Webasto Thermo Top White Smoke

Webasto Thermo Top white smoke is a common issue. White smoke on Webasto diesel heaters is a problem which requires immediate attention. Unless you are well versed in the functions and construction of your heater, this is something best left to a professional diesel heating engineer.

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Webasto Diesel Heater – White Smoke

This week we were called out to a boat in London with a Webasto Thermo Top heater, which had broken down. The client described the fault as the heater having cut out after 15-20 minuntes operation, for several days in a row. This problem had then gradually got worse with white smoke appearing from the exhaust. At first there were only small amounts of white smoke from the client’s Webasto Thermo Top. This had gotten worse and worse until it was impossible to run the diesel heater, because ‘the neighbours had called the fire brigade’.

Webasto Thermo Top - Diesel Heater - White Smoke

White smoke from Webasto Thermo Top Diesel Heater  – The Cause

Upon arrival, our engineer carried out routine checks and found the coolant header tank, mounted inside a cupboard, completely empty. There was also a large amount of coolant in the bilge, next to the Thermo Top Diesel heater. Upon further investigation, it appeared that this Webasto heater had been poorly installed some years ago. The coolant hoses were attached in way which made them rub against the engine when it was running. This had caused a small leak on one of the hoses.

As a result of this coolant leak the heater was running hot and had cut out automatically. This would have been an easy fix if the owner had called an engineer to fix the issue at this point. Because the unit was still being run with the fault, this had a knock on effect and caused further damage. The continuous overheating had then resulted in a cracked gasket between burner housing and heat exchanger, which allowed coolant to leak into the burning chamber, causing the white smoke.

White smoke from Webasto Thermo Top Diesel Heater – The Repair

Having contacted our supplier for Webasto Thermo Top parts, we were informed that the gasket between the burner housing and heat exchanger is not a serviceable part . The only option left now was to replace this whole section with a new one. We were able to source both the part and a new coolant hose with next day delivery and fix the problem within 24 hours. We also rerouted the coolant hoses away from the engine and relocated the coolant tank into the bilge, where it would be easier to check it routinely.

Preventative Meassures

The white smoke problems with this Webasto Thermo Top could easily have been prevented with the right routine maintenance. The repair costs could have been kept to a minimum too, if an engineer had been called out at first sign of trouble. Webasto diesel water heaters are generally very reliable and should give their owners many years of trouble free service, provided they are cared for.

Have an annual service and check up carried out be a professional engineer. Check your header tank  before you switch the unit on, every time you start it. The coolant level in the tank should be in between the “min” and “max” markers. Top up with the correct coolant if needed. Call one of our engineers on the first sign of anything unusual.