Why you should replace that timing gear....

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Why you should replace that timing gear....

Post by Dan Szwarc »

Got a 60s lincoln? 70s maybe?

Here is why you should consider replacing that gear if you haven't already.
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Broken teeth. Cracked Nylon all the way around. This gear was on the verge of failing completely. It was removed from dug's 66 in dec 2004.

Any questions?
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AnthLinc
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lincoln

Post by AnthLinc »

Did someone steal my picture? So familiar.
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TonyC
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Post by TonyC »

Yeah, that looks very familiar. The gear I replaced looked like that, except that the nylon teeth had not yet broken off--the fractures were all over, though. The gear on my original engine, though, looked three times that bad--it looked like the timing chain had crushed the nylon.

It was a nice idea to make the engine quieter, but they had no way of knowing what the long-term repercussions would be. And as far as I know, that practice is still in use--not just for Lincolns, but across the industry as well.

---Tony
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Post by mechatech »

TonyC wrote:It was a nice idea to make the engine quieter, but they had no way of knowing what the long-term repercussions would be. And as far as I know, that practice is still in use--not just for Lincolns, but across the industry as well.
I think long term than and now was about 4-5 years. Anything else was gravy :D Looks like an engine rebuild for me this spring.
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TonyC
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Post by TonyC »

That is true. Lincoln wanted to double that, and they did. Anything beyond, as you said, was gravy. That line of thinking still exists, even though it may have stretched to about ten years.

And how many are still using that practice?
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Post by princessmaggie »

Wow. I wish I'd had the chance to see mine when it was done a couple of months ago, but the tech that did the job threw it out. Nevertheless, it feels so good to know that it's done and I'll never have problems with it.
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Post by berigan »

Wish I had kept the Cam gear off of my '69 Impala! That 350 (with 140,000 miles) was missing most of the nylon teeth,(looked like it came off of someone's bike!) and the chain was soooo very stretched. How do people put 200,000+ miles on an engine without replacing them????
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Post by berigan »

Oh Dan, how many miles were on this engine, anyway?
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Post by bunyan »

Hi folks!

I cant wait to see what mines looks like (Yup my car still awaiting that chain :lol: ) I got the water pump off, now I just gotta jack up the engine and do the oil pan gasket and oil pump. We just got a warm spell starting today though so it might get done this weekend. Luckily I have a driveway and something else to drive so I can afford to wait. Unluckily the driveway is outside so I have to deal with the weather

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Post by TonyC »

I feel for ya, Bunyan. I had to deal with rain for the last three days (well, at least with that I can run the wipers to bleed the air pockets out of the fluid without looking stupid on the road :D ).

Berigan, actually it isn't so much mileage that causes the failure as it is age. After 25 to 30 years, nylon just deteriorates with age, regardless fo how much or how little the engine was used. After age, then use will accelerate the failure.

P.S. While you have the front of the engine opened, this will be a good time to check the accuracy of your harmonic balancer. I noticed this during my operation just two days ago, so I know it can happen to others. The ring on the balancer that has the timing marks has a tendency to slip. Because the rubber isn't in the same way it was when it was new, the ring will spin on its mount, almost like a hubcap, reading totally wrong. If you don't check this, you could end up trying to set your distributor when the marks are 45 degrees off or more. While your crankshaft and gears are still physically at #1 TDC, make sure the timing marks on the balancer ring also read TDC (you can start putting the cover and pointer back on, but don't turn the shaft at all). If they don't, you need to take the balancer back off, then remove the ring and reset it. Make a mark on the inside of the balancer where the 0-degree mark should line up before you remove the ring.
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Post by Dan Szwarc »

berigan wrote:Oh Dan, how many miles were on this engine, anyway?
According to dug, probably 125,000 miles.
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Timing gear

Post by autostick »

I finally got around to changing the timing gear. Much to my surprise the gear was intact, with no signs of wear or cracking. I changed it anyway. See original nylon gear in situ below.
If you get your replacement gear from Baker's, just note the one they sent me was 4/1000 too small on the inside flange. I sanded it down on a potter's wheel and it works fine.
Image
BTW, if you do this job inspect the front crossmember as this is a good point to put in new metal for a solid ride.
Good luck to you.
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Post by SatansEnemy »

does a 79 mark V 400 have this nylon coated timing gear?
if so i will get on that fixed soon.
thanks
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Post by Dan Szwarc »

SatansEnemy wrote:does a 79 mark V 400 have this nylon coated timing gear?
if so i will get on that fixed soon.
thanks
Yes.
Lugnut

Post by Lugnut »

A good rule of thumb to follow is to accept the fact an Original Equipment water pump was good for 75 to 100K miles in the '60s, '70s, and into the '80s. Those nasty nylon coated timing gears had about the same life expectancy. So, if one is replacing the water pump doing the timing gears and chain is a good idea since one is already taken off all the stuff to get to the pump anyway.

If there is a question about whether the timing gears and chain were replaced by a previous owner, it is just flat a good idea to yank both the water pump and timing gears so you know exactly what you have. Waiting for an indication of a problem with the gears can cause engine damage and lead to a complete overhaul.
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