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Cat D9N 3408 coolant loss

988Driver

Member
Joined
Aug 26, 2018
Messages
14
Location
Australia
Gday guys. I have started to find a few issues in my 3408 engine. Coolant loss in my system has been approximately 20-30 litres over 15 hours however most of this is expelled through the cap when I take it off to check it sometimes. The engine has not been getting hot however the radiator is being pressurised slightly. No major bubbling in the radiator to point to a cracked head or head gasket. Condensation is starting to show up on the under side of the oil filler cap, however it does not appear to be filling the sump with oil. I am waiting for some irontite to turn up next week to run through the system to hopefully alleviate any issues.

The engine does seem to be getting a bit sluggish and I’m also thinking that possibly the turbo could be leaking coolant into the system? Has anyone had any previous experience with this?

The main thing is that the engine does not get hot under load. The highest temp I have had has been around 80 degrees Celsius.

The engine has approximately 8800 hours on it, certainly shouldn’t be ready for a rebuild yet. Cheers.
 

Cmark

Senior Member
Joined
Jan 2, 2009
Messages
3,176
Location
Australia
The first thing I would do is to get an oil analysis sample done. This should give you an indication of whether the coolant is running out on the ground or going up the chimney. (Assuming your oil levels are all OK and not going up)
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,977
Location
G..G..G..Granville.........!! Fetch your cloth.
The first thing I would do is to get an oil analysis sample done. This should give you an indication of whether the coolant is running out on the ground or going up the chimney. (Assuming your oil levels are all OK and not going up)
Agreed, and the fact that there is condensation showing inside the oil filler cap would appear to indicate that at least some coolant is leaking internally into the engine. 20-30 litres of coolant loss over the time frame you mention is a significant amount. Obivous suspects for a leak of that magnitude would be a cracked aftercooler core, failed head gasket, coolant passage seals, or a cracked cylinder head.

I'd do all the above before pouring snake oil into the cooling system in an attempt to stop whatever leak you might have.
 

Cmark

Senior Member
Joined
Jan 2, 2009
Messages
3,176
Location
Australia
not forgetting possible failed water pump seal combined with blocked tell-tale hole, or liner seals. Much depends on whether the cooling system has been lovingly maintained with beautiful fresh ELC or filled with crappy old pond water.
 

kshansen

Senior Member
Joined
Mar 11, 2012
Messages
11,128
Location
Central New York, USA
Occupation
Retired Mechanic in Stone Quarry
not forgetting possible failed water pump seal combined with blocked tell-tale hole, or liner seals. Much depends on whether the cooling system has been lovingly maintained with beautiful fresh ELC or filled with crappy old pond water.
Crappy old pond water! That gave me a flash back to a 988 87A with a plugged oil cooler core!

20 to 30 liters in 15 hours? Had to convert that to the stone-age measurements we use in US, yikes that is as much as 8 gallons!
I know a D9N is a big machine but still just having a loss of coolant that you can detect in 15 hours would be extreme to me.

I could suggest a test method for the "condensation" on the oil filler cap but don't want to spoil anyone's breakfast, it's right on the tip of my tongue.

As for the "snake oil" cure, I might be tempted to try it on my old Farmall BN but if that fails to work all I need to do is use a different mower on the lawn till winter gets here. Not sure what the plans are for this D9N but I'm thinking a bit more is riding on it's life than keeping the yard neat for the next couple weeks.
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,977
Location
G..G..G..Granville.........!! Fetch your cloth.
20 to 30 liters in 15 hours? Had to convert that to the stone-age measurements we use in US, yikes that is as much as 8 gallons!
I know a D9N is a big machine but still just having a loss of coolant that you can detect in 15 hours would be extreme to me.
Put into context, the total system capacity is only listed as 81 litres, so the machine is losing anywhere from 25-35% of the total system capacity in 15 hours. Snake oil ain't gonna fix that .......
 
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