ciw65

We have had the same erratic problem with our quantum, a 1999 model with an EA7 470. Turns out the ECU is very sensitive to voltage drop. Anything below 11.5 volts and it gets the lack of will to work. Mack have installed a voltage warning light in the dash ( just a little red LED ). Is more of a problem on these buckets as the cab and chassis electrics are 24v and the engine is 12 volt. Check to see if you have a battery on the way out.

Digging through the mists of my memory, as glenn has said if they are both 2 valve heads and the model numbers match, should be a fit. However, in my experience, a properly adjusted dynatard works better than a jake. While the principle of operation is the same, Mack has done a bit more R&D on their gear and got the valve timing better. The biggest problem with both jake and dynatard systems is leakage. Those poor little o rings and seals cop an awful time in there and after a while go hard, split and leak, which dampens the operation. Put a seal kit through your dynatard units, not that expensive, and may give you a surprise. And just a quick thought on why Cummins jakes work better, they use cam actuated injectors, and the injector rocker arm activates the jake units for each cylinder, so the valve timing is much better. The older mechanical 3406 Cats however, as Glenn said work the same as a Mack, just more cubes. Chris.

HHHHEEEEEELLLLLLLPPPP!!!! I have just done an in chassis rebuild on our only (thank God) Mack Quantum. An interesting vehicle. A Renault Cab-over and chassis with 24 volt electrics, combined with an EA7 470 ETECH ( with 12 volt electrics), 18 speed Road ranger and eaton diffs. Interesting in so much as the ABS system runs a 12 volt control module and 24 volt modulating valves. To say these things are a F*&^ up beyond all description is being polite. 5 hours to REMOVE the sump, and that is from Mack trucks job time schedule. The front crossmember has to be unbolted to access the 2 front sump nuts and allow enough room to remove said sump. The crossmember also has the front engine mount on it! Any wonder I drink! But I digress. My problem after doing an in chassis rebuild on this thing is I can't seem to get the valve adjustment right, even using the valve set marks on the flywheel. The engine is an EA7 which has the unit injector modules on the outside of the engine on the camshaft/exhaust side with injector lines running up to and into the heads. Any help or hints would be greatly appreciated as I am ready to burn this heap of @$$^#.