Thermostat Housing (and coolant drain plug) Woes - Alfa Romeo Bulletin Board & Forums
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post #1 of 23 (permalink) Old 09-15-2019, 05:48 AM Thread Starter
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Thermostat Housing (and coolant drain plug) Woes

Car was blipping past 212 on the gauge a few days ago on the drive to work, so I decided to start with a coolant flush and thermostat replacement. Workshop manual states the thermostat on manifold is to be torqued to 25.3 to 29 ft-lbs. Well I got out a torque wrench and got started and tore one of the bolts in half. It was pretty worn out so I tried a new bolt. Something still didn't feel right, and before I got to 25 ft-lbs I removed the bolt and checked the intake manifold block to find I had stripped a bit of the threads already - what am I doing wrong?

While I'm at it, is there a proper torque spec for the drain plugs on radiator and block?
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post #2 of 23 (permalink) Old 09-15-2019, 06:10 AM
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I feel your pain...a simple project gone to hell!!
Hopefully, some experts can chime in!!
Are you sure your specs are correct? in-lbs vs ft-lbs?
I'm sure an expert can help
Good Luck
Paul
PS..How about you flush the radiator?
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post #3 of 23 (permalink) Old 09-15-2019, 06:52 AM
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Torque wrench may need to be calibrated too... hopefully you will be able to run the appropriate tap through there and save the threads...
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post #4 of 23 (permalink) Old 09-15-2019, 12:07 PM
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I seldom torque bolts, especially steel into aluminum. Torquing steel nuts on steel studs is ok. Head nuts, bearing caps, flywheel, suspension, and the like is good. This is just my take after 50+ years of working on Alfa's. Tighten evenly and snug. If there is a gasket present a good firm tightening should be sufficient. Use an alternating pattern like you do on lug nuts and draw down in stages.
Cheers, Jon

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Last edited by not2old4toys; 09-15-2019 at 05:16 PM.
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post #5 of 23 (permalink) Old 09-15-2019, 12:30 PM
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Yeah, those torque values in the shop manual are just for show.... But after you have wrenched a lot you get a feel for torque in your hands. You also get a feel if something is wrong, dirty threads, cross threaded, etc. It is always wise to keep a tap and die set around to clean stuff up when needed, a properly calibrated torque wrench becomes more accurate too. Another tid bit, always back off your torque wrench when done using it..
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post #6 of 23 (permalink) Old 09-15-2019, 02:48 PM
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Helicoil and forget about torque..3/8" ratchet gripped half way down the hand using WRIST action is enough. Once you compress the gasket the job is done.
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post #7 of 23 (permalink) Old 09-20-2019, 08:58 AM Thread Starter
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Friends, I believe i had read something on the order of 25-30 ft-lbs. I don't have the book in front of me at the moment, but now I'm not sure, maybe it was 25-30 in-lbs. I will confirm this evening. Fortunately the damage was not excessive, it felt wrong in my hands so I didn't dare finish tightening and so the holes are not fully stripped, just one thread perhaps.

I'm always afraid when I tighten a drain plug by hand, or even the thermostat cover with the gasket I can visually see is slightly compressed, that I have not done so to the correct tightness. Is there not a great risk of the plug falling out?? Having drove a car while the wheel has blown off on the highway (those kids in auto tech never listen, hitting everything with an impact socket), I am especially cautious as I want to do the best job possible.
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post #8 of 23 (permalink) Old 09-20-2019, 09:27 AM
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If it ain't leaking leave it alone .. if it is leaking ..tighten it some more until the leak stops
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post #9 of 23 (permalink) Old 09-20-2019, 11:08 AM
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I don't think the problem is that you used a torque wrench, I think the problem is you used the wrong spec. IIRC it's around 10 ft-lbs.

These guys telling you not to use a torque wrench have no idea what they're talking about. If there's a spec, use a torque wrench. Just use the right spec.

Tom

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post #10 of 23 (permalink) Old 09-20-2019, 01:30 PM
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Quote:
Originally Posted by Gubi View Post
I don't think the problem is that you used a torque wrench, I think the problem is you used the wrong spec. IIRC it's around 10 ft-lbs.

These guys telling you not to use a torque wrench have no idea what they're talking about. If there's a spec, use a torque wrench. Just use the right spec.
Gubi, with all due respect, Brake Bleeders have a torque setting. You must be the only person I know who uses a torque wrench on them if what you say is true.. It is not a sacrilege not to use a torque wrench on something as basic as the subject. Ga nite, Chet.
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post #11 of 23 (permalink) Old 09-20-2019, 01:34 PM
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I posted a fix, for the oem t stat, modification.. just dermal tool work, and you can use a reg. t stat in the housing.. check my name here, and t stat modication
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post #12 of 23 (permalink) Old 09-20-2019, 01:49 PM
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Never seen a spec for the Alfa bleeders, but ze German car zat ze wife drives has a brake bleeder torque spec, and I sure as heck use a torque wrench to tighten them. That way I know they're properly tight and I'm not going to snap one. Doesn't add any time for me to do the job right.

I mean, you can work on your car how you want, but maybe don't give other people bad advice. People - even experienced mechanics - are REALLY BAD at judging torque by hand. I've got plenty of experience turning bolts, but if there's a published spec I use a torque wrench: to do otherwise is just to be ignorant or lazy.

If your thermostat leaks, how do you know if the bolts are loose or if the gasket is bad? Just tighten it some more, and if you strip it then the gasket was bad? LOL.

Tom

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post #13 of 23 (permalink) Old 09-20-2019, 01:53 PM
But Mad North-Northwest
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Quote:
Originally Posted by bianchi2 View Post
I posted a fix, for the oem t stat, modification.. just dermal tool work, and you can use a reg. t stat in the housing.. check my name here, and t stat modication
I would just use a helicoil. It should be pretty easy in that location, and it'll be a lot stronger than the original aluminum so you won't have to worry as much about stripping it again.

Tom

1963 Giulia Spider (1750 engine)
1974 GTV
1991 Spider
Former: 1987 Milano Gold
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post #14 of 23 (permalink) Old 09-20-2019, 03:25 PM
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I'm out.. the torque setting on bleeders is 0.14 -0.25 Ft-lbs..Knock yourself out. Unsubscribed.. Gubi this is a pissssssing contest ina friggging gale. You win.

Last edited by divotandtralee; 09-20-2019 at 03:42 PM.
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post #15 of 23 (permalink) Old 09-20-2019, 04:34 PM
But Mad North-Northwest
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Whatever. Anyway, those numbers seem really low given that ze German car specs 6-9 ft-lb (though admittedly those are somewhat larger M10x1 bleeders.)

Steve, I'm afraid I can't find a torque spec for the thermostat for the earlier Spiders. My S4 spec's 7.4-11.8 ft-lb but it uses a different thermostat. It may be in the S3 service manual which I do not have.

Tom

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1974 GTV
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