MaxxForce DT Testing High Pressure Manifold

With the right fittings from your local hardware store you can test the injection high pressure manifold that can cause diesel performance problems on a MaxxForce DT when it develops an oil leak. As the video shows there is a substantial leak on this manifold. So we could have just removed the manifold and replaced all of the seals but firstly we wanted to confirm that there was a leak at the manifold and eliminate the HPOP high pressure oil pump. Once that was ascertained next step was to see where the leak was located…hopefully. Even after adding leak detector there were no obvious signs.

This a simple test that needs to be done when there is a problem with injection control pressure ICP. The high pressure oil pump which is accessory driven off the engine creates the high pressure oil that is sent to the manifold to operate the injectors and engine brake. When pressure drops there will be an engine code and poor engine performance. The injectors are not performing because of leakage in the ICP system.

The test set up in the video eliminates the high pressure pump and isolates the high pressure manifold. The seals are the most common issue so the parts involved in this repair aren’t a huge cost but there is a good chunk of labor to complete the job. Our fleet has experienced this failure numerous times and the seals fail which is not surprising due to the extremely high injection control pressures that this diesel needs to run properly.

At an idle the ICP has to be around 800 psi. The maximum depending on the load and RPM can get as high as 4500 psi. That is a lot of oil pressure to contain day in and day out. Something has got to give as they say and it happens. If there is a lot of engine vibration it could shake a sensor or solenoid loose and allow high pressure oil to sneak by and drop the ICP down substantially. The engine brake solenoid is a common component that loosens off and creates issues. The unfortunate thing about this problem is the o-ring that seals the solenoid is not available and you have to buy a new solenoid with the o-ring installed.

The solenoid is over $400.00 (Canadian funds) so it’s really frustrating to have to pay that much just for a circular chunk of rubber that costs 5 cents to make. That’s crafty marketing at it’s finest. After the first time this happened we will diligently dig around for an o-ring the right size that works. I hope this video helps you out and please leave your questions and comments.