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Mark I cam belt tensioner need advice  Rating:  Rating
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 Posted: 01-21-2014 12:46 am
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Palindrome
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I am trying to get 12465 ready for the road. Following advice from this site, I am replacing the timing belt and have intended to replace the tensioner bearings. It now seems that the Mark I presents way more problems than described in the process of renewing Mark 2 bearings.

I have the belt off and the tensioner loose, but now see that the nice cast-in timing mark extension blocks the removal of the tensioner. It appears that I will have to remove the crankshaft front cover to get the tensioner off. Yikes, I wasn't looking to rebuild the engine.

The current bearings seem to turn smoothly and I'm tempted to just push the tensioner back into place and put on the new belt. However, I can't see how to access the bolt on the back of the tensioner to tension the belt once it is on.

Does anyone have a suggestion for an easy way to deal with the Mark I tensioner?

As background; this car has been in storage for many years. The engine is very clean and appears to have been rebuilt not long before storage. The old timing belt looks fine, but seemed a little loose with the tensioner at what looked like maximum extension.

Thanks for any suggestions.

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 Posted: 01-21-2014 02:58 pm
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Brett Gibson JH5 20497
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My 2 cents would be change the bearing, a $5 bearing is not worth losing the engine over and you are questioning the setup so it seems you have doubts. As for adjusting the adjuster there is a special wrench that is stepped and goes behind the adjuster and turns it, I took a quick look in the Club Store but did not see it, maybe I looked in the wrong spot. It's a pretty simple thing that a diagram was posted once or twice on these boards for something you can make yourself, if not I'm sure Delta probably has them.

Brett

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 Posted: 01-21-2014 07:42 pm
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Dakota123
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Heh, removing the front cover doesn't make bearing removal much easier...

The tensioner needs to be rotated to give as much clearance between the timing pointer and the tensioner as possible.  I'm pretty sure I ended up removing the bearings out from under the outer 'cover' (it's three pieces, two bearings and the outer pulley that the belt rides on); the smaller size of the individual bearings clears the pointer.  Pretty sure I mounted the new bearings to the shaft first and then installed the outer cover over the bearings.  (Or maybe it was the inner bearing, then the cover, and then the outer bearing -- I don't remember.)

For reassembly I first heated the bearings to 200 degrees in an oven, while freezing the housing to -10 in the deep freezer.  Then froze that assembly in the freezer and heated the outer cover.  Went together pretty easily that way.  I ended up using a Mark II bearing shaft and adjusting eccentric to make adjusting easier.

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 Posted: 01-21-2014 08:03 pm
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Palindrome
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Thanks for your suggestions.

What tool do you use to remove the bearings (or outer cover) while the unit is still on the car? The directions I've seen for bearing removal involve a bench vice.

I guess I'd have the same question for reinstallation (especially with those hot and cold parts:-)

Thanks again.

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 Posted: 01-21-2014 08:22 pm
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Dakota123
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I cobbled together a small-ish two-jaw puller with standoffs under the ears to bear against the inner bearing.  To keep the outer cover in place I periodically braced the bearings against the support web and using a bronze drift tapped (pounded?) the outer cover back to its normal position.

Messy, and there's no turning back since bearing damage is almost inevitable.

Last edited on 01-22-2014 05:22 am by Dakota123

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 Posted: 01-22-2014 05:18 am
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Palindrome
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Dakota,
That sounds quite ingenious, but scary.

I wonder about putting a locking nut on the stud that goes through the excentric spindle into the block and unscrewing the stud out of the block. Then if the stud can be pulled out through the spindle, the whole tensioner could just be lifted out past the timing marker. My concern is that the stud may be frozen in the block and would strip out the threads in the aluminum block.

Any thoughts?

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 Posted: 01-22-2014 05:19 am
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Palindrome
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Thanks, Brett.

I intend to buy the wrench from Delta.

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 Posted: 01-22-2014 05:32 am
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Dakota123
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Would that it were that simple. The stud can be removed no problem, but the steel spindle is a press fit into the aluminum cover and isn't going anywhere without breaking something. In fact, it's really difficult even to rotate the thing to set the belt tension.

On mine at least, you may have better luck.

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 Posted: 01-22-2014 06:46 am
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Palindrome
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Oh yah!
I have already pulled the tensioner out as far as there is room, so I should have known that the stud would make no difference. Thanks for reminding me.

Hard to believe they could have designed it this way, but I guess they realized the problem after it was in production and eventually fixed it...that was the story of the 907 engine.

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 Posted: 01-22-2014 02:01 pm
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Brett Gibson JH5 20497
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On my engine at least the stud was not a press fit but threaded ??? later style engine, went to adjust it once and the thing unscrewed had to double nut it to get it back in tight.

Brett

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 Posted: 01-22-2014 05:53 pm
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roland11a
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Hi
Most of the advise I got was to put on the later bearing that can be adjusted from the front. This comes in one piece.

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 Posted: 01-22-2014 08:27 pm
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Brett Gibson JH5 20497
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And that is good advise.

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 Posted: 01-22-2014 08:30 pm
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roland11a
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Ah thanks. It was duly taken

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 Posted: 01-22-2014 10:40 pm
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roland11a
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I ended up dropping on a later lotus short engine with a good crank. also a set of original liners, pistons and bearings off ebay. rebuilt engine incorperating  the later modifications where posssible such as a smaller oil way into the head, small hole drilled in the oil pump , latest cam cover gaskets & no gasket in the cam carriers, to name the basics.

However none of this helps Palindrome

I don't remember having any trouble fitting the later tensioner bearing, just had to draw off the crankshaft pulley to allow the tensioner to be withdrawn


Attachment: cambelt tensioner.jpg (Downloaded 114 times)

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 Posted: 01-22-2014 11:18 pm
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Palindrome
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I appreciate all of these responses and such good advice.

The issue with the early engine is that the ignition timing marks, by the crankshaft pulley, is a lovely piece cast with the crankshaft cover plate. The timing pointer sticks out and up in front of the tensioner, blocking its removal. I can't seem to shrink down a photo to a small enough file size to post.

BTW I have ordered the special wrench for the nut on the back of the tensioner.

Another issue is that my camshaft pulleys have been reversed...marked x-110 and I-115 on the intake, I-110 and X-115 on the exhaust. Right now I'm hoping that I didn't bend the valves trying to line up the 110 marks before I realized the pulleys were reversed.

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 Posted: 01-22-2014 11:51 pm
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Dakota123
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There's a decent picture here:

http://www.jensenhealey.com/forums/view_topic.php?id=1500&forum_id=15&page=2

Doesn't do the interference total justice, but gives an idea at least.

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 Posted: 02-28-2014 06:02 pm
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redracer
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Unfortunately, you're correct about the earlier front crank housings. Either update that one to the later housing(don't forget the marks are 10 degrees off now) or file the old one just enough at the zero degree mark to put the belt tensioner on and off for the next time.
I SKYPE many who have questions as it is a lot easier in real time to fix, etc. whatever.
bruce madden
SKYPE name: RockClimber52

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 Posted: 03-07-2014 07:55 pm
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Palindrome
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Thanks.
I had wondered if the timing mark extension could be cut back. I'll probably try filing it. I'll keep your skype contact info. Thanks for your willingness to help.
Bob

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