why honda and others don't use timing chain in

[JTK]

A neighbor of mine had a 2002-03 Ford Explorer with the SOHC 4.0L. It quit on him on the fly. Per him it let out a *BANG* and the engine came to a screeching halt. Supposedly the timing chain let loose and tore holy he!! out of the engine. Per him they basically replaced the short block. It was all under warranty since the truck was like a year old at the time. I'm sure stuff like this is super rare though. As likely as an engine failure on a new vehicle.

Joel

 

[The Critic]

Originally Posted By: JTK
A neighbor of mine had a 2002-03 Ford Explorer with the SOHC 4.0L. It quit on him on the fly. Per him it let out a *BANG* and the engine came to a screeching halt. Supposedly the timing chain let loose and tore holy he!! out of the engine. Per him they basically replaced the short block. It was all under warranty since the truck was like a year old at the time. I'm sure stuff like this is super rare though. As likely as an engine failure on a new vehicle.

Joel

Timing chain problems on the 4.0 aren't uncommon. Whimsey on this forum traded his because of it.

 

[BarkerMan]

I'd like to ask again, does anyone know if chains throw higer wear numbers?

 

[JTK]

Originally Posted By: BarkerMan
I'd like to ask again, does anyone know if chains throw higer wear numbers?


No way of telling unless you have 2 identical engines using the same oil under the same conditions. 1 with chain driven cam(s), the other, belt driven. Theoretically? They should throw higher wear numbers due to the 100's of additional metal/metal oil lubed parts tossed into the mix.

Joel

 

[dustyjoe1]

My 02" civic has 98k miles and still on original timing belt...still looks in good condition btw: ( knock on wood). Will be replacing it in the next 10k though weather it needs it or not.

the cost is negligible compared to the altrernative...

 

[ikeepmychevytoo]

Shearing oil faster at highher revs?

 

[dnastrau]

I feel that timing chains really should be considered a maintenance item on older models as they do have a failure point. Of course, those never had a recommended replacement interval as far as I know. In my extended family, the following cars suffered chain/gear failure at around 150K over the years:

'67 Firebird 326 (Bent valves - junked)
'68 Impala 327 (Bent valves - junked)
'72 Caprice 400 (Got lucky - fixed)
'73 Impala 350 (Bent valves - junked)
'74 Celica (18RC - junked - too rusty)
'90 4Runner (22R - caught just before it jumped time)

With the proliferation of chains again I wonder if replacement intervals will eventually be recommended (?)

Andrew S.

 

[Kestas]

I'm not sure which models exactly, but for decades many of the old style V8s had plastic gears and required replacement somewhere around 100K. It's not so much the chain as it was the gears that required replacement. But even for all metal gears, the timing gear set should be replaced somewhere around 150K.

Andrew, were your GM failures nylon gears or all metal?

I know Ford transitioned from nylon to all metal gears some time in the late 80s.

I never remember reading in any owners manual about recommended replacement intervals for timing chains. I doubt they'll start recommending replacement.

 

[dnastrau]

The GM V8s in question all had factory nylon cam gears. The chain guides are what probably failed on the Toyotas (I know for sure on the '90.)

I think that most U.S. manufacturers switched to nylon coated cam gear teeth in the early to mid '60's to make them quieter (or perhaps to ensure built-in obsolesence.) Nylon tooth wear coupled with chain stretch spells disaster especially if it fails at speed (bent valves at least.)

I have also heard that the nylon on those gears gets brittle with age even if an old car has low mileage. A friend rebuilt a Chrysler 440 a couple of years back and nearly all of the nylon coating had come off of the gears. It was amazing that the engine hadn't jumped time. If I had an old car with a known nylon cam gear setup I would change it to be sure.

Andrew S.

 

[Kestas]

Some people say nylon gears started showing up in the 50s.

I did just a bit of research on this since I drive a 91 Grand Marquis with 90K on a daily basis. It reportedly has all metal gears.

But I was a bit confused when I rebuilt my 71 Cutlass Rocket engine and found the original gears to be all metal. I guess that adds to the good name of the Rocket engine.

 

[BuickGN]

The GN had a nylon coated cam gear. Found a few "teeth" in the pan. The chain had a TON of play in it.

Switched to a double roller chain and steel cam gear, ditched the tensioner, and it looked surprisingly tight at 60K. I also went with a .01 tighter chain to make up for the align bore.

Edit: I wanted to add that I couldn't tell a difference in noise but the car is pretty loud anyway.

 

[Steve S]

Originally Posted By: JTK
Originally Posted By: Squishy
I'll go one step further and say I prefer the pushrods. Really short chain (sometimes even gear driven) and they are generally tuned to be low-revving stump pullers..


Good point. One little dinky chain, no complicated tensioners, idlers, etc. On one of today's typical chain driven OHC setups, if that mile-long chain lets loose, that engine is done for. That sucker is going to weed-wack the front of the engine to bits. IMO, at the end of the day it doen't really matter. All that protects your engine from disaster is either a simple strip of reinforced rubber, or a more complicated, long multi-link chain. Worst part of a T-belt is the expense and time required to replace it @ over 100Kmi.

Joel
Been saying that for years .The minimal advantage to the consumer isn't worth the cost of an overhead cam engine.

 

[Steve S]

Originally Posted By: BuickGN
The GN had a nylon coated cam gear. Found a few "teeth" in the pan. The chain had a TON of play in it.

Switched to a double roller chain and steel cam gear, ditched the tensioner, and it looked surprisingly tight at 60K. I also went with a .01 tighter chain to make up for the align bore.

Edit: I wanted to add that I couldn't tell a difference in noise but the car is pretty loud anyway.
The difference is the quality of the installed parts.

 

[BuickGN]

Agreed.

 

[DmanWho]

Originally Posted By: BarkerMan
I'd like to ask again, does anyone know if chains throw higer wear numbers?

If Schaeffer's ever sends my UOA results back on my 2.0L Suzuki w/timing chain, we can start comparing it to other Japanese 1.8L & 2.0 belt driven engines.