1999 Mack E7 350HP, Jake Brake issues

[whskypete]

Happy Sunday to all, I am still working on this Mack E7 (ETECH) 350 HP with Jake Brakes. The cylinder head has been replaced, the valves have been adjusted as well as the Jakes, however my current issue is the Jakes.

When driving down the road and the Jakes are applied, there is a delay (long) or sometimes the Jakes don't work at all. I have installed a factory Jake Brake Kit which replaces all the springs, valves, washers, upgraded check valves (front rocker and rear rocker), o-rings and a number of other things but not the solenoids (not included in the kit).

Could my solenoids be the issue causing the Jakes to sometimes work and then not work? At idle, there is a small amout of oil coming from where the solenoids sit on the Jake brake housing (is this normal)?

Oil pressure at operating temp and idle is about 20 psi, which is within spec.

Any ideas would be greatly appreciated, please help me with this issue.

Thank you,

Pete

[fjh]

Did make sure the plugs were in the ends of the rocker shafts??? it is quite common for them to pop out!

[whskypete]

The plugs on the rockers were in, but I'll double check when the customer brings it back in a few days. The plugs you are referring to are on the end (sides) of the rockers. Correct?

[Challenger]

Did you have this problem before the repairs?

The old style Jake would've been adjusted to .017" The newer updated adjustment would be .021" Did you adjust them correctly?

When you installed the solenoids did you replace the solenoid orings or atleast make sure you put them back?

How many miles are on the truck?

Whats the oil pressure while driving and attempting to use the Jake?

Assuming you did everything correctly it could be low oil pressure. Within spec and optimal are 2 different things.

If everything is correct you could consider replacing your rod and main bearings and replacing the oil pump with a high volume oil pump.

There is also an external oil line kit you can buy that runs oil from the oil filter housing to the Jake Housings.

[whskypete]

The Jake kit called for a clearance of .015 ( but I can go .021), the o-rings on the solenoinds were replaced in both the front and rear jake. I'll have to double check on the oil pressure while I am driving. The tractor has between 250K miles but less than 275k miles in it. It was purchased from Boeing, so I imagine it was well maintained. I have never done the oil supply line to the Jakes before. Where should I go from here?

[whskypete]

Oh, yes I had the problem before the repairs. The repairs were done because when the Jakes were removed we noticed metal debris from the springs on the head,

[Challenger]

Im not sure why it said .015 that was the clearance before .017. The old style were .017 and the updated style is .021. With the Jakes installed you can tell the difference between the 2 by the length of the stud with the 3/4 nut. The old style were short and the newer ones are longer.

New Updated Jake kits clearance is .021".

Readjust and retest.

You can jump power from the alt to the jake connector with the wire off and hear the solenoid click. With the key on engine off remove the Jake wire from the spacer and tap the little connector stud with power, you should hear the click. Do it to both heads, no click means bad solenoid or solenoid wire.

Use the same wire and hold the wire to the connector while the engine is running this should activate the Jake and the engine will studder. Do this one head at a time.

Try this before and after you readjust the Jakes to see if you can hear a difference. This is just a quick way to see if there is a difference with out a road test. You'll still need to road test to make sure its all good and doesnt fade away.

Edited January 23, 2013 by Challenger

[fjh]

Cover the jake heads with a rag and operate it manualy by pushing in on the center of the sol with the engine running see if you can get it to operate Observe how much if any oil is getting passed the slave pistons on the under side of the housings if there is lots the housing are likly the culpret this was a real comon problem with these,The oil line kit will likly be pricy as it consists of new jake heads and spacer plates and lines! ALL of the above helped but only marginally The pump and bearings helped the most and would be allot cheaper than the oil line kit in my opinion!There was a special bearing supplyed for sum engines which reduced the bering clerance from 3 thou to1 .5 thou if I recall correctly!Ya may want to check into this IF you can find a good oldtine parts guy Barry may remember this or have a buliten he can look up!

and yes the plugs I spoke of are on the rocker shaft ends!If there is one missing you will only have one head operating!

As for setting them up 21 thou in my opinion is counter productive you already have a shit brake and 21will make it worse, I have always set them at 15 (even with the updated screws) when you think about how it works the more gap you give it The less you open the valve the less effective the brake! The 21 set would open the valve 6 thou less! Again just an opinion and a bit of Trial and error experiance.Less the error part !

Also run power to the jakes with a jumper wire and see if you and make em work cold then hot!

[staxx]

Mack stopped using the oversized bearings because techs were not measuring clearance before installing bearing and on some locking engines up , Mack's crank sizes were all over the place on early etecs that's why some had good oil psi and some not.

[fjh]

Thanx for clearing that up Staxx I Kinda wondered about the bearing issue ,they we only did half a dozen trucks here and heard no more about it, as time went on the issue kind of faded!

[whskypete]

Well, thank you guys for the information. I will start with the solenoinds and work my way from there. The new Jake Kit includes longer studs which through me off at first. I'll keep you guys posted in what I find. The truck will be returning next week for a follow up.

Thanks again

[butchs18]

I have a 2000 ch613. I had the Jakebrake installed by a Mack dealer. When I pulled out of the shop the Jake quit... after the oil warmed up... before I made it home. Went back to dealer and mack installed ribits in the oil holes of the rocker arms on the jake

to help oil pressure, This worked untill you pulled a hill and the oil heated up. No jake going down the hill untill the oil cooled.

I installed external oil line kit..$300 plus.. fixed the problem. Some guys put together their on oil lines and save $$.

Edited January 24, 2013 by Butchs18

[staxx]

To install external oil line kit the jake housing have to be drilled and tapped in a specific place that requires a mack tool to locate.

[Challenger]

Every oil kit I've put on solves the problem. I drill the Jake housing not replace them. Of course the oil lines are the last resort after troubleshooting, update kit, rod and main bearings, and the high volume oil pump. The Mack spec on the updated kit is .021" Its been that way for 12-13 years. I wouldn't even consider troubleshooting a Jake issue knowing that they were set at .015". I would readjust with the Mack spec and road test.

Edited January 24, 2013 by Challenger

[whskypete]

It sounds like the oil kit is the way to go, however I have never done this, are there any mechanics in Southern California (L.A) that have done this? I know there is a MACK dealership near by but I don't want to send my business away. Or is there any online information? Any help is always appreciated.

[KUTZIE]

Experiencing the exact same problem, why are the specs from Mack .80 for 1996 e7 350 with S3B turbo?

[Quanbigrig]

Having same problem ,just got it adjusted,still works sometimes.I notice it works good when first ran after it  been sitting for a couple days .Did you ever find out the problem?

[Joey Mack]

Hello 'Q'..  welcome aboard..  You commented on an old posting.  How about telling us the year and model, engine, tranny and the issue you are having?  You wont believe how many smart guys are ready to help you..  jojo

[fjh]

Good point Joe

[Quanbigrig]

1999 Mack ch613 8speed with a e7 jakes works for about first 5 minutes of a drive when it’s been sitting for while ,sometimes it don’t even work at all .Just got it adjusted after finding out it was running on one head .Cruise control works ,jakes never works when I need it 

[Joey Mack]

ok..  without going deep...   make a small gauge jumper wire..  to reach from the pos. on the alt.  about 3 feet long... crimp an alligator clip to each end, ( you will save this tool for later diag.) climb up there, and un-plug the 2 jake plugs at the valve cover spacers..  you will see an 1/8" pin sticking out..  with the engine running at low idle. simply, clamp one clip to the Pos. on the Alt. and use the other end to touch on to the jake pin at the jake spacer...  .  It should activate the the jake on that head, and cause the engine to stumble...   if it does not stumble the engine on that head,  then the celeniod is either unhooked/cut under the valve cover, then you fix the wire..  or possibly the celenoid is bad..  it is a simple test, that Work's..  Jojo

[Joey Mack]

Ok..  next....  who did the valve adjustment??   I'm a "Stickler"  about valve adjustment's an Mack engine's.. this is a side thought...     Let's first address my previous post..      you will have a bunch of guys that will join in and guide you...  jojo

[D-Day]

1 hour ago, Joey Mack said:

ok..  without going deep...   make a small gauge jumper wire..  to reach from the pos. on the alt.  about 3 feet long... crimp an alligator clip to each end, ( you will save this tool for later diag.) climb up there, and un-plug the 2 jake plugs at the valve cover spacers..  you will see an 1/8" pin sticking out..  with the engine running at low idle. simply, clamp one clip to the Pos. on the Alt. and use the other end to touch on to the jake pin at the jake spacer...  .  It should activate the the jake on that head, and cause the engine to stumble...   if it does not stumble the engine on that head,  then the celeniod is either unhooked/cut under the valve cover, then you fix the wire..  or possibly the celenoid is bad..  it is a simple test, that Work's..  Jojo

If you can hear the solenoid clicking it's working but a lot of times the o-rings on the solenoid get baked hard over time and lose pressure easy to change them out if you have not already 

[Quanbigrig]

Okay thanks I’m going to clean the solenoid and change the o-rings 

[Quanbigrig]

A guy that know the trucks did the adjustment ,he been working on it since 06 and did the last adjustment a couple years ago .He said I should get new solenoid but I don’t keep spending money if it’s not going to fix the problem