Doffer

im not sure, i'll have to pull the piping off and inspect for shaft play. It looks to me like it's a relatively new turbo housing, so im guessing it was replaced at one time ... but looks can be deceiving. i'll let you know what i find

Do you guys own Pumps too? I run a Schwing 42 meter pump and Telebelts myself. Looks like you got some nice, pumpable mix! Liked your FB page

~brandon

Wow , these are really cool looking trucks!

I doubt its the trans, sounded like you could hear the bounce in the exhaust, any chance that hill was slick and you were slipping a wheel causing some hop in your camelback suspension ?

yeah at the end its definitely audible .. the hill i was going down was completely dry as well.

Just for reference, this is the same truck that backfires out the exhaust when the engine first starts to warm up while using the engine brake

I've attached a video from yesterday, but its really bad since had my 4-ways on the whole hill so all you can really hear is BEEP BEEP BEEP... had about 45 cars behind me at the bottom of the hill ...

Anyways, whats going on is when i'm in the 1400-1700RPM range when using the engine brake the truck starts to bounce almost like its driving overtop of small bumps in the road. Im just wondering if the transmission may be going bad? Any tips on what you might think the problem is?

Thanks guys, your the best

Brandon

Guys I work with keep taking a screw driver and punching a hole through the buzzers because the turn signals buzz too. Its so annoying every time you get into another truck, and the low air buzzer isnt working

I used to work at Penske. Good company

I use the clutch always on the mr688s. I love upshifting because i can leave the jake on full and catch the next gear quicker but if I'm driving a freightliner I just float the gears. Only clutch for stopping and reverse

Im pretty sure that if the trucks performs the job, and is DOT legal, that it will stay in service as long as possible. The reason you probably don't have all new equipment is your likely from an area that isn't very big (just a hunch).

At my workplace, we have concrete pumps from the 80's, and they still go out and do jobs. Every once in a while we get a new model pump, and get rid of one of the older models.

The money probably isn't there to afford to buy three or four 1 million dollar pieces of equipment..

I really dont have any experience in the Firetruck field though, so my answer is just my opinion.. Someone who has experience will probably chime in

I would guess its probably time to replace the dessicant cartridge in the dryer, when you start getting anything in the tank after the dryer, its a good bet the dryer is ready for some attention. Bendix recommends that all AD-9 and AD-IP style dryers get a purge valve rebuild and a new dessicant cartridge once a year or every 100k whichever comes first. Its overlooked by just about everybody since its out of sight, its out of mind but if you havent gone thru it in a year or two its time, AD9 will run about $120 for a cartridge and a purge valve kit and takes about an hour to do no biggie, just make sure to get the purge valve tight or it will back off and then youll have to do it again. Its also good incurance against ABS and quick release valve issues, those ABS valves dont like contaminants in the air theyll act a fool and youll get an ABS light if they get gummed up. Just my couple pennies there!

Thanks SuperDog, very helpful information. I just got my first order in today from Mack, I'll order that stuff tomorrow!

Oh okay. I was thinking that the Air Dryer may be going bad or the compressor seals were going bad. Glad to hear its normal. Thanks

I am getting oil in my tanks when I bleed the air off over-night after work. Just a spirt of oil on the ground then just air. What causes this? seals in the Air compressor? How can I stop this from happening?

The truck just broke 500,000 miles

Yeah stupid me.. wasn't thinking, its the AC compressor.

Thanks for the info. Just have to slow down a few days to get at it. How long should this take? I have torches and tools to complete the job

I got a letter in the mail a few months ago sayin that if I did not get my Medical card sent in that they were going to remove my CDL from my license and I would have to re-take all of my permit / crap again. So I went and got it done ($130.00) and Overnighted them their damn medical card.

Really stupid. this is in Pennsylvania

Ok, so I got another new (to me) the middle of this week and it also has a bad exhaust gasket. The Gasket that is bad is the one that is towards the alternator.

Is there any way I can change the gasket without removing the entire turbo / manifold assembly? Like just remove the studs/nuts, alternator and slide it forward to remove it ?

Its on a 2004 Mack MR688S cab-over

Ain't Cadillac Pimpin' no more

I wonder how this is going to affect the 10 axle truck I drive ?

I was driving a detroit one time and it started dumping fuel into the oil. I looked out the passenger side and it was blowing oil out all over the entire side of the truck. Pulled over, pulled dip stick and it was overfilled, thin, smelled like diesel.

Be careful your not getting diesel in the block. I know with the older detroits this was an issue, so it might not be your issue. (what i've been told anyways. could be incorrect information)

Well I have a different truck now anyhow. They keep making me give up my normal truck for other trucks, not fun

That's good information !

I really don't know a whole lot about these trucks beyond the basics, I've only been running with my CDL for 2 years now. When I had my issue popping out of gear we just brought the rig over to mack and they fixed it. They explained to me what they found / did so I tried to relay what they told me.. It ended up being $1200-$1500.00 I believe total.

Well I have bigger issues than a loud exhaust at the moment. I think my manifold just cracked or the bolts broke or something. Definitely and exhaust leak

I had the same problem happen on my MR688S but only 6th gear for me. I took it to mack and they replaced some assembly that the shifter (high / low) attaches to. They told me the assembly teeth was worn out, and it was also popping from high to low while driving. They said it could be from quick shifts where the transmission doesn't go into gear all the way, but you still power through the gear (only partially engaged). After you do this partial engagement for a while (powering the accelerator) it wears a flat spot onto the synchro assembly, and allows the transmission to push out of gear.

Might be similar to what's happening to you.. My synchro assembly was changed at around 400,000 miles (14,000 engine hours)

Hah!! alright , well it sounds like it wouldn't be a great idea then. I commute between Pennsylvania, New York, Vermont, and Massachusetts... dont need to be getting busted every day because my truck is loud

Do you know if Pennsylvania or New York does? Thanks

Is it legal to delete the muffler on a 2003 Mack MR688S ? I love the open exhaust sound, but I'm not sure if its actually legal or not.