2011 Mack Titan - MP10 - Intermittent Jake Brake Failure

Question

I'm running a heavy haul Titan with the MP10 605hp. My engine brake has become unreliable. Sometimes I flip the switch and I get full braking, other times it feels like only one bank is engaging, and sometimes nothing at all.

It seems to happen mostly when the oil is hot. I've checked the dash switches and they seem to be sending the signal to the V-MAC, but the engine just won't deccel like it should. No active fault codes, which is the frustrating part.

ScannerSandy · Answer

Check your oil pressure. The Mack PowerBrake (MPB) relies on oil pressure to actuate the rocker arms. If your oil is too thin or your oil pump is getting weak, you won't have the pressure needed to hold the rockers open when the oil is at 220+ degrees.

PeterbiltPete · Answer

✅ Confirmed fix: This is almost always the wiring harness under the valve cover (the 'Jake' solenoids). The heat cycles cause the plastic connectors to become brittle and lose contact, or the wires rub against the rockers.

I found two wires with frayed insulation touching the head. Replaced the internal engine brake wiring harness and the solenoids. Since then, the MP10 has the strongest hold in the fleet again. Be sure to check the oil control valve for the engine brake while you are in there.

2011 Mack Titan - MP10 - Intermittent Jake Brake Failure

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