Mack E7 427 low pressure Jake issues

[Walsh&Sons]

Hi all, 

ever since my father purchased our truck from his friend back 10 years ago, the Jake has never worked properly. It’s a 98 ch613 with the e7 427 low pressure oil pump. His friend claims it’s a reman, replaced 400,000 miles ago. As far as the Jake goes, it never really had much effect to begin with, and always seemed weak compared to our other trucks. Another issue is when the motor would get hot, the jake would sputter and stop working. Yesterday with a little playing around we had found that the wire going to the back three cylinders of the head to the Jake wasn’t working all together, meaning only the first three cylinders were effective. However, Im confident this will not fix the cutting out issue, mainly because it’s got the low pressure oil pump. I had herd on another thred that there is a kit that runs oil from the oil filter to the head (or something like that) providing high pressure oil to the Jake, but I’ve had no luck finding one. I also have no clue if it’s a Jacobs brake or one made by Mack, or if that even matters. 
 

if someone could provide me with a link to the kit or any info that would be much appreciated. Thanks 

[Mack Technician]

98' could be a PLN engine or E-Tech. You have EUP style fuel system? It matters, the engine brakes had very different issues between the two motors.

[Walsh&Sons]

It’s an E7 so I’m assuming it’s an E-Tech, I’m not sure on the fuel system and who makes the engine brake.
 

I’m going to go through it tomorrow and keep you posted. 

[Glensts]

I have a 97 e-7 427 drop in Mack crate motor with the high volume lower psi oil pump.  We noticed no difference in the Jake from the original engine.  It still sucks.  They aren't good jakes in those years.  We also

have the factory butterfly valve in the exhaust pipe which will double the performance of the jake, so its just poor instead of sucky.

If you get all 6 banks working you probably still won't be happy but its better than nothing

[Mack Technician]

31 minutes ago, Glensts said:

I have a 97 e-7 427 drop in Mack crate motor with the high volume lower psi oil pump.  We noticed no difference in the Jake from the original engine.  It still sucks.  They aren't good jakes in those years.  We also

have the factory butterfly valve in the exhaust pipe which will double the performance of the jake, so its just poor instead of sucky.

If you get all 6 banks working you probably still won't be happy but its better than nothing

What He ^ said.

My supervisor at the dealership had the best idea I've heard so far in terms of how to fix the issue. He was going to put in a third relay for the jakes and make it control on/off air to a 10PSI regulated valve that in turn dumped the light PSI to the brake system. Then he was going to install a digital recorder on the same circuit that played a loud jake noise over the speakers in the cab.

[david wild]

Geez my engine brake works great, 98 not E tech ??

[Mack Technician]

25 minutes ago, david wild said:

Geez my engine brake works great, 98 not E tech ??

Your saying Mack transmissions are terrible, but those cheezy V-Mac II engine brakes are the bomb???? It's entirely possible you got the three relay retrofit my co-worker was going to patent. Play with the radio volume while your engine braking, does the loudness of the jakes go up and down too?