Thermostat housing mod, so it'll come off later

[Mick_Anik]

Hi all!

I just saw two hours of my life go down the pan yet again trying to get to the thermostat. As reported many times here, the alloy cover reacts with the three steel studs and gets well and truly stuck to them. Eventually I got the cover off in tact, and decided to try something new. Regular poster bmcecosse recommends running a drill bit through the stud holes in the cover and greasing the studs before replacement. I understand from this that the drill bit should be the same diameter as the holes, and that running it through the holes was aimed at removing the built-up gunge.

I got to thinking....so long as the three stud holes in the cover don't extend over the gasket, there'll be no problem if I drill them out so there's a space of about just under a millimetre between between the cover and the studs. So I did just that. Made a gasket, greased things up and replaced the cover, making sure that each stud was central in it's hole to avoid any contact between them and the cover. Without the contact, the cover and the studs shouldn't weld themselves together again.

Should they?

Let's hope not. I've run the engine for half an hour, and no leaks. The pressure from the three nuts will prevent the cover from moving about, even though it is now quite loose on the studs without them tightened down.

I had the further idea of dropping thin plastic tubes over the studs before putting on the washers and the nuts. A similar thing is done during an operation to repair a snapped tendon in the body. The area of repair is sleeved to prevent the tendon melding with the surrounding flesh. Maybe this sleeve melts away over time - dunno exactly, I'm not a surgeon. I had such an operation a while back, but didn't get the sleeve because it was an emergency rather than planned operation. The result was that my repaired tendon melded with the surrounding area and prevents me bending my right-hand ring finger. I was offered a second operation to free and sleeve the tendon, but declined....no big deal, that tendon is on my hammer hand and I can grip one very well. It's the other hand, my left, that does the precision work. I'm right handed.

Anyway, what an odd post . I didn't have any suitable thin plastic tubing, so I'll try that next time and report back. I suppose the plastic would have to have the right properties to be able to withstand the heat....food for thought anyway. The increased space between the cover and the studs might solve the problem - it certainly isn't causing any, so worth a try I reckon.

AHA!

I'm glad I posted this. Just realised....I need to put plastic washers under the original washers to prevent the originals from being in contact with the cover, otherwise the undesired chemical process will start between the cover and the metal washers!

I had the feeling I'd missed something....

[Biggles1957]

why not just clean out the holes and use copper grease upon re-assembly...........

[Mick_Anik]

why not just clean out the holes and use copper grease upon re-assembly...........

Why not try something different and see if it works out better?

Sometimes an idea can be applied in other areas....for example the rear axle differential holes and studs.....grrrr! I had a whale of a time trying to get a diff housing off an old axle today. It occurred to me that all but a couple of the holes in the diff housing could be slightly oversized to make it easier to get off years down the line. Two holes could be left as they so their studs serve as position locators. In view of the fact that this area doesn't get anywhere near as hot as the thermostat cover, I would then assemble using copper grease around the studs.

It's the pool of knowledge, you see....the interchange of ideas....discussion....the sharing of experiences....

I'm sure there are other ares in which a little oversizing of holes might prove of benefit for anyone maintaining their own classic car and planning on keeping it for many years. As I remember, though, "Useful Tips" should be a quick presentation of the idea and not involve too much discussion.

[bmcecosse]

My advice on the stat housing was indeed to run a drill through the holes - enlarging them somewhat. I may not have made that clear on EVERY post on the subject. Never had a stuck stat for many a year now....

[chickenjohn]

Use three bolts instead of studs to hold the housing on and PLENTY of copper grease on the threads. Using the standard thread size for the bolts (no drills needed!). Run a tap down the threads on the block before re-fitting the housing.

And I've never had a thermostat housing sieze on since.

But if you do, heat from a blow torch, gentle use of a pry bar and a gentle tap with a copper faced hammer can go a long way.

[M25VAN]

And you used to be able to get brass housings that don't stick either.
I got mine from Minor Developments a few years back.

[les]

Must say that clean holes to start with and copper grease work for me, Trying something else that might be better is great if better is needed, in this case copper grease allows the housing to be removed, you can't get better than that! Mick you say that the 'tips' section is supposed to be brief and to the point but I quite like a rambling post with a 'thinking aloud' type of approach, whatever section it's in.

[wickermonkey]

Must say that clean holes to start with and copper grease work for me, Trying something else that might be better is great if better is needed, in this case copper grease allows the housing to be removed, you can't get better than that! Mick you say that the 'tips' section is supposed to be brief and to the point but I quite like a rambling post with a 'thinking aloud' type of approach, whatever section it's in.

Copper grease is the best thing in the world and miles better for applications like this than normal grease, its not as effected by temperature and doesnt emulsify with water. anything i take apart gets copper grease on it

[rayofleamington]

Regular poster bmcecosse recommends running a drill bit through the stud holes in the cover and greasing the studs before replacement.

Glad to see that forum advice (pre-dating BMCe') is still finding new ears..
The oxide build up is driven by the dissimilar metals plus the water.
Taking the holes oversize does remove the contact, however due to the casting quality the coolant/antifreeze can still get into the cavity, so copergrease (or similar).

[bmcecosse]

Coppergrease is not actually a 'grease' and should not be relied on for lubrication - but it is ideal as a non-stick assembly paste - as suggested for this job by several above. Some may not have any , and I can assure that ordinary grease works well too. And yes in fact - I use Allen cap screws to hold down the stat cover.