SpreadingLime Posted October 26, 2023 Share Posted October 26, 2023 Hello all. Here's my question. Do you feel that the 675/676 engines can be kept running for say, another 10 yrs? I ask because I am a small business owner and I run R models daily. My go to is a 93 RD690 and my backup is an 88 R690. Both 300 HP and seven speeds. I have recently acquired two more R models for parts. One is a 60s R600 and the other is a 75 R685ST (I think). They both have tip turbine engines. The 75 looks to be a 237 that has had the aftercooler added on. The engine tag reads 675 and the hood has been cut to allow for the second breather tube. Both have cabs that are in decent shape , which is why I bought them. I know these old Macks are dead reliable , but they all need repair at some point. I am concerned with availability of parts (mostly engine). Is it a good idea to try and restore one of these with the intent to put it onthe road in 2023? Would a swap to a newer engine family be advised? Thanks to all. Quote Link to comment Share on other sites More sharing options...
Popular Post tjc transport Posted October 26, 2023 Popular Post Share Posted October 26, 2023 i see no reason not to do it. a friend here in New Jersey still runs 4 237 powered trucks every day. slow and steady keeps you out of trouble. 3 Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 27, 2023 Author Share Posted October 27, 2023 Thank you. That's good to know. Quote Link to comment Share on other sites More sharing options...
BOBWhite Posted October 27, 2023 Share Posted October 27, 2023 Some companies still make rebuild kits for these. Quote Link to comment Share on other sites More sharing options...
Solution Popular Post JoeH Posted October 27, 2023 Solution Popular Post Share Posted October 27, 2023 These motors will run until you break the carbide face on a valve lifter and wipe that lobe off the camshaft. Then you're borrowing the cam and a lifter from a spare engine. Could happen tomorrow, could happen in 20 years. 3 Quote Link to comment Share on other sites More sharing options...
BOBWhite Posted October 27, 2023 Share Posted October 27, 2023 4 hours ago, JoeH said: These motors will run until you break the carbide face on a valve lifter and wipe that lobe off the camshaft. Then you're borrowing the cam and a lifter from a spare engine. Could happen tomorrow, could happen in 20 years. Can you still get quality lifters for these? I would hate for some sub par Indian or Chinese lifters to wipe out an irreplaceable cam. Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 27, 2023 Share Posted October 27, 2023 *shrug* last time we lost a lifter the truck got the cam and a lifter out of our spare engine. Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 27, 2023 Share Posted October 27, 2023 If it happens again I've got 11 more good lifters in the spare engine, and I'll send the currently bum spare cam out to have a new lobe welded on while the good engine gets ready for cam swap. 1 Quote Link to comment Share on other sites More sharing options...
tjc transport Posted October 27, 2023 Share Posted October 27, 2023 We have a local (sorta) truck junk yard around 20 miles away. He has at least 50 Mack engines in the yard at any given time. 1 Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
mechohaulic Posted October 27, 2023 Share Posted October 27, 2023 On 10/26/2023 at 1:20 PM, SpreadingLime said: Hello all. Here's my question. Do you feel that the 675/676 engines can be kept running for say, another 10 yrs? I ask because I am a small business owner and I run R models daily. My go to is a 93 RD690 and my backup is an 88 R690. Both 300 HP and seven speeds. I have recently acquired two more R models for parts. One is a 60s R600 and the other is a 75 R685ST (I think). They both have tip turbine engines. The 75 looks to be a 237 that has had the aftercooler added on. The engine tag reads 675 and the hood has been cut to allow for the second breather tube. Both have cabs that are in decent shape , which is why I bought them. I know these old Macks are dead reliable , but they all need repair at some point. I am concerned with availability of parts (mostly engine). Is it a good idea to try and restore one of these with the intent to put it onthe road in 2023? Would a swap to a newer engine family be advised? Thanks to all. possibly the only reason you won't see the 675/676 engines in another ten years is because the government "stepped in' to say junk all those polluting engines that don't have enough electronics on them. there's a lot of meaning behind the phrase " BUILT LIKE A MACK " if it works the government will screw it up. 1 Quote Link to comment Share on other sites More sharing options...
tjc transport Posted October 27, 2023 Share Posted October 27, 2023 I had a 237 juiced to around 265 that passed smoke puff test for 2005 engines. 0nly blew 5% Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
JoeH Posted October 27, 2023 Share Posted October 27, 2023 The real driving force behind whether or not you'll see them in another 10 years is a) they aren't building them any more b) they're so old that it's unrealistic to expect Mack to keep making parts for them and c) the repair industry is so much further down the road simply because of a) and b). There's no real reason you shouldn't expect one of these to perform admirably for you. Nothing's bulletproof, new or old. On these, if you're prepared to dig for spare parts and fix it in house then I'd say go for it. Just remember, Mack engineered their whole engine/drive line to work together "as engineered." Dont go ramping up the HP, Mack already built their engines to their limits. Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 27, 2023 Share Posted October 27, 2023 Best thing to do is keep everything in the same engine family. That way one spare engine can supply the fleet, or if a truck goes down it still has Parts value. 2 Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 27, 2023 Share Posted October 27, 2023 Reading into your post a little more thoroughly, what are you using the trucks for? How many miles are on them? The older camelback suspension lacked a sideways torque arm, so the axles tend to wander. You'll want your steering and suspension components nice and tight to help stay in a straight line going down the road. King pins, drag link, tie rod ends, spring u bolts all tight up front, and trunnion bushings, elephant pads and torque arms in the rear. You'll also want to keep an eye out for vertical frame cracks under the cab where the frame starts splaying out to go around the engine and transmission. This is a single frame issue, haven't heard of a double frame cracking there. We've cracked/replaced both frame rails at different times on our '79 R686ST. Quote Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 28, 2023 Author Share Posted October 28, 2023 Morning guys. Sorry for the slow response. It's been a week. All of the info is greatly appreciated. 1. Joe, thank you for especially for the tid but on the lifters. If I decide to run these motors I'll have extra on hand. As to the torque arm, I have a second RD690 truck for parts. I have plans to use the front and rear suspension from it and put under the '75. I know it has a torque arm. 2. Bob, I like your way of thinking. I don't mind repairs but I would hate to put a Chinese "anything" in one of mine. 3. Too all. I make my living spreading commercial fertilizer and Ag lime in N Arkansas. 300,000ish miles on the '93 truck. Unsure of the others. 48k to 50k total weight is pretty normal for me. Lots of rough, steep ground to drive over . 2 Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 29, 2023 Share Posted October 29, 2023 That's good work for one of these trucks. Camelbacks have phenomenal articulation over rough terrain as I'm sure you already know. Quote Link to comment Share on other sites More sharing options...
Brocky Posted October 29, 2023 Share Posted October 29, 2023 I do not know what engine RPM your spreader needs to work properly?? With enough low gears in the tranny (quad or tri plex) you should be able to do your spreading work without abusing the engine so it should(???) last a long time. Especially if you truck the material to be spread to the yard or field rather than having the spreader chase a long way for it.. Quote Brocky Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 29, 2023 Author Share Posted October 29, 2023 The spreaders are New Leader 3020. They have step up motors that turn the fans. This keeps them turning at the same RPM no matter the trucks speed. Theoretically. 1500 RPM on the motor is where I typically run. This gets me 7ish MPH field speed and the beds seem to perform well at that RPM. And yes I've seen my camelbacks for some impressive stuff. My 88 has a 38k and the 93 has a 44k. Honestly the 38K gets better traction and holds the terrain better. 1 Quote Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 29, 2023 Author Share Posted October 29, 2023 My typical day Quote Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 29, 2023 Author Share Posted October 29, 2023 Quote Link to comment Share on other sites More sharing options...
BOBWhite Posted October 30, 2023 Share Posted October 30, 2023 Most of the older Macks around where I live are manure spreaders. I want to snag one if a nice one comes up, ever since the DEF stuff came out the price of anhydrous has gone through the roof. With 3-5 Tons of manure per acre you can whip any old land into shape. All with Mack power! That will be the dream! Quote Link to comment Share on other sites More sharing options...
SpreadingLime Posted October 30, 2023 Author Share Posted October 30, 2023 Not much anhydrous is used around here. That's flat land stuff. Ammonium Nitrate is all that available around here. Along with DAP and Potash it's the cheapest of the three, but still too expensive. Quote Link to comment Share on other sites More sharing options...
JoeH Posted October 31, 2023 Share Posted October 31, 2023 I'd love to see the rig you're hauling around at 30 degrees! That's a great gauge to have in the cab! Quote Link to comment Share on other sites More sharing options...
Popular Post SpreadingLime Posted October 31, 2023 Author Popular Post Share Posted October 31, 2023 Here she is. Ole reliable. 6 Quote Link to comment Share on other sites More sharing options...
MACKS Posted October 31, 2023 Share Posted October 31, 2023 I only owned one truck with a 237/6 speed,that was one sweet running truck.. Quote Link to comment Share on other sites More sharing options...
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