OM617 turbo - dropping fuel pressure under load - injection pump or lift pump

Started by ben_g_kingsford, 23-06-2026 11:18 AM. 11 replies. 347 views.

23-06-2026 11:18 AM

ben_g_kingsford Member

Join Date: Sep 2019
Location: Kingsford NSW
Posts: 249
Car: 1985 S123 300TD turbo wagon (USA import, inherited from Uncle Stavros)

1985 S123 300TD turbo wagon from USA, OM617.952. Uncle Stavros left it to me and it came out of the container last week. Light Ivory over palomino, left hook, auntie took the pics before they loaded it.

Drops fuel pressure under load above 3,000 RPM. Lift pump on the head or Bosch MW pump? dont want to order wrong parts twice from America..

23-06-2026 01:42 PM

Vasilios_Billy

Lifetime Benzer

Join Date: Mar 2008
Location: Campbelltown NSW
Posts: 1,699
Club: M.A.L.A.K.A.S.
Car: 2020 AMG GT C

Ben that spec was USA only mate, so dont chase Aust delivery parts books or youll go mad.

OM617.952 dropping pressure above 3,000 RPM is nearly always lift pump diaphragm.. Bosch MW doesnt usually die slow like that.

Do jar test. supply line off to IP, 1 litre jar. Under 80 seconds idle, under 50 seconds at 2,500 RPM. If slow fit Mercedes-Benz 617 091 00 01 or the Pelican Bosch one, $165ish. dont touch the IP yet.

24-06-2026 04:18 PM

ben_g_kingsford Member

Join Date: Sep 2019
Location: Kingsford NSW
Posts: 249
Car: 1985 S123 300TD turbo wagon (USA import, inherited from Uncle Stavros)

Billy - you were right. lift pump from the parts box, old Pelican invoice was $165. Problem gone.

95 seconds idle / 48 seconds at 2,500 RPM before. 62 seconds idle / 34 seconds at 2,500 RPM after. Import papers say 623 Light Ivory too.. uncle had taste lol

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