A7 Sludge trap plug problems

[Degsy]

Thanks guys
I get it now, it is a blanked off hole drilled for the oilway, but why someone should mess about with the crude punch marks on mine I don't know.

Anyway moving on...  I have a 1/2" drive large screwdriver blade socket on order and a set of new easy outs so I'll try and get some heavy torque on the slotted plug but the Allen key plug at the other end which is now rounded out will probably need to be drilled, as you say Richard carefully drilling larger holes and then an easy out sounds like the way to go.

I don't understand why we have so much trouble with these things, when you look at the plug there is not much depth of thread there and they spend their life bathed in oil so there not rusting in, ok loctite but that's not going to hold them like this.

What stops the plug going in too far on small bearing cranks like mine? these cranks have no sludge tube to stop the plug going too far in.  I read somewhere that people make the mistake of punching/straking the crank and not the plug itself, this would mean the plug would not come out but could go further in, I'll be using Loctite. when I eventually get them out.
Is using heat a definite must? given the large thermal mass of the crank flywheel and small mass of the plug is the plug going to expand quicker and into the hole in the crank?  or am I overthinking this and it is more important to soften the Loctite.  I saw one Youtube guy who spits on the plug after heating it, this seemed more like a ritual than a practical technique but it could cool the plug and cause it to contract slightly.

Degsy

[berger]

degsy I have given the depth of the oil gallery in a previous post so you know what clearance is behind the plugs each side, with the look of your timing side plug it is fully in, your timing side journal looks odd to me have you got a better picture of it

[Rex]

What stops the plug going too far in is your ability to know when to stop turning!
You'd need some serious heat to have any effect (so I personally wouldn't use it) and I hate Eazi-outs with a passion.
Drilling increasing sized holes is my preferred method, ie drilling until nothing but a small section of plug is remaining which can then be collapsed inwards with a punch.

[Swarfcut]

 Tapered stud extractors tend to spread out the offending item, I've had more success with  TORX bits hammered in. MIG welding something onto the plug uses the heat there to soften whatever is holding it, but a first step is to remove  the punch indents with a new, sharp drill ( to prevent wander). Drill the plug, not the crank.  If is is a real stubborn example, defying everything you throw at it, go with Rex's trick and simply use bigger and bigger drills until all that is left is a thin  threaded cylinder that can be collapsed inwards.

 There is nothing to stop the plugs going in too far. When you eventually get to ground zero you'll see how easy it is to block that oilway in the crank web. Pattern part plugs come in varying thickness. You may need to thin down your replacement on the timing side so the oilway remains open with the plug face flush with the outer web.

 Swarfy.

 

 

[RichardL]

Regarding easy-out extractors, please note the word "robust" in my recommendation. I happen to own some that are quite a bit larger than come in the typical hobbiest kit.  I think the largest (not the one I use for this task) is about an inch at the top. An undersize extractor could easily snap off (as you know, I'm sure). I'm not optimistic for your screwdriver approach, so, anxious to hear the result.

Richard L.

[RDfella]

I gave up using 'easy-out' extractors years ago (the conical threaded type). They're brittle and only serve to wedge the offending item even tighter. As has been suggested by Richard / Berger drill a hole then drive in an allen or torx bit (I prefer the latter). Use the type that comes in a socket set. They tend to grip well with little expanding element.

[Greybeard]

I bought one of these Impact Driver's to get my sludge-trap plugs out. And yes, I did brace the crank web before using the driver!

[Minto]

Hi Degsy
I've spent an hour in the garage this morning, took out the plugs and did some measuring, on the timing side the centre of the oil feed hole is 6mm deep into the hole behind the plug, the plugs from SRM and the original ones are 6mm thick, so even with plugs wound in so that they're flush, they'll still partially restrict this oil feed.
The thread on the crank for the plugs (on mine anyway) are only cut to about 7mm deep, normally this would tell you to stop winding them in.
I've filed a relief in my T/S plug this morning. This is what I did...
Mark the crank with a Sharpie pen where the feed is, then wind the plug in til its where you want it (flush), mark the plug adjacent to the crank mark, remove the plug, flip it over file it a bit with a round file, bit of thread lock on the top threads of the plug, wind it back in til your marks line up again, punch it a couple of times to be sure. See pics.
Cheers
Jase

[Degsy]

Berger when I split the crankcases I was surprised to find the timing side has had a needle roller conversion and I think that is what your sharp eye has spotted, see photos below.

Guys, thanks for all the advice on plug depths, at the moment my timing side plug is 4mm in from flush and the drive side plug is 6mm in from flush, so given the thickness of the plug it must be blanking the hole at least partially (is there an oilway on the drive side plug hole?)
I have taken the conrods off and the big ends do not look pretty (see photos below) I think this engine was not far off going bang!
For some reason the drive side bearing shells look worse.  The crankshaft journals look OK no scouring although I've not measured them yet.
I like your advice about marking the plugs and grinding a groove to give more space for the oilway, I'll do that when I finally! get the plugs out.  Regarding getting them out, I agree easyouts can be a nightmare if they break and they tend to expand the fixing into the hole, I like the Torx idea and I have a of Torx socket set which I never seem to use.  I have a manual (hammer) operated impact driver I might try that, although it was my Makita baterry impact driver that stripped the allen plug on the drive side (although it was already damaged). 
I still have hopes for the 1/2" socket screwdriver I have on order, if I can find a way of clamping it down onto the plug. 
With the crank upright I poured some "Kroil" (the best penetrating fluid but not cheap at £20 for 230ml from the USA) into the slotted plug and it disappears so I can't be completely sealed in there.
Cheers
Degsy

[berger]

  erm now the question is have they drilled down from that centre punched abused plug and met up with the oil way in the end feed on the crank!!!!, I bet they have me thinks compressed air or fluid is needed to try out the oil ways into the big end journals from the crank end before you start attacking it with venom , find out how its getting oil!!. answer to your question about drive side drilling is no there isn't one on that side because it doesn't feed oil from there, only timing side up into the crank. the drive side oil gallery is bigger than the timing side

[Swarfcut]

Drive side crank journal is on the end of the oil supply, so suffers the most. The original design requires a minimum  loss of oil pressure/volume at the timing side bush. Too much  running clearance here, together with unintended leakage and any impairment to oil flow to the big end journals is why they go bang. So we get an end fed conversion to guarantee oil flow  into the crank and thence to the big ends.

 To have found a motor with an end fed crank conversion yet with some fundamental assembly errors beggars belief, but the raw material you have is worth a great deal.

 Check the oil pick up pipe for oil/air tightness where it seals into the crankcase. Lack of scavenge due to a leak here is awkward to fix later. Ball valve to prevent wet sumping on standing is behind the small plug adjacent to the timing bush. Lots on the forum about this pesky li'l devil.

 Wear pattern on those shells suggests to me  taper ground journals, as the wear pattern is the same for both rods. Scrutiny of the journals will reveal all.

 Swarfy.

[Minto]

Hi Degsy
Looks like it was caught in the nick of time.
The slotted plug would be easy enough to weld a nut onto (weld from the middle of the nut), then spanner it out. I watched a video on YouTube recently about removing deeper studs, which involved copper pipe to protect the female threads then welding a nut on as above. If it's only 6mm deep it shouldn't be too hard. Could even hammer the copper pipe to on to the nut to hold it in position while you weld it
Worth a search and ponder if push comes to shove.
Jase

[RDfella]

Not one to disagree with Swarfy, as he's usually on the money, but surely the wear on those big end shells is on opposite sides, suggesting a crank out of true with the cylinders or bent rods?

[orabanda]

There are several critical paths where the oil flow from the pump can be lost.
These include:

• excessive clearance between timing bush and crank journal (wear on journal, and in bore of bushing) - #1 problem
  
  • between outside of timing bush, and alloy crankcase (housing invariably distorted eccentric)
  • 3/8" plug which holds anti wet sumping spring and ball in place
    
    • between big end journals and shells (excessive wear)
    • Between relief valve and housing (external; uncommon, but can occur)
      
      Internally across relief valve poppet or ball, and the seat
      
      • between oil pump and the crankcase surface (mounting gasket)
      
      and, the location pertinent to this thread, between the crankshaft and the sludge trap plugs.
      
      Try this; install the plugs dry and then pressurise the crankshaft with air; often one or both plugs leak.
      
      Oil takes the path of least resistance; any leakage from the plugs sealing the sludge trap is bad (and you can't see it when the engine is spinning!!)
      
      The plugs should be installed with a liquid (loctite) thread sealing product (stay away from thread tape; risk of tape breaking off and passing through the oil ways).
      
      Use Primer T to improve the setting of the sealant. Let it set for say 30 minutes before re-checking with air pressure.
      
      You can machine adaptors and plugs to do this, but it's easy enough to check with a hand held air gun with a rubber cone on the nozzle (for the hole in the timing journal) and a plug in each BE journal hole, held in place with a jubilee (worm screw) clamp.
      
      Richard
      

[Swarfcut]

 Degsy.  Whoops. Yes the wear pattern is on opposite sides top and bottom when the caps are replaced correctly. (Must have been the drink taking away sane reasoning).

    So something not quite right and worthy of further investigation. Bent rods certainly a possible, but as the wear pattern is the same for both bearings and the engine has had major machining for the conversion, we have to suspect the accuracy employed, as RD notes.

 Thanks to Orabanda for those reminders of things to consider with any rebuild to make sure the oil goes where it's supposed to.

 Swarfy