Timing chain tensioner bolt installation - Alfa Romeo Bulletin Board & Forums
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post #1 of 7 (permalink) Old 02-25-2018, 04:11 PM Thread Starter
Lew
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Question Timing chain tensioner bolt installation

Things are progressing with the head gasket (and head) replacement process. Now that I'm finally putting things back together, I have issues with the timing chain tensioner bolt installation.

When I removed the tensioner bolt from the old head, it was necessary to use a wrench to remove it due to the tightness of the bolt in the head. The bolt was in the old head until today when I removed it. When I examined the tensioner bolt after removal, I can see clearly that it's damaged, so I've ordered a new one. I see in the photo below from Vin's great head replacement guide (not his or my pictures) that the guy is hand threading the tensioner bolt into the head, and Vin says, "Patience. Place the bolt in when you feel it. Patience."

My question is, when I receive the new tensioner bolt, should it thread freely enough in the new head that I'll be able to hand thread the tensioner bolt all the way in and feel the pin on the end of the bolt seating into the hole in the retainer plate?
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post #2 of 7 (permalink) Old 02-25-2018, 04:21 PM
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Yes, it should thread in easily. If the threads in the head (or the bolt) are buggered, you'll want to use a re-threading tap or die. Unlike a thread cutting tap or die, a re-threading tap or die is designed to straighten out damaged threads without removing material (which would weaken the threads).

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post #3 of 7 (permalink) Old 02-25-2018, 04:34 PM
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Quote:
Originally Posted by ghnl View Post
Yes, it should thread in easily. If the threads in the head (or the bolt) are buggered, you'll want to use a re-threading tap or die.
Building on what ghnl said, in a normal head the bolt will easily thread in. But, I am worried by your comment "it was necessary to use a wrench to remove it due to the tightness of the bolt in the head" - that may mean that the threads were damaged by the expanded end on the bolt.

When you get your new bolt, try to thread it in by hand. If it won't go, don't force it. Clean up the threads as per ghnl's advice.

Note that when you are assembling the tensioner, you can sight through the threaded hole to verify that the hole in the little square pad is centered with the threaded hole while you hold the tensioner in position by levering it with a large screwdriver. It takes steady hands to hold it still once you verify the position of the square pad.

Screw the bolt in by hand so you can feel it engage the locking pad. But of course, use a wrench to tighten it, or the tensioner will fly out - it takes some torque on the bolt to lock it in place.

Jay Mackro
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'65 Guilia Sprint GT
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Last edited by Alfajay; 02-25-2018 at 06:13 PM.
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post #4 of 7 (permalink) Old 02-25-2018, 06:30 PM Thread Starter
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Thumbs up That's what I thought...

Thanks guys. I've concluded that it was definitely the B Team that did the work on my head back in 1999. From this retention bolt issue, to a wrung-off fuel injector retention bolt (as in one bolt holding the injector in), to a timing chain master link nowhere near accessible when #1 is at TDC on the compression stroke, to a stud in one of the camshaft caps so long it prevented the cam cover from making contact with the head to seal reasonably, nothing surprises me anymore about the work. Hard to believe this was my car.

Everything I've read led me to believe the tensioner bolt should thread easily. Thanks for confirming. The new bolt will go in a new/different head from the head that the damaged tensioner bolt was so tight in. When I receive the new bolt, I'll try to thread it in the new head by hand as advised and, if it won't go, won't force it but will clean up the threads as per ghnl's advice. I've already cleaned the threads in the new head with a round 20-gauge shotgun copper bristle brush, but will do the re-threading tap process if necessary.

I see that the Engine Overhaul Manual says torque to 10-14 lbs. and that there should be 1-1/2 threads exposed if the tensioner is assembled correctly. I hope I'm able to proceed to that step without further ado.

Thanks again for the help!

Lew
1986 Spider Quadrifoglio
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post #5 of 7 (permalink) Old 02-25-2018, 08:13 PM
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.... to a timing chain master link nowhere near accessible when #1 is at TDC on the compression stroke...
I don't think you can ever count on that one happening consistently. I doubt the length of the upper timing chain is an integral multiple of the circumference of the drive gear. And even if it was (and the ratio was "M"), the chain would only appear topside with a 1/M probability.

Jay Mackro
San Juan Capistrano, CA

'65 Guilia Sprint GT
'67 Duetto
'91 164L
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post #6 of 7 (permalink) Old 02-26-2018, 05:38 PM Thread Starter
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Originally Posted by Alfajay View Post
I don't think you can ever count on that one happening consistently. I doubt the length of the upper timing chain is an integral multiple of the circumference of the drive gear. And even if it was (and the ratio was "M"), the chain would only appear topside with a 1/M probability.
Thanks Jay. Which proves yet again that it is best to comment only on things one knows something about. My mother would not be happy. Have a good one!

Lew
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post #7 of 7 (permalink) Old 03-08-2018, 05:24 PM Thread Starter
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Quote:
Originally Posted by Alfajay View Post
When you get your new bolt, try to thread it in by hand. If it won't go, don't force it. Clean up the threads as per ghnl's advice.
The new bolt threads into the new head easily and freely. Wow! Now I know how it's really supposed to be. All is well with the world!

Will hopefully get to work on it some this weekend.
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Lew
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