Oil Gallery Plug Removal

[promotor]

What lies behind the plug which screws into the arrowed hole on the right hand side of the engine adjacent to the engine mount??

(Picture courtesy of RD Enterprises)

Behind that is the drilling that takes oil from the main delivery gallery across to the gallery that feeds the main bearings - the drilling passes between number 2 and number 3 cylinders. Can be a pain to get out if it is a slotted brass screw as you don't even have the chance to round it off like an allen headed one and you can't weld something to it if it goes wrong (if it's a brass one!!)

[types26/36]

#3 would be the plug (listed as an oil pressure gauge union)

[promotor]

#3 would be the plug (listed as an oil pressure gauge union)

As they say.... a picture paints a thousand words! Much easier to understand than my description!

[billwill]

From the position in that diagram it looks as if that hole was also used during manufacture to either drill or to clear/ream-out the cross-drilling gallery.

<later>
Oh I see someone already said that ...

[rgh0]

Yes thats the cross drilling behind it that takes oil across to the gallery on the other side of the engine

cheers
Rohan

[AlfaLofa]

Thanks for your replies - I shall now prevaricate over the removal of this plug.

I'm attempting to remove all the plugs because when I got this engine there was about 1/4 inch of semi-solid thick sludge residing in the bottom of the sump - which led me to believe that it might be a good idea to flush the galleries.

I've had a crack now at one of the hex plugs in the front of the block.

I've tried heat/freeze-spraying multiple times without any success and I have successfully removed all signs of the hex indentation in the plug.

I've now resorted to drilling.

As suggested by Leslie I started with a 3mm drill and progressed up to 6.5.

I've got larger drills on order now - but what size should I progress up to? Any suggestions - I was thinking 10mm or perhaps even 12?

[rgh0]

Go up to the ID of the plug threads if you have to with the drilling at which point it will come out in bits. The plug should collapse sometime before that point though or it will shift it with an extractor with some more heat into the block and chill spray onto the plug.

cheers
Rohan

[AlfaLofa]

Got the new drills this morning - I've now drilled the first plug out to 11mm.

A few bits of the plug broke away but there is still basically a thin "tube" of plug stuck in the block.

I am now thinking of using a small hack saw blade to carefully cut a few slots in the residual tube and then try to prise/tap the (nearly) separate bits out. (The trouble is that the plugs seem to be made of very soft metal which breaks/shears very easily - even with relatively gentle tapping).

I've got one extra 12mm drill available - but I'm wary of using this and destroying the threads.

I've also ordered a 1/4BSP tapered tap (which I might use on the "tube").

I've been using one of these to remove the swarf from the gallery during the drilling. It works a treat.
http://www.ebay.co.uk/itm/231269382064? ... EBIDX%3AIT

In fact it works so well I've ordered a 10mm diameter magnet capable of lifting 1.5kg. (which will also fit through the plug aperture). Mind you I will still give the block a flush (eventually).
http://www.ebay.co.uk/itm/330790610835? ... EBIDX%3AIT

Time for another think

I found this on elantrickbits.com :

http://elantrikbits.com/lotus-elan-blog ... ine-block/

And there was I hoping I could use propane/butane.

It's just a pity I haven't got a welding shop capable of heating to 3000 C

[promotor]

To get the remainder of a drilled bolt out I normally make a sharp pointed tool using an old punch. The point needs to be as pointed as possible (ie not shallow like a drill but more of a spike). Use the spike to get under the material of the drilled out plug - if it goes to plan the metal should fold in.
Obviously take care not to cause too much damage to the thread in the block but if you do it's not a total disaster as the plugs are tapered thread and the damage point may not actually sit on the sealing part. A bit of sealer will help seal any slight bits of damage without too much issue.
I prefer this method to the saw method as a groove can be cut into the threads quite easily by mistake and these can be harder to seal up.

[AlfaLofa]

Thanks for that Promotor - I'll sharpen up one of my punches and give it a go (perhaps tomorrow).

[ort]

The oil gallery threads in the end of the block are 1/4 NPTF the tapping drill is 10.7mm. The block cross gallery is 1/8 NPTF tapping drill is 8.25mm.

[AlfaLofa]

Ort - thanks for that.

So elantrikbits.com appear to have got it wrong.

In their article:

http://elantrikbits.com/lotus-elan-blog ... ine-block/

They state that "The plugs are 1/4? BSP tapered"

rather than 1/4 NPTF.

Edit/Edit/Edit:
Burton list the plugs as 1/4 NPTF
But
QED have told me they are 1/4 BSP

Does this quote from an ebay listing imply that the 2 thread types are interchangeable??:
http://www.ebay.co.uk/itm/Irwin-8203-1- ... 20c7bc4572

"Pipe Taper Tap, High Carbon Steel, 1/4" - 18 NPT, Carded Plug, Taper and Bottom Taps. Best suited for maintenance and repair work. Cuts internal threads in pipes. Nominal size of the tap is that of the pipe fitting being tapped. Available in National Pipe Taper (NPT) and British Standard Pipe Taper (BSP)."

[mbell]

Does this quote from an ebay listing imply that the 2 thread types are interchangeable??:
http://www.ebay.co.uk/itm/Irwin-8203-1- ... 20c7bc4572

"Pipe Taper Tap, High Carbon Steel, 1/4" - 18 NPT, Carded Plug, Taper and Bottom Taps. Best suited for maintenance and repair work. Cuts internal threads in pipes. Nominal size of the tap is that of the pipe fitting being tapped. Available in National Pipe Taper (NPT) and British Standard Pipe Taper (BSP)."

Is I am remembering my threads name correctly NPT (as used in USA) and BSP (used else where) are not interchangeable. I certainly couldn't to screw a NPT fitting into a BSP thread despite the same size/TPI.

I would have thought it was BSP like the oil pressure take off but that's just a logical guess that doesn't apply here....

[ort]

NPTF is also known as Dryseal the crest and root of the thread are controlled in size this means there is a full metal to metal seal and sealant is not required, where as NPT and for that matter BSPT require sealant as there is clearance at both the crest and root of the thread. The tolerances on carbon taps are not that great but for cleaning up a thread they are ok. NPT in all it's different forms are not interchangeable with BSP, although many people do.
As a side note I spent 25 years designing and inspecting cutting tools supplied to both Ford and Lotus.

Ort

[ceejay]

For future reference for removal of oil gallery plugs.
They are simple to remove with heat applied from a small Oxy welding pipe.
Read article here:
http://elantrikbits.com/lotus-elan-blog ... ine-block/
It is simple when you know how.
Ceejay.