Hi, all-- is anyone operating an exhaust brake yet on their LLY?

I had a Banks exhaust brake on my LB7 and was happy with that. I would like an one for my '04 1/2 3500 LLY. I understand the issue of EB compatibility with the LLY engine is its VGT turbo and Banks does not recommend the LB7 EB for the LLY, and has supposedly been developing a new EB compatible with LLY's VGT turbo. A Banks rep has told me for months that Banks is committed to developing this product but I haven't heard any news on it in awhile.

On the other hand, in November US Gear technical service let me know that in their opinion the miniscule delay in the US Gear exhaust brake D-Celerator engagement allows the vanes in the LLY turbo to return to rest before pressure is built and concluded that the current application for the Duramax (EXB-3554) will work for the 2004 LLY.

So, any LLY owners running exhaust brakes yet? I hear the Duramax LLY in the 4500 and 5500 trucks offer (or used to offer) exhaust brakes. Any opinions on the two manufacturer views above? Thanks. --wheeler
Posts: 55 | Registered: Nov 2001 *|* IP: Logged*|*

I believe there is a warranty issue with the LLY if you add an exhaust brake. IIRC several guys had installed them, I just can't recall if they were happy with them given the way the LLY already utilizes backpressure for grade braking. OOPS, way out of my league on that one, best to do a search on the forum. ):h I know there has been discussion on them. JJ :)

Hitting the tow\haul mode switch will activate the built in engine brake for the LLY. let off on the throttle and depress the brake pedal lightly the braking will engage automaticly. I love mine

That is not an engine brake, that is called a down shift LOL.

I've had a BD brake installed for the last 15K or so. Used it on 2 towing trips, approx. 7K each. CA through the rockies to MO and back, twice, traveling I-70 and I-80. Works as advertised (same as on the LB7).

Wyndzer, dmacy is corect in theory. He mad not have used the right words. The built in grade braking in the tranny is much more than downshifting. I had a EB in my Dodge, probably will not put one on my LLY with the grade braking as it seems to work very well towing my 12K trailer.

Just my 2 cents

Wyndzer, dmacy is corect in theory. He mad not have used the right words. The built in grade braking in the tranny is much more than downshifting. I had a EB in my Dodge, probably will not put one on my LLY with the grade braking as it seems to work very well towing my 12K trailer.

Just my 2 cents
Curious as to what "more than downshifting" it is?

The turbo is a varable displacement turbo charger. The vanes move to change the displacement. There is no waste gate. When engine braking is needed the vanes in the turbo close and create back preasure which is very effective in engine braking. This works in conjuction with the Allison which may or may not down shift depending on load, speed and grade. Together it works very well. I would recomend trying it before looking at any aftermarket add on. I have read some posts about add on engine brakes and the LLY. The computer and the turbo don't like them and can cause major mechanical problems. THIS ONLY WORKS IN THE TOW/HAUL MODE

So what do they do on 4500 and 5500s, they come from factory with exhaust brakes?

The turbo is a varable displacement turbo charger. The vanes move to change the displacement. There is no waste gate. When engine braking is needed the vanes in the turbo close and create back preasure which is very effective in engine braking. This works in conjuction with the Allison which may or may not down shift depending on load, speed and grade. Together it works very well. I would recomend trying it before looking at any aftermarket add on. I have read some posts about add on engine brakes and the LLY. The computer and the turbo don't like them and can cause major mechanical problems. THIS ONLY WORKS IN THE TOW/HAUL MODE
I had a BD exhaust brake on an 01 for about 65K miles, 35K were towing all over the US (approx. 7K without an EB). The 04 felt exactly the same, towing the same 11K lbs. trailer over many of the same routes, without the EB. You may be right about how the VVT works off throttle, but IMHO there is no seat of the pants difference to the LB7 with or without EB. The brake is nice to have coming down off the Sierra Nevada (especially east bound Tioga Pass) or the Rockies.

I tow a very heavy 5er. I came from a D*dge with factory Jake brake to 2003 Chevy 2500HD. I never tried the Allison Tow/Haul mode alone, I just had the Banks exhaust brake installed into the 2003 Silverado immediately. This year I traded the '03 2500HD for a 3500 with LLY. So I don't have an exhaust brake yet but I have been trying out the Tow/Haul mode engine braking. I still miss an exhaust brake but I have to say the engine braking works better than I expected.

But am I using engine braking correctly-- I was told there are two engine readlines on the tachometer and that the higher one is for the engine braking downhill mode. In other words, is the Allison smart enough that if I leave the transmission in Drive in Tow/Haul mode on steep descents, it will not over rev the engine dangerously-- period? Coming down some steep hills the engine was at very high RPMs but my downhill speed was pretty much restricted.

All in all I would still prefer to install an exhaust brake. Assuming Banks comes through on an EB for LLY, I'd like to do the full on Banks treatment (larger exhaust, Six Gun+Speedloader, etc., and exhaust brake)... but on the other hand I feel like that trio would be a whole new chapter of possible complications and problems.

Thanks very much for the input guys. --wheeler

The LLY does have separate redlines for engine braking and for acceleration. The truck won't let you exceed either. :confused: I posted earlier that adding an exhaust brake may void the warranty on the LLY, best to check that out first.:rolleyes:

Anyone besides myself humbled driving a truck that is smarter than themself? JJ ):h

Anyone besides myself humbled driving a truck that is smarter than themself? JJ ):hOn the one major trip I took with the LLY before installing the exhaust brake, I found myself manually dropping a gear or two (lockout or shifter) because the grade braking (in to/haul) didn't respond quick enough for me. I know the engine is made to handle 4000 RPM coasting, but with the EB you can have the same or more braking without exceeding the normal operating range. I really like the added safety plus the bonus of extended service brake life.

Interesting, JJ-- I hadn't heard about EB possibly voiding warranty. I'll check that out with my dealer. Hmmmm. I heard that EB's were factory available on the 4500/5500 Duramax trucks.... was that just the 04 models with LB7 engine? Does anyone know if EB is factory available on current 4500/5500 with LLY? --wheeler

I think I read on an earlier post that a guy had put an exhaust brake on an LLY and had blown the turbo charger. I don't know for sure but I thought it was a Banks. There was also a concern that the engine had aspirated some metal parts. I would be very carefull before adding any aftermarket componants to a $40,000.+ truck. To me it doesn't seem like it is worth the risk.

Posted on a different forum by R Hood who had an engine problem with a Banks Brake installed:

"At last I got my truck back and was able to return home, 4 weeks late.
As I posted earlier, the good news is that I have a new long block at GM's expense. The bad news is that it didn't come without a fight!

I now have 3,000 miles on the new one and it is obvious tat the old engine had problems from the beginning. This one doesn't smoke at all and is much quieter than the old one.

A special thanks to Jim Moore, Warranty Administrator, Gale Banks Engineering. Jim was extremely helpful in providing technical info that proved the Banks systems didn't cause the problem.

After I appealed my case to a manager at GM Customer Assist, he took the info from Banks to GM engineering and forced them to look into the matter. Up until then the zone manager (AVM) wouldn't allow anyone to touch my failed DMAX to even determine the cause of failure. Two days later the dealer and AVM couldn't to enough for me!!

Bottom line, I have a new engine, full warranty and the worthless dealer (Titus-Will, Olympia,WA)even re-connected all my Banks goodies!!

GM covered the $14,000 engine, rental car for over 4 weeks, lodging, food, etc. I had to fight them every step of the way, however, just to make them honor thier warranty."

Interesting that he has "full warranty" and they even reinstalled all the "Banks goodies".

Curious as to what "more than downshifting" it is?
Trans control module also keeps the Allison's torque converter fully engaged during grade braking- I think it stays locked all-the-way down to second gear when in tow/haul mode.
Ed

Correct me if I am wrong but, isn' t the exhaust brake in theory a flapper more or less in the exhaust line that closes, holds the exhaust in the engine until enough pressure builds up to override the force on the flapper to push it out of the way then it again closes and the process continues over and over again. Okay, if this is true, which I believe it is, aren't you people that have these on your engine concerned about all the garbage that stays in your engine during the application of the brake? People are disconnecting their EGRs to prevent running soot back through the intake but basicly are probably keeping more in with the brake. opinions?

Unfortunately it appears there is a lot of recirculating going on in the LLY. I disconnected my EGR valve several months back and liked the difference in turbo spool up, but the LLY didn't seem to engine brake nearly as well and since I'm mainly towing heavy I plugged it back in. I like the driving characteristics better when towing.;)

Everything appears to work in tandem on the LLY, i.e. EGR/turbo/allison to slow the vehicle down when grade braking. If additional backpressure from an exhaust brake is applied to the VVT could it damage it? :confused:

I am concerned about excess soot deposits building up which is why I have been using an additive. I'm also going to install a water injection system shortly which hopefully will help remove soot deposits. JJ :)

Correct me if I am wrong but, isn' t the exhaust brake in theory a flapper more or less in the exhaust line that closes, holds the exhaust in the engine until enough pressure builds up to override the force on the flapper to push it out of the way then it again closes and the process continues over and over again. Okay, if this is true, which I believe it is, aren't you people that have these on your engine concerned about all the garbage that stays in your engine during the application of the brake? People are disconnecting their EGRs to prevent running soot back through the intake but basicly are probably keeping more in with the brake. opinions?
It doesn't open and close over and over again. It moves to a position based on the air pressure regulator (on the BD system) and engine RPM and stays there. If the engine is coasting and no fuel is delivered, where is the garbage coming from?

PacBrake Service Bulletin #170
JANUARY 13TH 2004
Exhaust Brake for Duramax, 6.6 Liter Isuzu

ISUZU has made changes to the 2004 model year 6.6 Liter engine.
Due to the addition of a VGT turbocharger and an EGR valve, Isuzu will not allow exhaust brakes to be installed on 2004 model year engines until further notice. Before installing an exhaust brake on a vehicle built after December 31st, 2003 please check the vehicles VIN. The 8th digit in the VIN is the engine identifi cation and will be either a number 1 or 2. The number 1 in the 8th digit of the VIN is approved for the addition of an exhaust brake. The number 2 in the 8th digit of the VIN is the new engine designation and is NOT approved for exhaust brake use. We are currently in contact with Isuzu, attempting to validate exhaust brake usage on the 2004 engine. Pacbrake will advise the field when the use of an exhaust brake is validated.
Contact Pacbrake Service at 1 800 663 0096

Thanks for news BroncoFan. That doesn't sound real promising-- wonder if US Gear follows suit, and Banks' EB still not out for LLY; but hopefully this will proceed to a Isuzu-approved, definitive solution. --wheeler

Like others have said, the LLY has an optional exh brake when in the bigger trucks.

If you haven't tried the T/H Allison grade braking, try it before you worry about an exh brake. It just might surprise you. Granted the heaviest I've towed so far has been 17000 combined weight, but haven't had the need for more engine braking on some fairly steep mountains.

Yeah, I've tried Tow Haul mode alone without an EB and I have to say I'm surprised how very well it works on downhill grades. Have to get used to alarmingly high RPMs but once I did (I read that Allison or computer will not allow the engine to over-rev, I don't know if that's true), the rig slowed down considerably. I pull very heavy, about 16K pound trailer, so I have definitely wanted an EB but frankly I may need a larger truck.

Regarding an EB on the LLY in the bigger GM trucks (4500, 5500)-- I posed that question in this thread a few posts ago-- I know a factory EB used to be available with the LB7 engine in the 45- and 5500's but I don't know if there is currently a factory installed EB available in the MDTs with the LLY. I don't think so. --wheeler

Unless GM needs to update their website, I show the eb as optional on the TopKick except for the motorhome chassis.

Bump. On first glance I misread the above referenced Pacbrake service bulletin, thinking it was from this year but it's actually from 2004-- so, year old information. Nothing new or relevant to US Gear's announcement that their EB is compatible with LLY's VGT. Any other users experience with EB and LLY? --wheeler