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Old 08-16-09, 08:44 AM   #1
mlts22 
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Timing chain trick?

Would this work in practice as a cheap way to replace timing chains in cars?
  1. Punch out one of the pins on both the old and new timing chains (its not a bike chain so it would take a Dremel to cut the rivet's head off.)
  2. Attach via wire the new timing chain to the old.
  3. Roll the chain through until you are holding both links.
  4. Detach old timing chain.
  5. Put pin back in new timing chain, then spot weld that pin into place.

I thought of this because it is a lot easier to thread a new chain through as opposed to taking off all the pulleys, but if that pin that was removed and put back comes out, that would mean big trouble, perhaps a blown engine.
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Old 08-16-09, 08:49 AM   #2
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If it's OHC why bother? It's not that hard to take the timing chain cover off...

Besides that, why would you want to spot-weld a timing chain in-place? You'd likely end up welding it to the head...
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Old 08-16-09, 08:58 AM   #3
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I've found that the way it's done is the right way, anytime (most times anyways) one tries to do things "the eay way" one usually ends up paying more money to do it right the second time.
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Old 08-16-09, 09:05 AM   #4
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I've found that the way it's done is the right way, anytime (most times anyways) one tries to do things "the eay way" one usually ends up paying more money to do it right the second time.
Yeah, especially when the wrong way ends up with your car being towed to the shop with a new timing chain broken and spot-welded to the head...
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Old 08-16-09, 09:14 AM   #5
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Yeah, especially when the wrong way ends up with your car being towed to the shop with a new timing chain broken and spot-welded to the head...
Worse when it has to be towed in because the timing got messed up since you didn't have the marks lined up properly or the chain came apart and the pistons slammed into the valves. And I'd think it would take considerable force to "pull the chain through" since you'd be rotating the engine components.
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Old 08-16-09, 09:18 AM   #6
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Flatrater tricks sometimes cost more in time and trouble than they are worth.
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Old 08-16-09, 09:35 AM   #7
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Was just wondering. I was more concerned about the integrity of the weld breaking the chain, but misaligned timing marks are just as bad if not worse, especially when stuff doesn't fire when it should, such as a piston not being even near TDC, when ignition happens, pushing the wrong way on the crankshaft.

In any case, its not something I'd want to do in a half-arsed manner... timing chains cost up to $60 which isn't that much compared to a new block that runs $2500-$3000 (especially larger engines which are going up in price due to CARS).
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Old 08-16-09, 10:14 AM   #8
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What kind of car is it anyway?
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Old 08-16-09, 10:18 AM   #9
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Mainly a general question. I wouldn't be trying it on any vehicles anytime soon.
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Old 08-16-09, 10:34 AM   #10
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Well, most of my cars have had interference heads and timing belts. You can't weld rubber, and you can't get the timing wrong or the pistons collide with the valves and possibly destroy the head. Not to mention, all the things that need to be removed should any welding be needed are the same things needed to remove the belt the right way. itls pretty simple to do on a dohc motor anyway. With my current car, jusr take off some things, prop up the motor with a floor jack, undo the front motor mount and anti-roll mount, jack the front of the engine up a bit, remove the timing belt cover, crank it to TDC, mark everything w/ a grease pencil, take off the tensioner, belts, water pump, etc. Then put the new wate pump, tensioner, belts, etc. On. Then put everything else back together. Can be done in one afternoon and no welding required.

EDIT: if your car has a harmonic dampner, you'll probably want to replace that too, along with any balance shaft belts.

Last edited by turbo2L; 08-16-09 at 10:38 AM.
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Old 08-16-09, 12:40 PM   #11
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Timing chains don't need replaced unless your rebuilding the whole engine anyway so your going to already have the whole thing disassembled anyway.
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Old 08-16-09, 06:48 PM   #12
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I don't think the idea is too far fetched except for spot welding the link. Question is would it really be any quicker than the standard way?
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Old 08-17-09, 06:44 AM   #13
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Well, most of my cars have had interference heads and timing belts. You can't weld rubber...<snip>
There's a tonne of cars out there with timing-chains, not belts. There are pros and cons to both. One benefit of chains is longevity; it's not uncommon to go 200k-miles+ on a timing-chain. They are also more precise at high-RPMs (most precise is timing-gears where the cams are connected to crank through a series of gears, no slop from chain/belt tensionsers, good for 15K-rpms+).

Depending upon the OP's specific car model, there may be tricks and short-cuts that can be employed for that particular model. Some engines us tensioners that may be backed out far enough to slip the chain over the pulleys. Without knowing the specific car model however, we'd have no idea on time & labour-saving tips.

Also timing-chains face stresses that can't even compare to bike-chains and you simply cannot push a pin out and hope that the chain can be re-assembled safely. There's no way to push a pin out without destroying the integrity of the chain and I wouldn't trust a spot-weld. There's simply no way to clean off a chain well enough that's been bathed in oils and acids for years to get a clean weld.
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Old 08-17-09, 07:27 AM   #14
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Timing chains don't need replaced unless your rebuilding the whole engine anyway so your going to already have the whole thing disassembled anyway.
Almost always true but on some engines with long chains and OHC they can stretch after a couple hundred thousand miles.
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Old 08-17-09, 03:15 PM   #15
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Yeah, especially when the wrong way ends up with your car being towed to the shop with a new timing chain broken and spot-welded to the head...
Give the mechanic a good laugh and a month's rent.
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Old 08-18-09, 01:28 AM   #16
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Timing Chain? Dude,You need one of these...
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Old 08-18-09, 01:44 AM   #17
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Roller chain pins are hardened, heat from even a brief spotweld would leave a soft spot that would probably contribute to
premature failure and further engine damage.
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Old 08-18-09, 01:49 AM   #18
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...You can't weld rubber...
Yes you can.
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Old 08-18-09, 11:40 AM   #19
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Originally Posted by mlts22 View Post
Would this work in practice as a cheap way to replace timing chains in cars?
  1. Punch out one of the pins on both the old and new timing chains (its not a bike chain so it would take a Dremel to cut the rivet's head off.)
  2. Attach via wire the new timing chain to the old.
  3. Roll the chain through until you are holding both links.
  4. Detach old timing chain.
  5. Put pin back in new timing chain, then NO - spot weld - NO that pin into place.

I thought of this because it is a lot easier to thread a new chain through as opposed to taking off all the pulleys, but if that pin that was removed and put back comes out, that would mean big trouble, perhaps a blown engine.
I actually did this, with help from a pro mechanic (I was the delivery guy at an Alfa dealership) on my first Alfa, a '72 Berlina, with a 2-litre, DOHC motor. It had > 100K miles and probably not an exemplary maint. schedule, so there was slack in the bottom chain. (The Alfas have an idler sprocket, mid-way up from crank to cams. The upper chain is easy to replace, and has a master link, the lower one - not).

The job proceeded exactly as described above, except a master link (intended for the top chain) was substituted for the missing link/pin in the bottom chain that we cold-chiseled off.

As others have said, you need to be really careful that 1.) it all doesn't drop into the pan - use baling wire to "support" the chain and shop rags to keep the flying metal from entering the oil supply, 2.) keep the timing chains sync'd while you're doing all this, and 3.) don't FU the idler sprocket, other nearby links, etc. But, the procedure did work, with many more miles put on that motor, until the car was rear-ended on 19th Ave. in SF. I tried to salvage the motor but had no place to store it. I miss that car - as boxy as it was.

Mine never looked as nice as this one - it drove very well, though. I didn't have a venetian blind in the rear window, either.



I can't find a good schematic for the chain layout. I may need to scan one from an old owners manual.
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