How bad is the SOHC timing chain problem, really?

engine · Jul 23, 2018

Ford saw fit to put the 4.0 SOHC in Explorers and Rangers for many years and even Mustangs. Can the problem be so bad? From the forum and Wiki you would think it is inevitable for every engine. If this were so, how could the engine and the Rangers with the 4.0 SOHC have been so successful?

I'd love to know how many of the 4.0 SOHC's have gone the distance without a TC problem and what the chances are for any particular, well cared for, engine to make it. I think I appreciate the need for oil changes, and I think well cared for would be full synthetic oil at 5,000 mile intervals.

I'm certainly hoping that mine makes it!

cp2295 · Jul 23, 2018

It’ll eventually need it. Whether it goes 50k or 250k really depends on luck with those motors, but yeah it’s a pretty significant problem.

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Craig0320 · Jul 23, 2018

When it happens plan on pulling the engine or transmission to get to the chain in the back. No way around it.

adsm08 · Jul 23, 2018

It was probably no more than a 20% failure rate up to 2005. After that it was lower.

It was significant enough for Ford to redesign some parts and issue a TSB, but not bad enough to warrant a full blown recall.

We had an 05 with about 160K when we sold it, my dad's has close to 170K, both with no issues.

Dirtman · Jul 24, 2018

TSB = lawsuits are cheaper than a recall.
Recall = recall is cheaper than lawsuits.

adsm08 · Jul 24, 2018

Dirtman said:
TSB = lawsuits are cheaper than a recall.
Recall = recall is cheaper than lawsuits.

Not really, not anymore anyway.

A Technical Service Bulletin is pretty much never issued for something that would meet the threshold of being able to be sued over. They are often used to communicating diagnostic information, or information about common issues with uncommon causes. For example Ford issues one about the 4.0 SOHC timing chain rattle saying that if it has just started try replacing only the tensioners before pulling the engine. There was another one about putting foam strips on the wheel covers of the Fusion for a squeak when they first came out. Or one for the 2.5L Escapes to replace the alternator pulley for a thump at 2500 RPM with A/C turned on. None of those would rise to the level of a lawsuit.

Recalls are often based on complaints to NTHSA. NTHSA will then determine if a recall is needed to address the issue. Ford is very good about doing voluntary recalls though, and often doesn't wait for NTHSA to tell them they have to do it, unlike some other companies.

Denisefwd93 · Jul 24, 2018

adsm08 said:
Not really, not anymore anyway.

A Technical Service Bulletin is pretty much never issued for something that would meet the threshold of being able to be sued over. They are often used to communicating diagnostic information, or information about common issues with uncommon causes. For example Ford issues one about the 4.0 SOHC timing chain rattle saying that if it has just started try replacing only the tensioners before pulling the engine. There was another one about putting foam strips on the wheel covers of the Fusion for a squeak when they first came out. Or one for the 2.5L Escapes to replace the alternator pulley for a thump at 2500 RPM with A/C turned on. None of those would rise to the level of a lawsuit.

Recalls are often based on complaints to NTHSA. NTHSA will then determine if a recall is needed to address the issue. Ford is very good about doing voluntary recalls though, and often doesn't wait for NTHSA to tell them they have to do it, unlike some other companies.

The timing chain problem one of the reasons I made a conscious decision to go with older Ford Rangers

RonD · Jul 24, 2018

When you put 2 long timing chains in an engine it would be fair to say you would have twice as many timing chain related issues, even if the design is good, the math is simple, lol.

From what adsm08 said in previous posts the root problem(1997-2004) was the long chain hydraulic tensioners, the springs inside wouldn't hold the chains tight enough on startup, until oil pressure could take over.
This would cause chains to bang on the guides, which would break over time, and you get the "rattle" causing even more damage.

If pre-2005 4.0l SOHC engine tensioners haven't been changed to the new design it might not be a bad idea to change them, neither is that hard to change out, just some wrench work.
It wouldn't help "rattling" chains, the damage is done, but would be good preventative maintenance, IMO.

engine · Jul 24, 2018

My old '93 BMW (which I still have) advised to wait until the service reminder went out before commencing "enthusiastic driving". I think the same advice is appropriate here and that we should wait for a short interval before taking off. I really do like adsm08's well reasoned and knowledgeable comments. I'll take my chances as one of the 80% and enjoy the wonderfulness of the 4.0 SOHC. It is a great engine to me.

cp2295 · Jul 24, 2018

engine said:
My old '93 BMW (which I still have) advised to wait until the service reminder went out before commencing "enthusiastic driving". I think the same advice is appropriate here and that we should wait for a short interval before taking off. I really do like adsm08's well reasoned and knowledgeable comments. I'll take my chances as one of the 80% and enjoy the wonderfulness of the 4.0 SOHC. It is a great engine to me.

As far as internals beside the timing chain they are tough motors, and make respectable power.

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gw33gp · Jul 25, 2018

I have enjoyed my 4.0 SOHC for over 230K miles with out any serious engine issues. I think it has plenty of power for what it does for me and that includes towing a small race car in an enclosed trailer. I am one that feels you can never have enough power but more power takes more fuel too. I think the 4.0 SOHC does a good job of balancing power and fuel economy in a Ranger.

I also drive a 69 Fairlane Cobra with the 428CJ engine. In stock form it puts out about 400 hp and a bunch more torque. I get my need for power runs with it but would always like a little more power. I prefer to keep close to original from the factory though. It also sucks a lot a gas. They also built a "cammer" (overhead cam) version of this engine in a 427 displacement. That engine was a nightmare with timing chains for the cams. That didn't stop the racers from using it back then though.

engine · Jul 25, 2018

Thank you. It's nice to hear of another SOHC that is going the distance. I still think that a lot of the problem is the eager beavers that turn it on and immediately floor it. I don't think this engine deserves all the bad press it has gotten. Maybe some of it, but certainly not all of it.

Denisefwd93 · Jul 25, 2018

I don't want one, don't think I've ever even go to see one, but i wonder is there an easy way to replace the chains like use the old chain to run to new chain around the sprockets?

Dirtman · Jul 25, 2018

Denisefwd93 said:
I don't want one, don't think I've ever even go to see one, but i wonder is there an easy way to replace the chains like use the old chain to run to new chain around the sprockets?

Pulling the engine is the "easy" way lol.

Denisefwd93 · Jul 25, 2018

Dirtman said:
Pulling the engine is the "easy" way lol.

Whatwhoa! Omg

How bad is the SOHC timing chain problem, really?

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