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E7 460 Jake Brake Oil Pressure Loss?


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Evening folks,

Hoping someone can shed some light on an issue I'm having with my jake brake on a 2000 E7-460 I just picked up. Truck is a CH 613 tractor with 1.1m miles, past history not known aside from what the seller told me. Driving it home after purchase I noticed the jake did not work at all. Read all the appropriate forum posts here for troubleshooting (learned a ton, thank you everyone), confirmed the electrical side was good. I ran a jumper to the pass-through on valve cover with engine off and confirmed both solenoids clicked when 12v applied. I then pulled the front valve cover and checked the rockshaft plugs were still in on both sides, which they were. I started the truck with the upper valve cover off to inspect, which covered the passenger side tire in engine oil within seconds. 

From other posts ive read it sounds like I should be able to start the truck with the top portion of the valve cover off without that much spray, correct? Attached is a picture taken from the passenger side. The oil spray is coming from a small hole shown by the center circle on one of the uprights. The left and right circles are the same holes but look like theyve been filled by a rivet? 

Any guidance is greatly appreciated, I hate parts throwing hoping something sticks.

20200616_215345.jpg

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Weld’m shut. It’s a European fascination. Rivets in drill-through oil ports. When you pull the remaining 2 rivets you’ll see there’s no bore shoulder for the rivets to expand into. They rattle loose.

On the Liehberr I pull the upper rails, carve the rivets out and spot weld the ports shut. Otherwise they’re a time bomb. It’s not a matter of IF, but WHEN, they come loose and fall out in service. 

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Update:

Rivet hole is filled, so no more side spray. Ran a hot jumper to pass through with truck running and valve cover off. Oil shoots straight up from jake assembly when 12v applied but no change in engine sound. But now my windshield is covered in oil thanks to the fan. 

I havent pulled rear valve cover yet thinking id do one at a time, but now im thinking an oil leak on the rear portion may be enough to cause the other to not build enough pressure? I would have thought id get at least a stumble in rpm with one leak plugged. Thoughts?

Thanks

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On 6/17/2020 at 11:48 AM, longshipconstruction said:

What are the ports for??

The ports aren’t ports, they’re the unfortunate remnants of the engine drilling process. Your whole engine looks like Swiss cheese 🧀 after it runs through the factory gallery drilling process. Once the interconnecting/intersecting oil and fuel galleries are drilled they have to plug the drilling hole ends. If they’re being smart they tap and install pipe plugs. If they’re being thrifty they pop a cheesy rivet to plug the oil gallery and then it falls out later, as with yours. Spot weld them ALL, don’t leave the rest to chance, don’t reinstall a rivet, don’t stick a siliconed sheet metal screw in.  

 

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Update:

Pulled rear cover, all rivets and rocker plugs still in tact. Had someone hold throttle running and applied power to both passthroughs, no change in rpm. I can hear both solenoids click with truck off and power applied so im assuming they either work or they dont? Camshaft is $1400 and a jake rebuild kit is $780 from mack so im a little hesitant to start parts throwing. Is it possible the jake is just out of adjustment through wear, causing neither unit to work at all?

Thanks,

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Confirmed electrical side is working properly to the solenoids. 5.5v constant, and 14.3v when jake operated. Oil squirts vertically during jake operation so I would assume the issue is not with the solenoids. Is there a way to check oil pressure to the jake manifolds through a port? Its just odd to me that at 70psi of engine oil pressure on gauge it wont give me any audible jake operation at 1500rpm.

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I haven't been in a Mack rocker cover for at least 20 plus years and can't remember how I set it all up but from what your saying and what you've found I would say your losing pressure to operate the brake .

I would set / check the tappets and brake set up then you have started at the beginning then if all is ok run it on the road and operate the brake as you would use it if this proves no good possible then  the solution is the lose of oil pressure in the brake it's self .  

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Remove jake housing and check the oil check valve port to jake housing , yours looks like it’s bin updated already aka you have check  valves already in rocker to housing or upgraded one , but when techs did these updates and did not read institutions they would leave the factory check valve in the housing which is a circle clip spring and ball . If this is the case then oil is trying to go past 2 check valves to get to jake no good . Also stock brake setting  original was 15 then updated to 17 then with updated jakes or rebuild kits 21 👍🏁🇺🇸

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Staxx, that check is part of the external oil supply upgrade. Right? It keeps external feeder lines from back-feeding the lower engine bearings in reverse flow. 

Usually you would have an open nipple/dowel. External upgrade requires a no-reverse-flow measure.

Without that check valve installed the Jake would get the top external feed oil and let flow go backwards into the lower block and squirt out the sloppy bearings that were causing the issue in the first place. The check allowed the lower engine to feed Jakes from the bottom while externals fed Jakes from the top simultaneously, but never let oil return backwards to the lower block. If the Jakes were going to town and eating more oil than the external line could provide the check would allow the block port to subsidize flow creating two feed circuits instead of one. He doesn’t have the external kit yet. The check upgrade wouldn’t hurt him, but it wouldn’t help him in the fashion it was originally intended unless he got the whole upgrade. 

Edited by Mack Technician
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Valve is on rebuild kit for jake even non external kit , original was open on rocker but check valve in opposite side hole in jake housing spring ball clip . When go to update you remove spring ball and clip in housing .👍

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  • 5 months later...

sounds to me like a 690 brake that wasnt drilled for the top oil feed update.... I wonder who still has the drill jig to bore the oil gallery right... ??? i did a bunch of these about 18 years ago.. this plus a high pressure oil pump was the cure... however... mack got it right with "Powerleash"  after that...   as far as the check valve.. the others are correct... there was 5 pieces that had to be removed from the jake head, all replaced by the one check valve that replaced the allen headed delivery valve......Phhewwww. I just pulled that out of my.....A@#s.... correct me if im wrong... Go Bulldog!! Jojo.. Merry Christmas!

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Hello, Mainah,,,  The .021 lash is correct... When the update was done, The Jake reset screw were replaced with an armolly pin set... 215SB321 kit... Then the lash was set to .021... they tried .017 before that....    P/S. I lived in ME. for 25 years,, graduated from Gray New Gloucster high school, in cumberland county... Merry Christmas

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I remember there was a lot of screwing around with the engine brakes on these jake heads. The problem was when the engine oil reached operating temperature the oil pressure dropped just enough to not engage the pistons on the engine brake. The cure was to install a high volume oil pump and retro fit these jake heads to top oil feed. Here is the service bulletin. Happy drilling!

 

sb266015.pdf

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