Menu

Binding Crankshaft

This topic contains 10 replies, has 2 voices, and was last updated by Nightflyr * Richard Kirshy 4 months, 2 weeks ago.

  • Creator
    Topic
  • #954485
    Steve Hemingway
    Steve Hemingway
    Participant

    I’m trying to rebuild a 1971 Toyota 1F 3.9 liter L6 for my FJ40 Landcruiser. The engine was in running condition with 180k original miles @ disassembly. The block was cleaned, bored .020, crank turned .010 under (I haven’t dropped it), replaced cam bearings for new cam and lifters. This engine is very similar to the old 235 Chevy and uses shims between block and bearing caps, which I reinstalled in same locations. All machine work was down professionally, but by 2 different shops. we only have one Crankshaft grinder in the Tampa Bay area. I’ve gotten no further than test fitting the crank and new .010 mains and I can barely turn it with bearings properly placed, lubricated and sequentially torqued bolts per the manual. I have removed caps, turned crank and measured run out on all 4 MB journals with fixed dial indicator and miked journals at 4 positions and gauged thrust clearance. I don’t have a bore gauge and I imagine bearing Inside diameter must the problem. I have plasti-gauged the journals at 1 position and seem to be in tolerance but know this motor would lock up if fully assembled. To ad insult to injury, no reputable shop will build it for me, regardless of how well organized all parts have cleaned bagged and sorted. Like so many others, I’ve got a ton tied up in machining costs and parts and can’t blow this up. This ain’t my first rebuild but sure feels like it. Beyond dropping a small block V8 in it, what would suggest if this mess was tying up your garage?

Viewing 10 replies - 1 through 10 (of 10 total)
  • Author
    Replies
  • #954500
    Nightflyr *
    Richard Kirshy
    Participant

    Having to make some assumption here.
    1 The crank was properly machined.
    2 The crank is not deformed in any way.
    3 The main caps and block are not damaged in any way.
    4 The shims your installing are the correct thickness.
    This would lead me to believe the bearing are the cause, except for this:> I have plasti-gauged the journals at 1 position and seem to be in tolerance but know this motor would lock up if fully assembled.
    Which would point me to think there might be an issue with the crank
    If it were me, would try plasti-gauging all the journals at the 12,3,6 and 9 positions and record the measurements and see if there is a tight spot.

    #954625
    Steve Hemingway
    Steve Hemingway
    Participant

    JOURNAL POS. X POS.W POS.Z POS. Y STANDARD MIN MAX
    0 deg 90 deg 180 deg 270 deg
    #1 0.002 0.0015 0.0025 0.0015 .0014/.0018 0.004
    #2 0.003 0.003 0.002 0.002 .0014/.0018 0.004
    #3 0.0015 0.002 0.002 0.002 .0014/.0018 0.004
    #4 0.002 0.003 0.003 0.0015 .0014/.0018 0.004

    THRUST <.002 .0024/.0065 0.012
    Here’s what I determined after Plasti-gauging the crank in 4 90 deg. increments, torquing all caps in 3 stages (cleaned lightly oiled bolts), in 2,3,1,4 bearing order. I have found that thrust is .003 at bottom of bearing but won’t pass .003 feeler gauge at top of bearing .003 is my thinnest gauge. I removed #3 bearing but crank still turns hard. Obviously, I need more thrust clearance, but is that a matter of more machining off the recess of sanding the thrust collar itself? Also, if I must go back to the crankshaft shop, should I plasti-gauge the rod bearing journals to determine if they have issues, too? Thanks for your input.

    #954626
    Steve Hemingway
    Steve Hemingway
    Participant

    Sorry, damn spreadsheet didn’t copy as intended. BEARINGS ARE NUMBERED VERTICALLY, NEXT 4 VALUES ARE MEASUREMENTS AT 90 DEG. INCREMENTS, .0014/.0018 ARE MANUFACTURER’S FACTORY TOLERANCES AND LAST NUMBER IS MAXIMUM ALLOWABLE TOLERANCE.

    #954630
    Nightflyr *
    Richard Kirshy
    Participant

    If I’m reading your chart correctly.
    Most are above tolerance spec.
    So it appears there should be no binding concerns with the caps, bearings and journals.
    My next thought would be to spray a light ( very light ) coat of blue dykem on the crank shaft journals reassemble the caps and bearings and rotate the crank one turn then disassemble and look for any place(s) where the dykem has been removed due to rubbing.
    From that you’ll need to see of it is the crank or the bearing(s) and cap(s) causing the issue.

    #954980
    Steve Hemingway
    Steve Hemingway
    Participant

    It looks like I’ll be biting the bullet and going to the machine shop for answers, but before leaving you alone, I’d like to ask these general questions:
    If a crankshaft has been been machined to the proper tolerance, and the appropriate bearings have have been obtained for an engine that ran and had no considerable wear patterns on the old bearings and original factory shims properly replaced, wouldn’t the new bearings be suspect, some thing is not round? These are the first bearing I’ve encountered without alignment tangs on one edge, but there is an alignment dowel that is placed between the oil galley holes in the upper bearings. It allows little movement for equal crush ob opposite sides. I have lined up the oil grooves that seem to fit universally on the #1 and #2 bearings but wonder if there is a specific placement for the direction of these halves. Taking the bearings 3 and 4 into consideration that can’t be improperly installed, I’ve used the markings on the back of each bearing to assume their positions.
    If you’ll give me your feedback on this, I’ll leave you alone and thank you for your valuable time and consideration in this frustrating ordeal.
    I greatly appreciate your time.

    #954987
    Nightflyr *
    Richard Kirshy
    Participant

    It looks like I’ll be biting the bullet and going to the machine shop for answers, but before leaving you alone,
    Please keep us posted on the results.

    I’d like to ask these general questions:
    If a crankshaft has been been machined to the proper tolerance, and the appropriate bearings have have been obtained for an engine that ran and had no considerable wear patterns on the old bearings and original factory shims properly replaced, wouldn’t the new bearings be suspect, some thing is not round?
    Quite possible, some thing is not round or striaght
    Crank shaft may not be straight.

    These are the first bearing I’ve encountered without alignment tangs on one edge, but there is an alignment dowel that is placed between the oil galley holes in the upper bearings. It allows little movement for equal crush ob opposite sides. I have lined up the oil grooves that seem to fit universally on the #1 and #2 bearings but wonder if there is a specific placement for the direction of these halves. Taking the bearings 3 and 4 into consideration that can’t be improperly installed, I’ve used the markings on the back of each bearing to assume their positions.

    I wasn’t there to see what the original setup looked like and have no idea what the replacements compare to the originals.
    I would assume that there have been instructions included to their proper installation or at least a tech suppot number to make inquires.

    If you’ll give me your feedback on this, I’ll leave you alone and thank you for your valuable time and consideration in this frustrating ordeal.
    I greatly appreciate your time.
    These forums are specifically here to try to help people out on all types of repairs and those here do their best to assist where they can, so don’t feel that your wasting anyones time or efforts.
    I can only offer this:
    When doing a full engine rebuild you do need some basic measuring equipment IE, bore gauge, calipers etc to do the job.
    When getting the parts machine work done IE block, crank, replacement cam ( at least where I’m from ) it is common enough pratice that the shop is fully equipped to machine and test fit the major components to ensure it all fits and works together.
    I realize in your situation it required 2 different shops.
    I do not know if maybe one or both could have gotten something wrong with dealing with a engine that is 50 years old ( and likely older than most of the people working there. )

    #955039
    Steve Hemingway
    Steve Hemingway
    Participant

    After using plunger gauges on the loaded bearings, without the crank installed, I’m finding irregularities in the bearing inside diameters. With that information, how does a legit. machine shop attack this problem when the crank has been machined to a given dimension, particularly when working on older vehicles with limited parts distribution? I see where mechanics will interchange bearings and possibly mix bearing halves on a particular journal. I had a hell of a time sourcing over-sized bearings for this project to begin with. What do think a highly experienced builder might do?

    #955041
    Nightflyr *
    Richard Kirshy
    Participant

    What do think a highly experienced builder might do?
    I think they would do a bit of research before accepting the job of rebuilding a 50 year old engine.
    Try with in reason to get replacement parts, and if they can’t, they will tell you sorry parts are not available and not accept the work.

    If what your dealing with is poor quality bearings, you will have to dig deeper to try to find a good set of bearings.
    You could try contacting Toyota parts and see if new old stock is perhaps available or inquire if they were sourced from a outside vendor that may still have them, or see if there is a cross reference to another application that may be available.
    You could also make inquiries on Toyota forums for leads.
    Being it is a 50 year old engine, I can see where sourcing replacement components would be a serious issue.

    #955046
    Steve Hemingway
    Steve Hemingway
    Participant

    Richard,
    I greatly appreciate your time and patients taking my questions.
    take care

    #955047
    Nightflyr *
    Richard Kirshy
    Participant

    No worries, sorry I couldn’t be more helpful
    Please keep us posted on how you make out and good luck

Viewing 10 replies - 1 through 10 (of 10 total)

You must be logged in to reply to this topic.

Loading…