyone have any suggestions? Thanks in advance for any input you can give me!

typer2k1 · 07-11-2012, 08:57 PM

Ok, so today I took the camshaft out and found the journal closest to the timing cover scored pretty bad. There is a deep gouge around the journal. I have no idea how this happened. I checked the oil tube that goes across the valve train and it was clogged. I suspect oil was not getting to the valves and that was causing the tapping noise. I felt I had to remove the head because the clogged oil tube would not explain the rough idle. After I removed the head to my surprise it was fine. No damaged valves and no contact areas on the pistons. My next step is to remove the springs and valves to see if any of them are burnt. I'm going to keep this post going incase somebody has a similar issue and can benefit from my findings.

typer2k1 · 08-31-2012, 09:42 PM

Issue resolved. I removed the head And the valves were fine, no damage to the pistons either. I put everything back together and remembered I had the intake tube disconnected from the intake box to the throttle body. Dumb
me I realized this was causing the rough idle because the maf sensor was not getting an accurate reading. I disconnected the battery to reset the ecu and and now the idle is perfect. I also found the clogged oil tube was starving the valve train of oil, this was causing the tapping sound I was hearing. The explorer runs great, I'm glad to finally get it out of my driveway

06-27-2012, 10:58 AM	#1
typer2k1 Wannabe Elite Explorer 2002 Explorer 4.0 V6 4X4 Join Date: Jun 2012 Posts: 6 Vehicle Specs (Original Poster)	02 Explorer 4.0 rough idle tapping sound from valve cover Hey guys, I've been on this site looking around and getting ideas on how to fix my father in law's Explorer. He initially had an issue with the timing chain, at first you would hear the chain rattle on start up. I told him it should be fine, the chains rarely go out(dumb me, i know). Then one day he said the noise got really bad. I went over to his house, he started the truck and it was horrible. I towed the truck to my house, started looking for ideas what it could be. StreetRod with his informative posts really helped me out. I finally took the plunge and dove into this thing. I found the driver side tensioner and guide was destroyed, there were peices of metal under the valve cover, the chain was so loose it was slapping everywhere, not sure if it skipped a tooth or not. the front tensioner and guide had hardly any wear, the balance shaft tensioner was broken, and the rear chain guide was broken as well. Needless to say, i had to pull the motor. I made sure the timing marks were right on, i purchased a timing tool kit from Ebay. the little nipple on the drive side cam lobe was right near the pick up sensor, the passenger side camshaft slot was parallel with the head mating surface, and the crank pully was at 0 degrees TDC. I replaced all guides, tensioners, and chains. I purchased new jackshaft front and rear bolts, new crank pulley bolts and torqued everything down to specs. Last weekend, i had everything put back together, cranked the motor and she started, however it was running a bit rough and i could hear a tapping coming from the driver side valve cover. I thought it may have a bent valve, so i ran a compression test and got readings of 150 across the board. Now when i installed the intake manifold i didn't change the gasket, i was planning on starting the truck and spray carb cleaner around various areas to see if the engine surges this weekend, but do you think a vacuum leak could be causing the tapping sound i hear from the valve cover? I know this could be causing the idling issue. Do you think i could have bent a valve, broken a valve spring? I need to get this thing done soon, this Phoenix heat is only gonna get worse from here on. Any help and thoughts would be greatly appreciated guys, thanks!! 2002 Explorer Sport 4.0 V6 4X4 Last edited by typer2k1; 07-10-2012 at 10:38 AM.

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06-30-2012, 01:45 PM	#2
typer2k1 Wannabe Elite Explorer 2002 Explorer 4.0 V6 4X4 Join Date: Jun 2012 Posts: 6 Vehicle Specs (Original Poster)	Ok, so I've sprayed the engine with carb cleaner and found no vacuum leaks. I'm suspecting an issue with the rockers, hopefully. Does anyone know if a bad rocker will also cause the rough idle issue? Thanks in advance guys!

07-08-2012, 10:34 PM	#3
typer2k1 Wannabe Elite Explorer 2002 Explorer 4.0 V6 4X4 Join Date: Jun 2012 Posts: 6 Vehicle Specs (Original Poster)	Anyone have any ideas? I removed the valve cover and rotated the camshaft to relieve pressure on the valves and didnt see any obvious issues with the rockers or springs. Im going to remove the camshaft next, maybe tomorrow and inspect the valve train again. Its been over 100 degrees these last couple days and ive been using that as an excuse. Does anyone have any suggestions? Thanks in advance for any input you can give me!

07-11-2012, 08:57 PM	#4
typer2k1 Wannabe Elite Explorer 2002 Explorer 4.0 V6 4X4 Join Date: Jun 2012 Posts: 6 Vehicle Specs (Original Poster)	Ok, so today I took the camshaft out and found the journal closest to the timing cover scored pretty bad. There is a deep gouge around the journal. I have no idea how this happened. I checked the oil tube that goes across the valve train and it was clogged. I suspect oil was not getting to the valves and that was causing the tapping noise. I felt I had to remove the head because the clogged oil tube would not explain the rough idle. After I removed the head to my surprise it was fine. No damaged valves and no contact areas on the pistons. My next step is to remove the springs and valves to see if any of them are burnt. I'm going to keep this post going incase somebody has a similar issue and can benefit from my findings.

08-31-2012, 09:42 PM	#5
typer2k1 Wannabe Elite Explorer 2002 Explorer 4.0 V6 4X4 Join Date: Jun 2012 Posts: 6 Vehicle Specs (Original Poster)	Issue resolved. I removed the head And the valves were fine, no damage to the pistons either. I put everything back together and remembered I had the intake tube disconnected from the intake box to the throttle body. Dumb me I realized this was causing the rough idle because the maf sensor was not getting an accurate reading. I disconnected the battery to reset the ecu and and now the idle is perfect. I also found the clogged oil tube was starving the valve train of oil, this was causing the tapping sound I was hearing. The explorer runs great, I'm glad to finally get it out of my driveway