Vehicle With Atypical Reduced Heat Output (VERSION 4)

Publication date: 2025-04-01
Reference number: VERSION 4
Supersedes refnos: LI83.20-P-051802

VEHICLE WITH ATYPICAL REDUCED HEAT OUTPUT

TECHNICAL SERVICE BULLETIN

Reference Number(s): LI83.20-P-051802 Version 4, Date of Issue: April 01, 2025

MERCEDES-BENZ:	Models 168, 169, 245, 202, 203, 204, 216, 208, 209, 218, 219, 207, 210, 211, 212, 163, 164, 166, 251, 292, 220, 221, 170, 171, 172
FUNCTION GROUP:	83.20 - Heating
REASON FOR CHANGE:	Validity updated

COMPLAINT

Vehicle with atypical reduced heat output.

CAUSE

Silicate granulate may have escaped from a damaged bag in the expansion reservoir (not visible), reducing the coolant flow in the heater heat exchanger (see picture).

ATTACHMENTS

File	Description
Silikagel im Heizungswaermetauscher.jpg	Silica gel in heater heat exchanger

REMEDY

With the aforementioned complaint, make sure that the cooling circuit is inspected for silicate residues after all standard tests are completed.

The silicate residues tend to accumulate upstream of the shutoff valve for the heater hot water pulsed valve.

If there are silicate residues in the coolant, the engine must be flushed thoroughly.

To make sure that all silicate residues are removed from the cooling circuit, the following parts must also be replaced (cleaning of these components is not sufficient):

Coolant expansion reservoir, radiator, oil/water heat exchanger (oil cooler), heater valve, heat exchanger of heater, coolant and, if installed, the electric water pump for the residual heat utilization system.

Determine the parts for the respective vehicle in the EPC.

Disclaimer

NOTE: The information contained in this document is intended for use by trained, professional technicians with the knowledge to properly and safely perform diagnosis and repairs on Mercedes-Benz vehicles, using Mercedes-Benz approved tools and equipment. It informs service technicians about conditions that could occur in certain vehicles and provides information that could assist in proper vehicle diagnosis, service, or repair. It does not indicate that a defect is present in any vehicle referenced in this document nor does it imply warranty coverage. DO NOT assume that a symptom or condition, or a described cause of a symptom or condition, affects any particular vehicle or groups of vehicles, or that a described repair applies to any particular vehicle or groups of vehicles. There can be multiple causes resulting in the same or similar symptoms or conditions described in this document, and trained professional service technicians must use their diagnostic skills to make evaluations on a case-by-case basis. The information contained in this document does not guarantee warranty coverage nor does it extend the vehicle's warranty in any way.

SYMPTOMS

Body > Air conditioning > Heater > Remains cold

Body > Air conditioning > Heater > Insufficient heat output

OPERATION NUMBERS/DAMAGE CODES

Op. no.	Operation text	Time	Damage code	Note
			5010104	expansion tank