timing chain service life

[440Magnum]

Originally Posted By: TooManyWheels
Originally Posted By: mechtech2
Originally Posted By: Cristobal
Back in the day timing chains almost always lasted until the motor was replaced, rebuilt, or the car got junked.


No way.
Timing chains were a bread and butter daily job.


Thank you - That is what I remember also.


What I said here. ;-)

 

[440Magnum]

Originally Posted By: Hokiefyd
Originally Posted By: motor_oil_madman
I didn't know an engine could have more than one timing chain/belt. My goodness.


I really like how Cadillac did the Northstar's setup (and how Chrysler did theirs, now that I see it). They used an intermediate timing chain to an idler shaft, then ran shorter chain runs off that idler shaft. Chain runs were kept short and chain whip was reduced. It requires more parts to engineer, but in my opinion, is a superior arrangement to one or two longer chains.


I like the Chrysler 4.7 system a lot and it has a good rep, but at the other extreme, you have the Chrysler 2.7. Sorta the worst of all worlds- single LONG primary chain driving the intake cams in both heads, made worse by having to also drive the water pump, and then little short single-row secondary chains to drive the exhaust cams. Even though its out of production, I still have a hate for this engine

 

[TooManyWheels]

Originally Posted By: 440Magnum

What I said here. ;-)



Your point is that plastic coated gears wore. What I commented on is the corroboration that chains stretched. I remember both, and my point is that chains did stretch/wear even when on all metal gears. I have changed plenty, just on my own vehicles.

 

[440Magnum]

Originally Posted By: TooManyWheels
Originally Posted By: 440Magnum

What I said here. ;-)



Your point is that plastic coated gears wore. What I commented on is the corroboration that chains stretched. I remember both, and my point is that chains did stretch/wear even when on all metal gears. I have changed plenty, just on my own vehicles.


I'm agreeing that timing chain jobs were common for a window of time back in the 60s through 80s.

I've never had metal gears actually jump time, though. I've seen enough slop in a chain to cut a groove in a timing cover (and of course reduce engine performance- or at least kill low RPM torque by retarding the valve timing), but with the gears being metal the system rarely failed and jumped time. The "routine" timing chain jobs I remember doing were almost all due to the plastic gears combined with worn chains. Sometimes you'd get lucky and drop an oil pan due to low oil pressure and find all the plastic timing gear teeth plugging up the pickup screen before the chain jumped... that was always fun.

 

[TooManyWheels]

Originally Posted By: 440Magnum

I'm agreeing that timing chain jobs were common for a window of time back in the 60s through 80s.

I've never had metal gears actually jump time, though. I've seen enough slop in a chain to cut a groove in a timing cover (and of course reduce engine performance- or at least kill low RPM torque by retarding the valve timing), but with the gears being metal the system rarely failed and jumped time.


I'm in agreement with you here. I also agree that when the plastic gears failed they made one heck of a mess. When I was in college I put a new crank in a late sixties Buick where the gear had failed and made it past the pickup screen and into the crank/rod oiling. I was amazed the places I found plastic.

 

[spackard]

I had a 429 cu in '73 Mercury Marquis, all metal gears, slip.
My dad was rebuilding the distributor, put it in 180 backwards, went to start it, backfired and slipped but he didn't realize it.

I had to take it to a Ford dealer, who misdiagnosed it as a clogged muffler then as a downpipe with a hole in one of the two walls. After all that money *then* the cam chain was diagnosed. By someone else.

 

[SteveSRT8]

Originally Posted By: mechtech2
Originally Posted By: Cristobal
Back in the day timing chains almost always lasted until the motor was replaced, rebuilt, or the car got junked.

No way.
Timing chains were a bread and butter daily job.
Many older set ups were kinda crude.
Modern ones seem to have nicer rollers and construction.


This has been my experience with anything later than 72 on. Really old cars needed one by 100k miles no matter how you treated them. Then we went plastic and those really stunk IMO.

Current OHV V8's seem to be pretty bulletproof straight out of the factory. OHC setups are hit and miss. Some of those Ford multi-chain systems are scary to even look at!

 

[Jeff_in_VABch]

The timing chains in the 3.6L LY7 engine found in many 2007-2008 GM vehicles are prone to very early wear and failure.

So it's not like all the lessons of the past were well learned and done with.

 

[Robenstein]

I know my 3800 V6 1992 Buick Riviera never had a timing chain done and it lasted 256k miles when the combination of body rot and the original transmission dying sent it to the bone yard. I have seen several other 3800 GM cars approach the 250k mile mark with OEM chains.

On the old small block and big block chevys, the factory chains did need replacing, but I always had good luck with aftermarket double roller chains lasting the life of the engine on a rebuild.

 

[Hokiefyd]

Originally Posted By: 440Magnum
I like the Chrysler 4.7 system a lot and it has a good rep, but at the other extreme, you have the Chrysler 2.7. Sorta the worst of all worlds- single LONG primary chain driving the intake cams in both heads, made worse by having to also drive the water pump, and then little short single-row secondary chains to drive the exhaust cams.


The 2.7L's timing chain really drives the water pump? How is one supposed to replace the water pump if it starts weeping? Does that necessitate the entire disassembly of the front half of the engine to accomplish?

 

[MrWideTires]

after years of racing on drag strips, autocross, road courses, and rallies... I gotta say timing chain all the way.

Every time I have seen an engine with a belt getting miss-shifted at the track and over-revved, the belt snapped costing the owner many hours of labor, valves, sometimes pistons, sometimes even scarred cylinder walls so they needed a new engine.
I have seen this on fully built engines pushing 700hp... all it took was one miss-shift, belt snapped, no more engine.

However, I have never seen a chain snap, personally I have miss-shifted my SpecV at the track a few times sending it to over 8000rpm (redline is 6200rpm) and it's still intact.
A good friend of mine has a 2003 G35 he races also (with 260k miles) and has seen the same incidents, and still never snapped, and hasn't lost any power since the day it was new, my G35 has 88k miles and they both go head to head.

 

[mechtech2]

Originally Posted By: chevyboy14
It's usually not the chain that wears out it usually the gear with nylon tips or the guided and tensioners. My Saturn has 190 and I had the valve cover off few weeks ago chain looked great and had 0 play. They can last forever. If it ain't making noise its probably ok. Usually they will make a raket before they fail.


When new, they have more than zero play.
How did yours tighten up?

 

[artificialist]

Originally Posted By: Hokiefyd
Originally Posted By: 440Magnum
I like the Chrysler 4.7 system a lot and it has a good rep, but at the other extreme, you have the Chrysler 2.7. Sorta the worst of all worlds- single LONG primary chain driving the intake cams in both heads, made worse by having to also drive the water pump, and then little short single-row secondary chains to drive the exhaust cams.


The 2.7L's timing chain really drives the water pump? How is one supposed to replace the water pump if it starts weeping? Does that necessitate the entire disassembly of the front half of the engine to accomplish?

Yes, the front of a Chrysler 2.7 must be completely removed to replace the water pump. Also, since the chain tensioner must come out, the accessories on that side of the engine must come out.

For 2 weeks after I did that job, seeing another Chrysler Sebring Convertible gave me horrible flashbacks.

GM Quad4 engines have the same need, thankfully, the job is far less difficult.