HK Trucking

Good Morning Graham. I have not messed with the single axles in quite a while, so I can't remember the models offhand. However I did some research in my old Mack books and here is what I came up with: Previously you stated that your current ratio is 7.48. The book shows that ratio as being available in the double reduction front mounted carrier models CRD 116, CRD 117, CRD 1161, and CRD 1171. The entire list of available ratios in these models are 3.71, 4.00, 4.25, 4.62, 4.88, 5.43, 5.78, 6.36, 6.80, 7.48, 7.85, 8.39, 8.83, and 9.87. This leads me to believe that you have a CRD 116 or CRD 117 series rear end in your truck, however the only way to find out for sure is to find the model # stamped in the differential carrier housing. This should be at the right front area. According to the book, the CRS 84 is a single reduction front mounted carrier type with available ratios of 4.25, 4.63, 5.14, 5.57, 6.17, 6.83, and 7.14. The fact that a 7.48 ratio is not available in the CRS 84 leads me to believe that this is not what you have in your truck. Again, find the model # on your existing differential and this will ensure that you get the proper unit. Hope this helps. Herb.

The last Re Man rear I bought was from Weller Truck parts, if I remember correctly it was around $1600.00 with a one year warranty. That was for a CRD 93 @ 5.73 ratio. They delivered it right to my shop within 24 hours of my order. Certainly a junk yard take out will be much cheaper, but there's no warranty, and who knows how it was abused previous to the truck being scrapped. Also, you can waste a lot of time searching and running to junkyards etc. When a truck is down, time is money. Having the correct unit delivered within 24 hours gets you back to work a lot faster.

Like you said, just check that the bearings arent loose, especially in the back half, since loose bearings there could contribute to that whine in 5th hi. Also make sure the bottom end of the compound shift lever is not worn severely, because if it is, I have seen them jump out of one shift rail, resulting in the transmission being "jammed" in gear or if the lever gets into the other shift rail after it jumps out, it can cause the compound to lock up in 2 gears at once, and if the truck is moving when that happens, it's usually the end of the transmission. As far as finding a different rear end, if you can't find one on your side of the pond, try Adelman's truck parts in Canton Ohio. I've heard they have a lot of stuff like that down there. Herb.

Hi Rod. That sounds like you've got the Mack "Duplex Clarifier" type filter on there. That would account for the 2 large (approx. 1 inch diameter) and 1 small (approx. 1/4 inch diameter lines. Unlike a luberfiner the duplex clarifier is a combination full flow and bypass filter. Every bit of oil from the oil pump flows to the filter and then back to the bearings etc. thru the 2 big lines. The small line is a return from the bypass section of the filter. Those filters were used up til about the early 70's when Mack switched to the spin on filters. After a filter change, and before starting the engine, always pre fill the fiter housing all the way to the top, thru that large plug in the top of the housing. This cuts down on the time it takes for the oil pump to fill up that big filter and finally start feeding oil to the engine. A standard Luberfiner is a bypass only type filter and would have only 2 small lines running to it. My Mack book shows a capacity of 19 quarts in the pan, and 12 quarts in the filter for the ENDT 673 series engines. Herb.

Yup, and apparently the scoop and separate filter was still an option later on too. Here is a photo of a 1985 DM686s that I had, notice that it has the scoop.

Next time you go by, the Mack sign will probably be down, replaced with a Vo#@%o sign. It's a slow steady process, just as it was with White Autocar & GMC.

Hi Rod. The bottom inlet air cleaner I was referring to as not being used on turbo engine B models is shown in the following photo: http://bigmacktrucks.invisionzone.com/uplo...52_61_74818.jpg The top inlet air cleaner which was used on the factory turbo engine equipped B models is shown in this photo which I also found in the gallery: http://bigmacktrucks.invisionzone.com/uplo...6_74_462247.jpg Although I have seen some 711 & 673 non turbo B models with the top inlet type, I have never seen the bottom inlet type on a factory turbo B model. Herb.

Ron, I must admit I've never been to that show. Up until recently I was working so much I never had time to do that kind of thing. Now that I've sold the business and I'm working a 5 day week as a company employee things may be different. Wish I could answer your question, but maybe I'll get out there this year & check it out.

You could also just turn in the high idle stop screw on the side of the governor housing where the throttle shaft comes out of the governor. That would raise your RPMs. While you're at it, take off that cover at the back of the aneroid diaphragm and crank that screw in all the way. Then you'll get full fuel as soon as you hit the pedal, without waiting for the turbo to build up some boost pressure first. (You'll also get a cloud of black smoke initially, untill the turbo starts pushing enough air for a clean burn) I had a couple of those EM7 300's around here, and without the "treatment" they were gutless.

Graham, I looked at the photos and your air cleaner appears to be the type that was factory installed on the B613, for use with the ENDT673 @205 HP, or the ENDT673B @ 225 HP, both are turbo engines, not much different from your 250. I had a 1962 B613 with a ENDT673B and that is the type of air cleaner that was on it I also once installed a ENDT 675 Maxidyne into a truck which previously had a 711 and used the existing top inlet air cleaner without a problem. In my opinion that type of air cleaner is OK for a ENDT673C 250 HP, provided it is clean internally and kept properly serviced. The bottom inlet type air cleaner, as shown in the photos of Hot Rod's truck is the type I would be concerned about not supplying enough air for a turbo engine. I have never seen the bottom inlet type on a B model with a factory installed turbo engine. If you weren't getting enough air you would see constant black smoke, high exhaust temperatures, and lack of power, but lack of enough air would not keep your engine from achieving the proper high RPM setting at no load. As a side note, Watts Mack does have available a dry type air cleaner that is a direct bolt on replacement for your top inlet oil bath, no more messy oil changes & screen cleaning, and the appearance is darn near identical. Herb.

Tell them they're full of sh*t. As I stated previously, the ENDT 673 C 250 hp has an operating range of 1500 to 2100 rpm's, and a no load high idle speed of 2250 to 2310 RPM. These figures are from Mack tech literature of that era, I'm not making them up. Exhibit A: Get the darn thing running at the right RPM, then change the rear diff ratio. A ratio between 5.50 and 6.00 should get you where you want to be for top speed. I'm not familiar with what ratios are available for the front loaded rear, but if I remember correctly there were 5.88's and 6.34's available for the top loaded tandems (CRDP92 & CRD93 and CRDP112 & CRD113)

The Mack Guy wrote: It is what it is: A camouflaged Volvo engine. WV Dog Lover wrote: Amen. Certainly one thing they aren't is a Mack engine.

Today I checked that decal, it says 90 to 120 volts.

Did you ever look at the warning decal on the side of a C12 Cat engine? Something about hazardous voltage to the electronic unit injectors. If I remember it said 90 - 100 volts or something. Tomorrow when I'm at the shop I'll get the exact number.

Amen. I, too always set up the linkage so the clutch brake grabs at the very bottom of pedal travel, then set the internal adjusting ring for about 1 1/2 to 2 inches of free pedal. It's always worked for me! Depending on the particular linkage setup you have, there may just not be enough overall travel to make it work any other way. I've never measured the clearance between throwout bearing & clutch brake. In my opinion thats irrelevant as long as : (1) the clutch brake actuates at the bottom of pedal travel (2) The clutch pedal has 1 1/2 to 2 inches of free travel at the top.

And also very very Volvo.

Here's a post I saw on another trucking website, thought I would bring it to the attention of you Mack factory guys. Notice that the poster is from Pennsylvania - Mack Truck's back yard!!!! Somebody at Mack better wake up, and soon!!!!!

Last year I went to the dealer to get some parts for a 91 RB, and the partsman made the comment "I'm having a hard time finding stuff in my computer for an OLD truck like that. WTF!

Oh, well. R.I.P. Ingersoll Rand.

Here's a demonstration video of the "Super 10": http://www.roadranger.com/ecm/groups/publi...t/ct_056130.wmv

Good work Chris! Glad to hear you got it running. For added safety in the event of the rack sticking again, you could install a shutoff valve at the fuel supply line that runs from the secondary filter to the inj. pump. Hook up another dashboard mounted stop cable to it and you'll have an "emergency shutoff" that will cut off the fuel flow to the inj. pump if there's a problem.

I would recommend switching it over to a 12 volt negative ground system. Put a modern internally regulated alternator on it. (I'm sure a machine shop could fab a pulley for that wide belt). Then you could easily & simply use your 12 volt winch, CB, Stereo etc. without complicated trouble prone circuitry. Just be sure to install an ignition resistor in the supply wire to the ignition coil. In the past I converted a pickup truck to 12 volts and continued to use the 6 volt starter, it cranked very fast, and was still working when I sold the truck a couple years later.

If you have to ask, you wouldn't understand.

Most of those pressure relief valves "blow off" at about 150 lbs.

Should be an R688 with that engine & trans, unless they were swapped in later.