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MG TD TF 1500 - Core Plugs

We almost made it!!

What a beautiful day for a drive. Peter showed up in his TD and Al showed up in his Z3. My TD was prepped and ready to roll. We departed the my Brown Building at 8:30 and headed toward Tryon. After getting on 176 we turned right and took Hunting Country Road to just outside of Columbus. What a wonderful, relaxing drive. Cool temps, sweeping curves, beautiful scenery and very little traffic.

In Columbus we once again had breakfast at Southern Manners and it was just as good as the first time – delicious. Postprandial Peter and I said goodbye to Al (he lives in Tryon) and headed down 108 toward home. Both TDs were humming and it looked like we’d be at the BB before the summer heat really set in. Ahh! But not to be.

Just about three miles from the BB on 14 I noticed a slight hesitancy in the old XPAG and about that time Peter called on the radio to ask what my temperature reading was. I watch the temp regularly but am always looking for overheating. This time when I looked the reading was about 70⁰C (it usually runs at 90+⁰C). More importantly, the temp gauge was visibly dropping as I watched. Somewhere back in my lizard brain I remembered that if one lost all of one’s coolant the gauge would not go up but would drop precipitously.

Pull off the road (thankfully a nice wide shoulder), shut it down and pop the bonnet to see WTF. Nothing obvious. I had about a quart of water in the boot so after checking that the cap was not too hot, I opened the radiator and poured the water in. The water stayed in the block for maybe 2 seconds and then all drained out through the front side core plug. Time for Peter to the rescue.

Peter heads out in his TD and comes back with his truck and trailer. Load up my TD and it’s back to the BB. The motor seems to run fine and there is a replacement core plug in the mail. I expect to be back on the road by next week.

Dang!!! We almost made it.

Jud

More to follow. Sorry about the long intro.


J K Chapin

Well, back last year I rebuilt the old XPAG - new pistons, roller lifters and new cam and a few other necessary items. I took the block to my local machine shop for work that is way beyond my ability. Before going to the machine shop I bought a set of Tom Lang's excellent core plugs. I presented those plugs to the machinist and explained how they were to be installed by dimpling the dome to create a tight compression fit. The machinist said "Oh yeah, I'm very familiar with those. I'll put 'em in right."

Well, silly me, I never really looked at the installation and back in the car went the lump.

It's been running great for over a year now but decided to leave me on the side of the road yesterday. As you can see from the previous pic, there is no dimpling in the plugs at all. Tom's plugs are great but they won't stay in with just sealant.

So, off comes the manifolds, out comes the BGH and a long steel rod and proper dimples will happen.

More to follow.

Jud

ps: Tom is sending me a replacement plug. What a great guy!! None of this was the fault of his plugs.
J K Chapin

There is a "correct" method to install these plugs and it is not "dimpled with a punch"
See: https://www.seastrom-mfg.com/expansion_plugs.aspx
scroll down to "expansion plug installation"

I have installed countless (stainless steel) "plugs" in 14 liter Cummins cyl heads and done correctly they will withstand a 25 psi submerged test.

It is a small matter to make up the correct driver, for short runs I have made them using aluminum bar stock. Anyone with a lathe can make one up in short order.
J Stone

Good stuff. Thanks. Jud
J K Chapin

Hi Jud,
Be wary of putting cold water into a hot engine. That can result in a cracked head or block.
All of the core plugs in your image look a bit shonky. I suggest replacing them all.
I always use brass plugs but must admit I have never tried stainless steel.
Thoroughly clean the block holes where the plugs seat and use a good sealant. I use 2-part epoxy. The domed plug should be carefully "panel-beaten" until it is almost flat but not quite. A broad flat-faced drift is helpful, although I know it can be done with a small flat hammer if the wielder is very skilled, accurate and careful.
Good luck with the job.
Bob Schapel
Bob Schapel

Options, options! We removed the intake and exhaust manifolds but still couldn't get a straight shot at the core plugs. Pull the engine or remove the right side fender?? Pretty easy choice so the fender came off. That, of course, included the front bumber, the Moss badge bar and the pan under the radiator but still, I think, easier that pulling the engine.

For reasons that I can't fathom, I happened to have a five foot 1" stainless bar in the corner of the shop. We chamfered the end of the rod on the old grinding wheel and found, in another corner, an 8 Lb sledge.

That's me in the green shirt and Peter wielding the sledge. All but two of the core plugs had been whapped and were very tight. The one that came out was virginal and the one next to it had been gently bumped. All are now nicely 30% undomed.

Tomorrow the fender and the manifolds go back on and Sunday we'll head up the 7% twisty grade to Saluda (NC) for BBQ brunch.

Wish me Safety Fast and no roll back. I'll have Peter behind me to watch for a cloud of steam and I'll keep an eye on the temp gauge.

Just doesn't get any better.

Jud




J K Chapin

Classic picture! Love the 5’ drift and BFH in actual constructive use! George
George Butz III

Goodness me - it's only a poor frightened little core plug! That's one helluva BFH.
Still on core plugs, if you're interested look over on the Y site - guess who checked all his core plug/welch plugs EXCEPT the one at the end of the camshaft, hidden behind the flywheel. Yup, engine and gearbox out for a $10 core plug.
Lucky we wouldn't rather be doing anything else!
Good luck with the re-start, Jud.
John.
J P Hall

Finished the reassembly this morning. Took a 3 mile loop and all seems well. I'll take it out this afternoon to fill the tank for tomorrow's drive (60+ miles) and hope all goes well.

Of course, we couldn't get to the plugs at the rear of the block but the feel properly undomed and have no sign of leakage. I think someone just forgot to finish the job.

Jud
J K Chapin

70 miles of hilly, twisty, 85F ambient driving and no coolant loss. On the steepest longest uphill pulls the temp gauge got up to 94C. I think all is well except for what sounds like excessive timing chain rattle. That will be out next exploratory adventure.

Jud
J K Chapin

Mystery of "what sounds like excessive timing chain rattle" solved.

We inspected the TD pretty thoroughly yesterday and when we fired it up there was a slight rattle for maybe a second before the oil pressure built up (I thought the tensioner was all spring actuated but per the WSM it's both spring and oil pressure) then all internal extraneous noises went away.

There was, however, still a significant rattle coming from the left side of the engine compartment. This was traced to the dynamo pully which was floppy loose. Turns out that somewhere along the line the nut holding the pully on had departed. The only thing holding the pully on was the alignment of the belt.

The dynamo is an asian repop. My back-up dynamo is a rebuilt Lucas unit. So, of course, the nut from the Lucas unit (presumably Whitworth) doesn't fit the repop unit (presumably metric) Therefore the repop unit came out and the Lucas unit went in. Wow, the quietness is a marvel to behold.

Jud
J K Chapin

Please tell me what the small white dots are on both core plugs.
Sanders

Possibly calcium carbonate.
R WILSON

Sanders, are you referring to my first image above? If so, I'm guessing just a smidge of weeping that may have caused a galvanic reaction between the brass plugs and the cast iron block. I don't detect any actual leaking.

Jud
J K Chapin

Anyone had experience with the rubber core plugs with a bolt that tightens and expands them? Or anyone put a bead of J B Weld around the perimeter of the metal ones as extra insurance?
John Quilter (TD8986)

I have used the rubber plugs in a pinch, they work.
And like any temporary repair, they may last for years!

I use loctite 540 to seal metal core plugs
J Stone

They look terrible, and they protrude pretty far into the cooling passage, but the rubber plugs do work. They are generally used as temporary repairs but like Mr. Stone, I've seen them go for years without leaking.
Steve Simmons

As far as I'm concerned, rubber expandable plugs are only for emergencies when on the road. Carry one of the proper size in the tool bag and if a plug blows while on the road it'll get you home by just filling the system back up with water. Just make sure the engine is cool first. PJ
PJ Jennings

I read in one of the past Octagon Club magazines of a MG owner who "lost" a core plug and on calling out his road side assistance expecting no real answer was surprised when the attending mechanic went to his vehicle and returned with a cork plug. The mechanic is reputed to have said he'd successfully used one quite frequently. I seem to recall the car owner said it remained insitu for sometime afterwards.
JK Mazgaj

John, I had a small leak around one plug. It was solved with JBweld (araldite in France).
But the main difficulty was to have a very clean and dry surface. I had probem without the complete procedure hereafter described.

Engine drained.
Remove any rust or painting with brush, sand paper...
Then lots of water to wash coolant
Then compressed air
A one week delay
Acetone and finally JBweld.

I did it on a second plug with the same success.

Probably 4 or 5 years that those leaks are fixed that way.

Laurent.
LC Laurent31

This thread was discussed between 27/07/2022 and 07/09/2022

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