Radiator leak discovered - tank empties in 2 hours just sitting - W108 250S m108 engine - what to do?

Started by scott_h_caringbah, 04-12-2023 03:42 PM. 19 replies. 487 views.

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04-12-2023, 03:42 PM

scott_h_caringbah Member

Join Date: Oct 2019
Location: Caringbah NSW
Posts: 9

Radiator leak discovered.

Tank empties in 2 hours just sitting.

w108 250s m108 engine

Ok so my radiator starts leaking from one of the fins in the middle. I would think its age related as it is starting to look like this could be the 1st of many.

Looked around for a replacement "new or used" and not having much success. Havent even seen any sort of pricing.

The quote for fixing is quite high and I'm wondering if its worth the money being so old. Might just burst elsewhere!!

Can I solder closed the leaking fin or will it affect the system too much?

What to do?

If you have experienced the same issue how did you solve it?

W108 250S m108 radiator fin leak close-up

04-12-2023, 05:18 PM

Vasilios_Billy

Lifetime Benzer

Join Date: Mar 2008
Location: Campbelltown NSW
Posts: 2,118
Club: M.A.L.A.K.A.S.
Car: 2020 AMG GT C

Scott - leak is a tube, not a fin. fins cool, tubes carry coolant. your brass tube wall is eaten thru.

Soldering one tube shut works short term and loses about 1.5% cooling. M108 250S can tolerate that in Sydney. but if one tube is gone after 58 years, another is usually 6 months behind it.

Proper answer is recore the original. Theo at All Brass Radiators Lidcombe, $680, 5-7 days. keeps Mercedes tanks for HVS and gives new 3-row brass core.

New aluminium Classic unit is about $920 and 8 weeks. looks ok from 2 metres, obvious close up.

Id recore. solder-and-pray only if Theo has a queue. use 60/40 lead-tin, not silver solder.

05-12-2023, 09:42 AM

Hugo_Darlinghurst Senior Member

★ Gold

Join Date: Feb 2010
Location: Darlinghurst NSW
Posts: 524
Club: Mercedes Classic Drivers Australia (MCDA) - chapter committee
Car: 1968 W108 280SE 5.0 Coupe

W108 250S m108 radiator is 108 500 21 03. 3-row brass core, 36mm tanks, 2.2L in the radiator, 8.6L system. Theo at All Brass Radiators has done three of these for our lot in 18 months.

1968 Aus-spec is same as Euro spec for this part. recore yours and move on.

08-12-2023, 04:18 PM

scott_h_caringbah Member

Join Date: Oct 2019
Location: Caringbah NSW
Posts: 9

Billy, Hugo - thank you both. Booked the recore with Theo at Lidcombe for Monday 19-05. He quoted $680 as Billy said, 5-day turnaround. Will drop off Monday morning before work.

Soldering plan abandoned. Doing it properly. Will report back next week.

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