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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Corrosion in alumimun thermostat housing

A customer sent me this e-mail today, and since it has broader imnplications, he gave me the OK to post it.

"I installed an aluminium thermostat housing in my TC less than one year ago, during which time my TC has covered five hundred miles. Attached are a couple of shots of my old thermostat housing, supplied (new) by a well-known mg specialist. I removed it because the corrosion is extraordinary; what you cannot see is the quantity of corroded aluminium paste scraped from the thermostat before removal and that the upper hose seating rim has been reduced to the consistency of pastry - it distorts and crumbles under light hand pressure. And this with an aluminium-suitable corrosion inhibitor in the coolant!

To fix the problem I ordered one of Tom Lange’s stainless thermostat housings (mgtrepair.net) - the thermostat housing arrived promptly, beautifully finished and fits perfectly. It came with a new stainless thermostat (with bleed hole), stainless snap-ring, correct stainless screws and washers for the elbow, and both gaskets.

I have become sceptical over suppliers’ product claims, but Tom’s are entirely accurate – this is a beautifully cast and machined work of art, and functions flawlessly. It is not inexpensive, but quality never is. I wholeheartedly recommend it."

Tom Lange
MGT Repair



t lange

You call that corrosion? I'll show you corrosion! ;)

This one that was eaten from the inside all the way to the mounting studs. Aluminum was never a good idea here. The original cast iron ones last 50 years and can often keep going. But then the one pictured below was run for only 10 years before it sprang a leak. Stainless will probably last forever.

Then you get a head where the mounting studs are in the wrong place and you can't bring yourself to cut up an expensive nice one, so you use alloy because you have a pile of them anyway. But that's another story.



Steve Simmons

Should have clarified, the one pictured above is alloy.
Steve Simmons

Tom,

What we are seeing here is "cathodic corrosion" it is not related to the quality of the part. This occurs when two dissimilar metals and a conducting liquid (Iron, aluminium and coolant) are in contact an electric current is generated, causing electrons of one of the metals (in this case aluminium) to migrate. I am not sure but I suspect that the fact that we also force current through these parts aggravates the situation. The solution is to revert to a cast iron housing.


John
J Scragg

I've been running a Laystall head for the last 25 years. Having seen bad corrosion in Jag aluminum heads, I put a sacrificial zinc in the rear of my head. Every 5 years or so the zinc is gone and I replace it. The water passages in all the aluminum remains spotless.
The zinc I use is from the marine world, is 1/4" in diameter and 3" long
attached to threaded brass that I screw into an aluminum plate for the rear of the head. Using a good quality coolant also helps.
Charlie
c mac quarrie

This thread was discussed on 04/01/2019

MG TD TF 1500 index

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