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Common 4.0 engine issues to watch for
Thread Starter
3rd Gear Member
Joined: Jan 2007
Posts: 648
From: Acworth, GA
Common 4.0 engine issues to watch for
I would like for this thread to list common issues with our 4.0 engines that the owner should watch out for. I use www.fordpartsgiant.com to track part numbers and they are great for listing the dates a replaced part was in service. So here is my first one.
Pulley - Crankshaft - 09/07/2004 To: 06/25/2007
New part number 8L2Z-6B321-A
The pulley separates causing noise, then loss of the serpentine belt
Next on my list is the thermostat housing.
Pulley - Crankshaft - 09/07/2004 To: 06/25/2007
New part number 8L2Z-6B321-A
The pulley separates causing noise, then loss of the serpentine belt
Next on my list is the thermostat housing.
2nd Gear Member
Joined: Apr 2006
Posts: 276
From: WA
Thermostat Housing:
OEM part number: 2L2Z-8592-BA
Motorcraft part number: RH148
Year: 2002-2010
This part most likely has the highest failure rate of any part on the Ford 4.0 SOHC engine.
It is a two piece plastic part that is sonic welded together. The part cracks at the seam and also other places. This part is subject to heat, cold, pressure, vibration and chemicals. Why Ford engineered this as a plastic part makes absolutely no sense at all! I'm on my third one after 138,000 miles.
PS:
If your are installing an X-Charger Xtreme or any X-Charger that uses the new upper and lower housing it would be a good idea to replace this part while you are at it because you will need to remove the entire X-Charger assembly including the lower manifold to replace it at a later date.
OEM part number: 2L2Z-8592-BA
Motorcraft part number: RH148
Year: 2002-2010
This part most likely has the highest failure rate of any part on the Ford 4.0 SOHC engine.
It is a two piece plastic part that is sonic welded together. The part cracks at the seam and also other places. This part is subject to heat, cold, pressure, vibration and chemicals. Why Ford engineered this as a plastic part makes absolutely no sense at all! I'm on my third one after 138,000 miles.
PS:
If your are installing an X-Charger Xtreme or any X-Charger that uses the new upper and lower housing it would be a good idea to replace this part while you are at it because you will need to remove the entire X-Charger assembly including the lower manifold to replace it at a later date.
Last edited by Nice Pony; Jun 12, 2011 at 12:34 AM.
2nd Gear Member
Joined: Apr 2006
Posts: 276
From: WA
@2005Redfire6:
I have seen that failure and it is pretty common on the 4.0. although I have 138,000 miles on mine and it still seems to be OK, knock on wood, I do keep an eye on it.
@Buckshot Barry:
Good call on the alternator I have had to replace that also.
I have seen that failure and it is pretty common on the 4.0. although I have 138,000 miles on mine and it still seems to be OK, knock on wood, I do keep an eye on it.
@Buckshot Barry:
Good call on the alternator I have had to replace that also.
2nd Gear Member
Joined: Apr 2006
Posts: 276
From: WA
Not exactly related to the 4.0 SOHC engine but merits exposure:
Back when I still had a T5 5-Speed transmission this was an issue. The rear seal was leaking on my T5 transmission so I go to Ford and get the replacement seal. After taking everything apart to put it in it is obvious the they sold me the wrong one. So I go back to Ford and they pull it up on the computer again. The computer shows two seals. The one they sold me and another one. I ordered the second one in and it is the correct seal. Fords database is incorrect so this is something to watch for if you don't want to waste a lot of time on 10 minute job!
Correct seal is: 4R3Z-7052-AA
Wrong seal is: F6ZZ-7052-A
Back when I still had a T5 5-Speed transmission this was an issue. The rear seal was leaking on my T5 transmission so I go to Ford and get the replacement seal. After taking everything apart to put it in it is obvious the they sold me the wrong one. So I go back to Ford and they pull it up on the computer again. The computer shows two seals. The one they sold me and another one. I ordered the second one in and it is the correct seal. Fords database is incorrect so this is something to watch for if you don't want to waste a lot of time on 10 minute job!
Correct seal is: 4R3Z-7052-AA
Wrong seal is: F6ZZ-7052-A
Joined: Mar 2011
Posts: 33
From: alabama
I have an 05 here is the parts eaten so far.
Engine compartment:Coolant expansion tank,thermostat housing,cooling fan.
Inside:carpet,instrument cluster,stereo(shaker 500),drivers side middle a/c vent plastic chrome keeps peeling(replaced twice).Seat back handle on rear seat side broken it about ten times.I always buy two.( I blame it on the kids)
Transmission:T-5 has failed twice.first time it was out of fluid at 30k,second time was two weeks later.replacement has made it to 83k so so far so good.
Engine compartment:Coolant expansion tank,thermostat housing,cooling fan.
Inside:carpet,instrument cluster,stereo(shaker 500),drivers side middle a/c vent plastic chrome keeps peeling(replaced twice).Seat back handle on rear seat side broken it about ten times.I always buy two.( I blame it on the kids)
Transmission:T-5 has failed twice.first time it was out of fluid at 30k,second time was two weeks later.replacement has made it to 83k so so far so good.