jake

My brother And I are going. Have bin working on the B model since last June. Replaced the triplex, replaced the thermodyne, have some new glass in the cab,new batteries in the box, redone the radiator, and will either rebuild the generator or will install an alternator. It's about 1000 miles fron Wisconsin and we plan to take our time and stay all week. I need to thank a few people on this forum for the help I have gotten. Namely Herb and Glenn. Herb told me where I could find a transmisson and Glenn answered many questions on the engine.I bought some parts from Kevin All and had to call Matt Pfahl a couple times. Thanks guys. You can't beat MACK guys. The old B model won't be all done but like I have bin sayin, " It's better than it wuz!"

I was wondering if some one could provide some information on the L T model. I went back through the forum but didn't find much on them. I have a chance to buy one that is Cummins powered but I don't know much about them. Many years ago I drove an L J but this truck is much bigger. Were they built in California instead of Pa? Thanks. Jakebrake

glenn, My 711 ran good but it leaked antifreeze in the oil. Ithought it was head gaskets but when I tore it down I found some small cracks above the cam shaft and behind the valve lifter above #2 main. Sitting over winter it would leak about a pint in the oil. I would always drain it off at the oil plug before I would run it but what a pain. Between my son and myself we got 4 1/2 B53 s.( one is cut off right behind the cab.) All have 673 s. None have oil coolers. Three have turbos. All have the starters on the top left side. Two are BCRs with B53 serial number plates. The engine from the 1/2 truck is going in my B61. jake

glenn, My 673 has the three oil lines just like my 711. The oil cooler should work. The 673 runs very well but I think I would rather use the APE pump. I will let you know Steve if I dont need the rotery pump. jake

Thanks for the reply Glenn. I will check on monday to see which filter it has. The B 53 is a 64 model I think so it may be the later one. Also do I have to change anything in the APE pump to use it on the 673?

I found a good running 673 out of a B 53 that is going to replace the 711 in my B 61. Will the intake manifolds and oil cooler off the 711 work on the 673? Also the 673 has a rotary injector pump. Would there be any advantage in using my American Bosch off the 711? Would it work?

glenn, Tonite I removed the right fender, injector pump, and side cover. Icould see some crusty looking sluge right behind the tube that runs from the top of the block to the cam. After I clean and dried the area behind the tube it would slowly turn wet again. I think that has to be the place because I can follow a crusty white trail from there all the way down to the main bearing cap. I think the block had been treated with stop leak a quite a few times. I am wondering if epoxy would repair it? Do you know if that tube can be removed to make a repair easier? Thanks. jakebrake

Thanks for the replies. Today I took off the front head and it looked likeit was leaking between the heads also. Hoever we can't see any thing wrong with the gasket. Tomorrow I will take the head in to have it tested for a crack. I left the block level full of antifreeze and will look for any trace on the bottom. Maybe will get time to pull the other head also. Will order new gakets this week too. Thanks. jakebrake

fjh I think you're right. It is the block that is leaking. Ihave the block setting with antifreeze in it and it keeps leaking out the bottom. My nephew has a scope and we are going to look down a push tube hole and see what we find. Have you ever repaired a cavitated block? jakebrake

If its not a head gasket I beleive you'll find you have cavitated block not totaly un heard of on these older engines!Pull the side coves that should tell the tale!

Thanks for the replies. Today I took off the front head and it looked likeit was leaking between the heads also. Hoever we can't see any thing wrong with the gasket. Tomorrow I will take the head in to have it tested for a crack. I left the block level full of antifreeze and will look for any trace on the bottom. Maybe will get time to pull the other head also. Will order new gakets this week too. Thanks. jakebrake

Tonite I pulled the oil pan on the 711 to see where the antifreeze was coming from. It was easy to see. It was dripping off #2 main bearing bolt. When I followed it up I could see it was coming from a passage in the block at # 2 cylinder above the cam next to the cam follower. I was wondering if someone could tell me where this passage leads and what sould I look for when I remove the heads. Thanks. jakebake

last weekend we removed the Triplex in my B Model. It had a viberation, a growel and the compound would jump out of low. While the main box seems OK,the three way's in bad shape. The bearings are loose, two gears are real rough, andthe case has been brazed were it must have had about a 10 inch crack. Does any one know where I might find another Triplex for parts or I would put in a Quad box if I could find one. Looking mostly in WI or western MN area. Herb, is there any thing in your area? I will be going to Iola on friday and will be in Green Bay until Monday the 14th.Thankyou. Jakebrake

My 1964 B61 is getting antifreeze in the oil. It has a 711 with the large head bolts in the corners of the heads. The engine runs great and when it sets for a spell I drain it off at the oil plug before I start it. After it sat all winter I drained off about 1/2 pint. My question is what can I expect to find if I tear it down? I have heard that 711's where notorious for this problem. Was it usally head gaskets or cracked heads or block? How much in the oil will hurt the lower end? Should I keep running it like this? It is only a hobby truck and not a working truck. I want to keep it original so changing engines is the last option. I appriciate any suggestions. Thanks. Jakebrake

I love the 50's & 60's models. Always have. I started out in a 57 B. Then a 62 B and a 51 LJ. They are my favorites. Then on to U Models, many R Models, and lots and lots of miles in a 68 F Model. Now days I get my 64 B -61ST out of the shed just for fun. Who says I can't be young again? jakebrake

Thanks for the replies.I will try both remidies.I have found over the years that when lights and things like that act weird that it is usually a bad ground. Also sometimes I can bring things to life by turning the ignition switch on and off several times. Kinda' makes me think it could be the ignition. Thanks again. jakebrake

We have a 1980 and a 1986 Mack D M s. It seems thy both suffer from the same illness. Sometimes when we start the engine, only lights willwork. Nothing else. Not gauges, heater fan, radio, engine brake,or any thing that requires electrical power. Also when this occures, the volt meter shows no responce and you cannot hear the "click" of the relay that you normally hear. Today when this happened I stopped the engine and it would not crank when I tried to restart it. I let the truck set for five minites and it started right up with every thing working normally. I put a new relay on the 1980 but it didn't change anything. I work on them and drive them every day but this has me puzzled. Any ideas??? Jakebrake