Loosing Antifreeze

[Trojan]

My 671N J/T is loosing antifreeze out the exhaust I think. I have lost about a total of 2 gallon in 6mo. Should I be worried? The motor has never over heated. That I know of. Where should I start to look? There is no antifreeze in the oil. When I got the boat the antifreeze was real low and when I started it antifreeze came out the exhaust. I didn't think much about it at the time. Because the boat sat for 2.5 years. Are there any ideas out there. Bill

 

[Genesis]

All the places this can happen are not good.

FIND THE LEAK, because WHEN it goes back into the engine, not if, you will be buying cylinder kits - at best.

 

[Will]

You may have a leak between the raw water and coolant sides of the heat exchanger. An other possibilty is a crack in the water jacket of an exhaust manifold. Try pressure checking your cooling system.

 

[Genesis]

BE CAREFUL pressure-testing this.

If the leak is in the manifold you can hydrolock a cylinder VERY EASILY this way.

Hope its in the heat exchanger, although if it is, you can also get salt water back into the cooling system, which will do severe damage to the engine and in some cases and render it unrebuildable...... (when cold there is no pressure in the H/E, but there is in the raw water side when under load!)

 

[SKYCHENEY]

Good thing Trojan is in Lake Erie, I think. No salt there

Also, check your pressure cap. If it's weak, it could just be coming out the overflow. Oh, sorry, I see that you said it was coming out of the exhaust.

 

[Trojan]

I would have to lean toward the exhaust manifold. I'm also on fresh water. I lose antifreeze.If I have a leak in the heat exchanger as you say there would or could fresh water in the engine because of the preasure at startup. I'm always at a negative in the engine.

 

[Genesis]

If its in the exhaust manifold REPLACE THAT MANIFOLD IMMEDIATELY.

A leak there can and WILL leak antifreeze back into the engine through open exhaust valves and destroy the motor by hydrolocking it when shut down - next time you hit the button - BOOM!

This is not hard to find - remove the manifold and pressurize the coolant side with air, then immerse it in water. If there's a leak you'll see bubbles.....

 

[Freestyle]

What is hydro locking?

 

[SKYCHENEY]

Hydrolocking is when water gets in the cyclinder and when the piston comes up on the compression stroke, it can't complete the stroke because of the water in there. So, something has to give. Usually it is a broken rod or head.

 

[Freestyle]

What is hydro locking?

 

[Genesis]

See above.

Basically, water does not compress. If you get liquid in a cylinder and the piston comes up there is insufficient space and something will break.

That something is usually the head gasket, connecting rod, and in some cases the crown of the piston.

All of the consequences of this are "tear down engine and rebuild it" events. Very, very bad......

(That's ignoring the corrosion damage that water does in the engine in the meantime - before you start it...)

 

[Eufaula]

Seldom you will find a case iron exh manif. leaking. YOu mention anti-frz out the exhaust, question is does it steam out the exh. or ? If by chance it is steam then I would be checking the firing chambers. As someone mentioned, pressure check with your air box covers off and roll the engine by hand press. test should have a gauge, air regulator and ball valve no more than 2 to 3psi and see if the gauge goes down then I would start looking for the place the leak is coming from. If accessable at all the air box is good place to find it. Fix it before, like someone said it is big trouble. Good luck.

 

[spartonboat1]

Re: Loosing Antifreeze/Hydro Locking en masse

Mercedes-Benz installed diesels in some of their early '90's S-Class sedans. However, the engines got a bad rep for weak connecting rods, since the sympton was a high rate of bent rods. I think the finding was that a high rate of leaking head gaskets was allowing coolant to get into the combustion chambers, resulting in the attendant "hydro-locking"...much cost for warranty work on those engines. Don't know what MB did to sort it out....

 

[MikeP]

Knowing MB, I suspect they did nothing at all except perhaps add a few more cappucino machines in their showrooms. (The Admiral is an MB fan so I have to deal with those incompetent car makers and their even more incompetent dealers.)

OK, OK, I can't stop myself...a few years ago the admiral had a tranny problem on her out-of-warrantly S430. MB said the tranny had to be replaced - 4700 bucks. I changed out the faulty hydraulic piston, which is accessible with the tranny on the car, in about an hour. All fixed - total cost, 40 bucks for the new piston/gasket. Car's still running fine. As Cher said, MB dealers are Gypsies, Tramps and Thieves.

Sorry for the non-boat rant...

 

[SeaEric]

In recent years MB has done some strange stuff relative to transmissions. As an example, the dipstick is sealed so fluid level may not be checked. Eeek! I try to replace my MB's before the warranty ends!

 

[Trojan]

When I purchased the boat it had set for 2.5 years. In checking all the fluids before starting, I noticed that the anti-freeze was low in one of the engines. I didn't think much of it at the time because it had sat for so long. When I started the engine for the first time, green antifreeze and water came out of the exhaust,quite a lot,maybe a gallon, a liquid not steam. I thought ok, the fresh water system was just winterized. I didn't see any in the other exhaust. After about 3 months of operation I checked it again. I had to add about a 1/2 gallon. I thought ok, a bad cap maybe. At the end of the season 3 months later. It was down about a 1/2 gallon again. There has never been an overheat that I know of. The motor had only about 100 hours on it when I got it. It was a new engine. Its on the hard now till spring. But I would like to check something now before spring. I am planning a 1000+ mile cruise in the spring. At this time I think all that I can do is check the level and replace the cap till spring and see if I loose any fluid between now and then. I don't think its the cap because of the anti-freeze in the exhaust. Maybe an air pressure check can tell me for sure. The motor runs great. Checking and adding fluid is not a great problem to do. I just don't think that I should have to do that. The amount of loss is small ,but I would like to find out where its going. It dosn't seem to be able to enter the cylinders. So I tend to think it must be down stream some place if it is leaving the exhaust. I don't know the water flow on the engine yet but I will. If I don't find out where the anti-freeze is going by spring. What about adding a stop-leak of some kind? In as much it is on the closed loop side and its so small. Before I start it up in the spring I will roll it over by hand. To make sure it is not hydrolocking. I thought this would be an easy thing to find. I forgot this IS MARINE. Sorry for the long thread but I thought it needed more history to get all the brains a thinking. Bill

 

[Genesis]

Given that its showing up in the exhaust I would pull the exhaust connections at the manifold while you're down for the winter and have a look.

If there's liquid in the manifold......

If not, it may be leaking out the H/E bundle into the raw water side.

 

[Eufaula]

Some Stop-Leak are compatible with DD, however, if a Dealer is close by stop by and ask to buy from them. Your leak may be too much for Stop- Leak "green anti-freez out the exh." I sure as heck would find it before going on a 1000 nm venture. As mention prior, drop your exh manifold blank off the two out/in and pressure test. 2 to 3 psi also look into the six cyl. holds upon droping the manif. and see if any difference as clean hole or blk hole in sight. Not Steam, only likely place is the exh manf. James

 

[Trojan]

I talked with Detroit Diesel yesterday.They said to presure check the the inner cooler. Chances are the leak is in the heat exchanger. The antifreeze is leaking out into the raw water thruogh the heat exchanger. OK how does it come apart? Does the big cast iron tank need to come off? Bill

 

[Will]

I just did the Heat Exchanger on a J&T 6-71 TIB and found it to be quite straight forward. Assuming yours and mine are alike, look at the raw water flanges on both sides of the exchanger. You will see they are different. On one side, the flange connects directly to the H/E housing with 4 bolts. On the other side, the flange with four bolts, connects to a rectangular bronze casting that also holds the zinc (electrolysis electrode). That bronze casting is then bolted through the H/E core’s flange, to the heat exchanger housing with about 10 bolts (not exactly sure of the number but, you will see what I mean). To remove the heat exchanger core, first drain both the coolant and raw water from the heat exchanger. Then, remove the raw water flange that bolts directly to the H/E. You will see that it is sealed with an O-ring after you remove it. Next, remove the flange from the bronze casting on the other side of the H/E. Now you can remove the 10 bolts and bronze casting. If you look carefully, you can now see the flange for the heat exchanger core, which was sandwiched between the bronze casting and the H/E housing. Now comes the tricky part. From the side with the bronze casting, you must as gingerly as possible, pull and coax the core out of the housing. You can get replacement gaskets and parts from J&T (856-234-3570). Take the core to a radiator shop for testing and repair.