706D Exhaust Slobber

Have a friend that has a 706 with the German Diesel Engine. In this cold weather, it has started to slobber out the exhaust manifold (between the manifold and head). Is this just from the cold weather or are we looking at mechanical problems....like compression problems from unburned fuel?

Is it getting harder to start? Could need a ring job.

Pretty typical if you don't work them hard. Put it on a heavy load and work it awhile it will probably clean up.

My 826 with a German D358 does the same thing. They are very low compression, direct injected diesel engines with an efficient cooling system and they don't generate much heat at idle. When combustion temp gets too low, incomplete combustion occurs and slobbering begins. He's letting it run too cool and idle too long. While its doing the slobbering, it's also washing down the cylinder walls and diluting the oil. My policy now is:

1) In cold weather, never start (if you can, mine won't start very well starting at about 40F, even with ether, and at 30, fuggedaboutit) without the block heater run for at least an hour. I avoid startup until I know the tractor is going to be used very soon.

2) Minimize idling. It won't warm up much idling anyway and it won't stay warm enough not to slobber unless it's a very hot day. My tractor is either working or shut off.

3) If you must idle, keep it at about 1000 revs. Doesn't slobber much at that speed plus it generates a little more heat. Item 2 takes priority with me but after hard pulls, I let it idle a little to cool off before I shut down.

4) Make sure the thermostat is installed and working.

5) Install a block heater.

The results of this policy for me has been a drastic reduction in oil consumption (which is, in part, a byproduct of diluted fuel), much better oil analysis results (ZERO fuel dilution!) and less fuel used because it's either working or shut off. Anyway, through trial, error and good advice from the gang at YT, this is what has worked for me.

I should also add that my engine has 8300 hours. It's tired but still runs well. I now use no more than about 1-2 quarts per season, compared to 6 or 7 at purchase 4 years ago. I also changed from SAE 30 Case IH oil to 15W40 Rotella-T and the viscosity change accounts for some of the reduction.

What is exhaust slobber?

Exhaust slobber is also known as "Wet Stacking".

The quick answer is that its diesel fuel coming out your exhaust pipe.

Its what happens when certain diesel engines are allowed to run at idle or are not worked particularly hard. Jim pretty much summed it up when he said that its from the cool cylinders and getting unburned fuel in the cylinders, and consequently out the exhaust. I guess the older IH machines with a diesel engine were really built to just hook to something and go full out. They dont like to set around idling much.

You need to put it under a hard load for a few hours and it will quit. I have a 706 and 756 both with the 310. They are good engines long life.

as stated by Jim Allen a good thermostat is a must I also cover radiator in cold weather,fast idle engine in sub zero conditions these old girls like lots of hard work. Scott