garythomak Posted July 21, 2005 Share Posted July 21, 2005 Hi everyone,I have been in Alaska for the last 25 years and have semi-retired, moving to West Virginia where I grew up. I am cutting timber to suppliment the retirement check and am looking at a tandem 1971 Mack that is for sale. It is a dump but the with a steel bbed. The motor was using a copule of gallons of oil a day and then started knocking. I have the VIN number (U685ST4866) but can't seem to find the model or much about the truck. On the door it has a chasis number U685. The guy that is selling it doesn't know much about it, he gave me the VIN from the title but said there wasn't a GVW weight, just 59,900 weight which he said was what it had been licensed for.I would appreiciate any help on finding out the model number, etc. IHe did say the motor was a 237 and a 300 would fit in it. I would appreciate any suggestions on putting a used engine in it or rebuilding the old one. I will only be using it to move my equipment (Cat 955H track loader, about 12 ton).Thanks,Gary reg@wvlogging.com Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/ Share on other sites More sharing options...
Lmackattack Posted July 21, 2005 Share Posted July 21, 2005 Hello Gary and welcome to the boardSounds like the truck you are looking at is a little sick!a few gallons a day is very excessive oil use in my mind. If the truck has an offset cab then you are looking at a U model. If its a 71 look on the pass side frame rail just behind the tire, the vin number should be stamped there. many times cabs were replaced so the door tag is not the best way to determin the exact model. As far as engine model look on the pass side under the exhaust manafold for a plate or on top of the water pump it will be stamped ENDT675, or some thing like that. this will tell you the model and possible if its a newer engine. You can rebuild the 237hp or add a 300hp engine i\as it is basicly the same block will fit, you also could simply replace some parts on the 237 to achive 300 HP, as far as rebuilding the 237 kits are readly availible. I havent checked lately on prices so i wont comment. i do know the older Mack rebuild kits are cheeper than cat, cummings etc.... I have seen a few 237s and 300 hp engines on ebay for 1000-1500 but who knows why they were pulled. good luck Trent Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-506 Share on other sites More sharing options...
Barry Posted July 21, 2005 Share Posted July 21, 2005 Welcome to to BMT! Sounds like your looking at a U685ST (U-Model) also sounds like you will need to do an overhaul on that engine if it is using that much oil! I looked up your vin and it call for an ENDT675 so that is good...parts are available aand not tooooo expensive. Like Trent said, you will need to verify the engine stamping because an old truck can have alot of stuff changed through the years! Quote Barry - Watt's Truck Center Parts Manager and BMT Webmaster...1-888-304-MACK Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-507 Share on other sites More sharing options...
garythomak Posted July 21, 2005 Author Share Posted July 21, 2005 Hello Gary and welcome to the boardSounds like the truck you are looking at is a little sick!a few gallons a day is very excessive oil use in my mind. If the truck has an offset cab then you are looking at a U model. If its a 71 look on the pass side frame rail just behind the tire, the vin number should be stamped there. many times cabs were replaced so the door tag is not the best way to determin the exact model. As far as engine model look on the pass side under the exhaust manafold for a plate or on top of the water pump it will be stamped ENDT675, or some thing like that. this will tell you the model and possible if its a newer engine. You can rebuild the 237hp or add a 300hp engine i\as it is basicly the same block will fit, you also could simply replace some parts on the 237 to achive 300 HP, as far as rebuilding the 237 kits are readly availible. I havent checked lately on prices so i wont comment. i do know the older Mack rebuild kits are cheeper than cat, cummings etc.... I have seen a few 237s and 300 hp engines on ebay for 1000-1500 but who knows why they were pulled. good luck Trent ← Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-515 Share on other sites More sharing options...
garythomak Posted July 21, 2005 Author Share Posted July 21, 2005 Welcome to to BMT! Sounds like your looking at a U685ST (U-Model) also sounds like you will need to do an overhaul on that engine if it is using that much oil! I looked up your vin and it call for an ENDT675 so that is good...parts are available aand not tooooo expensive. Like Trent said, you will need to verify the engine stamping because an old truck can have alot of stuff changed through the years!← Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-516 Share on other sites More sharing options...
garythomak Posted July 21, 2005 Author Share Posted July 21, 2005 Thanks for the quick replies! This will help a lot, I will get the engine number and start checking prices. I first thought a used engine might be the ticket but I will check out the kits to see what they are. The guy who was driving the truck when it started knocking said he thought it spun a rod but even if that is the case it might still be worth a rebuild. I assume you can have the crank turned if necessary. I turn a few wrenches now and then but don't have any diesel experience. I could pull the engine and hire someone to do the work after that. If I decide to buy the truck I will look at the prices and see what I can find used. In some ways I like the idea of a rebuild better, you never know what you will get and used isn’t cheap.Where did you go to do the look-up on the Vin? I can find places that do the look-up for cars but even they can't usually find anything before 1971. Did it give any more information form the VIN number such as the gearing, rears, transmission etc.? The cab is offset so must be the U model. There are two sticks, the owner said it was a six speed with a two speed aux, does that sound right?Thanks again,Garygary@wvlogging.com Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-517 Share on other sites More sharing options...
Lmackattack Posted July 21, 2005 Share Posted July 21, 2005 The vin can be looked up at any mack dealer or thry the Mack museum. Most internet sites wont bother with old trucks or cars unless you have the 1982 and newer vins numbers. The Mack dealer can get you basic info on the spot but they wont have all the proper build sheets that have your trucks exact info. send a small donation ($10 or so)to the Mack museum when you buy the truck and they will tell you what the truck had when it rolled off the assymbly line. The 2 stick 6 speed is a great robust trans. You have a 5 speed main box and the aux box gives you Lo-Direct and Reverse. this is a 1:1 trans (no overdrive) you will have 5 reverse gears and 6 foward gearsif you are in a hole or in the mud with a heavy load you would shift like this..Main box in 1st gear/aux box in Low, let the clutch out accelarate out of the hole or incline etc... when you get on flat ground you shift the aux box to Direct(leave main in first) then after that gear winds out shift the main box 2-3-4-5(6 speeds total)if you are empty or normal driving you leave the aux box in Direct and only shift the main box 1-2-3-4-5.the rear end ratio will be on the top part of the diff housing on the slant part of the diff. (most likely a 4.17 ratio as that was a pretty standard ratio ....64mph) standing at the rear of the truck looking over the rear cross member it would be visible frome here. (bring a scraper and wire brush if its oily) if you need more help let us knowTrent Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-518 Share on other sites More sharing options...
garythomak Posted July 22, 2005 Author Share Posted July 22, 2005 The vin can be looked up at any mack dealer or thry the Mack museum. Most internet sites wont bother with old trucks or cars unless you have the 1982 and newer vins numbers. The Mack dealer can get you basic info on the spot but they wont have all the proper build sheets that have your trucks exact info. send a small donation ($10 or so)to the Mack museum when you buy the truck and they will tell you what the truck had when it rolled off the assymbly line. The 2 stick 6 speed is a great robust trans. You have a 5 speed main box and the aux box gives you Lo-Direct and Reverse. this is a 1:1 trans (no overdrive) you will have 5 reverse gears and 6 foward gearsif you are in a hole or in the mud with a heavy load you would shift like this..Main box in 1st gear/aux box in Low, let the clutch out accelarate out of the hole or incline etc... when you get on flat ground you shift the aux box to Direct(leave main in first) then after that gear winds out shift the main box 2-3-4-5(6 speeds total)if you are empty or normal driving you leave the aux box in Direct and only shift the main box 1-2-3-4-5.the rear end ratio will be on the top part of the diff housing on the slant part of the diff. (most likely a 4.17 ratio as that was a pretty standard ratio ....64mph) standing at the rear of the truck looking over the rear cross member it would be visible frome here. (bring a scraper and wire brush if its oily) if you need more help let us knowTrent ←Thanks again, if I get the truck I will definitely send a donation to the Mack Museum, from what I have seen it is a worthy cause in itself.Gary Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-519 Share on other sites More sharing options...
TimFBsucker Posted July 24, 2005 Share Posted July 24, 2005 There are a couple early 70s Macks on ebay reasonable if you are looking for a tractor to pull your lowboy. Tim Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-555 Share on other sites More sharing options...
garythomak Posted July 24, 2005 Author Share Posted July 24, 2005 There are a couple early 70s Macks on ebay reasonable if you are looking for a tractor to pull your lowboy. Tim←Thanks, I will check them out.Gary Quote Link to comment https://www.bigmacktrucks.com/topic/151-1971-mack/#findComment-559 Share on other sites More sharing options...
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