Thread: Any tips on removing corroded Thermostat Housing

You dont have a lot of choices. Drill the studs out if the rest of the housing is ok, or PM chazza to see if he has a new one and cut it off.

It only has a small chance of working, but you could try heating the housing with a hot air gun or even oxy if you are careful. Aluminium expands more than the steel studs, and this may loosen the grip on the studs.

Could try molasses solution, which is commonly used for getting rust off iron and steel parts. Turns it to black gunk which will scrub off. However, if these parts also have galvanising and/or aluminium incorporated in them, need to remember it also destroys these. Have seen it posted somewhere on aulro about removing aluminium pistons that are solidly seized in from a cast iron block that is probably reusable. If left long enough and strength of solution kept up etc end result is cast iron piston rings left in place in the bores unless partly dissolved pistons knocked out or otherwise physically destroyed beforehand.

Molasses should be easy to use for this job if head is removed. However, if it is to remain on block, would be helpful to get rid of some rust in water jackets but need to be kept away from aluminium components. Am not sure whether IOE Rover motors have any aluminium plugs in them but Series 2 onward petrol motors have them in the block. I recently used molasses solution to help clean bottom of water jacket on Series 2 while welch plugs were out. Aluminium plugs were well above level of them.

Its a common problem

I managed to get the housing off as you described, with a angle grinder . Try to leave as much of the studs length as you can . The studs should come out easily with a little heat applied. I have cast iron thermo housing somewhere , its my spare . Good Luck

Originally Posted by jedwards

I have an old and corroded aluminium Thermostat housing that seems very firmly stuck in place. As the connection tube is quite badly corroded, and leaks, so has to be replaced, but to do that I have to get the old one off first.

Any tips on how to do this without damaging the mating surface on the housing below it?
I've been soaking the studs in penetrating oil hoping it will ease the binding between the studs and the aluminium body, but tapping the housing carefully with a light hammer is not producing any signs of movement at all.

As a last resort I plan to cut it into pieces with an angle grinder in the hope of being about to ease each piece off its stud individually.

Any old -hands know a better way?

thanks in advance
Jeff

1953 Series 1 80"

Jeff, can we agree on some terminology first? According to the parts catalogue, the thermostat housing (233483) is a boxy-looking item which is bolted to the front face of the head. It has the water pump fitted up from below, an inlet elbow (212325) connecting it to the intake manifold on the right-hand side, and on top a "water outlet pipe, thermostat to radiator" (213721) secured by 3 studs, nuts, washers etc.
If we're talking about this last item you don't need to worry too much about the mating surfaces. The seal is made by the gasket supplied with your replacement thermostat, which is standard for 300Tdi engines. There's a machined annulus inside the thermostat housing onto which you drop your new thermostat, and the bottom edge of the water outlet pipe goes down inside the housing to meet the thermostat and complete the seal. I've recently done this job myself. I was able to get a heavy screwdriver blade between the top face of the housing and the underside of the outlet pipe flange and just worked my way around until it was free. I could write you a longer essay but I'll restrain myself!!!
Trust this helps,

Rob S

Hi Rob, you are quite correct. The part I am struggling with is the "water outlet pipe, thermostat to radiator" (213721). I have spare units on its way way, but was concerned about damaging the mating surface on the large boxy thermostat housing below it.

My current plan is to cut through the water outlet pipe (top housing) using a fine cutting disc on my angle grinder, then splitting the housing into three seperate pieces. That would then allow me to rotate each piece around it's sud and hopefully, simply screw it up and off (with a bit of leverage from underneath) .
I'd then clean up the studs, and using plenty of copper grease, install the new thermostat and top housing.

regards
jeff

The housing will be seized on the bolts , so just cut the side off the hole in the housing & then it should come off.

Hello again Jeff, sounds like you're on the right tram (Melbourne expression) now. Hopefully your t'stat housing is cast iron. As purchased my '53 siamese bore had an aluminium/diecast housing which I replaced with cast iron courtesy of John Craddock, some years ago. Earlier this year I replaced the original bellows-type t'stat (which had jambed shut) and the radiator cap which wouldn't seal. All good now - a thing of beauty and a joy forever!
Cheers, Rob S