Oil Gallery Plug Removal

[AlfaLofa]

As one of the rear oil gallery plugs already uses a core plug rather than a hex plug

Is there any reason why the plugs at the front of the block (or at least one of them) shouldn't be replaced with a suitably sized core plug after drilling out some thread?

I'm looking for a solution for a thread I've b******d up.

(Currently when I screw in a hex plug it now tightens when the head of the plug is below the surface of the block - and the rear of the plug is partially obstructing the oil feed to No1 main bearing).

Another possible solution is a 1/4 BSP helicoil - but it would have to be short to maintain the clearance to the oil feed to the front main bearing.

Another alternative might be an internally tapped interference sleeve.

Another alternative might be to scrap the block.

[ort]

just shorten the plug to clear the cross drilling without breaking through into hex. NPT and NPTF also have a shortened length just for this situation.

[ceejay]

If the plug is tightening when the the plug is fully in, you could machine a relief clearance at the oil gallery end.
Or wind plenty of teflon tape around the threaded plug before screwing it in.
Use a high quality pipe sealant similar to what one would use on industrial steam pipes..
If the thread in the block is over size, then a new over size plug is required, which can be machined to suit on a lathe if a taper turning attachment is available, which could also be used to cut a new over size tapered thread. There are always solutions to problems, it depends on resources, skills and workshop equipment available.

[2cams70]

Old thread I know but one good way I have found to get these buggers out is to use a 1/2" drive torx socket (solid type, not the security type with hole in the middle) where the diameter of the torx bit is larger than the rounded off hex in the plug (rounded off because that's usually what happens when you first try a hex key). Hammer this into the plug to make it fit. The multiple spikes on the torx will firmly bite into the plug. Then just wind it out using a handle on the torx socket.

[The Veg]

Old thread I know but one good way I have found to get these buggers out is to use a 1/2" drive torx socket (solid type, not the security type with hole in the middle) where the diameter of the torx bit is larger than the rounded off hex in the plug (rounded off because that's usually what happens when you first try a hex key). Hammer this into the plug to make it fit. The multiple spikes on the torx will firmly bite into the plug. Then just wind it out using a handle on the torx socket.

I do exactly this (but with the Torx socket in mole-grips) surprisingly often in the course of setting-up BRAND NEW industrial machines made in either Germany or Singapore. I don't know if these machines were made on Monday morning or Friday afternoon, but all too often I find hex-screws so over-torqued that the hexes strip with no hesitation. So much for German quality!

[ceejay]

No need for agricultural approach, the intense heating of the gallery plug with Oxy Acet and then cooling of steel plug with rag saturated with cold water which cracks the thread bind, plus applying some WD 40 allows easy undoing with correct hex key, but if you have no other way, then a bit of brute force with torx tool will work for sure.

[englishmaninwales]

Done this two ways, Torx hammered on one occasion and a nut welded to the plug on another.

[2cams70]

I use a T45 Torx socket. No heating of engine block required. It doesn't require much force to knock in as the plugs are made of a soft material which is why the hex rounds off in the first place. You need to replace the plugs with new of course but there is no risk of damage to block. Picture of removed plug and torx socket attached. You must use a solid Torx driver as the security ones with the hole in the middle are weak and likely to snap off.

[2cams70]

Only try this of course after you have tried the proper way with a hex tool. I find that by using a hex socket attachment rather than a hex key the risk of slippage is reduced somewhat.

[Kirbert]

Slight digression in topic. This is the best place I've found for posting this.

The car in question isn't a Lotus Elan, it's a Lotus 23B that belonged to my foster father in the 1960's. The important points are that the engine is a Lotus Twin-Cam with a dry sump and an electric fuel pump.

Engine got blown up -- a window in the side of the crankcase. Another engine was sourced and the salvageable parts from the blown engine were transferred to the new engine. The man who performed this work is of advanced age today, so some of his memory might be foggy. Between his foggy memory and what I've been able to gather, the story goes like this:

Upon removing the threaded plugs from the oil galleries, one was dramatically different. Rather than just being a stubby little plug, this one was about 5 inches long protruding *into* the engine. On the end was a little disc with a groove around the outer edge, and fitted in the groove was an O-ring that fit snugly within the galley. Unfortunately, it would not fit into the new block. The mechanic had to purchase the correct size drill bit and drill the gallery out to be able to transfer this funny plug to the new block. While the memory is an issue here, I have concluded that this long plug was fitted to the intake-side oil gallery at the flywheel end.

In the plain vanilla Kent engine, there are "lifters" riding on the nearby camshaft. A description of the oiling system on the Kent engine includes a note that oil is splattered onto the lifters from the nearby gallery. With there being no lifters on a Twin-Cam, this is a waste of oil that could be better used to lubricate something important like the main bearings. The splattering on the forward half of the "jackshaft" -- the original Kent camshaft that is only used to drive the oil pump, distributor, and fuel pump on a Twin-Cam -- is still necessary to lubricate the gear driving the oil pump and the distributor, but the splattering at the rear would only be necessary to lube the cam for the fuel pump -- and that fuel pump is not fitted on the 23B. Hence, it is my conclusion that this long plug is intended to block off oil flow to the rear half of the intake side oil gallery, thereby saving that flow for use elsewhere.

BTW, the jackshaft bearings are not lubed by this splatter; they are lubed by drilled oil passages from the main bearings.

I am curious to know if anyone else has ever seen a similar plug in a Twin-Cam. Meanwhile, perhaps this post will give some owners something to think about.

[Kirbert]

Whooops, I see the error in my thinking already. The intake side gallery cannot be the full length of the block because it'd pass right through the fuel pump opening. So that drilling is supposed to begin at the front and end just beyond the cross drilling.

Which means the most likely explanation for that long plug is that someone accidentally drilled that gallery too far and broke into the fuel pump opening. Massive internal oil leak, can't have that. So to fix it, they drilled from the back end and installed this plug. It would obstruct the fuel pump boss, but that's no big deal because the car has an electric fuel pump anyway.

Alternatively, perhaps my conclusion was incorrect and this long plug was installed in the front end of the intake-side gallery. I can't imagine why, though. It certainly couldn't have been installed in the exhaust-side gallery because it would have blocked oil flow to a main bearing at one end or the other.

[2cams70]

It's very difficult for anyone to offer any useful comment without a picture being posted.