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MG TD TF 1500 - TD Head Gasket Weeping

I'm about to weep myself...

A little background:

Rebuilt motor, started it up. Had some valve issues, so took the head to the machine shop and had all new valves and guides put into place. Head decked, but just enough to true it. Note that when I started it the head gasket sealed fine.

Installed the newly rebuilt head, making sure the block was clean, etc. Torqued to 42 ft. Lbs per the manual (stock studs). Used a new copper head gasket from Moss. Coated it with Copper Kote. Once filling the cooling system with coolant it started weeping coolant at the two corners of the gasket on the LH side of the engine.

Removed the head, cleaned everything up and retried torquing the head to 50 ft. Lbs. Since the head gasket didn't look like it had taken much of a crush I reused it. Still weeping in the same places.

Bought a new head gasket and ARP head studs. Redid the whole procedure again. Checked both the block and the head for true with a straight edge. No problem there. Was particularly meticulous in ensuring the head and block were scrupulously clean. Used Copper Kote on the new head gasket again. Torqued to 50 lbs. Still weeping (see pic).

The coolant is not getting into the cylinders.

What do to do now? Put in some radiator stop leak and run the engine? Just run the engine to full heat and retorque and see if it stops?

This is a banana head with a banana block and a banana gasket. Should I try a round hole gasket?

David Littlefield

I believe most people us 50 ft lbs of torque now a days.

Tim
TD12524
TW Burchfield

David

Confirm that coolant is bleeding from the gasket and not the head studs. I had ARP head stud sealing issues myself.

Graeme
G Evans

Probably unlikely, but are the cylinder head nuts reaching the ends of the threads on the studs before they clamp the head down - if so, washers could be fitted. Round hole gasket not suitable for your combination.
R A WILSON

How did you check the head for flatness? I checked mine, and the block, with a straight edged ruler and feeler gauges. Everything appeared fine but I still had a small leak. I retested using a ground flat block about 1.5" square and 15" long. This showed a warp across the head but fortunately the block was fine. The head was machined on a modern, high tec surfacing machine (diamond fly cutter with laser leveling and air bearings) and the problem was solved. I think a flat bar for testing is essential and you should check the block face as well.

Good luck

Jan T
J Targosz

Hi David. Could the block at the base of the studs be behaving a bit like tree roots under the pavement? During my rebuild it was suggested to me that as a precautionary measure I relieve the stud holes in the block slightly with a few turns of an appropriately oversized drill bit. The theory being that the area of the block at the base of the studs can be pulled up ever so slightly, as the head is always trying to part company with the block. This could possibly account for your symptoms. Cheers
Peter TD 5801
P Hehir

What brand gasket? Years ago had this problem with on of the new repro gaskets. I found a Hall's brand that was visually much better quality, and problem solved. Agree with two posts above, check those things. George
George Butz

I think that Tom Lange recommends the ARP studs should be torqued to 60 pounds. That is what I used on my TF's XPEG and it seals just fine.
Jack Long

I am by no means an expert, and I do not have the experience people like Tom Lange have. I would defer to their advise. Below is my .$02 for what it is worth (probably about two penny's...)
When I rebuild an engine, I place a chamfer bit in a drill and just lightly touch the deck where the head studs go. This removes a touch of the deck, preventing the possibility of the threads pulling above the deck surface. I check for flatness with an 18" metal ruler for a straight edge. I follow this up with a gentle rub with a known truely flat block and 80 grit sandpaper. Any irregularities will show up as dark patches, any high spots will show up as shiny spots.
I have found "bumps" near the area of the deck you mention. I have also found the area between cylinders 2 and 3 to be a common low spot.
Be well,
David
D. Sander

I'm with Peter and George. I pretty much exclusively use Hall gasket sets as they tend to have the best (IMHO) head gaskets and I've never had an issue. And as Peter noted, I always countersink the block's threaded holes to a depth of .125" to prevent the block pulling up locally around the stud - it's an old racer's trick and works well. I've never used any sort of coatings on normal head gaskets and never needed to. I also use grade-8 washers and nuts to prevent the washer flattening out over time and consequently loosening the head. One should always use Grade-8 washers in any situation where continued compression is critically required, such as on ring gears, suspension mountings, etc. (Sunbeam Alpines used soft washers on their ring gear bolts from the factory and after about 50,000 miles the ring gears start to loosen, sometimes with disastrous consequences!)
Kevin McLemore

I had the exact same problem with a new rebuild last year. I solved the problem by bringing the engine to temperature for 20 minutes, shutting down and letting the engine completely cool and re-torqueing the head nuts. I did this three times. Labor intensive but it worked. I think I read a post by Tom Lange where he does something similar. Try it before tearing into the engine again. John
JR Mahone

I looked at the image and it sure looks like it is leaking right out of the head gasket's metal seam where the edges come together.

I'm making up a couple more copper solid head gaskets.
JIM N

According to the sketches of the gaskets shown from Moss, your head gasket is on upside down which explains the leak.

There's no "sandwhich" to squish, sealing the water passage up to the head. What's worse, the passage is completely blocked off.

If this is the case, that leak was fortuitous. There'd have been zero cirulation.

JIM N

Interesting stuff:I am in the process of an xpag engine rebuild and would appreciate contact inform for the HALL brand of engine gasket. Thanks
gl rombough

Thanks, everyone, for your suggestions. Here are some follow ups:

The head stud holes were all chamfered by the machine shop.

I suppose the head studs could be leaking. The second time around with the stock head studs I did seal them with Loctite, but I didn't do that with the ARP studs. Perhaps I'll try some RTV next time I have the head off.

I don't think the threads are bottoming out. As a matter of fact, I did have the thick washers on originally, but they turned out to be unnecessary as there was so much meat on the head that the studs hardly protruded through the nuts. The ARP studs are slightly shorter than the stock ones, so I just removed the washers altogether this last time.

The gaskets I have are made in the UK as supplied by Moss. They do not have a brand name. However, when I first started the engine it didn't leak and I used a head gasket that I had purchased many years ago. Hmmm.

Where does one purchase the Halls gasket?

I'm tempted to take John's advice and run the engine through a few heat cycles before trying again, mostly because I don't know what else to try besides a different brand gasket.

Jim, I think you are misreading the Moss sketches. As far as I can tell, there is only one way for the gasket to go on the block and properly position the rear water passage hole. I think you are seeing the dotted lines as indicating that the seams should be on top where they are actually on the bottom. Below is a picture of the Moss gasket. As you can see, the only way it can be positioned on the block without occluding the rear water passage is with the solid copper side up.

David Littlefield

They provided illustrations and they were subject to interpretation. I'm glad the passage is not blocked. It wouldn't be the first one installed upside down.

Now explain to me why water is leaking out of the folds.

Again, I trust solid copper gaskets I cut out over the over-the-counter versions.

One of our foremost supplier shipped me a head gasket folded in half.

I might butter up the corners of the block & gasket with some good old fashioned Permatex to stop the leaks. It doesn't look like the 3 dimensional sandwhich construction is doing its job.

JIM N

That is a nice looking gasket. The early repro one I had issues with years ago had wrinkles in the bends of the steel parts and was really bad. I don't think Halls has made XPAG gaskets for years, but some do show up on ebay. Jim's comment about the fold may be correct also, seems that should be folded under or something. Don't feel bad. Years ago I did a valve job on my 280z and proudly drove it over to show my grandfather. There was coolant weeping along the entire length of the head. That was aftermarket gasket, factory one fixed that. George
George Butz

Because I have the ARP head studs are mine (see mgtrepair.net), I have a couple of comments. First of all, block stud holes rarely go into water passages. It's not unknown, but very rare - I check them with compressed air, and a rubber tip on the nozzle. Leaks like this are usually head gasket related. Pretty much everyone who sells new gaskets gets them from the same UK source, County, who has them made overseas somewhere.

Also, my installation instructions say to put a few drops of oil on the stud threads, which also helps seal the hole (do NOT squirt oil in the hole before you screw in the stud - the hammer lock effect will crack your block). Torque the stud into the block to 10 foot-pounds using the hex I have made in the stud end, and torque the head nuts to 20, 40 and 60 foot-pounds. I know some feel it is over-kill, but I strongly recommend re-torquing the head after it has cooled down the first time it is run, then again after been driven, and again at 100 and 500 miles. Maybe I am just lucky, but I have not had a blown head gasket with this procedure.

The threads on my head studs are actually 1/4" LONGER than stock, to accommodate heads that have been skimmed quite a few times, where stock head studs can run out of threads. I supply 12-point ARP nuts, since the original nuts can be distorted with age, and cause spurious torque settings.

Finally, do NOT use a new or sharp tap to clean out the block holes; one Australian customer removed so much metal that his new studs pulled out of the block, and thread inserts had to be installed.

If your head and block really are flat I would re-torque to 60#, and use the above procedure to repeatedly use the heat/cool cycle, and re-torque frequently.

Tom Lange
MGT Repair
t lange

Thanks, Tom. I'm going to do as you suggest. I'm going to crank the head nuts to 60 lbs. and run the engine, rinse and repeat a few times. I'll let y'all know how it goes.
David Littlefield

Payen gasket newly listed on eBay:

http://www.ebay.com/itm/NOS-genuine-Payen-head-gasket-for-MG-TB-TC-TD-AC390-/222409994139?hash=item33c8ab2f9b:g:oOcAAOSwA3dYVDxK&vxp=mtr

Tom Lange
MGT Repair
t lange

I have been advised NOT to biy the MM head gasket as it is too thin and will not always seal. I am having mine made.
colin stafford

Colin would you please provide info for the supplier of your custom made gasket. Thanks
gl rombough

This thread was discussed between 13/02/2017 and 17/02/2017

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