Boost...both Ways.

[Gambi80]

I have a 1997 CH 613 w/a 427 with approx. 600k mi. What is the max boost supposed to be at full throttle? Also, how much boost should the engine brake build...if any at all?

Full throttle boost varies between 22 and almost 30, different everytime I floor it at the same RPM. I really have no complaints on the power, MPG varies a lot...between 5 and 8...mainly due to the work I do with it.

I suspect the engine brake isn't working correctly, for whatever reason. It doesn't sound like it should or build any boost and there is little feel to it when I turn it on. It sounds like its hitting on all 6, but very weakly(?). Any ideas..? Or is this all I get? I want it to work 100% because I mainly do construction work-dump trailer with it, so there's a lot of stop and go.

I've had this truck for almost a year...bought used (have had a couple suprises already!) Any replies would be appreciated.

[rw613]

Does your truck have a stealth break in the exhaust pipe under the cab some did some didnt you should here it it sounds like somthing sucking shut you should have turbo pressure also unplug your jake one head at a time see if it mackes a difference that might tell you what head the problem is if any could be a broke spring or a seliond

[Barry]

I have a 1997 CH 613 w/a 427 with approx. 600k mi. What is the max boost supposed to be at full throttle? Also, how much boost should the engine brake build...if any at all?

Full throttle boost varies between 22 and almost 30, different everytime I floor it at the same RPM. I really have no complaints on the power, MPG varies a lot...between 5 and 8...mainly due to the work I do with it.

I suspect the engine brake isn't working correctly, for whatever reason. It doesn't sound like it should or build any boost and there is little feel to it when I turn it on. It sounds like its hitting on all 6, but very weakly(?). Any ideas..? Or is this all I get? I want it to work 100% because I mainly do construction work-dump trailer with it, so there's a lot of stop and go.

I've had this truck for almost a year...bought used (have had a couple suprises already!) Any replies would be appreciated.

Boost should be anywhere from 24 to 32 depending on the load. I would suggest testing your aftercooler for leaks and look into getting the engine brake rebuilt. How does your oil pressure look?

[ThaddeusW]

Oil is used to drive the dynatard or jake brake and if there is an oil pressure issue then the performance will be poor. I remember someone saying there is an issue in the E7's where the oil pressure to the engine brake is insufficient and an external oil line is installed to get more oil to the engine brake fixing the problem.

[TOMD]

EXTERNAL OIL LINE KITS WERE ONLY USED ON E-TECH ENGINES.

[ThaddeusW]

EXTERNAL OIL LINE KITS WERE ONLY USED ON E-TECH ENGINES.

Thanks, my mistake.

[rw613]

Thanks, my mistake.

my mistake if you have a stealth break you will not have turbo pressure i had to watch mine today to rember mine carries 35 to 38 of boost in high gearand it is a 97 427

[Gambi80]

Thanks, my mistake.

Well...keep in mind I'm no mechanic. I'd make a good parts changer but no doctor. If the 'stealth brake' is what I think it is, my truck has one. A doo-dad about a foot back from the turbo with what looks to be a shock absorber hooked to it. If that's all it has for engine braking then I guess I have to deal with it..? Or is that in addition to a regular jake brake? I suppose I should make sure of what I have before firing questions.

[ThaddeusW]

Well...keep in mind I'm no mechanic. I'd make a good parts changer but no doctor. If the 'stealth brake' is what I think it is, my truck has one. A doo-dad about a foot back from the turbo with what looks to be a shock absorber hooked to it. If that's all it has for engine braking then I guess I have to deal with it..? Or is that in addition to a regular jake brake? I suppose I should make sure of what I have before firing questions.

The stealth brake is an exhaust brake that I believe is paired with a Dynatard. The shock absorber thing is the air cylinder that closes the flap in the exhaust brake. If that cylinder is stuck or getting no air then that would be a problem.

[Gambi80]

The stealth brake is an exhaust brake that I believe is paired with a Dynatard. The shock absorber thing is the air cylinder that closes the flap in the exhaust brake. If that cylinder is stuck or getting no air then that would be a problem.

Would it be a BFD if I took it out? A decent portion of the exhaust needs to be replaced anyway. It has duals and the 90* elbow where it splits is cracked, among other things. I about crapped my pants when I went to the parts counter at my local dealer and priced parts...$800+ for just the elbow and 4' or so of pipe (the shiny one of course!) to the passenger side muffler! I think I'm going to get creative with flex pipe and an exhaust catalog.

[CML Service]

I don't see any advantage to removing the exh brake. Wouldn't it be better to understand it's function and repair it? You say your exh is cracked. Depending on how badly, it could effect many things including you perception of the engine brakes performance. As for $800 for exh parts consider if this is a working truck time spent working on it is costing you money. The factory parts should fit and do thier job correctly without extra trips to the parts store. Also be aware that DOT has rules about flex pipe usage, they especially don't like any long length of it. Then no matter who is doing it it's difficult to get multiple pipes to seal and stay in place with clamps. It's no fun to melt an air line and have to deal with it on the side of the road.

Please don't take this the wrong way. I've been a mechanic for 25+ years and have dealt with the results of quick or inexpensive repairs. If you value this truck why take chances, the factory engineering got it to 600K miles.

Chuck

[theakerstwo]

I don't see any advantage to removing the exh brake. Wouldn't it be better to understand it's function and repair it? You say your exh is cracked. Depending on how badly, it could effect many things including you perception of the engine brakes performance. As for $800 for exh parts consider if this is a working truck time spent working on it is costing you money. The factory parts should fit and do thier job correctly without extra trips to the parts store. Also be aware that DOT has rules about flex pipe usage, they especially don't like any long length of it. Then no matter who is doing it it's difficult to get multiple pipes to seal and stay in place with clamps. It's no fun to melt an air line and have to deal with it on the side of the road.

Please don't take this the wrong way. I've been a mechanic for 25+ years and have dealt with the results of quick or inexpensive repairs. If you value this truck why take chances, the factory engineering got it to 600K miles.

Chuck

On top of everthing else beside the point that it is a danger to your heath the flex is a way to loose hosepower and i have seen that happen many times.I have seen trucks with 10 ft of flex and that is a lot of ehauxt leaks.

[rw613]

Well...keep in mind I'm no mechanic. I'd make a good parts changer but no doctor. If the 'stealth brake' is what I think it is, my truck has one. A doo-dad about a foot back from the turbo with what looks to be a shock absorber hooked to it. If that's all it has for engine braking then I guess I have to deal with it..? Or is that in addition to a regular jake brake? I suppose I should make sure of what I have before firing questions.

YES THE STEALTH IS ON THERE WITH THE JAKE IF YOU TAKE IT OFF YOU WILL KNOW THE DIFFERENCE I HAVE NEVER HAD TO DO ANY THING TO IT AT A MILLION 2HUNDRED THOU THOUSAND

[Gambi80]

On top of everthing else beside the point that it is a danger to your heath the flex is a way to loose hosepower and i have seen that happen many times.I have seen trucks with 10 ft of flex and that is a lot of ehauxt leaks.

I was joking about the flex pipe. I was just saying how I didn't expect the replacement parts to cost so much. I intend to do it right, couple extra bucks for peace of mind. Just curious what people with way more experience than me had to say.

[Lmackattack]

Well i buy alot of mack parts just for the support and ease of getting the right stuff. However I would rather make myself an exhaust for $150-$200 than pay volvo $800 for one pipe. You say your not mush of a Wrench so that doesent help you much LOL... I made my own dual exhaust with some crome 90' elbos "t" pipe and then used aluminized steel from under the truck to the turbo. only flex pipe I have is a 1" sectio from the turbo down pipe to the long pipe to the stacks. only reason I used it was because I was in a hurry. most expencive parts were the $90 mufflers. I still plan on making a down pipe from the turbo to connect to the rest of the system elimanating the one flex joint. Start getting good at making your own stuff. Volvo does not want to support the older dogs and they will keep on keeping on with that attitude.

[theakerstwo]

Well i buy alot of mack parts just for the support and ease of getting the right stuff. However I would rather make myself an exhaust for $150-$200 than pay volvo $800 for one pipe. You say your not mush of a Wrench so that doesent help you much LOL... I made my own dual exhaust with some crome 90' elbos "t" pipe and then used aluminized steel from under the truck to the turbo. only flex pipe I have is a 1" sectio from the turbo down pipe to the long pipe to the stacks. only reason I used it was because I was in a hurry. most expencive parts were the $90 mufflers. I still plan on making a down pipe from the turbo to connect to the rest of the system elimanating the one flex joint. Start getting good at making your own stuff. Volvo does not want to support the older dogs and they will keep on keeping on with that attitude.

In detroit diesel school i learned that all new EGR vavle engine have a exhaust backpressure range to stay in or the ECM will have a active code and derate because it will efect the emmissions out put.I learn that flex pipe has a lot of restictions for ever " of flex and i always though that before then, but hot flex is resticted more than we can understand.I never did use more than 18" on any thing.

[RRJordan]

Very old flex pipe memory: Something over 50 years back the LF dump had rusted out flex pipe from under the cab to the muffler stack. The Lanova was powerful for the day, but very smokey. When I showed him the rusty flex, the mechanic "fixed" it with a good kick and left a 4" pipe pointing right at about car window level-in the summer and before A/C. That truck and I made no friends for the company for a few days.

[Gambi80]

So someone mentioned rebuilding the jake brake, what all is involved with that and maybe ballpark the cost...?

[Packer]

As a Jake brake fan, I've rebuilt several.

The cost of a rebuild kit was just under $100.00.

The kit has all the'O' rings, pistons.and etc to rebuild one back to top form.

When new, a jake will STOP an idling engine - - - and usally using only one head!

When they work right they, are great!

When worn they're not up to much.

Valve adjustment (read Jake adjustment) will also have some value in preformance.

TIC is where I got mine kit - - - good people!

Packer

[Gambi80]

As a Jake brake fan, I've rebuilt several.

The cost of a rebuild kit was just under $100.00.

The kit has all the'O' rings, pistons.and etc to rebuild one back to top form.

When new, a jake will STOP an idling engine - - - and usally using only one head!

When they work right they, are great!

When worn they're not up to much.

Valve adjustment (read Jake adjustment) will also have some value in preformance.

TIC is where I got mine kit - - - good people!

Packer

That's some good news then as I was expecting buku bucks for parts. Is it very labor intensive or just pop off the rocker covers and pick apart some parts? I'm a big fan of the jake brake too. Makes for a much nicer to handle and drive truck, not having to use the brake pedal near as much.

[rw613]

That's some good news then as I was expecting buku bucks for parts. Is it very labor intensive or just pop off the rocker covers and pick apart some parts? I'm a big fan of the jake brake too. Makes for a much nicer to handle and drive truck, not having to use the brake pedal near as much.

look on your valve covers they may tell you a different ajdustment than the book does go by the valve cover it is for your engine

[Packer]

A set of picks are best but a piece of wire might work in a pinch.

Pull the covers, take the plates off, pull the bad parts out, (The 'O' rings sometimes stick in the bottom, that's where the picks come in), and put the good parts in.

Nothin' to it!!! LMAO

If you tend to be fumble fingered, best to pull the Jakes clear off!

Those tiny screws tend to drop in the damnest places!

While your at it, just as well run the valves and set the valve lash and Jake lash. Then replace those leaking valve cover gaskets you've been watching drip.

On a 'B' model that would eat up a Saturday afternoon - - - on one of those new-fangled tilt hoods --- who knows?

Packer

[Noid93]

your engine at 1800 rpm with the jake on high(with s3b or s4d turbo) should be building more than 7 pounds of boost according to the mack manuals. My truck that was factory at 400 hp( has a different turbo than yours) builds up to 14 psi with jake on high at high rpms.... max boost under load 28 to 35 psi(keep in mind my truck is chipped with a blixxton power module)..Your boost on load is perfect. 97 e7 @427------- 24 to 32 psi. Thats right out of the mack manual.

Edited January 12, 2008 by Noid93

[Gambi80]

your engine at 1800 rpm with the jake on high(with s3b or s4d turbo) should be building more than 7 pounds of boost according to the mack manuals. My truck that was factory at 400 hp( has a different turbo than yours) builds up to 14 psi with jake on high at high rpms.... max boost under load 28 to 35 psi(keep in mind my truck is chipped with a blixxton power module)..Your boost on load is perfect. 97 e7 @427------- 24 to 32 psi. Thats right out of the mack manual.

Thanks for the info. What led me to wonder is that my dad's truck, an '88 R-model w/a 350 has a jake on it (one setting only) and it makes about 7-8 lbs boost at a high rpm. I figured my engine, bigger displacement and bigger power should make more than that. I was planning on having the rack run sometime in the near future. I don't know if I'd want to tackle that myself or not. I suppose I could have the jake looked at at the same time. From the way it sounds it's not too big of a deal to have it rebuilt.