4.0L OHV Timing chains

Sndsational · 05-14-2010, 08:03 PM

So I have been reading up on the timing chains in the Explorers and I see alot on the SOHC. I also see stuff aobut front and rear, left, right....ugh!

I have the 4.0L OHV it has about 102K on it. I am trying real hard to stay on top of it to get the longevity out of the truck, seeing as how it has caused me much grief recently and has hadnumerous parts changed. All of which include a new transmission! In any event, I will be putting new bolt on heads and exhaust manifolds in the near future. My question(s) though is/are, with all the miles and what I see regarding the SOHC timing chains, should I be concerned enough to do mine while I am in there? Are these prone to fail at a certain mileage? Does the motor need to be pulled to do any of them?

Any info on this as well as links with process, pictures, etc. would be helpful.

Thank you

**Maniak** · 05-14-2010, 08:07 PM

Short answer no.. don't worry about the OHV 4.0 timing chain. There are a bunch of 200k mile and some 300k mile motors out there..

When we rebuilt ours it had 355k miles on it.. Timing chain still looked good (head issue and one ring issue caused by a bad spark plug pushed me to rebuilt it).

~Mark

Sndsational · 05-14-2010, 09:28 PM

What was the issue you had with the spark plug? I am looking to try and stay on top of things. Also, what about the heads i intend on changing.....while I am in there should I be able to determine ring condition?

*ranger7ltr* · 05-15-2010, 08:14 AM

I have had a 99 Explorer for 15 months and after getting a new oil pump and fuel pump in it drove it and put 19k on it...Had a minor external coolant leak and after a year decided to change the head gaskets and install new heads I bought when I bought the truck...

Mind you this engine was running very well;I did have the minor leak and I could tell the valves were not completely sealing but I was still getting 20+ mpg on the highway and had at least 120 psi in all cylinders... This engine did have lots of sludge when I got it at 151k and still had lots at 169k even though I used synthetic the entire time...

BTW the timing chain was on my list to replace as well as the heads since I didn't know its condition but it looked like a new chain and gears when I pulled the cover off of the front of the engine...

This is what I found when I removed the drivers side head...This bore is wavy and the top 1/3rd of the cylinder measures .110-.125" bigger than the lower 2/3rd of the same cylinder...And yes this engine had no miss nor did it burn oil... I put in 5 qts and 3k miles later I would drain out 5 qts...

**Maniak** · 05-15-2010, 11:03 AM

Quote:

Originally Posted by Sndsational

What was the issue you had with the spark plug? I am looking to try and stay on top of things. Also, what about the heads i intend on changing.....while I am in there should I be able to determine ring condition?

I changed plugs one time and within 10 miles the tip of the plug broke off and part of it hit the rings and part of it got stuck between the valve and the head.

The 2 pieces you need to worry about or lower intake and heads. The heads will crack if you over heat it and the lower intake on some vehicles comes a little loose allowing fowling of the plugs. Some people can get away with just re-torquing the lower intake while others change the gasket.

I've read of a couple people with oil pump issues but considering how many people are on the site I wouldn't call it a common problem. The pickup screen on our '92 at 355k miles was still clean.

~Mark

EDIT: I just noticed you have a 2000 4.0 ohv. You have the much later design of heads.. you don't hear of them cracking like the 1st and 2nd series (90tm and 93tm). IIRC you have 98tm heads.

Sndsational · 05-15-2010, 11:19 AM

Thank you for all the good info. My heads seem to be good as far as them not being cracked leaking or anything else. I actually had the head gaskets replaced maybe a year ago because of an external coolant leak. The reason I am planning on completely changing them, is because I noticed the bolt hole on the port is broken and the port has an exhaust leak because it cannot torque down. Figure I may as well do both since I will be in there and just wanted to know how hard it was or the project involvement. I noticed that the truck is running better with the new Cat Converter. better power! My thing is that I just want to do things once and get the longevity out of the motor. If I need to fix something, may as well fix all involved!!

05-14-2010, 08:03 PM	#1
Sndsational Wannabe Elite Explorer Woonsocket, RI '00 Ford Explorer Sport Join Date: Nov 2009 Posts: 67 Vehicle Specs (Original Poster)	4.0L OHV Timing chains So I have been reading up on the timing chains in the Explorers and I see alot on the SOHC. I also see stuff aobut front and rear, left, right....ugh! I have the 4.0L OHV it has about 102K on it. I am trying real hard to stay on top of it to get the longevity out of the truck, seeing as how it has caused me much grief recently and has hadnumerous parts changed. All of which include a new transmission! In any event, I will be putting new bolt on heads and exhaust manifolds in the near future. My question(s) though is/are, with all the miles and what I see regarding the SOHC timing chains, should I be concerned enough to do mine while I am in there? Are these prone to fail at a certain mileage? Does the motor need to be pulled to do any of them? Any info on this as well as links with process, pictures, etc. would be helpful. Thank you

05-14-2010, 08:07 PM	#2
Maniak Moderator-Stock 91-94 Vail, Arizona 1992 XLT 4x4 Join Date: Feb 1999 Posts: 10,749 Vehicle Specs	Short answer no.. don't worry about the OHV 4.0 timing chain. There are a bunch of 200k mile and some 300k mile motors out there.. When we rebuilt ours it had 355k miles on it.. Timing chain still looked good (head issue and one ring issue caused by a bad spark plug pushed me to rebuilt it). ~Mark __________________ Click HERE to see our Explorer Specs

05-15-2010, 08:14 AM	#4
ranger7ltr Elite Explorer Great State of Texas 1999 Sport Join Date: Nov 2001 Posts: 1,139 Vehicle Specs	Well let me see... I have had a 99 Explorer for 15 months and after getting a new oil pump and fuel pump in it drove it and put 19k on it...Had a minor external coolant leak and after a year decided to change the head gaskets and install new heads I bought when I bought the truck... Mind you this engine was running very well;I did have the minor leak and I could tell the valves were not completely sealing but I was still getting 20+ mpg on the highway and had at least 120 psi in all cylinders... This engine did have lots of sludge when I got it at 151k and still had lots at 169k even though I used synthetic the entire time... BTW the timing chain was on my list to replace as well as the heads since I didn't know its condition but it looked like a new chain and gears when I pulled the cover off of the front of the engine... This is what I found when I removed the drivers side head...This bore is wavy and the top 1/3rd of the cylinder measures .110-.125" bigger than the lower 2/3rd of the same cylinder...And yes this engine had no miss nor did it burn oil... I put in 5 qts and 3k miles later I would drain out 5 qts... Attached Images __________________ When in doubt, use a bigger hammer! 2008 Dodge Charger R/T 2003 Ford F-150 XLT Supercab 1999 Ford Explorer Sport [new playtoy] 1983 Ford Ranger V8 [soon to be gone]

05-14-2010, 09:28 PM	#3
Sndsational Wannabe Elite Explorer Woonsocket, RI '00 Ford Explorer Sport Join Date: Nov 2009 Posts: 67 Vehicle Specs (Original Poster)	What was the issue you had with the spark plug? I am looking to try and stay on top of things. Also, what about the heads i intend on changing.....while I am in there should I be able to determine ring condition?

05-15-2010, 11:19 AM	#6
Sndsational Wannabe Elite Explorer Woonsocket, RI '00 Ford Explorer Sport Join Date: Nov 2009 Posts: 67 Vehicle Specs (Original Poster)	Thank you for all the good info. My heads seem to be good as far as them not being cracked leaking or anything else. I actually had the head gaskets replaced maybe a year ago because of an external coolant leak. The reason I am planning on completely changing them, is because I noticed the bolt hole on the port is broken and the port has an exhaust leak because it cannot torque down. Figure I may as well do both since I will be in there and just wanted to know how hard it was or the project involvement. I noticed that the truck is running better with the new Cat Converter. better power! My thing is that I just want to do things once and get the longevity out of the motor. If I need to fix something, may as well fix all involved!!