Thermostat housing

[paul 300358]

About 15 years ago, someone called Minor Developments produced and sold brass thermostat housings. I didn't bother getting one as I had fitted a 12g940 head and used a pre 67 MGB housing. Does anyone know if they were successful or did they cause the water pump to corrode faster? Has anyone ever made them for the MGB?

Cheers, Paul

[philthehill]

The someone was called John Vine, Hoobank, Kiderminster Worcestershire.
I used to get Minor parts from him.
I have a Minor Developments parts catalogue somewhere but cannot remember any reference to a Minor brass thermostat housing.
I have a cast iron MG thermostat housing with bracket for mounting the air injection anti pollution pump.
As regards the brass thermostat housing causing water pump corrosion I have never come across any corrosion caused by mixing brass and steel/aluminium.

[les]

Maybe the OP was thinking of this, doubt this would be the case in his example. An interesting read however.
https://www.allmetalsfab.com/galvanic-r ... ar-metals/

[paul 300358]

I was also wondering if anyone had used galvanized studs and nuts to fasten the thermostat housing to prevent the build up of corrosion products. Phil, is your thermostat housing cast iron or cast steel?

[philthehill]

You may be right in that it is cast steel.
The Part No: is 12H2447.

Thermostat housing 6.JPG (76.78 KiB) Viewed 541 times

With the alloy housings I drill the 5/16" holes out to 3/8", plaster the studs in copper grease and grease the gasket.

[svenedin]

I was also wondering if anyone had used galvanized studs and nuts to fasten the thermostat housing to prevent the build up of corrosion products. Phil, is your thermostat housing cast iron or cast steel?

I have used stainless steel studs, washers and nuts and liberally greased the studs with silicone grease (this acts as an inert barrier). I have done the same with the heater studs. I only did this some months ago so I cannot report on whether it has been a success. One thing worth mentioning is that both the heater studs and the thermostat leaked where the stud goes through to the water jacket but using Permatex sealant on the UNC part of the stud that threads into the block worked perfectly.

I do remember a brass thermostat housing for Minors. It looked great but was too expensive for me (it was a long time ago). It was an extremely niche thing as I recall.

Stephen

[King Kenny]

I used copper grease on mine (I used to steal it from work). Works well.

[paul 300358]

Thank you all for your replies, I am considering making a brass housing but I don't want to spend a couple of days making one to find that I've caused corrosion elsewhere.

I also use Kopr-Kote on the studs which I got from a similar place to King Kenny

[philthehill]

I found the Minor Developments spares catalogue (1994) and yes there is a brass thermostat housing listed under Part No: 10M220B.

Minor Developments.jpg (1.32 MiB) Viewed 452 times

There are several pieces of brass in contact with engine coolant in the 'A' Series for example the brass plugs in the cylinder head, the brass heater tap (if fitted) and brass radiator (if fitted) and no concerns have been raised about those. So I think you have very little to worry about when fitting a brass thermostat housing. To me it does seem a lot of work to achieve very little. It is not as if there are no alloy thermostat housings available and there are precautions you can take to ensure that the studs do not seize and limiting housing corrosion.

[Mick Lynch]

Maybe the OP was thinking of this, doubt this would be the case in his example. An interesting read however.
https://www.allmetalsfab.com/galvanic-r ... ar-metals/

The OP is somewhat correct in his assumption that by adding brass to a system then aluminium will corrode faster. In the presence of a more ‘noble’ metal the less noble aluminium becomes a Sacrificial Anode.

However the only way the aluminium would become a sacrificial anode on a minor cooling system is if you were using sea water as a coolant, and if you are doing that then you have bigger problems at hand - or are underwater.

This principle is well understood in shipbuilding and tanks, pipes, valves and sea inlets on ships in contact with sea water are equipped with sacrificial anodes, usually zinc or magnesium bars cast around a bar and the bar welded to the hull.

The anode changes the polarity of the surrounding area sheds electrons and protects the hull by giving itself up in preference. It’s 60% physics and 40% Black Magic.

Ships now use impressed current where a low voltage is run through the hull to retard corrosion on same principle.

I’ve often wondered if using an old scrapped SA in the sills would have a similar effect, but I’m sure if it would then they’d be selling them at Halfords.

Not a bad question though

[paul 300358]

The problem is that by replacing the housing with brass the only aluminium left will be the water pump. The question is, would this then corrode quicker? Also, the aluminium oxide (corrosion product) has to go somewhere, like blocking the radiator.

I have just replaced the housing due to it corroding right through from the inside.

I was hoping that someone had tried one of the original housings from Morris developments.

[svenedin]

The problem is that by replacing the housing with brass the only aluminium left will be the water pump. The question is, would this then corrode quicker? Also, the aluminium oxide (corrosion product) has to go somewhere, like blocking the radiator.

I have just replaced the housing due to it corroding right through from the inside.

I was hoping that someone had tried one of the original housings from Morris developments.

I have not had this problem of severe corrosion of the aluminium alloy thermostat housing and I have had my Morris for 35 years. I have had the problem of the housing stuck fast on the studs. Do you replace the coolant mixture every 2 years and keep the required quantity of Bluecol antifreeze in the system? This helps to reduce corrosion. Somewhat over a year ago I gave the entire cooling system a very thorough flush out as part of removing the heater and replacing the heater matrix. I unblocked the rear engine coolant drain, took out the radiator and ran a garden hose though the system until (eventually) the water ran clear. Then I refilled with Bluecol and distilled water. The coolant has stayed absolutely clear with no sign of any rust.

There is an upgraded thermostat gasket available (not cork) and you can use stainless steel studs, nuts and washers. If you slather the studs in silicone grease then the dissimilar metals are electrically isolated and in theory there should not be any electrolytic corrosion other than of course the coolant possibly acting as an electrolyte. That is why I use the distilled water. It seems to work. Or if you really want, you may be able to use a waterless coolant and that is the end of corrosion. This is expensive and I am not sure whether A-series engines are suitable candidates for this.

Stephen

[philthehill]

I consider that you are looking for larger problem than you will ever encounter.
Phil

[Mick Lynch]

would this then corrode quicker?

Technically yes

Would you ever notice it in the scale of a human lifespan: No.

[myoldjalopy]

I have had a thermostat housing corrode through from the inside - after 65 years. I replaced with like and slathered the studs in copper grease. The cork gasket I used did leak and so I replaced it with one of the upgraded types (for a mini?) Stephen refers to. Sorted.

[Bill_qaz]

When changing the badly corroded housing on mine, one of the three studs came out with the nut with no thread on the cylinder head side. At first I thought it had snapped but the end was clean cut and had been bonded into the hole. In the cylinder head was the remnants of a broken tap that a previous visitor had left down the hole.
I managed to drill it out with diamond tipped core drill and lots of patience and retap the thread.

[myoldjalopy]

Hmmm, yes, previous owners often have a lot to answer for! As we all know