Slight coolant loss at coolant connection fitting in engine 651 – GI01.30-P-058933

See my post below for more info!

W212 OM651 E220 Coolant Leak – Fuel Filter Housing – Common Problem

Introduction Whilst this problem is not just limited to the E Class, it is certainly a common problem on the OM651 engine. Many a time we come across the customer complaint of coolant light coming on, but no obvious leak. There are a few usual suspects, namely the coolant pump or thermostat housing, but one of the more common ones was to find the leak coming from the fuel filter housing. Your initial thought may be how does the fuel filter housing relate to a coolant leak? You’re certainly not the only one! This housing has coolant run through it….

Topic number – GI01.30-P-058933

Date – 03-22-2017

Validity – All models with engine 651

Complaint
– Slight coolant loss between coolant connection fitting (jam_rs edit: in layman’s terms, fuel filter housing!) and cylinder head.
– Coolant warning in instrument cluster

Cause
Sealing surface of coolant connection fitting may leak under operation because of boost pressure fluctuations.

Remedy
Replace coolant connection fitting with seal. It is absolutely essential to install the coolant connection fitting together with the new seal provided, and to tighten the bolts in the sequence below.

The use of lubricant and sealing agent is not permitted!

– Tighten the two bolts for the two-hole flange on the cylinder head first to 10 Nm.
– Then tighten the three bolts for mounting onto the intake manifold with 8.5 Nm.
– Fill and bleed the cooling system in accordance with the TIPS document of Group 20.10 “Diagnostic aid for coolant loss in engine 651”.

Note:
The coolant connection fitting should be mounted onto the charge air manifold under tension, because the charge air manifold will move upwards when boost pressure is applied.

Symptoms
Power generation / Engine cooling system / Indicator lamp / Illuminates yellow
Power generation / Engine cooling system / Function / Coolant level too low
Power generation / Engine cooling system / Display message / Coolant – Serviced Required

Parts
A 651 200 39 00 Water outlet nipple parts kit 1 X
A 651 142 24 80 Metal seal for EGR cooler 1 X