Kawasaki FD620D Liquid Cooling System Issues

[Lobsterbox]

Hello everyone! I'm relatively new to Argos and completely new to 6x6world.com (this is my first ever post). I regret to say that my need for help with an engine problem I'm facing right now outweighs posting a proper introduction; my apologies for that. I have recently bought a 1997 30th anniversary edition Argo Conquest 8x8. I'm just out of high school and still working my first job so it took a slap year of putting away nearly every cent I made to afford the $5,500 CAD price of one of these things on the used market.

Anyway, I fear my ignorance of liquid cooling led me to overlook this issue upon purchase. My engine is overheating. Once it starts up, it will warm up and the gauge will park itself right on 220 degrees Fahrenheit. After a bit, it will go back down to 190 degrees Fahrenheit. Then it will briskly go back up until it hits 220. This cycle repeats indefinitely as long as the engine is running, essentially the temperature is fluctuating. I knew this needed attention, but I figured it was ok to keep driving. I've put about 8 hours on it running like this.

It got more serious the other day, however, when I was out on the trail and the coolant got up to 240 degrees. It kept fluctuating between 200 and 240 and I had to limp it 30 minutes like that back to my house, there was nothing I could do, not even taking the hood off helped.

A couple of things to note:
- The higher the engine revs, the faster the fluctuation.

- Once, I turned the key on [EDIT: cold engine] and the temp gauge pegged itself without the engine running. I started the engine and it returned to the bottom.

- The upper rad hose is hot, the radiator is hot, the lower rad hose is lukewarm.

- The coolant overflow bottle has been steadily loosing coolant.

I ordered a new thermostat from John Deere, I'm hoping that is the issue, however, it seems as if the cold lower rad hose connects to the water pump and the hot upper rad hose connects to the thermostat.

I hope you guys can help me, I'm really stumped and being so far out of pocket for something with issues like this is getting me a little worried. Thanks in advance!

[riotwarrior]

Welcome to 4x4 world.

I cannot speak from experience with your particular machine however up down or cycling is a normal function in the cooling system.

I'm not sure if the degree or should I say the amount you are experiencing is normal but hot coolant leaves engine cooler material enters via the lower rad hose as you have explained. Most every vehicle does some fluctuation to some degree or another.

Waiting for others with more experience related to these machines is a good idea. Changing a thermostat would likely not hurt. Use new coolant of the right type for your engine, and only distilled water few bucks a gallon at grocery or pharmacy store...steam distilled water has no foriegn minerals or such and won't cause the build up in the cooling system you may have seen in radiators.

What tempurature was the environment that you where using the machine.

BTW I too am in Canada, BC to be exact, where are you located?

And some pictures would be nice too.

[Lobsterbox]

Welcome to 4x4 world.
What tempurature was the environment that you where using the machine.

BTW I too am in Canada, BC to be exact, where are you located?

And some pictures would be nice too.

Thanks for the quick reply! It was a particularly hot day when the machine reached 240 degrees. The ambient temp was around 35 C. I live in Edmonton, Alberta. I would have uploaded a couple pictures of the Argo itself and the temperature gauge but my internet was giving me grief and Flickr wasn't working.

Cheers!

[Tomo]

HI
First and easily done -change thermostat. Please take note at what temperature is printed on the thermostat is the minimum operating temp 170f [71c],180f [80c],195f [92c] [there can be hotter but unlikely ].This will be the minimum the engine will operate at after 20 min warm up.
The system needs to be pressure tested at 5 lbs pressure above the radiater cap pressure for coolant leaks . Test radiator cap blow off pressure .[with the same tool]

Test operating temp of system .Run engine with a thermometer in radiator neck .U will see the coolant flowing and the thermometer will go up and down with the electric fan .
The fan on -off temps will always be above the thermostat temp

Only fill system with demineralized water50/50 with coolant or u can buy complete fill [already mixed ]
Use either a glycol based or a hybrid glcol/OATS.
Flush old coolant out with house water then fill with demineralized and dump ,u r now ready to fill .
The hybrid will mix with almost any coolant remains of any type

Radiators have cooling tubes that block easily .
A radiator shop can rod the tubes in the radiator [u cannot test for this u just do it ]

If equipped with thermo fan. Verify operation .
The electrical sender unit may not be working properly and/or to specification

Check for corroded water pump impellor [remove to inspect]
Check fan belt if equipped and mechanical fan if equipped
Check for blown head gasket [pressurize cooling system and see if water comes out cylinders/plug holes when engine turned over.
U can also TK check which is exhaust leaking into system .

Pay close attention to cooling air into the body /engine area and the out let for all the hot air .
A few ideas ,,,Leave the bonnet off ...bilge fans ...very good ducting with the muffler inside to remove the hot air
tomo

Ps in hot weather the 8x8 do get hot in the tropical area I live in . The dealer used to install an additional fan . Where and how I do not no. This came up when I was looking for a used 6x6/8x8.

[msafi65]

My first thoughts are thermostat but my gut feeling is failed head gasket. My favorite way to test head gaskets on liquid cooled engines is as follows. Find an air holder capible of supplying compressed air to the spark holes. A compression tester with the check removed or a spark plug with the porcelain broken out can have a fitting brazed to it. Remove both spark plugs, valve covers me all the rocker arms. Pinch off the tube from top of radiator to coolant tank. Fill radiator to top don't leave any way for air to escape. Apply at least 90 psi air to cylinders one at a time and watch for coolant discharge from radiator. If it holds air for more than 2 minutes head gaskets are good. I've found scratches in heads that were just a black line that leaked under power this way. Parts are available for this engine. Hope you don't need any more than a thermostat.

[Lobsterbox]

Thanks for all the good advice guys! Msafi65: Now that I'm dealing regularly with Liquid Cooled engines, a cylinder pressure tester would be a handy tool to make I'm sure!

Good news guys (I think). I decided to remove the thermostat completely today and see if that made a difference. I put it all back together and filled the radiator back up with what I had on hand (some no name brand ethy. glycol concentrate and bottled water). It took a while to get up to temperature but it ran nominally and never even went over 180 degrees F. I put it through it's paces with two hours of wide-open-throttle swamp bogging and it didn't skip a beat!

Since it preforms well with the thermostat out do I need to worry about head gasket failure and/or a bad water pump?

[ARGOJIM]

Since it preforms well with the thermostat out do I need to worry about head gasket failure and/or a bad water pump?

Probably not, get a new stat and try it out. Also verify temp with an infared tester or contact gauge, as it may be a bad gauge or sender.

[Lobsterbox]

Probably not, get a new stat and try it out. Also verify temp with an infared tester or contact gauge, as it may be a bad gauge or sender.

Tomorrow I go to John Deere and pick up my thermostat. I've got to try stopping at Princess Auto to buy one of those infrared sensors, since the gauge pegs itself whenever I turn my lights on. Turn them off again and after a moment or two the gauge snaps back to normal.

[philipatmaxfour]

you might not want to leave that bottled water in your cooling system. As others have said you want distilled water with no minerals in it in your cooling system. Some "natural spring water" types have a lot of minerals in them that settles out so bad that you can see them floating around after long storage.

[Tomo]

HI
Running a cooling system without a thermostat is typically not a good idea
Some engines will overheat without a thermostat coolant goes to fast thru radiator
Sometimes the opposite happens , the cooling system runs very cold
When running cold ........a lot........ of engine wear occurs

If the engine overheats with a thermostat installed the engine has an issue somewhere else

tomo