MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

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 Midget and Sprite Technical - thermostat housing...

yep...Chaps...it's stuck down firmly onto the head..any tips for separation??
Thanks!
David Cox

if you have a aluminium housing, to save any damage to the gasket surface on the head or thermostat recess in the head and damage to the studs, buy a new one, and cut the old one off, by using a chisel down the side of the studs to cut way the housing, this will expose part of the stud, then you can just tap it off,
Andy Tilney

thanks for that, Andy. I expected to sacrifice the housing....
David Cox

The stat housing on my B was stuck when I tried to remove it, recently. I couldn't even remove the studs using the 'two nut' method.

I then used some heat and penetrating fluid. Left it for a few days, heated again then a combination of levering and hitting it with a plastic-faced hammer.

My housing was cast iron and also had a handy lug for mounting the air pump.

I may still have some 1275 cross flow housings lurking in the garage.

I wonder if it would be a good idea to open the holes up, so they give a bit more clearance, but not quite all the way through, leaving maybe 1/8-3/16" at the top to locate it.
Dave O'Neill 2

yep, a combination of a big hammer, a slitting disc and pulling any free studs will get it off
S G Macfarlane

When you replace everything you could coat the non-threaded part of the studs with grease or anti-seize to cut down on the galvanic action between the steel and the aluminium.
Martin

...thanks for everyone's input. Might search out some ss bolts when it goes back together...
David Cox

I like Dave O'Neill's idea of putting a drill through the holes a tiddy bit oversize. I don't think there'd be a problem with location - shouldn't the thermostat locate it okay?

Best grease I've ever come across for this sort of thing is called Triple Guard. It's meant for marine drive shafts so you can get the propellor off again. Really thick clingy stuff - it stays put and it's utterly impervious to water. It's a bit dear, but you might cadge some from someone who does outboard motor servicing for example. I have loads of it, but I'm not exactly round the corner :-(

If you're going to try the penetrating fluid and patience approach I recommend PlusGas. I think I'd want to try that before destroying it. Good luck.
Greybeard

There's a coincidence, I've just posted this on B forum -

PlusGas is made by a different company now that seem to say it's the same stuff as before. It's freely available on t'web (and Euro Car Parts stores(?)), I bought a spray can very recently to supplement my drip can (it's now with a black label rather than the previous blue - even if the seller shows the old can as I found).

http://www.plusgas.co.uk/
Nigel Atkins

I used AS Hardware and anti seizure compound for spark plugs

And chased the holes with a tap/die set,
1 Paper

AS = SS

Prop
1 Paper

I have been using heat shrinking tubing and PVC tape as well.

Flip
Flip Brühl

I think there are several UK suppliers who can sell you a set of ARP stainless steel studs and nuts.
Daniel

thanks for everyone's input..just putting the story to bed now...the housing yielded to cutting disc through the webs ..knocking chunks out and pulling...very satisfying! Judging by the amount of crud in the holes it was never going to give way without drastic action. There will be a ridiculous amount of prep going on to stop it from happening again!
David Cox

I decided to have a play with my 'stat housing this afternoon.

I ran a 3/8" drill part way through the holes.


Dave O'Neill 2

The housing is 21mm thick, so I drilled through to a depth of 17mm, leaving 4mm at the top to locate on the studs.


Dave O'Neill 2

Hopefully that will leave enough clearance for some Coppaslip, or similar anti-seize.

If the original holes were tight to the studs, the housing would have a tendency to scrape off anything that was applied to the studs. This would then end up being pushed down onto the gasket.


Dave O'Neill 2

..neat idea, Dave! May well adopt that strategy on reassembly...
David Cox

I like it, cool imaginative thought

Prop
1 Paper

I seem to recall someone selling housing studs in s/s which were relieved /waisted to give more clearance to the housing. Achieves the same results at Dave O's suggestion.
Doug Plumb

Brass studs?
GuyW

brass nuts, certainly...but been swayed away from ss studs by advice from some old school engineers who claim they are prone to be brittle and I worry that they could crack without me knowing...bl**dy midget!!
David Cox

There is very little meat between the inside of the thermostat housing (the wet bit) and the holes for the stud and I think I have had problems in the past with corrosion eating through here and making a seal difficult. I would therefore be wary of drilling out the holes and reducing the wall thickness any further.

A very light smear of anti-seize compound should help to prevent corrosion between the housing and studs. If you introduce the anti-seize into the holes in the housing rather than putting it on the studs, any excess will be pushed up out of the hole instead of down onto the gasket.
Jonathan Severn

David Cox,

I wouldn't call any common grade of stainless likely to be used for studs brittle, quite the opposite it's a very ductile material. What they may be confusing brittleness with is a tendency for notch sensitivity which can lead to cracking and crevice corrosion and it's still likely to suffer from galvanic corrosion to some extent in that situation.
David Billington

Galvanic chemistry is a real can of worms, ain't it...let alone stress analysis and so on....
Thanks for everyone's input.
It's fixed now anyway....now..what can go wrong next?
David Cox

David,

Yes apparently, a mate worked on the McClaren MP4-12C project and one thing he was made aware of was that graphite, like in the chassis, is at the very top of the galvanic series and everything below it reacts if appropriate precautions aren't taken.
David Billington

From the galvanic table, mild steel is closer to aluminium (so less prone to a galvanic reaction) than either stainless steel, or even worse brass.

It is the aluminium that corrodes first, more than the stud, as the aluminium is 'less noble'. As above, graphite is the most noble of all!

Using stainless steel or brass studs does not help the potential for a galvanic reaction, but clearance does, and combined with a liberal use of anti-seize to create a water barrier between the housing and the stud, is well-proven to work.

As an example, I have used a 'B' Series housing on the 1380 in our Minor (different top connection to a Midget) to get a reasonably similar outlet position for the top hose connection. The hole pattern is slightly different, so I have drilled the holes to 3/8", plus a small bit of easing and used plenty of anti-seize. So far, the housing has come off very easily when required - yes, I know, don't tempt fate!

Richard
Richard Wale

anti-seize compound contains copper. It did not work for me.(galvanic range?) so I changed to PVC tape witch worked 6 years later.


Flip Brühl

another picture


Flip Brühl

Flip

I'm not sure about blue 😳
Dave O'Neill 2

I seem to remember there was some sort of paste specially for this, I remember fitting fire-wires in a GR5 harrier engine bay and having to use it between the clips and the fire wall, all i can remember was it was a yellow colour.
mark heyworth

Ditch the studs and fit UNC bolts. Liberally coat the threads with high melting point grease
Chris at Octarine Services

I suggested ARP stainless steel studs because they are a much 'stronger' grade of stainless steel than other grades. It's misleading to describe stainless steel as brittle, and you could say the same thing about any steel. Steel and stainless steel comes in large number of different compositions being an alloy. A high speed steel drill bit is not made of stainless steel but it could be described as brittle. I do use copperslip grease on the ARP studs and bolts I use on my car.

I'm not a fan of using a bolt, even an ARP stainless bolt, where the component was designed to be fitted with a stud. However, it always seems odd that the thermostat housing is fitted with studs and nuts and the water pump fitted with bolts.

Like Dave I do have a cast iron thermostat housing (sourced from the USA model with the air pump) if anyone wants to buy it.
Daniel

Mark, I wonder if the 'yellow' paste was zinc chromate based?

When I worked at Dennis, the commercial vehicle manufacturers, in the 1970's, they used to paint the steel body frames for the refuse collection vehicles with a thick yellow zinc chromate primer on the surfaces where the aluminium panels were bolted.

The 'chromate' bit makes it carcinogenic, so not sure if it is used very widely these days?

Richard

Richard Wale

What do Landrovers do with their aluminium body panels bolted to steel (or maybe galvanised?) chassis?

GuyW

Corrode, I presume is the smart answer!
GuyW

This thread was discussed between 24/03/2018 and 29/03/2018

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.