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Discussion Starter #1
Help!
Sound like a rattle at 3000 rpm from engine. 1974 spider. Figured I should check the timing chain tension but after loosening the tensioner lock nut one complete turn the chain tensioner doesn't budge in either direction. Seems to be jammed and can't pry it out to tighten the chain. There is a groove in the timing chain cover on the driver side but I wonder if this might be old.

Anyway, any suggestions would be welcomed. I am as stuck as the tensioner at this stage. Not sure how much force can be applied to make it shift. Am I missing something here?

The engine was recently rebuilt by a good machine shop here in seattle.

Thanks for any suggestions

Ts
 

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Ts (Tom Swifty?) does your tensioner bolt have threads visible when it is tight?
http://www.alfabb.com/bb/forums/engine-rebuilding/147708-tinkle-tinkle-little-chain.html
It can take a good deal of force with a pry bar to move the tensioner. Does it retract into the engine under force? You mention tightening the chain- what caused you to want to do so? There should be no slack at all. The chain should be taut. If there is enough slack that the chain droops or sags, and the head has been off recently, the reassembly was not correct.
 

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is the bolt still showing 2-3 grooves when fully tight (ie. the head of the bolt is not flush with the head)?
If not, the machine shop might have messed with it and not realised the bolt locates into a locking wedge, in which case the bolt would tighten down fully flush and maybe the wedge is jammed?

I suppose you could take out the huge hex plug (19mm or something like that) behind the tensioner (if you have one) and release it that way.......
 

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Discussion Starter #4
Thanks Jim
The chain is deflecting by about half an inch so seems excessive slack. I cannot move the tensioner in either direction but haven't tried with any great force. There are about three threads visible when the tensioner lock nut is tightened down. Perhaps I just need to use a little more force to get the tensioner moving. It does seem to be jammed however.
Any ideas about what to do next? How much force might it take and how to apply the for e without breaking something.

Thanks for the help

TS (actually Third Spider)
 

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I am as stuck as the tensioner at this stage. Not sure how much force can be applied to make it shift. Am I missing something here?
I don't think you are missing anything, no. With the bolt loose, the tensioner should be free to pop out and take up any slack in the chain. Of course, you do need to use your cam turning tool to first remove any slack on the exhaust side (e.g., between the idler sprocket and the E cam) and top (e.g. between the I and E cams). If there is slack on the intake side and the spring behind the tensioner can't push it out, then yes, something is jammed.

Unfortunately, we can't tell you exactly what is jammed. Probably something to do with the wedge that the bolt tightens against the tensioner. With the engine installed, it is pretty hard to remove the special bolt, and sight down its threads to see if the wedge is properly in place.

The engine was recently rebuilt by a good machine shop here in seattle.
You might want to rethink that opinion.
 

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Try taking out the bolt on the intake side that retains the front of the head. If this bolt has been replaced by one with a an incorrect length, It can get into the tensioner bore and jam it. Don't ask me how I know :)
 

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You can also take the tensioner bolt out, it should have a small pencil lead sized pin sticking out. Then take a mirror and look down the hole. You should see a flat surface with a hole the size of what it sticking out the bolt. If not something got jammed. I usually loosen mine with the wooden handle of a ball peen hammer. Stick it down to where the end is on the rolling gear of the tensioner and from the right side of the car pull the top of the hammer back to you. I should slide back into the head easily. If it is hard to get it to move then you are going to have to get it out and find out why it won't move. just put some rags down below the roller gear so nothing can fall down. I'd also get it to tdc and the cam lobes on 1 pointing out before I unhook the chain. Sometimes you can get the tensioner out by using a big screwdriver on the back of the tensioner and the head and pry it out if it is indeed stuck. When going back together get some heavy grease and put the wedge on the tensioner and slide it back into the head pull it back with the hammer until you see with the mirror the hold is centered in the tensioner bolt hole. Keep it their and put the bolt back in. As said above when the pin goes into the hole you should see a couple of threads left exposed on the bolt. Good luck!
 

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Richard Jemison
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Stuck tensioner

The only safe way to deal with this is to remove the socket head plug and remove the spring.
You can then fish out a misplaced wedge with your finger or a magnet.
I suspect that your mechanic missedplaced the "wedge" and screwed the bolt in on the tensioner which will not only not hold it in place long will bugger the metal surface so it wont move by spring pressure.

If you recover the wedge, then the simple solution is to tap the tensioner out to tension the chain, then slip the wedge back into it`s slot from the rear until the hole aligns with the bolt`s centering point.

This is a very common issue with non Alfa specialist working on these heads.

Commonly since dealing with high lift cams causing higher than normal chain loads on the stock tensioner, I build adjustable stops to keep it in place so there is no slippage.

Pics below show how it is built.
The original cap is welded flush, drilled for the threaded pin then a recess is cut for the sealing "0" ring to compress into.

Prevents problems before they occur.
 

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Discussion Starter #9
Well, I had become a little discouraged but thanks for all the helpful responses. I will start to do some investigating to figure out what has happened. The tensioner is very stuck, I cannot lever it in either direction so something is jamming it. I wonder if tapping it from the plug end might break it free. Also, do I need a cam turning tool to adjust chain tension? From what I have read most write ups indicate that turning the engine will distribute the slack onto the intake side.

Thanks for the help. I will have a look around this area tonight or tomorrow and may be looking for more guidance as I proceed.

Ts
 

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do I need a cam turning tool to adjust chain tension? From what I have read most write ups indicate that turning the engine will distribute the slack onto the intake side.
Yea, you could probably do it that way. You could also use a 22 mm open-end wrench on the big nuts at the ends of the cams - just don't apply enough torque to loosen the nuts! But don't use vice grips on the collars of the cam sprockets - that leaves the "mark of the turkey".

genericwood said:
Try taking out the bolt on the intake side that retains the front of the head. If this bolt has been replaced by one with a an incorrect length, It can get into the tensioner bore and jam it.
I wasn't aware that the threaded hole for the intake side front head hold-down extended up into the cam tensioner bore. This is a suggestion worth exploring before looking into more complicated causes & fixes. It may be a long shot, but it's easy to test and if it solves the problem.....
 

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Discussion Starter #11
Here's a picture of the view into the threaded hole housing the tensioner lock nut. Looks to me that the merl wedge is not where it should be, but I am not entirely clear what I am looking at here. Any thoughts? Unfortunately backing off the he's bolt failed to free up the tensioner, pity.

Ts
 

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As best as I can tell from your picture, the wedge does like it is in the right place - I don't see a problem. How did the bolt look when you took it out? Did it have a little nub on its end, about the diameter of the smallest hole visible in your photo?
 

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Here is a picture I hope will help you. It shows the wedge in place. I think yours is there as well. If the wedge was missing or in the wrong location you would see the spring.

36.jpg

With the pin re installed (no picture of the pin, sorry), have you tried to roll the car in 5th?

BTW, Do not do this with engine running and ONLY forwards. Going backwards will slacken the chain and it might jump a tooth. ONLY FORWARDS!

Good luck,

Vin
 

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Ok, found a couple pictures put up by Papajam that shows the bolt, and wedge in position. Yours is there.

Tensioner%20Bolt.JPG

Tensioner%20Wedge%20Hole.JPG

Good luck,

Vin
 

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Discussion Starter #15
The little nub on the end of the locking bolt is much smaller than the obvious aperture at the bottom of the hole on the picture. I think that the ring of metal at the bottom of the hole is part of the front case of the block and not the wedge. Deeper on the hole there is an odd reflection that also doesn't look like the small hole on the wedge. I will go back to look again since I am confused by what is seen here.

Ts
 

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Discussion Starter #16
Hi vin
Just got your post after I sent last. That's great, looks just like what I see and the reflection is a coil of the tensioner spring. So looks
Like its in place. Do you think I cannot push the tensioner in because its fully retracted, and can't push it out because the chain is restricting it? I think not because there isn't even a micromovent when I lever it pretty hard on either direction.

Do you think that removing the plug will allow me to get more force into the tensioner to dislodge it and get it moving.

Perhaps I am not going about this the right way and it isn't jammed, just my brain that is jammed?
 

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Discussion Starter #18
Vin
Answering your question about 5 th gear roll, I have been turning the engine (using the fan with the spark plugs out) counter clockwise (looking forward) to get slack onto the intake side.
 

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Discussion Starter #19
Based on that photo it's not fully retracted. Has about 3/4 inches of the shaft visible beyond the block. So that helps in the analysis, it does indeed seem to be jammed since if not, I guess that I should be able to compress the tensioner spring and push the tensioner into the block with leverage sufficient to make the engine rock on its mounts.

Thanks for the input alfa jay and vin. Getting a better understanding of how it should look. This helps greatly.
 

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The wedge is in place, so that's good.
The tensioner sounds well and truly stuck (you should be able to move it IN at least, since, as you say, it's showing 3/4" - so not fully home) you are using enough leverage, right?

I see 2 possibles:
1. the bolt below the cylinder head has been replaced with one too long and is somehow protruding into the tensioner....it certainly looks possible from this diagram, and genericwood says above he had that exact problem - loosen that bolt and see.

if that does nothing, then...

2. the tensioner sleeve has been scored somehow - replace the tensioner locking bolt just enough to locate the wedge, then remove the big hex plug behind the tensioner, remove the spring from the back, and go from there (if it still does not move try putting a short metal rod behind the tensioner and tapping it...the shock might free it up)
 

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