Either one will work. I believe the original caps were 1.2 bar, but were superseded by 1.4 bar.

If the 1.2 bar cap is readily available, get the 1.2 bar.

I have searched this forum and have come across several instances where it was pointed out that the difference between the 1.2 and 1.4 bar caps is an important one and not to be taken ligthly. For example:
another temp. question
Also, this is evidenced by the guy from the online auto parts company (who came across as knowing what he was talking about) saying that I should find out which of the two I need specifically before ordering (there is a significant difference between the two).
However, I haven't been able to find which one specifically is advisable in my case ('79 240D) by searching and reading the various threads in this forum .

I don't mean to belittle your advice, tangofox, but I would very much appreciate hearing from someone with a sure understanding of this matter. Which cap do I go for, or where can I find this information?

Thanks.

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1979 240D, W123, 105K miles, stick, white w/ tan interior.

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=28Z10J5ZH2F116U2WG&year=1979&make=MB&model=240-D-002&category=G&part=Expansion+Tank+Cap
my 79TD has the brass tank radiator. my 80TD has the plastic one... guess which one is leaking... the "lifetime" warranty on the brass radiator will never need be tested I bet.
go with the 1.2Bar cap.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

BTW in Canada Wal_mart carries Zerex G 05 - and it is clear like water

OK, I've ordered a new radiator (Behr) plus parts, which should get here next week. The question now is, can I start doing some cleansing procedures now, while waiting, with the old radiator on? If possible, it seems to me it would be best, so as not to cause all the gunky stuff that is now in the cooling system to go through the new radiator once it is mounted (the cooling system hasn't been flushed for at least over three years - perhaps the reason why the old radiator finally failed).

Please advise.

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1979 240D, W123, 105K miles, stick, white w/ tan interior.

Can I start doing cleansing cycles with the old radiator on?

Anyone?

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1979 240D, W123, 105K miles, stick, white w/ tan interior.

I don't see why not if your careful to keep the levels up and the temperatures down and have a way to catch the leakage.

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1983 300D-Turbo - Deep Blue w Palomino MB Tex (total loss in fire 1/5/09 RIP)
1995 E320 W124 Polar White/Grey Mushroom MB Tex
2005 F150 Supercrew - Arizona Beige - Lear topper
1985 Piaggio Vespa T5 - Black and Chrome

www.cphilip.com

I thought so... I'd rather not use citric acid this time, though. Would Purple Power be a good choice, or should I use something else? (someone suggested dish washing soup... I don't know about that...)

So, how do you suggest I cycle it? How many times just tap water, how many times (Purple Power), and what ratio water/degreaser?
Also, can I do it with the fan off (car stationary), and how long to keep the engine running each time? My idea is to keep it running shortly each time (given the leak) but long enough to do some actual cleansing. Does anyone know how long it takes for the liquid in the cooling system to circulate fully with the engine running slightly faster than idle speed? (Of course, when the new radiator is on, I would also do a few full force flushes) How hot should I let the car get, in this particular situation?

Much appreciated...

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1979 240D, W123, 105K miles, stick, white w/ tan interior.

Got my 2 gallons of Zerex G-05 today from AutoZone... (AutoZone is half a mile from my house... NAPA and CarQuest over 20 miles away...)

Here's how I did it:

Yesterday, I called the store and asked to speak to a manager. When the manager came to the phone, I said, look, we got a situation here. Your clerks refuse to place an order for the Zerex G-05, but I have an email from Valvoline saying they do deliver it to your warehouses... I would like you to go ahead and order me 2 gallons of G-05. Silence for several seconds, then the manager profusely apologizes and mumbles that the difficulty lies in the fact "we need a special license to transport that stuff," then says, no problem, come tomorrow afternoon and we'll have 2 gallons for you. Did that today, got my 2 gallons of G-05. If you want to get it from either AutoZone or PepBoys, proceed the same way as I did. They ARE SUPPOSED to get it for you, since Valvoline supplies their warehouses with it. (see email from Valvoline I posted previously in this thread)

By the way, can someone knowledgeable please answer the questions in my previous post? Thanks.

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1979 240D, W123, 105K miles, stick, white w/ tan interior.