Just happened tonight coming home. I had to hit the binders for some quick lane changer in front of me. Anyhow, just after that now my brake pedal/hydroboost is hissing whenever the steering is at center or you have no load on the brakes. Also now the pedal has slow to react when you first hit it, the boost comes on slower. Sounds like there is something stuck in the bypass valve. The fluid seems good still as its only got 15,000 km on it.

Sure, just get happy with my ME conversion and I probably have to get to the dealer for this... Any suggestions?

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97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...

Checked the fluid level and it was fine, still smelled like clean ATF.

Called dealer that I trust and the tech there said with the combination of steering and braking at the same time, it could be an air bubble in the hydroboost that will work its way out. I hope so, its annoying.

See my response in TDR.

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Jim W. DTR Megacab Club Member #167
08 2500HD Mega Cab, CTD, 68RFE Auto, Mag-Hytec Trans Pan, Front & Rear Diff cover, Smarty, MBRP 5" Exhaust, Silver, Gauges Optix Pyro, Boost, Trans Temp, Westin Side Steps, Bed Cover, Line-X Bed Liner, Prodigy BC, 15 K Reese Hitch and Pulling a 11K 5er.

I did Jim, thanks.

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97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...

Today I went to town on the system doing full lock to lock turns with the steering and holding the brakes to full travel and releasing quickly to get the flow and bypass to cycle.

The good news, its gone away, sort of.. Now if I tap the brake pedal slightly, it goes away. IF, I pull back on the pedal with my foot, it comes back.. So now I have narrowed it down to the booster, just why is it hissing when I pull the pedal fully back?

Input please... Thanks.

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97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...

I believe (I am retired hydraulic engineer) that the booster which is an amplifier may have an issue with the relief valve in it. Most booster have a relieve valve built in to prevent over pressurization of the brake fluid. This may have a tiny piece of debris sticking in the relief valve or the valve has malfunction. From the panic stop that you preformed. This will cause a hissing sound as oil is pass thru the valve. This should be normally closed unless pressure is to high, then will open and maintain the proper operating pressure.
I would suggest replacing the booster as the relief valve is not serviceable. At least I have never been able to find a relief valve for one before.
Good luck.

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Jim W. DTR Megacab Club Member #167
08 2500HD Mega Cab, CTD, 68RFE Auto, Mag-Hytec Trans Pan, Front & Rear Diff cover, Smarty, MBRP 5" Exhaust, Silver, Gauges Optix Pyro, Boost, Trans Temp, Westin Side Steps, Bed Cover, Line-X Bed Liner, Prodigy BC, 15 K Reese Hitch and Pulling a 11K 5er.

That sounds like the problem. THanks Jim.. I will have to book in the truck for some service.

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97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...

That stinks. Let us know how you handle it. Maybe you can leave you stuff as is since it is not "related". It would certainly suck to have to revert and then re-revert to where you are now for such a thing.

By the way, did 300 miles of towing with the set-up and had no issues, ran like a champ, drove 65 to 70 the whole way and have 11.5 mpg on my overhead! Heck ya. Still need to get those gauges though, maybe I will cut some real gauge corners and at least get an insight to plug in... Had the watchdog and it was a POS in my opinion, returned it...

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2007.5 Ram 3500 SLT 6.7L Megacab, 4x4, 6sp. Auto, Electric Blue, Nav & 6 disc changer, Smarty S67 ME14 (SW3), Revertable EGR Plugging and Exhaust Deletes, S&B intake, Amp Research Steps, Prodigy Brake Controller, Wolf Liner O.T.R.

DTR Megacab Club Member #152

Thanks Mega.

From another site I frequent, some Dodge technitions offered up some possible sollutions. Apparently the pressure lines are lined with a teflon tubing and it sometimes gets pushed into the booster cylinder.

I pulled it out today and found it to be flared and worn like it has been rubbing in there on something, just as these guys told me. Got all giddy thinking I had it fixed, but 10 minutes into my drive, it started to hiss again. This time not as loud and I could not get it to temporarily stop like I did before by tapping the brake pedal. Maybe a small piece of that teflon is stuck in the booster somewhere??? Dunno..

Here is what I found..

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97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...

A couple of months ago, I had to replace the booster in my Mom's GMC Jimmy (a 97 with only 60K miles). There was hissing noise and not much "boost" helping out. Needed a lot of force to stop it and it scared me to think of my Mom driving it that way for a bit... Anyway, I'm glad it was the booster that was the issue as replacing it solved it and it was actually easier than I thought. Getting to the bolts inside at the firewall was the trickiest because of the tight spaces. Beside body contortion a swivel on the socket did the trick. If your truck is under warantee, it sure would be nice to get it taken care of and ignore the motor stuff.

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2007.5 Ram 3500 SLT 6.7L Megacab, 4x4, 6sp. Auto, Electric Blue, Nav & 6 disc changer, Smarty S67 ME14 (SW3), Revertable EGR Plugging and Exhaust Deletes, S&B intake, Amp Research Steps, Prodigy Brake Controller, Wolf Liner O.T.R.

DTR Megacab Club Member #152

So being frugal, I just trimmed the tubing about 1/2" sticking out of the tubing and put it back in. Drove it for 2 days and now it starts to hiss again. I pulled the fitting apart to look see and its the same failure.. The tubing is creeping in the hose. I have a new hose ordered for it, ~$100 or I reassemble for them to do it under warranty.. I need the truck today, so I might just bite the bullet for the $100..


Here is todays tubing, hard to tell the difference..

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__________________
97 2500 4X4 LWB CC SLT Laramie 5spd LSD 3.55.
Isspro EV's pyro/boost, #10 Plate, PEAK 3K GSK, AFC Spring, DDP III injectors, S300 Turbo, PEAK IC Boots, TAG III, South Bend 13-1.25" Con FE clutch, SCOTTY II-UNI, MBRP XP 4", KDP Tab, 16° Timing, SS DSS / 03TBK, Roda Deaco PAS. Espar D5WSC heater. B-Quiet sound deadening inside.
Dyno 09-2009 401 RWHP / 1050 Ft-lbs

'08 2500 4x4 MegaCab Laramie, 6.7, 68RFE, 3.73 LSD, S-67 R15ME.

Alberta Chapter #5 Prez... PM me for details...