Timing chain woes

[tig1]

Originally Posted By: Colt45ws
There are some Ford 4.6L V8 with a bad run of tensioners. The chain would wear though the nylon very quickly (relatively, under 100k usually) then go metal on metal with the aluminum base.


When I bought my old 96 Merc GM 4.6 nearly new, I ask a Ford Guru friend about the OHC chain. He said they required oil that kept the engine from sludgeing and clog the very small oil holes that lub the guides and chain. If they clog, the nylon guides were history. Well I never had a problem with mine, but it only had 218K when I sold it.

 

[Spazdog]

Originally Posted By: Colt45ws
There are some Ford 4.6L V8 with a bad run of tensioners. The chain would wear though the nylon very quickly (relatively, under 100k usually) then go metal on metal with the aluminum base.


One of my co-workers has a 4.6L 2002 Explorer. I thought his failed tensioner/jumped timing chain was an anomaly. I never had any timing problems with my earlier model Mustang 2V Modular's timing chain, but there was apparently a problem with a lot of Explorers in that time frame.

 

[Nick R]

Originally Posted By: Spazdog
Originally Posted By: Colt45ws
There are some Ford 4.6L V8 with a bad run of tensioners. The chain would wear though the nylon very quickly (relatively, under 100k usually) then go metal on metal with the aluminum base.


One of my co-workers has a 4.6L 2002 Explorer. I thought his failed tensioner/jumped timing chain was an anomaly. I never had any timing problems with my earlier model Mustang 2V Modular's timing chain, but there was apparently a problem with a lot of Explorers in that time frame.


The truck and Mustang engines while technically very very similar, were built at two seperate plants. The mustang engines were built in Romeo Michigan, and the truck engines were built in Ontario.

 

[Hokiefyd]

Originally Posted By: Spazdog
One of my co-workers has a 4.6L 2002 Explorer. I thought his failed tensioner/jumped timing chain was an anomaly. I never had any timing problems with my earlier model Mustang 2V Modular's timing chain, but there was apparently a problem with a lot of Explorers in that time frame.


One of my co-workers had one, too; except I think his was a 2000 or 2001 and his was the SOHC V-6. It lunched the engine at 140,000 miles or so, but it gave plenty of warning. Like, YEARS of warning, with the rattling timing chain. Something was definitely up with that particular design.

 

[meep]

I'd always been a fan of chains due to their longevity, but that was back when chains were short. SBC's and jeep I6's just had two sprockets, one chain, no guides-- same with the infamous and ubiquitous (got my vocab for the day!) chrycho 3.3/3.8. you just didn't hear of frequent, or even regular failures there... just every once in a while it would happen... about as often as someone throwing a rod! My small jeep V6 uses 6 sprockets and 3 short-ish chains-- no idea if there are tensioners or guides in there, but it's triple the wear over a traditional pushrod motor. Even now the complex chain systems still hold one stark advantage-- they are sealed from the elements.... so in vehicles that see the occassional stream or nasty, nasty use, they have an advantage. also fewer oil seals.

But all of these complex chain systems seem to be losing their advantages over the belt these days. OEMs were going back and forth between the two for things like noise, packaging requirements, manufacturing cost, rather than pure engine design. I used to hate belts... but now IDK... they are a known entity... at 100k, go in there, pull the belt, WP, all the seals, the tensioner and idler, and replace. Done. Do it all. Good for another 100. On a chain, change the oil more often, don't mess with it... it will either fail brilliantly or outlive the vehicle, and as they stretch, the timing will retard some and you live with the slight drop in performance.

From years of cycling I'll tell you this... if you DO replace a chain that has *any* kind of stretch, you must change the sprockets as well. they wear together and the chances of jumped teeth or worse is very, very likely if you don't.

IDK-- if I end up in another sedan or passenger car, I won't fuss if it has a belt.

 

[SLCraig]

I still prefer chains.
One of the reasons I went with my newer Honda over the older ones.
I did replace a DOHC Saturn timing chain/guides/sprockets but it was because the car was previously neglected. It is still running good to this day on the replacement timing set. (not in my hands)

 

[CBR.worm]

Some cars have chains and belts. a particular Audi we had, there was a belt in the front, and a chain between the cams in the back. The chain tensioner went bad around 40k. The chain was only about 8 inches long. Luckily in our case it just made a lot of noise and was a pain to replace, a friend of mine had the same engine in a VW and it jumped a tooth when his chain tensioner went bad.

 

[Win]

Originally Posted By: Colt45ws
There are some Ford 4.6L V8 with a bad run of tensioners. The chain would wear though the nylon very quickly (relatively, under 100k usually) then go metal on metal with the aluminum base.


Ford's timing chain setups stunk (stink?) across their entire product line.

The early 4.0 Jaguar V8's were notorious for catastrophic tensioner failure.

The second revision was not a lot better.

Our 4.2 AJ-V8 has rev three which is supposed to solve the problem(s), but I swear I think I can hear a start up rattle after it has sat for a few weeks, and it just turned over 30K miles.

In contrast my old AJ-6's went 236K and 177K respectively, with no chain/tensioner issues on nothing but the cheapest mineral oil swill, and still ran like scalded cats when I got tired of them.

The near twenty year old chains and tensioners on my V12 are still perfect, but it has only 75K or so.

 

[Win]

Originally Posted By: 2004tdigls
yes, they would stretch and the timing would jump a tooth


+1, that was relatively common.

 

[rshaw125]

Originally Posted By: Old Mustang Guy
You guys have given me something else to wonder about on my 01 Escape with 177k. It has the Duretec v6 with timing chain.


Very reliable robust engine. I have had two of them with high miles. Never a problem with timing chains.

 

[Spazdog]

Originally Posted By: rshaw125
Originally Posted By: Old Mustang Guy
You guys have given me something else to wonder about on my 01 Escape with 177k. It has the Duretec v6 with timing chain.


Very reliable robust engine. I have had two of them with high miles. Never a problem with timing chains.


Some of the early VVT Mazda MZI variants of the Duratec had VVT related problems with the timing chains and the SHO V8 variant of the Duratec had HORRIBLE cam gear problems. They had ironed out the problems with the VVT long before Ford started using that design in the Fusion and the Taurus SHO V8s have all either had their cam gears welded to the cams by now or they have long been dead from piston to valve strikes.

 

[Lyman]

The 4.6 in my Mustang still has the original timing chains. 155k and still quiet as can be. On my Harley I swapped the timing chain set up out for a gear drive set up.

 

[Hokiefyd]

Originally Posted By: Spazdog
...and the Taurus SHO V8s have all either had their cam gears welded to the cams by now or they have long been dead from piston to valve strikes...


What would happen...would the drive gear come loose on the cam and "lose time" with the camshaft? Very interesting, and surprising. Much of that engine, in fact both SHO engines (V-6 and V-8) were Yamaha designs, weren't they?

 

[caravanmike]

i too always thought the timing gear problem was on the yamaha motors. i was never aware of the duratec with the problem?

 

[rcy]

Originally Posted By: SLCraig
I still prefer chains.
One of the reasons I went with my newer Honda over the older ones.
I did replace a DOHC Saturn timing chain/guides/sprockets but it was because the car was previously neglected. It is still running good to this day on the replacement timing set. (not in my hands)


Not sure if Honda has figured out the chains on their newer vehicles, but my friend has a 2003 Accord and is on very good terms with the mechanic at his Honda dealership. He was warned that by around 200 000 to 250 000 KM, the chains have stretched enough to cause problems.

 

[Spazdog]

Originally Posted By: Hokiefyd
Originally Posted By: Spazdog
...and the Taurus SHO V8s have all either had their cam gears welded to the cams by now or they have long been dead from piston to valve strikes...


What would happen...would the drive gear come loose on the cam and "lose time" with the camshaft? Very interesting, and surprising. Much of that engine, in fact both SHO engines (V-6 and V-8) were Yamaha designs, weren't they?


The heads were still Yamaha. The bottom end was basically a 60° 2.5 Duratec with two extra cylinders. (yep. 60° V8...had to have a balance shaft) They would press a steel ball into the hollow camshaft to spread it out to attach the cam gear to the cam but it would eventually slip. The engine was an interference design so that was a disaster when it did. Weld the gears in place, no problem.