Rob

Hi Michael and FJH, I wanted to say "thank you" to you both personally as your input was the inspiration to make this thing right. All of the input received was positive inspiration as I have a hard time living with something that is not "quite right". If I have an inkling of bettering something, I usually jump right in. It really was fairly easy to machine the new parts but I have access to the needed tools/equipment. I have not checked the lower ends of the shift levers but what is sloppy is the "slots" in the shifter ball or the guide pins are worn/broken. The transmission gear selector, (5 speed handle) has a lot of rotation available instead of a nice front to back and side to side motion. The transmission shifts fine, and once used to the power curve of this engine, it is not that bad. I could live with it but the cab is a bit cramped and my wife is going to attend the truck shows with me so I need all the room in the cab, (for baggage, not her) I can get!! Thanks again, Rob

Hi Fred, great to see you post on the board again! The V8 really does run well now. Spent about an hour and a half yacking with the fuel injection guys about matching pump and turbo outputs today and giving thanks for their guidance with my governor. With their recomendation, I'm going to cut the fuel back just a bit as I don't want anything on a trailer painted black from the smoke!! Also wanting to install the 13 speed later this month and get some license plates, so the future is looking brighter! I'm planning to make the show at Elnora this year, (with this Mack) but first I've got to do something about the wiring. I don't feel it would be wise to trust the current installed harness. Don't expect any changes in the trucks outside physical appearance by then, I've not had much free time lately. Talk to you soon! Rob

I've got an oil leak in my V8 Mack engine that is coming from one of the "buttress" bolts through the side of the block to the number three main bearing cap. My question is can I remove the bolt, after cleaning apply sealer to the threads and or a gasket and retorque the bolt? Should I remove the oil pan, and remove the main cap bolts first? Never worked on this engine other than the governor and it doesn't leak oil anyplace else. Thanks, Rob

I dunno there Paul; I've sure turned down a few offers on both the Detroit, and the Mack engines. If this Detroit engine that I have was not so damn "familiar" to me, I would just leave the V8 in place. This truck really runs out well, but the front end is very sloppy due to tie rod ends being shot. Under 40MPH and it is alright on smooth pavement but above that is anybody's guess. I absolutely despise the six speed transmission because of the shifter "slop". I purchased a reman RTO-12513 from a Mack RW-613 and will try to get it installed before the end of August. Time is short right now with all the construction projects going on at work so I don't get to "piddle" in the shop much. Hope you're doing alright and making progress with your Mack. Keep me posted on the drive axle from Tulsa. Tell your uncle I said hi. Rob

Well tonight I reinstalled the rebuilt governor assembly back on the truck. As king Richard used to say, "Man, What A Difference"!! There is a bit of a lengthy story to get to this point so bear with me through the details: Upon dissassembly, the flyweights were found to already have oversized pins installed and the correct bushings were no longer available, and these were worn out. In fact when the pump was rebuilt once before with new pins installed, one of the oiler holes was not lined up properly so the pin and arm was starved for lubrication from the get go. Long story short is that I rebored, and reamed the holes in the flyweight(s), made new bushings to fit the new pins, installed new springs and thrust bearing, then hand cut the top, and rear cover gaskets, (they are no longer available). The gasket that sandwiches between the governor housing and the main pump body is still available, but at a different thickness necessitating fuel rack adjustment(s). As FJH said, it was a real somebitch to get the yoke back into the fuel racks. It sure was easier to get it apart!! The engine now idles/runs steady at 725rpm with both the compressor running, and off. Off idle response is great. I need to shorten the adjuster on the throttle linkage as the engine will run much slower with this linkage disconnected. I've already run the idle adjust screw out as far as possible. It's determined the gasket at the governor housing is causing this as it is nearly 3 times as thick as the original. There is plenty of room for adjustment through the linkage. Really appreciate the help and all the pointers here. I've got about 8.5 manhours into this thing but I usually work cheap on my own stuff. Besides, I've learned quite a bit and that is basically a miracle, (the learned part). Thanks again, Rob

HI Trent, hope you had a good time. Had it been next weekend I would have showed up. Your last picture looks as if you are missing a chunk of frame just back from the driver's rear tire. If that is so; I've never seen something like that before. Rob

Hi Dave, I've maintained this engine for the last 17 years of it's service life and when it was time for replacement, I kept it. There are N80, green tag injectors installed. Both turbochargers are Garret T18A40's with .96 A/R on both turbine and compressor sides. They spin up really fast. The spec sheet that the vendor supplied many years ago lists the engine at 586HP at 1800 rpm. There is no listing for torque nor any curves supplied with the package. Slobbering, or "wet stacking" was never really a problem with this engine as it had "load shed" with it into a load bank. I keep it in tune to load the genset to 60% of rated capacity when running and supplying emergency power. I could go to 85% capacity but that just wears the engine much faster. I do have photos of the engine but not on this old computer. I will post a couple pictures in a bit. I can't really remember the engine number but it is a 12V-71N series and the first four of the model number are 7103-XXXX. It is a left turning engine, (looking at the rear of engine) and has a "00" flywheel housing mounted. I have purchased a very good running 8V-71 engine to switch out flywheel housings, and flywheels, etc to make the V-12 a truck engine. It will be installed into a 1977 R-795 Mack. (More on this truck in the feedback section if I don't get a couple of parts that were paid for). I've found a couple of pictures from another place I visit so I'll try to get them over here. Hey what do you know, that worked!! Anyway, I plan to use the truck for pleasure only and it will not be a real working unit. This engine has just over 6300 hours on it and has had the oil changed at 200 hour intervals since new. I suspect that unless something is grossly out of kilter, it should work well for my application. Any and all help and insight appreciated. Thanks, Rob

Hi Dave, thanks for your thoughts. I had wondered about the lack of a charge air cooler on two cycle Detroits myself. I've seen in marine applications the intercoolers sandwiched between the bottom of the blower, and intake manifold and have heard they are restrictive. With the added height, they would not fit under the hood of a truck without modification. My engine is from a genset and has two T18 Garret turbochargers that are plumbed to the air boxes. It would be entirely possible to not use a charge air cooler as the engine is much higher in horsepower than I will ever need as it sets. Thanks, Rob

Very "classy" working truck there Rick. A couple of fresh tires on the tag and all will be perfect. That is the kind of truck that makes real money. Rob

If you are smelling the sulfuric acid from overcharging, your regulator for the alternator is bad or needs adjusted. This was a common occurence and regular maintenance interval in a earlier time. Ignition coils have either a primary resistance wire that is disconnected during the engine crank cycle, and enabled during the run cycle, or an external ballast resistor that follows the same theory. The purpose of a ballast resitor is to limit voltage to the breaker points to extend their service life. In normal operation, full battery voltage is applied to the ignition system during a crank cycle, and limited to an area between 9.25-9.75 volts when the engine is running. You can run full battery voltage all of the time, but the breaker points will not have a very long service life. If you do not have resistance wire in your cranking circuit, a Chrysler ballast resistor is easy to obtain at your local parts vendor, and easy to install. Rob

That's good "food for thought" Herb. I've been around a lot of broken differentials; All single drive axle that would not move a vehicle once failed. I suppose a Mack inter axle power divider with it's full time driving ability would still power the truck forward on the opposite of the failed axle. It would reason that as the missing or broken teeth engaged and let go, the result would be quite noisy and a severe shock to the driveline. Rob

While true of natural rubber, or to an extent, Neoprene, oil/grease will soften and attack rubber where polyurethane, (of which the conversation speaks of) is impervious to attack from petroleum products. I actually use silicone grease, (dielectric compound such as used on spark plug boots) for lubrication of urethane parts. It keeps the speaking to a minimum long term. Rob

Hi Greg, if you would like, give me a call as I may have access to what you can use possibly? Thanks, Rob Swallows 309-219-2070

I've seen several of the polyurethane bushings break the lower caps upon tightening up the bolts and nuts. This is usually the result when an impact wrench is set on high torque, and the fasteners are not drawn down evenly. I usually tighten in a four step torque process using an "X" pattern. Ultimately, these fasteners need about 1250-1400 ft. lbs. applied. It is easy to get "over zealous" to get the job done quickly. Also, be sure to lube up the exterior, and interior of the bushings before installation. This will allow them to move a bit as they compress. Good Luck. Rob

I've facilitated this same repair both ways. A 3/32" 6013 rod melts at a low enough temperature as to not make the spindle a safety hazzard. Removing the spindle and chucking it up needs to take place no matter which method you choose. Two that I have welded up and machined to the proper diameter had frozen the bearings and destroyed the spindle so there was nothing to lose. To the best of my knowlege, both trucks are still in service. Rob

If your tachometer is cable operated, the drive cable is binding and letting go inside the jacket. Take the cable loose from the back of the tachometer, and use speedometer lubricant to take care of that problem. If the tachometer is electronic driven, and driven by the alternator windings, chances are that a diode is blown in the alternator. Have you noticed a degredation in battery charging performance at all? Rob

I'd be willing to bet the items you are asking about are all available new from your local Mack dealer. The worst enemy to plastic is the sun and heat. If you locate used parts, they will probably break, or fatique in a much shorter timeframe than new items. I'll bet you would be surprised that some parts are very affordable. Just my thoughts. Rob

Thanks Mike, I contacted these folks: http://detroitradiatorcorp.com/ as far as building a radiator for me. I want to go with a "side by side" configuration, (radiator, charge air cooler) as to leave room for an a/c condensor up front yet retain the original shutters. They will build anything by request but I'm wanting a rather "custom" installation. They need the heat generation potential of the engine to build an adequately sized core. Knowing that some type of Mack chassis was factory equipt with the V-12 Detroit, saves a lot of guesswork as they have the parameters, but needed a model number to associate to. I'll keep you posted on progress. Rob

Paul, I've got a technical school coming up in August at OKC. I could bring that axle assy from Tulsa to either my place, or Morgans, towards the end of August if you have no luck by then. Hauling would be "dirt cheap". Rob

Hi there, what was the model number for the chassis when factory equipt with a V-12 Detroit engine on an R model? I need to get a radiator manufactured for mine and have to have some sort of baseline for fitment. Thanks, Rob

I agree Glenn. The injection shop I'm working with does not have the correct adapter to "spin" this particular pump. If it still presents any problems upon reassembly it will come off and go in the mail to another shop I've spoken with. Thanks, Rob

I can sure see how that would be a problem. Before pulling the governor assy. from the pump, I viewed the area with a small inspection mirror, (lighted) and then squeezed the arms of the yoke together just enough for the "doglegs" of the yoke arms to barely disengage the racks. It will probably be a little more difficult to reinstall so I will enlist a third hand via my daughter. I also noticed the thrust/roller bearing is a little notchy in operation so I have ordered another to be on the safe side. This should be in on Monday and I hope to reinstall the parts early next week. I'll try to get some pictures up as I'm sure others have never seen the internals to one of these either. Thanks again for the help!! Rob

Well, curiosity got the best of me and I pulled the governor from the back of the pump without removing the pump from the engine. Really a simple little contraption but took some engineering to make work. Long story short is that $65.00 bought me new bushings, shafts, seals and gaskets, springs, and a good set of installation and calibration proceedure(s) from the local fuel injection shop. Along the same lines as Michael had mentioned; I put the front axle in a ditch out front of my shop and the truck ran very smooth, and stable, without fluctuation at idle. I was surprised how smooth it actually is. It accelerates very well but at 40 MPH, it is hard to keep in one lane. The tie rod ends, and drag link are shot, shot , shot. Since this truck will ultimately end up with my detroit engine, I really don't want to sink a lot of money unnecessarily into this V8. Appreciate all the advice!! Rob

Hey Fred, Let's put a positive spin onto this one because aluminum scrap is at an all time high!!!! You even have a decent loader tractor to help shove it onto your trailer, Haaah, Haaah!!! I also know and believe you have a good one there; After a little beggin, pleadin, and most of all apologizin for your ways, all will be just fine. (At least that's the way it works with me). I may be around to assist in the driving if you need it. Rob

I'm getting ready to swap out my two stick six speed for a Roadranger 13 speed (RTO12513) and don't want to use the Mack transmission as a core if someone may be able to use it. I don't really feel the Mack trans would work well behind my Detroit engine too well. The donor transmission is from a Mack Superliner and will be complete with everything needed for the swap. There is nothing wrong with the Mack transmission that I know of other than the shifter assemblies could use a little "tightening up" but is very useable as is and does not howl, or hop out of any gears. Rob