alex g Posted February 16, 2020 Share Posted February 16, 2020 You can take rad out and a rad shop could flush it out for you. I have a 41 Plymouth and had same issue. I ran water and dish soap instead of antifreeze and flushed it out about 5 times. Running it til it's at operating temperature then repeating. That slime is probably just buildup from running water all those years. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-442920 Share on other sites More sharing options...
Maddog13407 Posted February 16, 2020 Share Posted February 16, 2020 those western battery box covers were about the worst thing Mack ever put on a truck next to a push button signal switch on a B model. probably the previous owner stepped on them and fell on his ass when the cover flew off. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-442928 Share on other sites More sharing options...
Ditchdiggerjcf Posted February 16, 2020 Share Posted February 16, 2020 5 hours ago, alex g said: You can take rad out and a rad shop could flush it out for you. I have a 41 Plymouth and had same issue. I ran water and dish soap instead of antifreeze and flushed it out about 5 times. Running it til it's at operating temperature then repeating. That slime is probably just buildup from running water all those years. I was always told to use dishwasher detergent. Easier to clean out. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-442933 Share on other sites More sharing options...
david wild Posted February 16, 2020 Share Posted February 16, 2020 take to rad shop and have it tanked, pretty cheap. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-442934 Share on other sites More sharing options...
Quickfarms Posted February 17, 2020 Author Share Posted February 17, 2020 take to rad shop and have it tanked, pretty cheap.That won’t clean the crap out of the block Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-442983 Share on other sites More sharing options...
h67st Posted February 17, 2020 Share Posted February 17, 2020 When I worked at Cat we would put Tide laundry powder in the rad with water and run till hot, then drain and flush with plain water. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443010 Share on other sites More sharing options...
Quickfarms Posted February 18, 2020 Author Share Posted February 18, 2020 I took the dog out for a walk today. This is the first time it has been on the road in 11 years Then I came home and drained the radiator again. I will refill it in the morning with water again 2 Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443043 Share on other sites More sharing options...
Quickfarms Posted February 18, 2020 Author Share Posted February 18, 2020 The only bad thing I found was a good leak from the rear valve cover and the front valve cover is wet How hard is it to do the valve cover gaskets? How are the jake brake spacers held on? Or are they just sitting there?Should I use the cork or rubber gaskets? Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443065 Share on other sites More sharing options...
Quickfarms Posted February 22, 2020 Author Share Posted February 22, 2020 The speedometer is not working Are there any typical problems on a Mack?How do you disconnect the cable from the back of the speedometer? Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443522 Share on other sites More sharing options...
alex g Posted February 23, 2020 Share Posted February 23, 2020 Cable should just unscrew. Check cable to make sure it turns while truck moves. Could be broke where it goes into transmission. Valve cover gaskets are no big deal to change. Not sure if you can get rubber. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443533 Share on other sites More sharing options...
Lmackattack Posted February 23, 2020 Share Posted February 23, 2020 I would fill the radiator with water and then put dish soap and then run/ Drive it so it gets good and hot for a few hrs then drain it. you will need to do this a few times to get the brown color out. that slime you see can be alge. I would flush it a few times like this before you re fill it with Anti freeze. they make a chemical that you can add into it as well if you dont think dish soap works good. Valve cover gaskets are super easy. pull them off and the gasket is right there. I like rubber gaskets as they dont leak as bad. the speedo cable just screws into the back of the gauge. some pliers is all you need. Same deal near the trans output shaft yoke at the adapter. If the cable is still good you should add some sort of oil or graphite into it from up by the gauge and let it soak in the cable to help prevent rust. it will also help keep the gauge from jumping if the cable is binding a little . Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443541 Share on other sites More sharing options...
Freightrain Posted February 23, 2020 Share Posted February 23, 2020 (edited) Ditto, valve covers pretty easy. Jake spacers just sit on there. I think I used rubber when I put mine together. Put some RTV on one side of each gasket to hold in position. Still dry after a couple years. Edited February 23, 2020 by Freightrain 1 Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443552 Share on other sites More sharing options...
Quickfarms Posted February 24, 2020 Author Share Posted February 24, 2020 I think I found the speedometer issue. The drive tang was broken off and stuck in the transmission The valve cover gaskets should arrive tomorrow afternoon 2 Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-443610 Share on other sites More sharing options...
Quickfarms Posted March 9, 2020 Author Share Posted March 9, 2020 I wonder if this is the reason my valve cover is leaking After degreasing the valve covers today I noticed the the rear valve cover is not sitting squarely on the jake brake riser.The bolts on this valve cover were only hand tight Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-444832 Share on other sites More sharing options...
j hancock Posted March 11, 2020 Share Posted March 11, 2020 Sure isn't helping to keep the oil on the inside... Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445024 Share on other sites More sharing options...
Mike Harbison Posted March 13, 2020 Share Posted March 13, 2020 Before you put the valve covers back on take a 2x4 and a hammer,turn the covers upside down and give them a rap or 2 at the bolt holes, they have a tendency to get sucked down from tightening and don't seal the best. I've only ever seen rubber gaskets for these. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445241 Share on other sites More sharing options...
Mike Harbison Posted March 13, 2020 Share Posted March 13, 2020 Also I've found Cascade dishwasher soap works really well for flushing. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445242 Share on other sites More sharing options...
Rob Posted March 13, 2020 Share Posted March 13, 2020 Cascade makes a great final wash, or to remove residual oil after an oil cooler leaks into the cooling system, but to get the nasties out of a cooling system there is better available. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445246 Share on other sites More sharing options...
Quickfarms Posted March 15, 2020 Author Share Posted March 15, 2020 Due to all the rain here in sunny southern I have not been able to work on this truck Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445592 Share on other sites More sharing options...
Quickfarms Posted March 15, 2020 Author Share Posted March 15, 2020 I need a replacement bumper, what are the options? Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445593 Share on other sites More sharing options...
Freightrain Posted March 15, 2020 Share Posted March 15, 2020 My Jake spacers aren't perfect matches to the valve cover either, but do like mentioned and flatten the cover slightly to increase clamp pressure when tightening the bolts. They do bottom out on a shoulder of the bolt. New sealing washer on top might also help. Maybe mock up without gaskets might give you some insight on how much crush you will get. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-445598 Share on other sites More sharing options...
Quickfarms Posted May 30, 2020 Author Share Posted May 30, 2020 I tried to do the valve covers last weekend and discovered that the jake brake spacers will not come off without removing the jake brake assembly.I also discovered that the rear valve cover is messed up but I found a PAI one for a decent price and am just waiting for it to get here.The engine has a lot of gold paint on it. Is gold the correct color for the engine and what is a good source for engine paint. Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-452291 Share on other sites More sharing options...
Brocky Posted May 31, 2020 Share Posted May 31, 2020 For the paint contact Eddy Lucast for KBS Coatings:: Eddy.Lucast@remotedata.com or http://kbs.justoldtrucks.com/ Quote Brocky Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-452363 Share on other sites More sharing options...
Quickfarms Posted June 1, 2020 Author Share Posted June 1, 2020 For the paint contact Eddy Lucast for KBS Coatings:: Eddy.Lucast@remotedata.com or http://kbs.justoldtrucks.com/He does not have a specific Mack gold engine paint.Does it cross reference to anything? Quote Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-452459 Share on other sites More sharing options...
Brocky Posted June 1, 2020 Share Posted June 1, 2020 Quick I just knew he had a lot of high temp engine paints.. I am Surprised he does not have the Mack Gold?? Quote Brocky Link to comment https://www.bigmacktrucks.com/topic/54460-1975-rs685lt/page/6/#findComment-452492 Share on other sites More sharing options...
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