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Thread: 084 Oil Filter Adapter Threads

  1. #1
    Junior Member Bart's Avatar
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    084 Oil Filter Adapter Threads

    i was visiting with Aewrigh about the oil filter adapter on the 084 motor, where his concern was that the 3/4-16 threaded close nipple that the filter screws onto appears to be at an slight angle, that allows one side of the gasket to come in contact with the housing, and the other side still has an gap between an 1/16' to an 1/8" . i thought is was kind of odd, so i started looking at the couple that i have on the used 042 motors i picked up last summer. thinking that it might be just a defective adapter he had, i was going to send him one of mine. they looked good, i didn't notice any signs of old oil on the outside of the filters, so they must be non-leakers.
    but after i drained the oil out of the filters and cleaned things up a little bit, the motor had around 2000 hours on it.
    i noticed that i was seeing the same gap the Aewrigh was finding on his.
    the other thing that i noticed was that the threads felt a lot tighter on the 084 filter adapter when screwing the filter on, there is not much play or slop in the threads.
    i dug out an old chevy filter adapter, to make some comparisons. it has the 3/4-16 threads also.
    I am thinking that most of us have changed out an oil filter just more than a couple of times. but usually they are in an position, at least for me that i could not see if the contact surface is true to the threads or not. you just tighten it 1 turn after the gasket makes contact with the base. and check for leaks,
    (and usually if someone tightens it real tight, there is a lot of cussing and the filter can come off in just a few pieces.)
    so there are a couple of differences that i noticed real quick

    on the 084 there is no wiggle room, one the gasket gets close to touching the base, you can not rock it at all.
    with the chevy adapter, i took 3 pictures to show how much you can rock it back and forth with just your finger, you can get one side of the gasket to touch the base when it is still an 1/8" away from coming in complete contact with the base.

    the next step was to see what the outside of the threads were between the 2 threaded nipples. the chevy measured just a little over .7100 of an inch. the 084 measured .7500 of an inch.
    on an side note the old filter that was on the chevy, would only go on the 084 a couple of turns then it would get tight. ( i could have forced it, but at the moment i am still evaluating every thing)( and didn't want to force anything beyond hand tight.) it felt kind of like just a bur catching on the threads,
    but the filter that was on the 084 adapter fit the chevy threaded nipple very loosely.
    i was able to unscrew the nipple out of the chevy adapter. as the pictures show the base threads of the chevy are a perfect match to the 084 nipple.
    where as longer threaded part from the chevy adapter does not look even an close match to the threaded nipple off the 084.

    next I put an 3/4-16 die on the threads, to see what gives. on the chevy upper threads it fit very loose. on the chevy base threads i could turn it on by hand about 4 thread lenghts, before i would feel it start to bit and remove metal.
    i put it on the 084 threads and after 3 turns it felt like it was ready to start removing some metal. so i went no further.

    i pulled the filter adapter off of the other 042 motor i had, and it was the same.
    also it appears that the male threads on the 042/084 oil filter adapters. that the close nipple goes into. is not quite a true 90 degrees to the base surface of the housing. the gasket will touch the front part of the housing, leaving an gap on the back

    so in thinking about this.
    i am assuming that when they assembled the filter housings for the 042/084 motors, this threaded piece off the chevy adapter was not available. ( on the one i have in hand, there are not enough threads on the chevy adapter to just swap out. the threads on the filter would go past the threads on the adapter and then the filter would just spin.)

    or it is cheaper just to install an threaded close nipple with the threads not cut so deep. thus allowing it to thread tight into the housing.
    i don't know if they used loctite on the close nipple that is in the housing. i haven't tried to remove it yet.

    the 2 solutions at the moment that i see, as to have the gasket come in contact with the filter house, would be find an adapter similar to the chevy style of close nipple BUT with more threads on the body.
    or run the 3/4-16 die over the protruding close nipple threads on the 084 filter housing, (removing the taller factory threads) . this would allow the the threads that are on the filter a little more play.

    on my 084 motor it has the stock filter in a canister. but when i get this motor going, i am leaning toward intalling one of these newer filter adapter housings. so i can use the larger 2 quart oil filter.
    i remember reading that Papee, took off his stock oil filter and is running an remote aftermarket filter placed under his motor.
    but up to now i have not seen where anyone has talked about the slight gap that is on this style of oil filter adapter. if some are just tightening the filter just a little more than the customary 1 turn after the gasket makes contact. to where oil is coming past the gasket and the mating surface of the housing?
    any thoughts are welcome
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    Last edited by Bart; 07-17-2017 at 03:45 AM.

  2. #2
    Junior Member Bart's Avatar
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    Re: 084 Oil Filter Adapter Threads

    A couple more pictures
    i was using a new oil filter, that is for my Dodge truck, ( this was the only clean filter i had, didn't want to drip old motor oil on the kitchen table) this filter went smoothly on both filter adapters, even though the threads don't look like they match at all. on the 084/042 nipple, you could hand tighten it all the way, but there was no slop.
    but on the chevy filter adapter, well the pictures don't lie.
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    Last edited by Bart; 07-17-2017 at 03:49 AM.

  3. #3
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    Re: 084 Oil Filter Adapter Threads

    if aewright's filter screws on easy i would say the filter is bent or if another filter does the same than the threaded adapter has been installed cross threaded most oil filters are sloppy fit anyway. i have seen bent filters out of the box and had them replaced.

  4. #4
    Super Moderator Corky's Avatar
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    Re: 084 Oil Filter Adapter Threads

    I would assume the threads are tight initially to take into account how many times a filter will be spun on them, but as you take off/install a few filters those threads will end up like your chevy adapter...I wonder how much deflection the filter has to conform to the mating surface ??? Mabe the filters will seal up anyhow...I'll have to check mine after the initial break-in and see if they're all a touch off axis...
    Last edited by Corky; 07-17-2017 at 08:10 PM.

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