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Thread: Changing the crankshaft pulley - looking for guidance

  1. #1
    Senior Member
    Join Date:  Jun 2011

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    Changing the crankshaft pulley - looking for guidance

    My crankshaft pulley has been a little bent out of shape since I got the car in 2007. It rotates true, the misshapen part is out at the edge. The V groove for the alternator belt got pushed in slightly in one area, so the belt does not sit down nice and flush whenever it passes that spot. It's harder on the belt and I'd like to finally get around to replacing it.

    So, how do I do that?

    I'd like to hear from others on what parts I need, tools I need or tips on an approach to use.

    The crankshaft pulley is p/n 102469 and they are not cheap and not readily available. There are remakes available in the UK though from what I can see. A new nut is p/n 102474.

    What else is going to need to be replaced doing this job? Or things I should replace since I'm in there? What seals am I going to have good access to while taking all of this apart?

    I know I'll remove the rear fascia and muffler/exhaust. That's all been done before on my car so shouldn't be too terribly difficult other than the time and patience to do it again. I have a couple things I'd like to do with my fascia anyway, so no issue removing it. I'm unclear as to what special tools are needed though, specifically with something to hold the nut and pulley and crankshaft in place while you use some sort of breaker bar extension to free up the torqued on nut. How do you do that?

    I'll look to do this sometime in the winter, so no real rush. Just trying to get my ducks in a row ahead of time.


    Sept. 81, auto, black interior

  2. #2
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    I used a quality impact gun and socket on mine and it came out without issues. The nut does take a beating though, so you might have to replace that along with your pulley. I only removed the muffler and the rear fascia lower support bracket for access. I didn't have to remove the rear fascia although it'll certainly help and you might need to if your impact is too big.

    As for the seal I was able to track down an original driver for that seal, but you should be able to install it slowly and evenly knocking at it through a block of wood. Key thing is to make sure you coat the outside of the seal with RTV and use some assembly lube on the inside the seal so the inner spring doesn't pop out when you drive the seal and pulley in. Don't forget to sleeve the new pulley BTW.

  3. #3
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    Cool, thanks. And when you used the impact gun on the nut, did you have to do anything to lock the crankshaft itself in place? Or does the engine just naturally do that itself? For some reason I was thinking that it would rotate along with the nut unless you held it in place somehow.

    I was wondering about the sleeve. I see it shown as an extra part on the DeLoGO website, but then it's mentioned as already being part of the replacement pulley on the UK website.

    Might have to see if I can find a YouTube video showing what you mean about driving it home with the piece of wood and getting the seal in there properly...


    Sept. 81, auto, black interior

  4. #4
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    Unless the crank seal is also leaking, I would see if it is possible to straighten the bend first. Worst case you ruin the pulley and have to replace it which is what you are planning to do anyway.
    David Teitelbaum

  5. #5
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    Thankfully there's been no leaking from there on my car. It drips on the other end of the engine, between the engine and trans, but not at that crankshaft pulley.

    I'll come back and post a picture of the pinched spot on the pulley later. It's hard to capture because it's only on one section of the pulley and it hides if the engine doesn't turn off with the particular portion pointing down.

    I know my limitations pretty well and I don't give myself credit for being able to hammer this dent out nice with it still on the car. I just don't have that kind of flexibility or patience anymore. So if it has to come off the car to get it fixed, then I'm back with the same job, just whether I put a new part on or the old one again. I'd like to think the pulley can be repaired, just not by my hands unfortunately.


    Sept. 81, auto, black interior

  6. #6
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    key....

    be sure to have crank rotated with the pulley key
    vertical so it doesn't fall in the oil pan when the
    pulley comes off....

  7. #7
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    The engine didn't turn at all with the impact so no need to lock it. Like mentioned above, I would also make sure the woodruff key is facing up. Also, after installing the seal, make sure you use some oil (or assembly lube) on the outside of the installed pulley sleeve (where it contacts the seal).

    Quote Originally Posted by Jonathan View Post
    Cool, thanks. And when you used the impact gun on the nut, did you have to do anything to lock the crankshaft itself in place? Or does the engine just naturally do that itself? For some reason I was thinking that it would rotate along with the nut unless you held it in place somehow.
    ...

  8. #8
    Senior Member DMC-81's Avatar
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    My experience

    Hi Jonathan,

    In addition to what was posted above I would suggest that you do not need to remove the rear facia depending on the tools that you have available. You do need to remove the exhaust and the lower support bracket (P/N 101764), at least that is what I found in my experience. I used an impact wrench and a short 35 mm socket to remove the crankshaft nut. You'll also need an appropriate gear puller to remove the crankshaft pulley without damage. I bought special flywheel lock tool for use with my manual transmission to lock the engine in place but I'll defer to others whether you need that for the automatic transmission. I think the use of an impact wrench negates or reduces the need for this lock tool on removal, at least that's what I found with my car. But where you will need a locking mechanism is when you retorque that nut to 135 ft/lbs on installation. Here are some pictures:

    Approach to remove the crankshaft pulley with just the exhaust removed:


    Tools used:


    After removing the nut and washer, I marked the position of the woodruff key on the pulley. Then I reinstalled the nut just tight enough to rotate the engine to get the key in the 12 o'clock position:


    New seal: (In this pic you can see the woodruff key on the crankshaft positioned at 12 o'clock as mentioned in above posts)


    All buttoned up:
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    1985 Chevrolet Corvette, Z51, 4+3 manual
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  9. #9
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    Trying to fix the pulley isn't all that hard. I would find a short piece of round stock that fits the groove nicely and then using a small hammer, try to force the bent part out and once near straight, hammer it back against the piece of round stock. Take your time and move the metal in small increments. Perfection is not required.
    David Teitelbaum

  10. #10
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    Wow, very helpful. Thanks guys.

    Good call on it not needing to be perfect. I can definitely try banging it back into shape and smoothing down any rough edges. I think I had forgotten how low the pulley is and that you can go straight at it from underneath the lower lip of the fascia. Might not need to remove the fascia afterall.

    What is the part number on the seal I would need in there? I'm not 100% clear on where/how it goes in along with the sleeve. That gear puller looks like a good way to go. Especially trying to pull it off straight and not all cock-eyed.

    That makes sense to me about needing to lock the engine in position for at least one of the directions... either tightening or loosening the nut. Is there a definitive way to do this on the automatic transmissions? I don't have any of those types of locking gadgets at the moment.


    Sept. 81, auto, black interior

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