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Re: Draining antifreeze

PostPosted: Thu May 03, 2018 10:31 am
by billwill
alan.barker wrote:Bill,
i see you have 2 overflow tubes. 1 from the Thermostat housing and 1 from the Rad Cap.
How does that work, does your car have 2 Expansion Bottles :?:
Alan


Yes I have two such bottles, the second is a used 2ltre ginger-beer bottle just lying in the trough under the washer bottle. But they don't both act at the same time as one of the rad caps is a higher pressure than the other, so only the lower pressure cap (usually mounted on the rad) acts as the overflow.

Re: Draining antifreeze

PostPosted: Thu May 03, 2018 5:02 pm
by William2
Just drained the antifreeze today and managed to undo the brass plug in the block using a 14mm spanner as suggested by 2cams70, so thanks for the tip. The antifreeze was very clean, even from the block which was what I would have expected from a fully rebuilt engine and a new alloy rad, etc.
However when I started filling up with new antifreeze a piece of what looks like black silicone sealant about 2.5" long and about 1/8"- 1/4" in width appeared in the rad cap area!! For something like this to get into the upper chamber of the rad I would have thought it could only get there via the top hose. I wouldn't have thought it would have come up south of the thermostat, so a bit of a mystery.

Re: Draining antifreeze

PostPosted: Fri May 04, 2018 11:13 am
by Robbie693
Had that happen to me, it was curved at the same radius of the thermostat housing so must have been from someone trying to seal it without a gasket!

Robbie

Re: Draining antifreeze

PostPosted: Fri May 04, 2018 11:18 am
by rgh0
Thats why I try to avoid using silicone except in very small amounts in very specific locations - the same thing you find in sumps and in oil passages of engines rebuild with generous amounts of silicone as you found in your water passages.

cheers
Rohan

Re: Draining antifreeze

PostPosted: Fri May 04, 2018 3:34 pm
by 2cams70
Silicone is best avoided but there is a special grade supposedly more tolerant to anti-freeze than the regular stuff. I use a small amount of supplementary silicone on gaskets only when there is significant pitting on the mating surfaces - eg. as occurs frequently on thermostat housings.

https://www.permatex.com/products/gaske ... ne-gasket/

Re: Draining antifreeze

PostPosted: Fri May 04, 2018 4:08 pm
by William2
Another question. Having refilled the system with fresh antifreeze I was convinced that I filled up with less than I drained off! However, I took the car out for a 10 mile run with the heater valve still open so that the coolant could flow around the complete system. All seemed fine and temp gauge at it's usual 82 degrees with hot air flowing out of the demister vents as per normal. On my return I waited several hours for everything to cool down and removed the rad cap The coolant level was at it's normal level of about 1" below seating of cap. Can I assume that any airlocks in the system would have cleared after this run or can airlocks sometimes take a while to clear.

Re: Draining antifreeze

PostPosted: Fri May 04, 2018 11:43 pm
by USA64
My understanding is that with an overflow bottle in place there should be no air gap in the radiator itself; that's what the overflow bottle is for.

Re: Draining antifreeze

PostPosted: Sat May 05, 2018 6:19 am
by alan.barker
USA64 wrote:My understanding is that with an overflow bottle in place there should be no air gap in the radiator itself; that's what the overflow bottle is for.

+1 That's what i have on my Sprint, Rad 100% full full and overflow bottle half full.
Works like a dream and the otter switch which is at the top of Rad always in contact with the coolant :mrgreen:
Alan