M103 head gasket - 1989 300E - water in the oil at 248k - is it worth it

Started by darren_h_punchbowl, 18-05-2021 11:48 AM. 28 replies. 687 views.

18-05-2021 11:48 AM

Join Date: Jun 2019
Location: Punchbowl NSW
Posts: 319
Car: 1989 W124 300E (M103, daily)

1989 300E (M103 3.0L SOHC). 248,000 km on the clock. White cream in the oil cap. Coolant level dropping 200ml per week. Compression test 145 / 140 / 145 / 92 / 140 / 140 (cylinder 4 is the bad one).

Head gasket is dead. Question: is it worth the rebuild at 248k? Or is the M103 a parts car at this point?

18-05-2021 12:42 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

Darren - the M103 at 248k is a long way from done.. the factory design life for the M103 is approximately 400k kilometres with one head gasket replacement at the 200-250k mark. Your timing is exactly normal..

The decision tree:

Head gasket DIY - $480 in parts (Reinz MLS gasket, head bolts, valve cover gasket, intake gasket, exhaust gasket), 2 weekends of work. Worth it if you have done a head gasket before. Cylinder 4 compression at 92 suggests possible valve damage from coolant ingress, so plan on a valve job ($380 at a machine shop).
Head gasket professional - $2,800-3,400 at a competent workshop. Worth it if the rest of the car is sound. the W124 chassis is good for another 200k after the gasket.
Walk away - only if the body is rusting through, the transmission is failed, and the interior is destroyed. None of which you have mentioned, so the answer is fix it.

The M103 head bolts are torque-to-yield single-use. Do not reuse. Reinz MLS gasket (part number 02-29320-01) is the correct service replacement.

18-05-2021 04:14 PM

darren_h_punchbowl Member

Join Date: Jun 2019
Location: Punchbowl NSW
Posts: 319
Car: 1989 W124 300E (M103, daily)

Billy - thanks.. DIY route. body is straight, gearbox just had a service, interior is original cloth in good condition. The car is worth the fix..

18-05-2021 06:42 PM

Boonie_W108 Senior Member

Join Date: Feb 2014
Location: Marrickville NSW
Posts: 1,418
Club: M.A.L.A.K.A.S.
Car: '67 W108 250SE

DARREN. M103 IS A GREAT MOTOR. DO THE GASKET MATE. SHE'LL GIVE U ANOTHER DECADE.

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