IMT fault 155

[Nick Wootton]

Further to my last post had both turbos reconditioned to cure ‘sticky’ wastegate valve as the main suspect for the temperature fault. (Engines 200 hours so seemed possible – conscious of under use of engines) However went to use yesterday and at low speeds no issue at all – but as soon as add power and turbos engage IMT fault code yet again same side even though not necessarily that old turbo was installed on the same side as both literally came off the bench of a reputable turbo recondition firm…only other obvious difference which I would not know if related was that Gear Temp on the ‘faulty’ side was showing 47 degrees and on the ‘good’ side 78 degrees (that seems a more normal temp to an untrained eye for oil circulating around a gear box?)   So where now – Tony mentioned cleaning the HX but nothing on the diagnostic software led engineer to believe this would stop the fault – coolant temps both sides normal and HX I believe is after the turbos – also no overheating at low speeds. however, post an expensive non resolution, I feel worth rydlyming both sides altho not sure how it would  prevent fault 155 but other than replace temp sensors not sure what else to try – wiring fault? – poor earth connection somewhere? swap ECUS? any help gratefully read and acted upon

Thanks nick  

Topic

[Nick Wootton]

Thank you Gene – I wasnt ignoring Tony’s advice- I relayed to my engineer- there are literally 2-3 in UK that will touch CMDs (American) – nearly everyone here VP

I asked about the HX etc and taking apart and even ordered Simply Green but he advised turbo removal and refurb. He is 100% a good guy – nothing untoward – he is knowledgeable and helpful and not overpriced like a lot of VP guys here – his opinion was that more likely wastegate valve stuck and not releasing excess heat before hitting fans – creating IMT

I am not mechanically minded so dont really understand the difference between aftercooler / ‘air side’ and HX – I am assuming the small tubes transport the raw water and cool the air side but where is the air side???

Is the heat exchanger the same as an aftercooler?

Sorry for being dumb and trust me I am so appreciative of you guys out there helping! There are so few CMDs here – I order from SBMAR and they are awesome!

Thanks Gene

Nick

[Gene Fuller]

Tony mentioned cleaning the HX

You might want to read his advice again. He suggested that you remove the aftercooler and do a complete service on the bench. It needs to be taken apart and cleaned.

If the air side of the aftercooler is dirty there will not be enough heat transfer from the raw water flowing through the tubes. The intake air will not be sufficiently cooled and the IMT error is a possible outcome.

The air side of the aftercooler cannot be seen without doing the complete on-bench service.

The primary observation due to a dirty HX is high engine coolant temperature; a completely different subject.

[Author]

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