JoeH

@petehall12 how's it running, any better?

And is this truck deleted identically to the other trucks?

It would be nice to know what fault codes the truck has....

Dumb question, are your starter cables and wires tight?

This truck is a ***** to work on the engine.  I really like my MR688. 

https://macktrucks.vg-emedia.com/ProductDetail.aspx?ProductId=6147

Go to that link and click "View File" in the item description.  It'll download the book for that engine. Page 401 starts the Valve Adjustment Procedure. Follow it to a T.

Don't know about other DM's but this one definitely has 2 cylinders cooking away inside the cab.

Frame depth taper is from about 13 or 14 inches just behind the cab down to about 11 inches for the rears.

Here's some DM pictures for you @mrsmackpaul

Interesting air filter pipes on the R model, I knew the rear cab corners were different on Iranian R's but hadn't noticed the different filter housing ductwork.

IDK, I ran into this on a 2000 or 2003 e7.  

On 5/7/2024 at 6:38 AM, HarryBiron093 said:

Good morning,

 

Truck is a 2001 RD 688 with E7 460. Driving down the road the other day at the engine light comes on and stays on. Its a 3-1 code, I replaced the pyrometer as they seem to only last a year anyway. No change same code still on all the time. I got out the service manual last night and followed the procedure. I figured i would find something in the wiring but it all checked out good less than half a volt everywhere that the testing required and continuity where it was supposed to have it. I get to the second to last step and it has me check continuity between the V2 connector and the rest of the plugs on the VECU. IT says if there is continuity then replace the V2 connector. I had continuity from the V2 plug to certain pins on both the V1 and V4 connectors. The plug visibly appears to have no damage at all how could this be my problem ? Light doesn't ever go out its on as soon as the key is on. I did run jumper wires out of the vecu to the pyro as i wasn't quite sold on the fact that it wasn't wiring. Has anyone seen a failed VECU ?

Sorry for taking so long to respond.  RD model windshields/firewalls leak water and ruin the VECU.  EECU is waterproof, VECU is not.

The two hot wires threw me for a loop when we were getting a spare engine running in a parts truck we bought. It uses a switched ground to run the solenoid. So both sides will test hot, but the power can't travel til you supply a sufficient ground.

36 minutes ago, petehall12 said:

It is cv 713 yeah I am going to figure out how to pressure test it with the smoke.  But what ever happened yesterday happened all at one time I heard the pop and after that I had the boost problem.also when it pops you get puff of black smoke out the exhaust.  But also the primary filter is only half full of fuel isn’t that supposed to completely full all the time? I also have replaced the fuel lines from the tank to the filter and the filter to the pump. 

Measure inside of the CAC rubber boots, if it's same as my '95 RD then two 4 inch pvc pipe caps should fit in there, one on inlet, one on outlet. Mount a tire valve stem on one and pressurize it.  Should hold up to 35psi with no leaks, but if there's a leak you'll hear it quick. 

Does this turbo have a waste gate? Your waste gate could be faulty, which would explain sudden black smoke and low boost.

You'd need to pressure test it, not just smoke test.

What chassis is this? Probably not an RD600, but the charge air coolers on RD's do tend to crack along the seams where the core mates to the tank. But this shouldn't yield the popping sound in your exhaust, just the low boost.  My '95 RD688 went down to 21 psi max til I noticed it had cracked.

How are your oil seals on your turbo? Do you have oily soot in your exhaust or oil in your intake pipes?

I'm wondering if there's a fuel delivery/ignition issue?  Loading up fuel in one cylinder from poor atomization in a failing nozzle, or there's a hot spot on one piston that occasionally causes an untimely detonation.  Our 1979 endt676 had a slight miss when my dad bought it, wound up being a piece of silicone stuck in the piston cooling nozzle. But that was before I was born, so just anecdotal on my part... Just throwing out dumb ideas...

I know you're working on the Volvo engine, but at the end of the day they all do the same thing.

My 2003 ai350 had a loose EECU fuse.  Check your fuse boxes and see if wiggling your EECU fuse helps out.  Also check your battery voltages. The vmac iii EECU shuts off around 9.5 volts, so if your power drops notably while cranking then you could just have battery issues. It's possible your alternator died and batteries dropped down, but I assume that'd trigger a code....

Im 5'11" and the backs of my knees start to burn when I reach down halfway down my shins, lol. 15 years in R models has shortened the tendons and muscles on the backs of my legs!

The +3 can was likely introduced at the same time Mack went from the steel dash to the plastic curved dash.

Cabs are the same on U and DM. However, the R/U/DM cab started out early as a "flat back" cab, then they updated the cab to a "+3 inch" back wall.  They added 3 inches to the back wall to allow more seat room.  Not sure how long the U model was I'm production, don't know which backwall our U had, i gave the cab off to someone on here some years ago.