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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

Engine Seized

  #1  
Old 12-08-2018
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Engine Seized

Hey guys. Bought my son a 2003 Ranger 2x4 extended cab with the 4.0 and 148k miles, automatic transmission. Truck is in pretty good shape overall. He was driving it to school Tuesday and it was about 18 degrees outside. He made it to school about 2 miles away but said when he stopped at a light and it wouldn't move. He had to shut the engine off and restart to move again. After school he cranked up and left and engine sounded louder than usual and died about a 1/4 mile down the road. I was at work but talked with them and the said it was just clicking when they tried to start it. I thought o.k the cold killed the battery because it was our first cold day. Bought a new battery and installed it same clicking. The old battery was 7 years old so no big deal putting a new interstate on it. Sounded like the starter was kicking the bendix out but couldn't turn the engine over. Then thought it was a bad starter. Pulled the starter and it's fine. So this leading to the point that now it seems the engine is seized. I"m wondering if anyone has ever had a timing chain that broke that seized things up? No reason for the engine to have locked up. Oil is clean, no metal and no burned smell. The engine ran great for about the 200 miles we drove it. Not noisy, idled great antifreeze was clean. Just trying to figure this out. Tried turning the crank with a breaker bar but no luck. Just not making any since to me. If I have to rebuild/replace the engine then I will I'm just baffled about this one. Bought it from a used dealer so he picked it up today to have his mechanic take a look at it so he's being good about it. Thanks in advance and I'll keep you guys posted.
 
  #2  
Old 12-08-2018
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The 4.0l SOHC engine, 2001-2012 Rangers, was an interference engine, so valve can strike piston and could "lock engine up", if that was the case you should be able to turn it in reverse direction

These engine have 2 long timing chains plus a few short ones, the long chain tensioners were an issue in these engine from 2001 to 2004, but there would be a loud "rattle" on start up and mid-RPMs when that was happening.
A long chain could break and lock the engine up, but you would have LOTS of noise before that happened

The not moving at after stopping, and then moving again after restart is odd
Bad/failed Torque converter can't lockup engine, well, never seen it happen in 40+ years
But bolts can come out at flexplate which could account for the no movement, then bolt gets wedged at restart, so works again, and now bolts are lodge in a manner that has locked flexplate from turning

Spun main bearing will lock up an engine, but usually there is some heating up first
 
  #3  
Old 12-09-2018
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Thanks Ron. As I wasn't driving the truck at the time I'm not sure how much noise it was making. I"m learning about the timing on these trucks also. I have a 2008 F150 and they also have the issues with the timing chain guides if not properly maintained. The F150 has some updates to some of the timing systems now. Do these 4.0's have the same? Is there a specific brand I should look for if I need to do a timing job? Like I say the dealer is being good with this and working with me. He doesn't have to so this is very nice of him. He has the truck at his place now and is going to look at it. Also if the engine has to be replaced, what are most guys doing? Used engines or crates? Thanks for all the info.
 
  #4  
Old 12-09-2018
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The 4.0l SOHC engine(205HP) was first used as an option to the 4.0l OHV engine(160HP) in the 1997 and up Explorers
By 2001 there had been enough Timing chain issues with the SOHC for Ford to have a look at the design, failures couldn't all be placed at the owners feet, lol, because of lack of service.
Many failures were happening to Ford Serviced SOHCs
It wasn't 100% failure rate so it was hard to get an "ah ha" thats the problem discovery

But the problem was found, the long chain hydraulic tensioners
They had springs inside to hold the chains tight for startup, until oil pressure could take over
The springs were failing, so on start up the long chains would beat on their guides until oil pressure pushed chains tight, i.e. "slight rattle on startup"
Another issue because of the springs is that if tensioner's oil holes should get a little dirty, so less pressure, the failing springs couldn't hold chain tight enough, rattle at mid-RPMs.

The long chain beating on the guides eventually broke the guide away from it's mount, causing loud rattle at startup and in mid-RPM range, damage was done at this point

Engine needs to be pulled out to replace the rear long chain and guides(cassettes) on this engine so not a small matter.

The fix was a redesigned of the tensioners and re-enforced guides, this made its way into engine production in late 2003/early 2004, but since engine manufacturing and vehicle assembly is not on the same time table , 2004 Ranger 4.0l SOHC engines could have either old or new timing chain setup, 2005 and up will have the newer design

If there is no noise at startup then you can just put in the newer design tensioners, a little disassembly is required but not much, couple of hours to change each one, there are 2
But it may have already been done, by previous owners.
The older guides are OK to leave in place if the old tensioners never failed, but if you pull the engine then you replace all of it.

FYI
Its become standard now to NOT USE key ways, woodruff keys, on cam/crank timing, tapered fit is now what is used, less machining needed, so less cost
4.0l SOHC uses that on the Cam's timing gears so they can lose time if gear slips on the shaft, unlikely to happen, but can happen

The Rangers 2.3l Duratec engines use that as well, and most of the Modular V8s
 
  #5  
Old 12-09-2018
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Great info. I'm waiting to see what the shop says they found. Not sure if they plan to do anything to help me out or not. They certainly aren't required to as I bought the truck as is. Was really surprised they wanted to pick it up and look at it. Like I said the trucks in pretty decent shape so not ready for the salvage yard by any means. Still has a lot of miles left ahead of it. I'll post back when I hear from them and what the thoughts might be on which way to proceed. Again thanks for your time.
 
  #6  
Old 12-10-2018
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Here's where we are at now. Pulled the valve covers and notice lots of slack in the rear timing chain. Ran a scope thru the heads and no bent valves or holes in pistons thank goodness. But they cant see that the chain is whats causing the issue. So the engine has to come out. With the engine seized they had to pull the transmission to get to the torque converter. So still investigating as they pull the engine. Obviously going to do a timing job so I'm thinking replace the oil pump since the engine is out and new rear main. Anything else that's suspect with these motors that you would replace while it's out? I'm still learning about the 4.0's. Thanks.
 
  #7  
Old 12-10-2018
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I agree with mechanic, loose timing chain couldn't seize engine
Valve strikes can happen but the cams neutral positions don't have valves open far enough for that, neutral is where a cam would stop if chain broke or was slipping
This is what it can look like: https://www.explorerforum.com/forums...vement.345348/

But wouldn't seize the engine
The seize part is the concern, of course


Replace the Knock Sensor, its under the intake, not expensive just hard to get at, and the wires would get hard and break
Check thermostat housing, these could crack and leak, and replace thermostat
 
  #8  
Old 12-10-2018
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I didn't think a timing chain could seize an engine either. Only way I could see it remotely possible is if it jammed up between the sprocket and the housing. I'm going to check out your link. I'll keep you posted.
 
  #9  
Old 12-11-2018
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Rear main bearing is toast. Said it looks like one of the journals clogged and wasn't oiling. So going to put a used motor in it and put it back on the road.
 
Attached Thumbnails Engine Seized-photo970.jpg  
  #10  
Old 12-11-2018
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Never heard of that with the 4.0l SOHC engines, bummer it happened

Make sure it is a 2005 or up 4.0l SOHC so it has the newer tensioners and guides
 
  #11  
Old 12-14-2018
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Here is an update. Motor is coming out of a late build 2002 explorer with 114k miles. Bottom of the engine and under the valve covers really clean. Also going to update the timing, new guides and tensioners but the chains that are in it now are tight and the cassettes are good just doing the upgrade because of known issues. New plugs, rear main and front seal in the transmission. Should be back on the road next week.
 
  #12  
Old 12-20-2018
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My sons Ranger is back on the road! Like I stated above motor came out of a late build 2002 Explorer with 113K miles. Timing job is done and runs great. Got a little more power than the original motor. This thing should last for a long, long time. Thanks for the info Ron. Now I gotta do a drivers side wheel bearing and keep it maintained.
 
  #13  
Old 12-20-2018
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Good stuff

Thanks for the update
 
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