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Adding pressurised overflow bottle to 300td radiator

Posted: Sat 14 Apr, 2018 2:13 pm
by EddieMurphy
Hi all,

I had a post recently about my water pump falling apart at 100kmh on my 81 diesel 300td w123 and destroying fan and radiator, it has been very difficult to find a replacement radiator in au to fit. I thought I had one sourced and was assured by parts place that it was the correct radiator but upon arrival it seems to be the w126 radiator which requires a pressurised overflow bottle. As it has no radiator cap and an extra hose fitting down the bottom. I can source an overflow from a w126 easily.

So my question is are there any reasons for me not to go this route of retro fitting a pressurised overflow bottle, are there any benefits and how can I be sure to have it at the correct height to ensure that the radiator fills to exactly the right amount and the overflow be accurate?

Also If I shouldn’t do this does anyone know where a radiator for my model can be sourced?

Re: Adding pressurised overflow bottle to 300td radiator

Posted: Sun 15 Apr, 2018 6:14 pm
by tsharkey
Hi Eddie,
I fitted the system you described to my 300TD. Get the reservoir and hoses that run between the reservoir and radiator from a W126 (The need some slight trimming as the W126 is bigger), or order a new set for a W123 from the sponsor. The existing main radiator hoses should fit OK. You can wire in the No Water warning switch if you want, otherwise leave it unplugged on the reservoir. You will need to make a bracket up to hold the reservoir in place, between the SLS oil bottle and top of the wheel arch.

Here is a picture of another of my wagons with this system
OM617A RHD Factory.JPG
I prefer this system as you can see at a glance the water level.

Re: Adding pressurised overflow bottle to 300td radiator

Posted: Thu 10 May, 2018 9:21 am
by EddieMurphy
Hi and thanks for the reply.. did you have any issues fitting the radiator shroud from the original radiator to the newer radiator as when I had a quick look at the two they didn’t match up exactly. Also what was the newer radiator off.. w124? I’m having a bastard of a time locating an original radiator without overflow to fit... even my radiator guy said it’s not available anywhere.

Re: Adding pressurised overflow bottle to 300td radiator

Posted: Thu 10 May, 2018 11:48 am
by 300TDT
I found these people very helpful in the past.
www.nissens.com
www.radiatordirect.net.au
They offered air freight direct to you for about $100 more than sea.

Re: Adding pressurised overflow bottle to 300td radiator

Posted: Thu 10 May, 2018 12:40 pm
by tsharkey
I bought two radiators for a 300TD - Turbo version "chassis WDB123.193" - I have been informally advised it is the same radiator as the W126 V8. You can get the correct radiator for the non turbo chassis (WDB123.190) - no pressurised overflow bottle.

I used this site to get them sent from Europe. www.spareto.com This is the link to the W123 models https://spareto.com/t/vehicles/mercedes-benz/ - Enter your year and capacity a 3.0 l and the models come up.

It took a couple of weeks but the price was well below any local sourcing I could achieve. I originally order BEHR (as the OEM) but was quickly advised BEHR no longer make these and was offered Nissens for the same price (BEHR was cheaper).

Good question re the fan shroud, Everything lines up except the two plastic prongs at the bottom. I have made up a small plastic strip that uses the displaced retaining slots to hold the prongs in position. All else lines up.

Re: Adding pressurised overflow bottle to 300td radiator

Posted: Tue 26 Jun, 2018 6:06 pm
by EddieMurphy
thanks for the info tsharkey... its a bit pricey at $630 aud to actually get the nissans through that link. will have to think about if i want the extra trouble of the overflow bottle and shroud modification. It would save about $250 id say but take me a while to get that sorted but its also a month delivery times on the original from europe...