Kia / Hyundai 1.6 CRDi MHEV Engine Failures

Both Kia and Hyundai have seen swathes of failures of the 1.6 mild-hybrid diesel engines fitted to the Sportage and Tuscon, various attempts have been made to recall and correct the issue but failures continue which normally result in a full engine rebuild being required.

A mild-hybrid system is basically just a two-way alternator that as well as generating electricity from a torque import it can also produce a torque output and turn the engine over (in essence electrically assisted) via the crank pulley but the Kia/Hyundai group totally overlooked the fact their new 1.6 CRDi (D4FE) engine has a woefully inadequate locking pin on the pulley end of the crank and as such they are getting snapped off resulting in a destroyed engine.

Why is the D4FE engine so terrible?

The D4FE engine utilises a small pin to lock the timing pullet to the crank. Unfortunately this type of keyway is not particularly strong compared to the Woodruff / shaft keyway used on most other engines.

This weakness was exasperated by the addition of a mild-hybrid system (MHEV) which added additional load to the bottom pulley (which was also increased in mass as part of the MHEV development).

2018+ 1.6 CRDi Kia and Hyundai vehicles have been plagued with engine failures when the tensioners on the MEHV system have failed/seized and even non MHEV equipped vehicles have experienced engine failure after the regular alternator has seized.

When the the locking pin fails the the crank is in essence moving independently of the cam and as a result there is piston/valve interference resulting in either bent valves and broken rockers or the gears in the cam shaft carrier are stripped.

This insufficient crank keyway is just the tip of the iceberg the engine has further “interesting” features that are possibly a side-effect of cost saving.

The main caps are integrated with the girdle / upper oil pan and the oil pump feeds the block via channels in both the lower and upper sump (girdle) which means any damage to the caps renders the engine scrap as they cannot be independently replaced and line-bored.

But that’s not the end of the cost cutting, the oil pump is also driven by a rubber belt that is permanently submerged in oil which means you must be extra vigilant when it comes to regular oil changes and using the correct oil formulation or you risk degrading the belt which could result in catastrophic engine failure.

8 thoughts on “Kia / Hyundai 1.6 CRDi MHEV Engine Failures

  1. akhtar Reply

    I have ceased D4FE engine, can it be changed for another model of engine instead of D4FE without having to change anything else major , ie gearbox?

    Best Regards

    • admin Post authorReply

      Hi Akhtar,

      You could theoretically change it for the 2.0 model from the same year but you would need to swap over the wiring loom, body control module, cluster etc. etc. which wouldn’t really be viable.

      When replacing the D4FE engine the hybrid and non-hybrid models are interchangeable once you swap over the fuel-pump/alternator bracket.

  2. Mohammad Reply

    Hi, I’m looking to replace a D4FE engine on a hyundai i30. Does it matter if the replacement engine comes from an automatic car. My car is a manual. Also anything else I should be wary of when replacing a D4FE engine. (Apart from the above comment)

    • admin Post authorReply

      Hi Mohammad, it doesn’t matter if its an Auto, manual or hybrid the D4FE blocks are all the same.

      The only complication is the alternator / fuel pump bracket are different between the hybrid and non-hybrid but its easy enough to swap them.

  3. Mohammad Khan Reply

    Hi again, thank you for your response. It’s much appreciated. So it turns out the vehicle had been filled up with the incorrect fuel. It runs on diesel but petrol was found in the fuel tank. (My guess whoever filled up heard it was a hybrid and immediately went for petrol.) After the fuel and oil filter were changed (oil was very thick) the car started and on revving the engine was knocking. I’d say medium knocking and we think it could be the injectors. Was wondering if you’ve come across this and if not would love to get your thoughts. Thank you

    • admin Post authorReply

      If enough neat petrol has been through the high pressure fuel pump it will start to breakdown sending swarf through the injectors 🙁

  4. Mohammad Khan Reply

    So it could need a new high pressure fuel pump as well as new injectors? Would these sort of faults throw up any codes.

    • admin Post authorReply

      You should measure the pressure at the fuel rail when its running (assuming you can get it to idle).. fault codes wise you’d get misfires..

      There’s a fantastic company called WTDiesel that can do exchange injectors.

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