156 JTS coolant pipe & thermostat

[bteoh]

Will be changing the rigid coolant pipe and thermostat this weekend. Just wondering if it's recommended to apply additional sealant on the mating surfaces or are the supplied o rings on the parts sufficient?
Thanks for any info

[colcol]

If it has an o ring, then that should be ok to seal it, metal to metal or with a paper gasket i would use a hardening cement such as loctite fully hardening, [not the soft hardening type], for the plastic rigid cooling pipe i wouldn't use any sealants, as they sometimes seal so good, you might break it getting it off next time, by the way, why are you changing the rigid coolant pipe on the motor?, is it leaking or some other problem, i have looked at my JTS and wondered if it is a problem area, how much did it cost and where did you buy it from?, Colin.

[bteoh]

The rigid coolant pipe is a known source of leaks. Mine has developed a leak at the seams as well as the area around the "o" ring I think (I can see coolant dripping down onto the oil filter). I bought mine from Jamie Porter Ltd from the UK. Excellent service and good pricing too.
Their website is www.alfaworkshop.co.uk
I bought the generic Behr thermostat but you can also order the oem Alfa thermostat. They were out of stock for the genuine one and the Behr was reasonably priced.
Cheers

[wankski]

were an o ring is used, all u need is a smear of silicone or red rubber grease... helps it seal.

[colcol]

I got around to fixing the leak from the rigid plastic pipe in my JTS.
The tell tale signs of red coolant leaking onto the airconditioning compressor bracket and coolant on the undertray.
Lots of things to remove to get at it, the serpentine belt cover has to come off, the serpentine belt has to be loosened off, and the belt taken off the compressor, then with 4 long bolts to undo, the compressor is taken off the compressor bracket and then 6 bolts are removed to remove the compressor bracket, off the engine.
Then you can get at the fasteners that hold the coolant pipe on, there are about 2 on the nearside and there are 2 that hold the coolant pipe on the offside and that is part of the problem, the water opening is quite large for only having 2 fasteners holding such a large opening, 4 bolts, 1 at each corner would have been better, but all those Italian cost cutters and accountants take their toll.
I replaced the old pink seal with a black o ring that was 3mm thick, the depth of the coolant pipe was 2,8mm, which meant that the o ring would sit up proud ,2mm, just enough to seal without distorting, a 3,5mm, o ring sat up a bit too high, and may cause the coolant pipe to distort.
I cleaned up the cylinder head and the coolant pipe with some scotch brite, so i didn't remove any material, but cleaned all the rust off and cacked on pink coolant and then cleaned it up with some metholated spirits to remove any grease.
I used some RTV, [Room Temperature Vulcanising], RED Silicone, that i got from Repco, i looked at all the silicones, and the red one was good for 650 F degrees, where the other silicones had a lower temperature rating.
I put the red silicon sealer on the rigid pipe and cylinder head, did up the fasteners up on the nearside and then did the fasteners on the offside on the water seal, as i didn't want to distort the seal around the water union by doing it up first, as it would have no support, and would be moving all over the place.
Did the fasteners up to about 10 lbs per sqaure inch, until the silicone was slightly forced out, then according to the red silicone instructions, let it dry and settle for 24 hours.
Then after 24 hours, gave the  2 fasteners a tweak with the torque wrench, to make up for the silicone and o ring settling.
Next, filled up the coolant and let it sit for 24 hours to check for any leaks, no leaks, which is a good sign, but not out of the woods, as it may leak under pressure.
Next day, put all the airconditioner and belts, etc and started the car, and you little ripper, no leaks, thanks mr red silicone and new o ring, this was about 11pm one friday night, love late nighters!.
That weekend went for a drive with the Alfa club to Ballarat, [thanks Shane and Kerry], to see the new Alfa Dealer in Ballarat, Peter Stevens Motorworld, had coolant and tools in boot, but not needed.
When i first bought the 156 JTS, i looked at that rigid coolant pipe and i knew it would leak, the next time it does, and it will i will put a new coolant pipe on as they are known to leak and the pipe does split along the edges, the fun never stops, Colin.