AMGeneral

Awsome, Hopefully we will be able to make it!!

Any further updates ? Considering a trip to Gerhart equipment about Oct 1-2.

Sorry it took me so long to update this thread, It's been busy here, Long story short, I actually ended up sourcing a New camshaft and 12 new tappets from Capitol Reman in CO, they stated that PAI in GA still produced the parts, part # PAI272949 or ECM-9002 for the cam and EML-8583 for the tappets. I did measure all the surfaces before installation and noticed that all cam lobes had at least .015 wear on them when compared to the new one. I got a new upper and lower gasket kit from my local Mack dealer as well as the 2 rubber inserts for the front engine mount. I did inspect and clean my oil pump and found several metal shavings that were not allowing the relief valve to move at all, after assembly and cam break in time I now have 45 to 55 psi oil press at idle hot and 85 to 90 psi hot at 1600+ rpm w/ 15w40 Rotella oil. It barely made 20 psi at idle before the repair. It runs sweet and smooth ,I guess it's ready for another 20+ years!!

I do not know about a complete engine, But I have purchased parts from them for my T676 engine and I have nothing but good things to say.

I hope so, I really don't want to have to upgrade to a newer truck, I talked to one of the guys at Watts, PAI produced parts are no longer available, they are checking other aftermarket sources for cam and tappets. I know the cam is available through Federal Mogul, but the tappets may be the problem.

I talked to one of the fellows at Watts Mack, The cam is no longer available, the tappets are possibly, but both were available aftermarket, all total for cam, 12 tappets, upper and lower gasket kits and a new rubber insert for the front motor mount is roughly $3500 with tax and shipping. My oil pump holds a steady 25 psi at idle hot and 50 to 60 above 1600 RPM, both verified with a mechanical gauge, I may go ahead and replace the relief valve and spring in the pump while I am in there.

Pictures of the damage,

Thanks Mr. Hancock, Than information confirms my suspicion on this truck, The Mack museum and my local dealership state that this truck was built with a ENDT 675/ 237 Mack engine. I am guessing it had a ENDT676/285 swapped in sometime before I got it. At any rate, I cannot find any numbers stamped on the block or front cover anywhere, so I have no clue on the serial # for this engine. My suspicions were confirmed though, after pulling the oil pan this morning I could clearly see that #3 intake valve cam lobe and tappet have some serious damage, I got most of the engine torn down today and will hopefully get the cam and tappets ordered tomorrow.

Thanks Terry, I will check there, Would a factory New short block be stamped with a serial number? I have noticed that the bell housing and injection pump drive are still painted the gold color the Maixdynes were painted from the factory but the engine itself is Mack gray.

Hello fellows, I have posted here before, I now am running into a problem with my 69 R685, Last week while hauling stone for a local job, I noticed a noise from the RH side of the engine, not really a knock, but a rythymic high pitched tapping. Upon getting home I pulled the valve covers to find #3 and #5 intake valves with about 1/4 inch lash. I pulled the rockers and checked the push tubes for bending or deforming, all good, It seem to me I am gonna be replacing the cam and tappets now. I am fairly sure this is not the factory engine for this truck as I believe the Tip turbine aftercooler did not come out till 73? My problem is that at some point it has had a Mack reman engine installed before I ended up with it, and there is no serial number stamped anywhere on the front cover or behind the injection pump, or anywhere on the engine for that matter. I am wondering now whether I need to order parts for an EM6, T675 or T676 engine. Pics attached

Sorry it took me a while to get back, busy here lately, The dozer in the picture is a 1953 Caterpillar D4, 7U series with a Caterpillar 4A manual angle blade, direct drive, pony motor start with 6796 original hours. The picture was taken the day I picked it up a couple months ago, I use it in my part time grading business along with my Cat 941B.

Another picture of the truck in question

Yeah, I bought it about 3 hours east of me , It is a bit cramped for me at 6' 1" , no power steering either, so you have about 1 inch between the A pillar and the 22 inch diameter steering wheel.

I did both by myself here in the shop( I worked for Freightliner as a Class 8 truck mechanic for several years) in about 5 hours, but my front axle is only a 10K unit. I did put an OEM kit in it from my local Mack dealership. I think it was $ 250 for the complete kit, bushings, pins and bearings.

Yes sir, R and 1-5 on the main, like a typical Mack 5 speed, High and Low on the Aux, but you can only shift to High in 4th and 5th gears, R and 1-3 are locked out by an internal gate.

Thanks Macktruckman, It's not an a pronounced noise, just noticeable, even with hearing protection on in the cab. I guess I am a stickler for everything being "right" on a truck I drive, and since I use it for my part time grading business being down isn't a option. I guess this would be considered an OD trans then? It tops out at 42 mph in 5th low , and about 63 mph in 5th high. No speed demon, but it pulls my 20 ton dovetail and track loader with ease. I wish I could say it was in good shape when I bought it, but after going through both rears, new axle shafts, new u joints, new clutch and new king pins and bushings, it does OK now. I guess this isn't really my first Mack, I have owned several of the 673 powered military trucks so no stranger to the Mack name!

Howdy All, First post here, long time Mack lover, first time owner, I have a 1969 R685ST currently set up with a 14 ft Heil dump bed, 285 tip turbine engine, 38k rears with a CRDPC 92 front and CRD 93 rear diffs, both with 6.34 ratio. It has a TRDXL-1070 6 speed, 2 stick trans.... Anyone have any experience with this type of transmission? evidently it is an odd bird as most local Mack guys have never heard of it, and my local Mack dealer is about the same. I am not having any major problems, other than a "whine"? in 5th gear, high range. Fluid is clean and at the proper level, magnets are clean and no difficulty in shifting.