Jake cutout

[ramz trk]

2000 mack e7-460. The jake cuts out at 1600. is the computer limited or something else. What are the options to fix?

[br549]

Low oil pressure could be cause, all of the 2000 models had jakes cut out early especially on a hot day when the oil really heats up, not enought oil pressure to the jakes . We put a higher speed oil pump on ours, it helps out but they did make a kit to feed oil from the main oil galley on the block to the jake spacers and feed direct oil to Jakes. If yours have been changed you will have external oil lines on the drivers side going to the jake spacers. I have seen several of the freeze plugs in the end of the rocker arm come out and loose oil pressure, but most of the time that head quits working. See how much oil pressure it has when it cuts off, I think it takes 35 lbs for jake to work so you need to have around 50 lbs on the gauge in truck to work.

[jklj]

I run 2 gallons of Lucas heavy duty oil stabilizer in my 460 and that seems to make the jake work better

[rsb502]

Yep, thicker oil = better engine brake for an E7, the high volume oil pump helps a lot.

[ramz trk]

yeah it keep around 60 psi at those rpms. is the hose deal something bolt on or does engine have to be disassembled? any part numbers?

[Challenger]

If you're talking about the external oil lines for the Jakes, you would have to drill and tap the Jake housings to add the fittings. Everything else is pretty simple.

[theakerstwo]

Yep, thicker oil = better engine brake for an E7, the high volume oil pump helps a lot.

That is the reason I use Mystick 15W50 in the summer cause jakes do some better.

[theakerstwo]

If you're talking about the external oil lines for the Jakes, you would have to drill and tap the Jake housings to add the fittings. Everything else is pretty simple.

Do you think it would make the jakes more respounceive? I just installed a E7 in place of my E6 and the jakes don't come on as fast as the E6 with dnytrad.They work good but if you use them for shifting they are too slow. glenn

[Challenger]

Do you think it would make the jakes more respounceive? I just installed a E7 in place of my E6 and the jakes don't come on as fast as the E6 with dnytrad.They work good but if you use them for shifting they are too slow. glenn

I was just replying to your previous question. External oil lines help if your Jakes are weak or fade away.

Im a little confused on your complaint.

Are your Jakes weak and or fading away?

Or

Are your Jakes strong and cutting out at 1600rpms. Do they feel like they cut out electronically? Meaning, theyre there, theyre there, boom theyre gone.

[theakerstwo]

No what I am talking about when you hit them they come on slower than the ones on my E6 and there is a ssmall delay making it hard to use them to shift with on a hill in low gear.They are strong when they come on just slower than the older engine that was in that truck.

[Challenger]

Got it. I would think your complaint is just one of the differences between Dynatard and Jakes. I dont think you can change any parameters for the engine brake. As far as I know, you just have one parameter box to click for the engine brake, on or off. Everything else is set by Mack.

[theakerstwo]

Thanks

[ramz trk]

Mine feels like it is electronicially being cut out.

[br549]

Put a test light in cab of truck and run long wire and unhook one of the jake wire at the valve covers and hook it to it. Test drive see if the light goes off at 1600 rpm, if the light stays on but the jake quits its problem with Jakes internal or oil pressure problems, might need a tune up kit or soleniods. If the light goes off at 1600 it is in electrical but I don't remember a place to set cut off in settings in computer.