6V71 Detroit engine antifreeze leak

[Old Iron nut]

Neighbour has a 6V71 Detroit running an air compressor and the engine suddenly developed a severe loss of antifreeze leaking out ot the air boxes and the exhaust pipes. Is this a case of cracked heads or bad head gasket o-rings? I know that these engines can be problems and I couldn't give him a definite answer. I feel that he is going to have to tear the engine down to find the problems. Not an easy job considering that the unit is mounted on a mobile truck frame. Any suggestions, guys? Happy New Year, & thanks in advance. Old Iron nut.

[snowstorm]

if it was overheated it could have cracked the head. some say they crack easy but i ran one for many years without any trouble. it dosent have a normal headgasket. has fire rings and orings. first thing to check is the water pump. saw a 92 series do this water pump seal leaks  into the motor. the little tube it should have leaked from was full of rust

[bandmiller2]

Detroits are very sensitive to low coolant,could be cooked/hard/cracked head seal rings or a cracked head anyways he will have to pull the head.Be sure he drains all the antifreeze its pure poison to a diesel if its in the oil. Frank C.

[Old Iron nut]

 Thanks, guys, will pass message on to neighbour. I thought that the heads will have to come of as it is leaking out both sides. Not my favourite motor to work on. These things are expensive to fix. Old Iron nut.

[bandmiller2]

Iron nut,you know there are two types of diesel mechanics,Detroit mechanic,and everything else. Frank C.

[Old Iron nut]

Frank, those boat anchors were made for the military as a throwaway motor and as far as I'm concerned they should have thrown all of them in the Mariannas trench when they were done with them. I had a customer in the late 80's that wanted an  8V71T overhauled. After the dust had settled he had over $17,000 in parts and machining alone in it without my labour. At the time he could have bought a 3406B Cat for $17,000 with a year's warranty. His last words on the subject were, "We sure as hell won't do that again!"

[snowstorm]

they were a far cry from a throwaway engine. are the new ones better yes until you get to 04 with cooled egr. i still have a 6v92 that i bought in 1983 been inframed once. a series 60 with 30,000 hrs. still a lot of 2 strokes in boats here in the northeast. might be a lot of smoke and noise but they were tuff

[sandhills]

I have to agree with snowstorm, a throw away engine they're not, even though I'd like to throw ours away  .  We have a 6V71, a 671, and a 318 (two power units for irrigation and the 318 in a semi tractor) and all I can say is they will hold their own for a long, long time, but invest in oil and buy some ear plugs.  I didn't realize they were that expensive to overhaul nowadays, my dad and I overhauled the 6V71 (we helped the retiring mechanic) about 10 years ago and if memory serves me correct I thought it only cost about 3k.

[bandmiller2]

I have worked on the 2 cycle detroits all my life Navy,continental bakery fleet, and the fire service,they are a remarkable engine totally different from most.If you get a good one life is good.If they have ever lost coolant and overheated the trouble starts.They used to be the cheapest engine to overhaul,now nothing is cheap. Frank C.