Cleaning oil passages in block

Discussion in 'Workshop Forum' started by B0b, Nov 11, 2019.

  1. B0b

    B0b Daily Driver

    what is the best way to do this?
    The plugs are staked, so they don't look easy to remove.
  2. EricH

    EricH Eric Hamilton Moderator

    Durham NC, USA
    Do you have a 1300 or a 1500? The plugs are different between the two.

    Either way it’s not hard to get the plugs out. If simple manual methods don’t work drill a 1/8” hole in the plug, turn a sheet-metal screw into the hole, grab the head of the screw with pliers or vise grips and pop them out.
  3. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    I just removed all the plugs from 4 engines, including all of the different sizes and types (some are cup and some dish). After trying a couple different techniques I found it was much easier to just drill a hole and use a screw as Eric described. I have a vice-grip with a ring welded to the handle so I can use a slap hammer to yank things like this. It is worth removing the plugs as I found a fair amount of debris despite already flushing all of the passages thoroughly (with the plugs still in). However be sure you can get replacement plugs before you remove the old ones. I found they weren't quite as readily available as I thought.
  4. MikeHynes

    MikeHynes True Classic

    Goodfield, IL.
    Once you get the plugs out you can tap the holes and plug them when you put it back together. The plugs are readily available and won't pop out.
    If you do this be very careful with the oil passage under the aux pulley cover. You have to use a "short" plug there because you don't want to block the oil passage that feeds oil to the aux shaft. Once that plug is installed you can insert a wire up the passageway to confirm that it's not blocked.
    myronx19 and lookforjoe like this.
  5. B0b

    B0b Daily Driver

    Thanks for the info. Pulled one with a slide hammer and the used a rod to knock out the other.
    Glad I did; there was a small amount of crud, and in any case there will likely be more once the block is machined.
    I'd rather not bother tapping the holes. MWB lists the plugs but is there any trick to reinstalling them?
    I guess just tap them into place and then re-stake the block to hold them in.
    See,s flimsy - anyone ever added some JB Weld or another sealant?
  6. EricH

    EricH Eric Hamilton Moderator

    Durham NC, USA
    That's why I asked if you has a 1300 or a 1500. If you're using the 1500 cups they'll probably stay on their own, I have years and tens of thousands of miles on a 1500 I built that way.

    The wide dish style used in the 1300 block is appreciably harder to seat reliably, and in my most recent engine rebuild I actually had one of them blow out under oil pressure. Of course :( it was the one inside the sump that closes the bottom of the vertical passage to the aux shift so I had to drain the oil and remove the oil pan to fix it. Yes, second time around I tapped the opening and screwed in a suitable plug.

    This all happened while the motor was out of the car on the engine stand. I attached a mechanical oil pressure gauge to the port for the idiot light sender and spun the aux shaft with a power drill to verify that I was building oil pressure properly. I very very very strongly recommend that you do the same before the motor goes back into the car - you do not want your first indication of an oiling problem to be that the idiot light in the dash stays on.

    If you do have a 1300 and you do choose to tap, the existing holes are the right size for a non-metric 1/2-20 tap, so no drilling needed. I made the threaded plugs by cutting short lengths off of a 1/2-20 bolts and using a cutoff wheel to slot them for a flathead screwdriver.

    JB Weld is the wrong stuff - dries hard and doesn't bond well to oily metal. For my threaded plugs I used one of the standard hardening gasket sealants.
  7. B0b

    B0b Daily Driver

    Sorry - I should have mentioned it is a 1300.
    If it as easy as running in a 1/2-20 tap then that sounds like a good approach.
    The preoiling idea probably has some startup benefits by filling all the oil passages.
    Thanks for the info
    myronx19 likes this.
  8. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    The 1300 isn't the only block with dish type plugs. Some 1500 also used them (I have both types on various 1500 blocks). There are a couple different diameters as well. So double check the size before tapping threads. It will be obvious when you get in there. But something to consider when getting new plugs of any type.

    Regarding tapping the holes for threaded plugs. Some blocks have a stepped bore size at the entrance of the hole. It is where the stock plug seats against. That makes tapping threads a bit harder because you are dealing with two different diameters and the tap will fit one or the other. Unless you drill out the 'step' a bit deeper (it is only a shallow step). And as mentioned, in some locations the head of the threaded plug needs to be flush (or under), so finding or making the correct length plug is necessary.

    If you decide to use the stock type plugs it is like installing standard 'freeze plugs'. A sealant is a good idea. Some prefer gasket sealants like "Indian Head" others like silicone sealants.
  9. B0b

    B0b Daily Driver

    The step in my block is consistently from 16mm (where the plug sits) down to 12 mm for the oil gallery itself.
    A 1/2-20 tap goes in but the resulting thread is pretty shallow, only about 0.007" thread overlap on a standard bolt, compared to 0.015" with a standard tap dill.
    The loads are small so likely not an issue except the plug on the front where the drilling to the aux shaft bearing is close to the end of the gallery, leaving room for only two threads.
    Since that one is under a cover, maybe setting the screwed plug so that is flush with the face of the block would allow the aluminum cap to retain it.
    I think I'll do that and lock the plug in place with Loctite 620.
    The other two ( stupid question of the day - are there only three plugs in the block?) have a lot more thread so strength won't be an issue.
  10. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    I'm trying to go from recall: three large (40 mm) freeze plugs on one side of the block (under the manifolds). One oil plug inside the oil pan area of the block near the oil filter inlet area (next to one of the main caps). One oil plug on each end of the block - the one you described under the aux shaft cover and one exactly opposite it on the rear end (that passage goes all the way through from end to end). And one more oil passage plug on the front of the block near the water jacket cover (also leads to the oil filter passage, from a different direction). So four small ones, seven total. Hopefully someone will correct me if I got that wrong.
  11. B0b

    B0b Daily Driver

    I missed the one by the filter - thansk - but I think that's it.
    Surprisingly little crud but necessary anyway to flush out after machining.

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