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MG TD TF 1500 - MGTF manifold studs

I have noticed peculiar rust flecks/spots on the 4 manifold studs of my TF 1500 after about 100 miles of driving. Do these studs go into the water passages in the head and do their threads need to be sealed with thread sealant.? It looks like steam or hot water may be being sprayed out onto the studs. ( it's not the head gasket)
T W Moore


TW, The studs don't go in to the water jacket. No sealant required. They get hot though and its hard to keep paint on them unless it is the very high temperature cured stuff. If your getting water spray-- check to see if the water pump might be seeping at the weep hole on the bottom just behind the pump pulley. If so, water can possibly blow back along the head
Richard Cameron

Thanks Richard. I'll try some black caliper paint. Centre frost plug found to be weeping coolant, could be the source of the unusual rust patterns on the studs.
T W Moore

ANYONE with leaking core plugs should seriously consider replacing them all with brass ones, which will last the life of the engine.

See mgtrepair.net

Tom Lange
MGT Repair
t lange

This core plug was newly installed by the M/shop that did the engine machining. About 2 hours on the engine now. 7 out of 8 = 87.5 %!
The original core plugs weren't leaking after 60+ years.
T W Moore

Undersize diameter and paper thin varieties of the large central/rear plugs have been around for years. They tend to suddenly fall out while driving! I second using Tom's brass ones.
George Butz

T W Moore

You are on the right track, my studs were bleeding at the thread penetrations into the head. Against some advice offered here I wrapped the stud threads with high temperature teflon tape, problem fixed.
G Evans

I found my original post on this subject:

G Evans, New South Wales, Australia

Well an update is in order after pulling the carbies and induction manifolds today.

Coolant was seeping from the head at NO3&4 induction port and from three out of four of the manifold studs. Worst case scenario sprung to mind my new head was cracked. I removed the manifold gasket cleaned up the coolant and attached my radiator pressure tester and pressurised the system.

Result no more coolant in the induction port however 3 studs leaking profusely. Removed all studs and applied 350 deg C Teflon plumbers tape to the threads and reassembled. Repressurisation revealed problem fixed, obviously over nite coolant seeping from the stud had tracked along the gasket and entered the port.

This explains why I was continually topping up the radiator and the hiss of coolant splashing on a hot exhaust manifold

Bonus was the core plugs are sound and removal of paint revealed they are brass.

What the next gremlin with this car will be who knows, simple things are set to try us. I wonder if this was common practice to drill the stud holes into the water jacket?
G Evans


G Evans, Interesting, I stand corrected. I guess anything is possible, I have 5 TD engines and I hope none of mine were drilled too deep. None of my studs or stud manifold holes showed any signs of corrosion.
Richard Cameron

I certainly have a weeping core plug (steel,from either Moss or Abingdon, I can't remember) but don't see how the manifold studs have got all rusty in the short time the engine has run. A little coolant leakage from stud threads would explain this. I'll pull them and put some Permatex thread sealant on the threads.
Thanks everyone for your valuable input.
I also plan to machine up some aluminum frost plugs with oring seals (similar to a block heater). Always used this approach when racing an MGB, after having a block plug pop out.
T W Moore

I removed the 4 manifold studs and confirmed with a piece of wire that they all connect to the water jacket area in the head. (This is a TF1500 head, others may be different?). All 4 studs were moist on the inner end and showed minor corrosion pitting.
Sprayed the studs with black caliper paint and will use Permatex thread sealant when I put them back in the head.
T W Moore


Just to make sure I wasn't going to have problems with leaks on my TD engines, I did the wire in the stud hole test on a freshly built engine (head number 22952) and the holes on this engine did not go in the water jacket. They all had a solid bottom.. There must be differences in the heads. Good information exchange here and something important to be aware of.
Richard Cameron

Mr. Moore - do you not experience corrosion issues with your aluminum plugs? I would think those would cause a good deal of contamination.
DLD

In my experience aluminum doesn't do much reacting in an antifreeze solution. There are rust inhibitors in the antifreeze which seem to function well. My Saab 900 and twin-cam Ford in a Lotus Elan both have cast iron blocks and aluminum heads which don't show corrosion. And many aluminum accessories (eg water pumps) are bolted to cast iron blocks and heads.
T W Moore

TW - my experience with aluminum is not the same as yours. I have thrown away many replacement aluminum thermostat housings because they start to degrade to white powder almost as soon as they are installed. Aluminum corrosion is significant in a T-type (I can think of only one factory aluminum T-type cooling system part, which ALSO corrodes badly); that is why I make and have successfully sold many hundreds of sets of brass core plugs, and dozens of stainless steel thermostat housings.

See the "before" photographs of both at mgtrepair.net. I will have more stainless thermostat housings within the next month, as soon as they can be shipped from Australia by the foundry, and have plenty of sets of brass core plugs on hand.

Tom Lange
MGT Repair.
t lange

The grade of aluminum used may have an influence.
G Evans

This thread was discussed between 15/07/2015 and 19/07/2015

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