tenfive0 Posted March 12 Share Posted March 12 (edited) I am looking for medium size Dump Truck to move soil around for some planned property improvements this spring. If I get a truck I'd prefer it to be A MACK. Turned up a 6 wheel 1978 R686. Looking over the truck it has 377000 plus mile. Started the engine and if fired right off stone cold. Checked the coolant after the engine ran for 5 to 10 minutes. When I removed the cap the radiator was pressurized, the level was low and I couldn't see coolant. I asked the owner if there was any problem with the cooling system. He said they just replaced the water pump? He assured me there wasn't any known problems or issues with the truck. A little concerning. The seller has contacted me asking if I am interested in the truck. I told him I might be if he tops off the coolant, if I can further inspect the truck and take it for a test drive. One thing I found strange, odd or unusual. When I pulled the dip stick the side closest to the frame (facing me) was clean with no oil. I asked about the oil and I was told the oil was just changed. I re-dipped the stick and it came out clean again. Wiped the stick with my finger and the dip stick on the engine side had oil. Dipped the stick again and the same results. The frame side was clean. With the stick pulled I turned it over and it showed full. What the heck is up with that? Anyone ever had that experience? Goofy question - Is it something to be concerned about? Edited March 12 by tenfive0 Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/ Share on other sites More sharing options...
terry Posted March 12 Share Posted March 12 Sometimes when you pull dipstick it will rub one side clean. terry Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-548019 Share on other sites More sharing options...
Freightrain Posted March 13 Share Posted March 13 Ya, if the tube has a bend in it, it can wipe it making it difficult to read properly. Especially with clean oil. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-548042 Share on other sites More sharing options...
tenfive0 Posted March 13 Author Share Posted March 13 Thanks for the help. Still on the fence with the purchase. I might schedule a 2nd look. Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-548048 Share on other sites More sharing options...
JoeH Posted March 15 Share Posted March 15 Great trucks; you're going to want to fix this intake tube though, keep rain from getting in and ruining a nice truck. Also its letting unfiltered air in. This radiator has the reservoir in the top, you should just barely be able to touch it with your fingers. You can spot coolant leaks by looking for salt trails, common leak spots are the freeze plugs on the driver side, as well as the crossover hose (very short) between the front and rear head water manifolds, also on the driver side. Does seem strange that the oil is only on one side of the dipstick. Next time check the oil before starting the engine. I have an E7 that if I check it 5 minutes after shutting off it'll be a gallon low on oil, but if I check it first thing in the AM it's full. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-548125 Share on other sites More sharing options...
Lmackattack Posted March 15 Share Posted March 15 .If you think the coolant is pressurized. You can bring a fairly cheap co2 tester with you. You will want the truck to run for a bit to see if combustion gasses are entering the coolant. RELD Head Gasket Tester Kit Combustion Leak Detector for 50 Tests https://a.co/d/4va7zaw Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-548129 Share on other sites More sharing options...
tenfive0 Posted March 29 Author Share Posted March 29 (edited) First, (1st) of all thanks to everyone for their input, help and guidance. Second, (2nd) I wound up passing on the Mack. My little voice inside just said NO. They say first impressions are everything. There was just something about the truck and the hard sell tactic the seller was pushing. One of the first flaws I noticed on the truck was the hole in the intake tube. That would have been the first thing I would have fixed. How obvious of an easy fix would it have been for the seller to just temporarily fix the problem with duct tape. I have no idea how long the truck was run that way. It is an issue I didn't ignore while looking at the truck. I don't want to talk bad about the seller but there were a lot other issues that turned me away from buying it. Third, (3rd) perhaps the worse part is I bought a GMC - Combination with an Equipment Trailer. I was looking for a (not for hire) truck and trailer to haul around my Skid Steer and Mini Excavator. Found the GMC for sale with a trailer for slightly more then the Mack alone. Sorry, to the faithful. Maybe I shouldn't even mention GMC? Well at least It isn't a FORD! When I started out looking for a dump truck I would have preferred a Mack but I was willing to settle on a JIMMY. Definitely wasn't interested in a FORD of any kind. If there is any consolation? I had he Jimmy Hauled home on a lowboy trailer drawn by a Mack Tractor. Edited March 29 by tenfive0 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549086 Share on other sites More sharing options...
terry Posted March 29 Share Posted March 29 Got to go with what works out best for you! terry 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549095 Share on other sites More sharing options...
JoeH Posted March 31 Share Posted March 31 There is room for the GMC here in there other truck brand section. All our trucks are Mack's, except for a 1995 Ford L8000 single axle cab chassis we picked up for $2500 from a local oil delivery company I drove for briefly. We slapped a dump on it and a salt spreader a year or two later. The right truck is the right truck to come along at the right time. Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549172 Share on other sites More sharing options...
tenfive0 Posted April 2 Author Share Posted April 2 (edited) It is what it is. I am trying to take command of our properties with a Bobcat E35 Mini Excavator and Bobcat S205 Skid Steer. GMC - 1990 C7000, 366 Big Block/Allison AT545 with a Chevy (tilt) plastic nose and trail combination. With slightly less the 50,000 original miles. No complaints so far. It is the right truck for us right now. Like anything used it needs some massaging and love. The first thing is to add a Tru-Cool 40k Transmission Cooler before we put it to ant serious work. Edited April 2 by tenfive0 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549278 Share on other sites More sharing options...
terry Posted April 2 Share Posted April 2 Nice looking rig, i like that tilt hood for working on it! terry Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549280 Share on other sites More sharing options...
70mackMB Posted April 2 Share Posted April 2 Nice! Even with the skid steer on the trailer, l have plenty of room to park that in my driveway here in NH. lol .....Hippy Quote Link to comment https://www.bigmacktrucks.com/topic/73956-1978-r686-coolant-oil-dip-stick/#findComment-549281 Share on other sites More sharing options...
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