If you’re an owner of a Hemi engine, you may have heard about the infamous MDS (Multi-Displacement System) lifter failure. If you’re beyond your factory powertrain warranty and looking to modify your engine whether it be for power or longevity, it might be wise to consider replacing your MDS lifters with standard lifters. Luckily, there are several options available to you, ranging from using stock non-MDS lifters to high-performance lifters from Competition Cams and OEM Hellcat Lifters
To swap to non-MDS lifters, you’ll need a set of new lifters and retainers, as well as four plugs to block off where the solenoids are installed. These plugs, Mopar part No. 53032221AA, are the same ones found in non-MDS Hemi’s. Accessing the lifters requires removing the heads, so you’ll need a head gasket set, front timing cover gasket, and head bolt set. Additionally, an ECM flash is necessary to eliminate the MDS before starting up your engine.
Despite the initial investment, swapping to non-MDS lifters will ultimately save you from having to perform a MDS lifter repair (Heads off), complete engine overhaul or an engine swap with a fresh core change down the line, at a cost from anywhere between $16000-21000 Australian Dollars. Plus, the minimal loss in fuel economy, even if you keep the factory cam timing and equipment, this makes the decision to switch a no-brainer. As more MDS-equipped Hemi engines age, this swap is becoming an increasingly popular solution for longevity and reliability.
Here at GDL we use and recommend a Modern Muscle Extreme custom camshaft and MDS Delete Kit, there are a few things you need to know before you start the process. Installing a modern muscle extreme custom camshaft from comp cams/ MMX requires deleting your MDS system. If your car is equipped with MDS, you can tell by the presence of solenoids instead of plugs. Typically, any automatic-equipped Chrysler vehicle from 2005 up will still have an MDS system installed. Manual transmission vehicles are usually the only ones that did not receive the MDS system. You can opt for cheaper or alternate non MDS lifters for your Hemi but we highly recommend the modern muscle kit as almost every other lifter kit on the market, including lifters from large parts wholesalers are inferior in terms of oil supply and will not maintain the specified oil pressure the system needs to operate correctly which can put strenuous strain on your valve train with potentially damaging effects. Stay put for the video on this issue, We’ll make it one day.
If you install the modern muscle extreme or any custom camshaft, you must get rid of the MDS system. The MDS lifter does not interface correctly with the custom camshaft, resulting in a lot of lifter ticking issues. There have also been many MDS lifter-related failures. The actual roller bearing inside the MDS lifter can seize up and fail, chewing its way through the lobe on the camshaft. Instead of spinning as it should, it stays stationary and eats its way through the camshaft, putting metal throughout your engine.
The solution is to get rid of the MDS lifters altogether. One option is to get a factory non-MDS camshaft, which is much less expensive than doing a custom cam, typically between $400 and $650 for the camshaft itself (If you can even source one anywhere in Australia), depending on whether you have a 5.7 or 6.4. However, even with a factory non-MDS camshaft, you still need to delete your MDS lifters, as this lifter will not work with the factory Mopar non-MDS camshaft. The lifter will collapse on itself and shut down four cylinders for better fuel economy reasons, but it also doesn’t work on the factory non-MDS camshaft. You’ll get a really rough idle and possibly misfire codes on those four MDS cylinders.
If you’re thinking about the longevity and working life of your engine, you need to do an MDS delete. That is if your vehicle is equipped with an MDS system. One thing to note is that if you buy the MDS delete kit, you’ll receive the newer updated large roller bearing. This is the lifter that is in production and comes in the new 700 horsepower Hellcat engine, making it a much more reliable lifter. There have been no lifter-related failures with this lifter. When the MDS system fails, it takes out everything, including the camshaft, bearings, and cam bearings. It can make a big mess of the entire engine if you don’t catch it soon enough.
So if you’re planning to purchase a custom camshaft, want longer life out of your Hemi or just want your Jeep to sound the part everywhere you drive, we would recommend installing the delete. The system may offer some fuel economy gain, but it’s not worth the risk of damaging your engine. Deleting the system and replacing it with a non-MDS camshaft and the modern muscle extreme MDS delete kit with the newer updated large roller bearing is a much more reliable option for your Hemi in the long run.
Depending on the year of your Vehicle (2015+) You will need a PCM unlock and a custom tune, though we always recommend an aftermarket tune to suit your needs, once you have gone to the effort of installing a custom cam.
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Contact – Parts@gdlauto.com.au to get a quote for the MDS Delete kit installed in house at one of our Sydney locations.
You can also buy the kit itself from us once we have enough stock in the country and our website is up and running on:
Above is a 60 second video of a customers 5.7L Hemi out of a WK2 Jeep Grand Cherokee that had been completely destroyed by a Lifter Failure, sending metal shavings through the entire motor. We quickly tore it apart to inspect the camshaft. This motor will be sent off as a core exchange to be rebuilt.