Removing 105 screw in thermostat? - Alfa Romeo Bulletin Board & Forums
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post #1 of 8 (permalink) Old 04-20-2012, 12:31 PM Thread Starter
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Removing 105 screw in thermostat?

I did a search on this, but nothing popped up.

Is it 'simply' a matter of heat - and patience - to remove them?

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post #2 of 8 (permalink) Old 04-20-2012, 02:09 PM
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I'm assuming it won't budge, you could try heating the outside of the manifold where thermostat screws in and using some penetrating oil. I think the trick is to get a snug fit on the hexagon head and give a sharp yank to free it up. Never had a problem with one myself but there's not a lot to grip onto unles you've got a big socket which should make it easy.
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post #3 of 8 (permalink) Old 04-21-2012, 08:15 PM
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They can get really stuck; sometimes you have to punch or cut them out. Just try not to hurt the manifold's threads in doing so. Heat and penetrant I would try first.
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post #4 of 8 (permalink) Old 04-22-2012, 06:01 AM
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I just did this last week. I heated the manifold around the thermostat with a blow torch and then used a big spanner.
When you install the new one you dont need do it up tight because it can never unwind because of the hose.


Last edited by Johnny Woods; 04-22-2012 at 11:59 AM.
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post #5 of 8 (permalink) Old 04-22-2012, 09:06 AM
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I did this a couple of weeks ago, fully expecting a huge hassel removing the screw-in theromostat. Surprisingly, it came out quite easily thanks to the thoughfullness of some unknown Dutch mechanic who reassembled using anti-seize.

Once you get it off be sure to use anti-seize going back in and you'll save yourself grief in the future.

Jim . . . '72 Super 1300, '70, 1750GTV, 2nd series,
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post #6 of 8 (permalink) Old 04-22-2012, 11:54 AM Thread Starter
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Thanks for the suggestions. Unfortunately this one is really stuck on. I've been using my 16" 'adjustable wrench' and three pound hammer with the manifold in a padded vise, along with a lot of PB Blaster, and have only managed to round off the edges.

I happen to have a socket about the right size but I don't have a 3/4" socket wrench. I'll borrow one tomorrow when my friend returns to work. I'll also use a bit more heat. Something has to give.

Drilling/grinding out will be the very last resort.

Since I have your attention...obviously one of the two hose connections at the rear end (firewall side) of the manifold is for the heater. Which one, the one sticking downward or the one sticking straight out, goes to the heater? Then what is the other hose connection for? Ya don't have the out and return lines going to the same place.

Are there readily available metal hose connectors like the ones on the manifold? Also, in the same area, is the plug on top for bleeding the coolant system?

I'll add that I have both a knowledge and reference material gap between the 750/101 1300's to the 105 1750's. And the client had already removed the engine when I received his '66 GTV.

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post #7 of 8 (permalink) Old 04-22-2012, 12:44 PM
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upper hose goes to heater left connection, lower on "T" on hose from water pump to right heater connection

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post #8 of 8 (permalink) Old 04-22-2012, 02:42 PM
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You need to be careful with stuck thermostat removal. Many good manifolds have been cracked by too much force. I repaired one that had the threaded end snapped off! If it does crack perpendicular to the threads, it can be repaired by welding, but there is NO tap to recut the threads. I used a mill to cut the penetrating weld out of the inside, and then a jig on my lathe to lathe re- cut the threads. And a fun job it was not! The snapped off end was easier. I machined an aluminum tube to look like the outside of the manifold end on my lathe, then without a fixture and the whole manifold flailing about, cut threads only deep enough for the new thermostat. I then tack welded it to the, now cut smooth manifold, and ran a penetrating bead around. Then with a die grinder I refinished only the outside. After a course carbide media blast, followed by a finer glass bead clean up, it could not be told from new.
If you have rounded off the brass, drill out the guts until you have just a brass liner in the aluminum. You may have to use a carbide bit in a die grinder to get this nice enough to work on. Then use a sawsall CAREFULLY. You will cut through the brass into the aluminum, and you will need THREE cuts. Then you can knock the pie shaped pieces out with a punch. That done, clean the damaged threads with a sharpened right angle steel pick, LUBRICATE the threads with silver anti-seize, and screw in and out a new thermostat, until it fits flush. As mentioned above DO NOT tighten it! The anti seize will fill the cuts in the threads, and it will seal just fine for normal use.
I got tricky once, and after getting the new thermostat to go in and out easily, I cleaned everything with solvent, painted the thermostat threads with Epoxy Release Compound, filled my saw cuts with JB Weld, and screwed the thermostat in. Next day it actually came out easily, and the threads were restored. I smeared silver anti-seize on and reassembled the final time. This last trick is not really necessary, it's just nicer than saw cut damage in threads.
From my experience.

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