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MG MGB Technical - Removing oil Gallery plugs

Hello all.
Just trying to to understand the locations of all the plugs that need to be removed before hot tanking.(tried the archives but couldn't find anything) After reading Steve's "book" I believe there to be ten press fitted plugs. Is this correct? And I would like to know a little more about removing them. Can they just be drilled and pried out like the frieze out plugs or are they different? Specifically #3,5,and 6 in my pictures. Once out can you tap out the holes and use a threaded plug or are the new ones only press fitted? Thanks again

Dave Noe

Driver side

Dave Noe

Pass side

Dave Noe

Bottom

Dave Noe

Dave-
Not like core (freeze) plugs, They are slightly tapered brass, a bit longer than the diameter usually. You or your shop <should> be able to make new ones and press back in, but the usual method is to thread and use allen head screws with LocTite.
Easiest way to get them out is drill and tap for an appropriate sized screw, then pull with a nut, washer, and sleeve.

FRM
FR Millmore

Thanks FRM
Sounds like the pivot pin removal tool for a GM steering column.Easily enough to make one. Do they come out easily or does it require hardened bolts and the use of heat?
Dave
Dave Noe

Make a quick stop to the local hardware store ans was able to make a puller. 5" threaded bolt a nut and some washers and a spark plug socket. 1/4-20 NC tap and pulled the first one no problem. hope the rest go as well. All the ones I numbered do go Right?

Dave Noe

Bit of overkill there!
As you now know, they are not hard to pull, and some have been known to leak or move all by theyselfs! Hence the threaded plugs after.
You will want something smaller for the small ones. 8-32 usually works, 10-32 is max for a 1/4" plug. Don't want to get into the block when you drill.
I'd pull all of them, not difficult enough to take any chance on a piece of debris someplace.

FRM
FR Millmore

Mine were in very tight they all made a popping noise when they let loose. Was able to get # 1-2-4 and 8 today. actually had to go to 3/8 on #4 it kept bending the other bolts because of the angle it was on. Guess I didn't really need to remove that one I didn't see it blocking anything. But its out. Ran out of time hope to finish tomorrow.
Still no signs of any blockage yet. block seems clean there also. Thanks
Dave Noe

It's not so much cleaning out stuff that's already in there, as making sure you get all of the swarf and rubbish out after machining.
Dave O'Neill2

Your right Dave. But I had lost all oil press one day and spun a rod bearing. I'm still trying to figure out what went wrong so that it doesn't do it again. Thanks
Dave Noe

Dave-
Pics of OP relief valve? Especially looking for signs of scoring or something jamming.
Pics of bearings?
Oil pump and its drive shaft? Looking at length of engagement on the tang.

Dave O'Neill - really is "whatever is in there" and you do not know until you look. Dave has an unexplained, and worse yet "self correcting" (after it killed his motor) problem.

FRM
FR Millmore

The oil press relief valve did have some wear on one side. Not sure what normal wear looks like. There didn't seem to be anything that would make it stick. Could not find any debris in the cavity.

Dave Noe

other side

Dave Noe

here is the mains bottom

Dave Noe

top

Dave Noe

Relief valve looks far better than usual, consistent with the low miles and generally clean interior.

Bottom of bearings look wiped, can't tell about tops from pic.

Were the oil pump nuts loose? Pump to block gasket all there?

FRM
FR Millmore


FRM
The gasket was all there.The bolts weren't abnormally loose. and when I removed the pump I had to whack it with a rubber mallet to loosen it. The bottom bearings are a bit shot the tops looked OK.
Thanks Dave
Dave Noe

For archive sake there was an eleventh plug
to the right of # 4 under the oil press spring. Did I miss any more?

Dave Noe

What you need to do is follow all the passages, and figure out how they drilled the holes; that finds all the plugs - and is the path(s) for cleaning.

I am totally mystified as to how you could totally lose oil pressure, and more so how it came back, all assuming it actually had oil in it.

You might want to go to the MGExperience> Motorsports board, where there are a couple of discussions re oiling problems, and some very knowledgeable guys. Includes the recommended mods to them.

FRM
FR Millmore

Dave & FRM

Well, I can think of one very remote possibility for loosing all the oil pressure, and then getting it back. I bought a GT a few years ago with a GK 5 main engine. It was reported to have about 4000 miles on a rebuild. The engine had a tendency to kick backwards a quarter or half revolution on shut down (long and irrelevant story there). Anyway, I started it up at an autocross event, and had zero oil pressure, when it had just had plenty a few minutes before. It turned out that the wrong oil pump had been installed. It looked right except the round part of the housing that goes up into block and carries the drive spindle was about 5/8 inch too short.

This meant that the drive spindle was not captured between the pump body and where the spindle enters the block above the pump. It also meant that the spindle/cam gears were barely in engagement. When the engine kicked backwards, the spiral cut of the drive gears caused the drive spindle rise up so that the tang was no longer in engagement with the pump gears.

I never tried to start it again before tearing it down, but if I had it seems possible that the drive spindle could have droped back down and reengaged the pump, and the oil pressure would have returned.

Like I said, it’s a long shot. I never did figure out what the pump was supposed to fit.

This might be as good a time as any to mention that most gasket sets come with two oil pump gaskets. One for the 3-main engine and one for the 5. Make sure you pick the right one or it will not want to make oil pressure. Check the gasket against the pump because they both look right if you check them against the block.

Charley
C R Huff

Charley-
Yes, you will find on Dave's original thread that I related a similar tale about an XKE, and suggested careful examination of the drive and engagement.

I remember you telling this a long time gone!

FRM
FR Millmore

FRM,

Now that you mention it, I do remember the story, but I had to go back and reread to get the details.

Yes, at one time some years back I think I unrolled the laundry list of bad work that had been done on that engine. Each screw up I found just left me more amazed than the previous one. But, it had a lot of good parts in it.

Charley
C R Huff

So gentlemen, what is the concensus once these oil gallery plugs are out, and th block washed etc, new brass plugs back in or tapped plugs? And are these easy to remove in the future?? Mike
J.M. Doust

FWIW, I replaced mine with NPTF threaded plugs. Can't tell you about future removal because I haven't tried yet (I hope not to have to for a very long time! ;-)
Rob Edwards

Rob-
With the exception of aluminum components, have all of your components, including the oil sump , rocker arm cover, crankshaft, engine block, heads, connecting rods, and rocker arms hot tanked in caustic cleaning solution in order to remove the years of accumulated crud that is to be found inside of all old engines. Prior to this being done, insist that all of the gallery / core / frieze plugs be removed from the engine block so that the chemical solution can get into all of the spaces inside of the engine block. Be aware that it is advisable to remove the camshaft bearings before the engine block goes for hot tanking, as this can help with removing deposits that might be stuck in the oil gallery at the back of the bearing. However, be aware that all too often hot tanking alone is insufficient; it is very common to have serious blockages that do not completely dissolve out. Consequently, it is necessary to first remove all of the gallery plugs of the all of the oiling passages inside of the engine block, and then clean them out with brushes. Unthreaded plugs can be removed by drilling them and threading them with 1/4”-20 UNF tap, and then using a socket head cap screw and a socket in order to remove them. Use rifle bore brushes to thoroughly clean all of the passages. Once you think that you have them clean, do not be surprised if you see more crud remaining inside of the nooks and crannies. Dig it out, and then clean the engine block again. If you do not, it will come loose and destroy your engine, more often sooner than later.

In order to be aware of the location of the various plugs and fittings that will need to be removed so that the passages within the engine block may be adequately cleaned, it is best to understand the engine’s oiling system itself.

Just above the oil pump, a passage runs horizontally from the pump outlet port to the back of the engine block where it is blocked with a press-fitted plug. There it intersects a lateral passage, which is located a few inches toward the centerline of the engine block. This lateral passage is plugged on the outside with a 3/8” BSP threaded hex-head plug that is sealed by means of a copper washer and serves to duct oil to a point just inboard of the position of the seat of the oil pressure relief valve. There it intersects with a descending passage which serves to conduct oil flow to the input end of the oil pressure relief valve. This descending passage is stopped at its bottom with a press-fitted plug. Another passage passes laterally and parallel beneath the upper passage in order to intersect the descending passage. Its inner end is of a relatively smaller diameter, while the outer end is counter-drilled to a larger diameter and machined in order to form the tapered seat for the oil pressure relief valve, allowing for a slip-fit of the relief valve. The outer end of the passage is plugged with a ½” BSP threaded domed spring cap, which retains the compression spring for the oil pressure relief valve. This plug is factory-sealed with two fiber washers, but one sealing washer will usually work just as well. In order to allow for fine adjustment of relief pressure, building up thickness of sealing washers will reduce tension of the spring of the oil pressure relief valve oil and thus slightly relieve pressure on the body of the relief valve if so desired. In a corresponding manner, installing shims under the spring inside of the oil pressure relief valve will increase the tension of the spring of the oil pressure relief valve and thus result in an increase of the oil pressure. However, a less time-consuming method of adjusting the relief pressure is to install an adjustable oil pressure relief valve from Advance Performance Technology (APT Part # OPRV-ADJ). This clever, yet simple device permits the tension of the pressure relief spring to be adjusted to any desired level while the engine is running.

A descending passage intersects the oil pressure relief valve passage immediately outboard of the seat of the oil pressure relief valve. This passage is left open at the bottom in order to provide an open circuit for the oil from the oil pressure relief valve bypass to drain into the oil sump . Another descending passage passes parallel to it in order to intersect the oil pressure relief valve passage farther outboard, well behind the oil pressure relief valve, and is plugged at the bottom with a press-fitted plug. A lateral passage connects both of these descending passages and is stopped at the outside with a press-fitted plug. In combination, the lateral passage and the inner descending passage make available a free-flowing vent from the rear of the oil pressure relief valve to the oil sump . This allows the oil pressure relief valve to move freely with no pressure interference from behind. The shallow hole in the side of the engine block near the plug is a tooling hole that was used for alignment purposes during the original machining of the engine block.

An ascending passage passes parallel to the back of the engine block and at an angle from the right rear corner of the engine block in order to intersect the upper lateral passage. This sends oil to the high-pressure gallery, which runs the full length of the right side of the engine block to intersect the ascending passage, and is blocked at both ends with press-fitted plugs. This ascending passage terminates on the right with a special threaded fitting that is sealed with a copper washer. This fitting has a long nose that extends into the engine block with a very close fit inside of the passage so that it will be sealed around its nose. It then ducts oil flow from the passage to the outside of the engine block while blocking any cross-flow between the ascending passage and the high-pressure gallery. With the fitting properly installed, oil exiting the engine block passes through external plumbing for the oil cooler and / or through the oil filter assembly to reenter the engine block on its right side, flowing into the high pressure gallery which feeds the main bearings of the crankshaft by means of descending passages that pass obliquely upwards from the gusseted main bearing saddles. Oil then flows thenceward to both the big end bearings of the connecting rods and to the camshaft bearings. Should an improper fitting without this extended internal nose be employed, the oil will pass freely from the rear lateral passage into the high-pressure gallery, bypassing the oil cooler and / or the oil filter.

On top of the oil filter mounting area on the right side of the engine block is a downward-angled passage that is fitted at its outer end with a press-fitted plug. This passage marginally intersects the tapped passage for the oil filter mounting bolt and exits inside of the crankcase just aft of the center web of the engine block casting and just ahead of the #3 cylinder bore. This passage serves as a drain in order to eliminate any possible hydraulic lock when installing the center bolt for the oil filter canisters used on the 18G, 18GA, 18GB, 18GD, 18GF, and 18GH engines so that the for the center bolt oil filter canister can be screwed all the way in without resistance, and then accurately torqued to 15 Ft-lb.

The low-pressure gallery runs the full length of the engine block above the camshaft, and is fitted at both ends with press-fitted plugs. Oil is fed into the low-pressure gallery from the center camshaft bearing through an extension of the passage from the crankshaft’s center main bearing. The low-pressure gallery intersects the journal passage for the top spigot of the oil pump driven gear, supplying oil to both it and its helically-cut drive gear on the camshaft.

An ascending passage intersects the rear camshaft bearing in order to feed oil from the rearmost camshaft bearing upward into the cylinder head. The oil for lubricating the rear camshaft bearing is fed into the bottom of the bearing. The rear journal of the camshaft has a circumferential groove and two opposite grooves running part of the way across the length of the journal so that when the grooves align with the passage inside of the bearing as the camshaft rotates, oil pulses through to the upper oil passage and onward to the rocker shaft. Corresponding with this passage is another ascending passage. A horizontal passage runs from the back of the cylinder head forward about 2” below the rear exhaust port, intersecting the ascending passage and is stopped at the back with a press-fitted plug.

Another ascending passage intersects the horizontal passage in order to feed oil into the rear rocker shaft pedestal and lubricate the rocker arm assemblies. It should be noted that, with the exception of the 12H 906 cylinder head casting that was used on the 18G, 18 GA, and 18GB engines, drainage channels are cast into the top surface of the cylinder head in order to duct oil from the vicinity each cylinder’s set of valves to the pushrod passages for additional lubrication of the intake tappet. This is due to the fact that the 19% heavier weight of the intake valve produces greater pressure upon the interface of the lobe and the tappet, plus the lobe for the intake valve has a steeper clearance ramp profile than that of the exhaust lobe, and thus benefits from a greater degree of lubrication.

Within a visible depression immediately behind the front engine plate on the lower right hand side of the engine block is a small flush-fit press-fitted plug. This plug closes a cross-drilled passage that supplies oil from the front camshaft bearing to the camshaft drive chain tensioner. Above the sump flange nearby there is also a slotted screw plug that blocks its unused port. This unused port is for the dipstick tube that is used on other versions of the B Series engine.

Be sure to remove the aluminum Engine Number Tag and all other aluminum components from the engine block prior to hot tanking, as the caustic chemicals will dissolve aluminum. The engine number plate on MGB engine blocks is held in place by two rivets that are driven into holes in the side of the engine block. Be aware that these rivets have steep wedging threads on their shanks. Simply file a notch on either side of each rivet so that it can be securely gripped, clamp a set of vice-grip pliers onto the rivet, then twist the rivet counterclockwise (anticlockwise). You will find that using this method allows the rivets to come out quite easily. Always discard them and replace them with new ones.

After hot tanking, all of the internal passages should be chased out thoroughly with brushes and flushed. Be sure to tell your machinist that the area around the rear cylinder inside of the coolant jacket of the engine block is commonly a trap for sediment and to be sure that all of it is removed.

Note that no plugs of any kind should be installed until after all machinework on the engine block has been performed and the engine block thoroughly cleaned out in order to ensure removal of all grit and metal swarf as these passages and chambers can become a repository of such materials. Insist that new oversize bronze plugs be shrink-fitted and pressed in to a depth that is slightly beneath the surface of the engine block so that they will not interfere with proper gasket sealing of the oil sump and the front and back plates. If you wish, you can do this yourself. In order to shrink-fit them into the engine block, the plugs should be sprayed with WD-40 in order to displace any moisture on them, placed into a well-sealed Ziploc bag in order to prevent ice from forming on them, and with the thermostat on the deep freeze set as low as it will go, they should be left in there to chill overnight. That shrinks them to a smaller diameter. When they are ready to be installed, they should be taken out, then immediately seated into the engine block with a flat-nosed punch. When they warm to room temperature, they will be in there good and tight because they will have expanded in place! The only way to get them out will be to drill and tap threads into them and use a puller! Bronze, being an alloy of tin and lead, has a higher coefficient of expansion and contraction than iron. It thus expands more than iron when it gets hot, so there is no way that they will ever come out while driving down the road.
Stephen Strange

CR and FRM
I'll post some pictures of the oil pump shafts. I didn't see any particular wear on these either. They don't look scored or misaligned. But if you see something let me know. I'm still going on the assumption that everything inside the motor is stock and hasn't been apart until now. The screen was clean and besides a little wear on the plate everything looked good.

Dave Noe

Having some difficulties up loading a picture hope the doesn't post multiple times. Sorry if it did

Dave Noe

Rob
Do you remember what taps and the type of plugs you used. I believe there are three different sizes, I'm thinking of going this way. Thanks
Dave
Dave Noe

John,

I don't see any obvious problems with the pump pictures, but it needs hands-on measurments to check the condition.

Charley
C R Huff

Charley where would one find what measurements to take and which ones are correct for my pump. don't think I'll find that in my Hayes books. Thanks
Dave
Dave Noe

Dave, It might be in the Haynes. I'm not sure and I don't have mine here. Have you looked on Paul's website: http://www.mgb-stuff.org.uk/

Also might try looking on the John Twist/University Motors site. They have a good set of instructional videos: http://universitymotorsltd.com/

Charley
C R Huff

Pump & shafts looks good.
WSM (Bentley):
Pump outer to housing .010" max
Inner to outer rotor at close approach points: .006max
Rotor to end cover .005 max. I set at .002.

FRM
FR Millmore

Dave,

Excellent advice and references provided above. Barney Gaylord also has an excellent coverage of this topic on his MGA site. Reference is:

http://mgaguru.com/mgtech/engine/of1.htm

He illustrates with photos and advises on a potential problem with reinstalling plugs in the bottom rear corner of the block - some people have managed to mix up a flow line required in that area and install a plug where it shouldn't be, cutting off the oil flow path.

Well worth a read if you are doing this yourself and probably well worth printing off the advice if you are having the job done by a shop.

Regards
Roger

Roger T

Thanks Roger
That was a good read. Very helpful and I can now deduct the wrong gasket as why I lost oil press.Mine had the right one) It always helps me to have pictures :)
Dave
Dave Noe

Dave,
No I don't, but I think I remember what I did with the tap. I'll see if I can find it and report back on the size.
Rob Edwards

This thread was discussed between 26/05/2012 and 31/05/2012

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