6-71 inline detroit diesel water in oil

[Guy 6-71]

I have a 1968 terex 72-51 loader, running a inline 6-71.

I was told by the previous owner that the engine was rebuilt and would now have no more than 1500 hours on it and had a 4 valve head installed, I have no reason to doubt his info.

Engine starts easy and runs fine.

After a few hours of light work I noticed the oil that dribbles out the discharge line had a grey look as I was reversing, drove the machine back to camp and parked it up.

I have read plenty about cracked heads and injector liners but have not gone that deep yet.

Coolant in oil, no oil in coolant, coolant that I drained was clean, however I did notice the issue pretty quick and didn’t run the machine more than 10 minutes after I noticed.

I have pressure tested the oil cooler and it is good, I have pulled the head off the compressor and it is also fine.

Is there any way water can get into the oil through the water pump? Some say yes. Some say no.

I don’t think I can pull the sump off in frame, so if I pressurised the cooling system I will only be able to inspect from the air box covers and rocker cover.

I would like the issue to be the water pump but I am not too hopeful on that.

I am in Australia and about 4 hours drive from anyone with experience with detroit diesels.

Any advice on my issue will be much appreciated

Cheers Guy

 

[Vetech63]

injector liners but have not gone that deep yet.

A 71 series is a dry sleeve engine. There are no liner orings.

Is there any way water can get into the oil through the water pump? Some say yes. Some say no.

Yes, through the shaft seal.

Most common failure outside of what you have asked is a water jacket oring under the cylinder head.

 

[Vetech63]

Injector tube leaks usually occur at the tip. That coolant ends up on top of the piston and unless the engine is on the downstroke of a cylinder with a leaking tip, the cylinder will hydrolock.

You can remove a water plug just below the cylinder head deck, drain the engine oil and leave the drain plug out. Fill the system with water to the top of the radiator. At some point, the water leaking will stop coming out of the drain plug............you need to see where that level is. Your leak will be at that level somewhere in the engine. This works more accurately on the wet sleeve engines.

 

[Guy 6-71]

Injector tube leaks usually occur at the tip. That coolant ends up on top of the piston and unless the engine is on the downstroke of a cylinder with a leaking tip, the cylinder will hydrolock.

You can remove a water plug just below the cylinder head deck, drain the engine oil and leave the drain plug out. Fill the system with water to the top of the radiator. At some point, the water leaking will stop coming out of the drain plug............you need to see where that level is. Your leak will be at that level somewhere in the engine. This works more accurately on the wet sleeve

 

[Guy 6-71]

Injector tube leaks usually occur at the tip. That coolant ends up on top of the piston and unless the engine is on the downstroke of a cylinder with a leaking tip, the cylinder will hydrolock.

You can remove a water plug just below the cylinder head deck, drain the engine oil and leave the drain plug out. Fill the system with water to the top of the radiator. At some point, the water leaking will stop coming out of the drain plug............you need to see where that level is. Your leak will be at that level somewhere in the engine. This works more accurately on the wet sleeve engines.

Thanks for the reply, will try to get the water pump out for inspection this week, not really looking forward to pulling the head off in the scrub, but will do your water level test before I get onto that.

 

[crane operator]

If you have air brakes, it could be in the air compressor.

I had a oil cooler that I thought was good- pressure checked cold. but it would evidently seep once it got warm.

Pressure checked it with the pan off and the windows opened on the sides of the block? That would show a cracked head or bad orings in the head.

 

[kshansen]

I would also remove the valve cover and check for leaks around the injectors. The copper tube the injectors are in have an oring at the top and with age can get dry and hard and cause leaks.

Actually that would be my first thing to check! I tend to do things in a lazy way, in other words, check the stuff that takes the least amount of time and effort! Valve cover off and looking, other than a little pre-cleaning' costs nothing or any parts to put back together. Way less than removing oil cooler or head that's for sure.

Water pump seals are also a common source of coolant getting into the oil. There should be a weep hole to let the coolant drip out before getting past the water seal but sometimes mud daubers or other insects will seal the weep holes up!

One more some what distaste full test would be to take a spot of that grey goop coming out of breather and touch to tip of tongue to be sure it is anti freeze. If you have never tasted antifreeze before it is very sickly sweet. Don't swallow it as it is deadly poison! Also can cause you to spend many hours on internet answering all kinds of questions with long drawn out replies!

 

[Guy 6-71]

If you have air brakes, it could be in the air compressor.

I had a oil cooler that I thought was good- pressure checked cold. but it would evidently seep once it got warm.

Pressure checked it with the pan off and the windows opened on the sides of the block? That would show a cracked head or bad orings in the head.

I have had the head off the compressor and all is good there, I didn’t think I can pull the pan in frame.

 

[Guy 6-71]

I would also remove the valve cover and check for leaks around the injectors. The copper tube the injectors are in have an oring at the top and with age can get dry and hard and cause leaks.

Actually that would be my first thing to check! I tend to do things in a lazy way, in other words, check the stuff that takes the least amount of time and effort! Valve cover off and looking, other than a little pre-cleaning' costs nothing or any parts to put back together. Way less than removing oil cooler or head that's for sure.

Water pump seals are also a common source of coolant getting into the oil. There should be a weep hole to let the coolant drip out before getting past the water seal but sometimes mud daubers or other insects will seal the weep holes up!

One more some what distaste full test would be to take a spot of that grey goop coming out of breather and touch to tip of tongue to be sure it is anti freeze. If you have never tasted antifreeze before it is very sickly sweet. Don't swallow it as it is deadly poison! Also can cause you to spend many hours on internet answering all kinds of questions with long drawn out replies!

I will have a look at the orings after the water pump, as there is a bit of gear to remove to get at the valve cover.

I think I will pass on the taste test

Handy info thanks

 

[IceHole]

I would also remove the valve cover and check for leaks around the injectors. The copper tube the injectors are in have an oring at the top and with age can get dry and hard and cause leaks.

Actually that would be my first thing to check! I tend to do things in a lazy way, in other words, check the stuff that takes the least amount of time and effort! Valve cover off and looking, other than a little pre-cleaning' costs nothing or any parts to put back together. Way less than removing oil cooler or head that's for sure.

Water pump seals are also a common source of coolant getting into the oil. There should be a weep hole to let the coolant drip out before getting past the water seal but sometimes mud daubers or other insects will seal the weep holes up!

One more some what distaste full test would be to take a spot of that grey goop coming out of breather and touch to tip of tongue to be sure it is anti freeze. If you have never tasted antifreeze before it is very sickly sweet. Don't swallow it as it is deadly poison! Also can cause you to spend many hours on internet answering all kinds of questions with long drawn out replies!

A taste of Antifreeze isn't deadly poison.
Good thing too, cause I'd be dead a few times a week l.

 

[kshansen]

I will have a look at the orings after the water pump, as there is a bit of gear to remove to get at the valve cover.

I think I will pass on the taste test

Handy info thanks

Well is the a dealer or lab you could have an oil sample tested to see if it is in fact coolant getting into the oil and not moisture from some other source?

Understand not wanting to do the taste test but how about a "sniff test" often you can tell from the sweet smell there is coolant vapors coming out the breather.

 

[Guy 6-71]

Water pump looks good, I will put it back in on the weekend.

Better do that taste test on the oil

So the next thing to check seems to be the orings on the injectors.

I figure pressurise the cooling system and look through the air box covers to see if there is any coolant leaking into the cylinders.

Any advice on the procedure is appreciated