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Thread: Bad squeaky sound, probably bent crank (3.0L)

  1. #1
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    Bad squeaky sound, probably bent crank (3.0L)

    About a month ago I took a break from my working on getting my 3.0L swap running to replace the entire A/C system with the help of a friend of mine (who is an actual mechanic, mostly working on classic cars). When it was time to fill the system, we tried cranking the engine and got this horrible squeaking sound. Our assumption was that the flex plate bolts or torque converter bolts were scraping against something. We confirmed the sounds related with every revolution of the engine by looking at the missing tooth gear on the crank pulley.

    ~10 second video of the noise: https://youtu.be/vvou5ZHh1tc

    At one point, we looked up through the inspection hole in the automatic transmission and noticed that the flex plate is moving in and out, implying that it isn't seated correctly.

    ~6 second video of the wobble: https://youtu.be/9UqkfG25lPA

    So we pulled the motor, leaving the transmission in the car (my friend is confident that it won't be that hard to reattach; I'd have pulled the engine and trans together, but hey). We checked the flex plate with calipers against a flat surface and found it to be pretty much perfectly flat. When we remounted the flex plate (which sat flush against the crank), we noticed it seemed slightly tilted, like the top was closer to the engine than the bottom.

    IMG_0752.jpg

    We tried turning the engine with a wrench, and got the same horrible squeaking sound, even without the flex plate attached. Measuring with calipers after rotation the engine in 60 degree increments seemed to find a deflection of about 0.26mm (not that I'd necessarily trust the measurements, but it fits with the very slight tilt of the flex plate).

    At this point, we're assuming the crank is bent. How this happened is unclear.

    This engine has never been running, not completely. I have turned it over by hand before putting it in the car (it was tough at spots, but that was just the engine compression -- our attempts today seemed much tougher than that). I had also cranked it with no issues. I had gotten the car to run very poorly with MegaSquirt for some initial testing (forgot to connect MAP, only two plugs were firing, timing way off, etc), but never heard this noise.

    In fact, the noise only started after we replaced the A/C system. We did not turn the engine at all during that process. We raised and lowered the nose of the car, but that's all we did. It seems unlikely that we knocked something loose or out of alignment in the engine simply from that.

    My friend assumes me that the untuned engine didn't bend the crank, as it is more likely that I'd have destroyed something else before the crank bent. He thinks the engine was overheated by the previous owner (it had 35k miles, according to the junkyard, and was working), and that this softened the metal enough to warp it slightly. But I can't explain why this noise suddenly started happening. I didn't think to look for flex plate deflection when I put everything together in the first place, so I don't know if this was present before.

    Next weekend we'll likely tear down the engine, and I'll be hunting for a new 3.0L to install in its place. Luckily the amount of work here is only a small part of a 3.0L conversion, although obviously not a trivial amount of work. Hopefully it'll go fairly quickly.

    Mostly I was wondering if anyone had seen this sort of thing before. It's very odd.

    Thanks!

    -- Joe
    Last edited by jangell; 03-11-2018 at 06:38 PM.

  2. #2
    Senior Member DMC5180's Avatar
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    Bad squeaky sound, probably bent crank (3.0L)

    Remove the belt and turn the engine over. This should eliminate many items that could produce the sound you heard. The squeal screeching sure sounded like the belt was dragging across a frozen pulley. In the video i could not see the A/C pulley rotate due to the dark black paint.


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    Last edited by DMC5180; 03-11-2018 at 08:40 PM.
    DENNIS

    VIN 5180, Frame 3652, STAGE I, DM-eng Solid State Solutions (RPM Rly, Dm.Lt.Mod., Fan Fail Mod. , FAN Rly, HS.Rly) , HID sealed beam style headlights, SPAX user since 2009, Eibach springs, Mid-State Club Adj. Rear LCA's, DPNW poly-sway bar kit, DMCEU LCA Stabilizer link kit, DMCMW Illuminated door sills, Aussie Illuminated SS Shifter plate, GENUINE MOMO EVO Steering wheel, DELOREANA Extended View Side Mirrors w/ Heaters, DELOREANA LED Door Lights.

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    Quote Originally Posted by DMC5180 View Post
    Remove the belt and turn the engine over. This should eliminate many items that could produce the sound you heard. The squeal screeching sure sounded like the belt was dragging across a frozen pulley. In the video i could not see the A/C pulley rotate due to the dark black paint.
    The first video does have the belt still attached, but I removed it soon after to rule out the accessories (I was really, really hoping it was the belt). There’s a slight squeak from the alternator, so I got a new one, but the other very loud squeak is still present.

    At this point, the engine is no longer in the car, has no accessories or the transmission hooked up, and it still makes the loud squeak when turned by hand.

    My mechanic friend showed the second video to his boss, and they theorize that “it might likely have spun a bearing towards the rear of the engine and that's why that it's so hard to turn over by hand and that it has a slight wobble”. Possibly repairable, unless it damaged the crank or the block, in which case it’ll be cheaper just to get another 3.0L engine. We’ll be tearing it down this weekend, and then we’ll know how bad it is and how we’re moving forward.

    Thanks

    — Joe

  4. #4
    Senior Member Josh's Avatar
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    I can confirm the alternator and crank pulley are good (parts I supplied). No such noises on the accessory drive with my 3.0

    This is a really strange problem, best diagnosed through isolating and eliminating components as mentioned by Dennis.

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    Since we're down to "the engine is out of the car and is really hard to crank by hand with no accessories and still makes the squeaking sound", the next step will be tearing down the engine.

    My current theory is that maybe I didn't properly tighten the main bearing nuts properly when I swapped out the lower crankcase (although I swear I did it to the specs in the manual -- I even got an angle torquer for the required extra 75 degrees), that one or more of these came loose and it's letting the crank shift. I'll know if there's permanent damage (and if that's even what happened) once I get it apart. I'll report back when I know more.

    I was hoping to have it on the road in time for Ready Player One (no particular reason; just seemed like a good arbitrarily deadline), but that's pretty unlikely at the moment.

    Thanks again

    -- Joe

  6. #6
    One of those purists you keep hearing about. sdg3205's Avatar
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    Did you reassemble everything with assembly lube?
    Dave

    Here, somewhere.


  7. #7
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    I only disassembled the lower crankcase to swap it with the 2.8L one, and didn't go any further than that. I didn't touch the crank or pistons at all, so I didn't do anything with any lubricants.

    That's not to say I did it correctly (to be honest, I'm a little surprised everything had been going as well as it has, considering I've never done this before), but I did follow the instructions in the 3.0L manuals as closely as possible. I've detailed what I did here: http://www.tmproductions.com/repairs...ower-crankcase.

    -- Joe

  8. #8
    Administrator Ron's Avatar
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    Bent Crankshaft: I don't see anything in the info that would lead me to believe the crank was bent enough to cause the amount of movement I'm seeing in the flywheel/converter. (That would be hard to do in any case.)

    Bent Flexplate: In one of the links a screwdriver was being used to hold the flexplate while torquing it. Unlike a flywheel, a flexplate is prone to bend if the screwdriver is not held perpendicular to the mating plane. Hard to do...I'd bet it's bent

    Noise: Wild guess- Thrust washer segment(s) or main bearing shifted/moved while removing the lower crankcase (or "foreign object", e.g. tool, replacement bolt too long, or cap flipped/out of order.)
    Did you check for end play/float after re-assembly?

    Yeah, this IS odd! Should be easy to spot though...

  9. #9
    EFI'd dn010's Avatar
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    Are you sure you have engine / trans alignment dowels installed?

    Edit: Scratch that, I just realized you said it was doing this even out of the car. My apologies! If you put the bearings in without any assembly lube then you'd have destroyed the bearings, same if you put the wrong bearings in the wrong places. I imagine you'll find out the issue as soon as you remove the lower CC.
    Last edited by dn010; 03-15-2018 at 09:47 AM.
    -----Dan B.

  10. #10
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    Quote Originally Posted by Ron View Post
    Bent Crankshaft: I don't see anything in the info that would lead me to believe the crank was bent enough to cause the amount of movement I'm seeing in the flywheel/converter. (That would be hard to do in any case.)
    That's what I've been thinking too; all the information I've been able to find suggests this is highly unlikely.

    Bent Flexplate: In one of the links a screwdriver was being used to hold the flexplate while torquing it. Unlike a flywheel, a flexplate is prone to bend if the screwdriver is not held perpendicular to the mating plane. Hard to do...I'd bet it's bent
    That was my initial assumption as well, that it was either bent or somehow incorrectly mounted. But we took it off and checked it and found no deflection. I actually do have a bent flex plate that I had to replace (I was worried about using heat to break the main crank nut free due to a poor understanding of how much of a heat sink the engine block is and that I wouldn't risk damaging anything), although there I bent it at where the screwdriver went through the hole. I do wonder if I could flatten it back out, but I'm not willing to try it.

    But the replacement flex plate appears to be unbent.

    Noise: Wild guess- Thrust washer segment(s) or main bearing shifted/moved while removing the lower crankcase (or "foreign object", e.g. tool, replacement bolt too long, or cap flipped/out of order.)
    A foreign object is a possibility. I don't think I replaced any of the bolts here, but I did replace a lot of other ones, so it's possible I used the wrong length somewhere, or accidentally put a 2.8L bolt in instead of a 3.0L bolt. I'll be checking to see if anything has shifted as well.

    Did you check for end play/float after re-assembly?
    Not in any specific way, other than eyeballing it. Also, I had cranked the engine over after it was completely assembled, and I had it running (very, very poorly) in December and it was just fine. It was only after raising the car to do A/C work and lowering it again that it started doing this. Which means something must have have been just a TINY bit off.

    I'll see what I find this weekend. Thanks!

    -- Joe

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