Mower losing coolant

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I have a 2022 Kubota ZD1211 with ~80 hours on it that is randomly losing coolant all of the sudden. It has a diesel 1100 cc liquid cooled engine.

It was fine all last season, but up until now it’ll loose around 1” of coolant from the reservoir after every other use or so. The radiator is full and the machine isn’t overheating… the coolant just has to be going somewhere so I am concerned. Also, the oil is fine and I’m not seeing any obvious leaks when it’s parked and running.

I should really take it to the dealer, and likely will, but I am hoping to diagnose/ fix it myself to eliminate the hassle and downtime.
 
I will second the thoughts of Lubener. Do a pressurization test along with visually verifying the external integrity.

This might be a perfect situation to try to analyze the lubricant to see if it has had coolant ingression.

Hopefully your issue is with something simple to repair like a hose or radiator. Doing head gaskets can become a can of worms if you have to resurface block decks and heads OR deal with cracks.

Keep us posted please.
 
UOA to rule out head gasket, cracked head, or oil/water heat exchanger if equipped

I'd carefully inspect all hoses, clamps, radiator, water pump.... .and look for signs of leakage, as those could be easier DIY repairs.

If under warranty, you will have to take the downtime if you can't replace a headgasket.
 
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I like UV dye in the coolant. It will detect even the most tiniest seepage. The kit is handy for other vehicles also. Nothing on the UV then a UOA is in order. I had the UV cooling system dye show up in the oil in a GM 3.1 with the famous intake gasket issues. Slight UV was detected, UOA confirmed the leak.
 
I’ve used it twice since making this post and haven’t had any noticeable lose.. though I haven’t checked the reservoir cold since using it yesterday.

I did send for a uoa kit too.
 
I like UV dye in the coolant. It will detect even the most tiniest seepage. The kit is handy for other vehicles also. Nothing on the UV than a UOA is in order. I had the UV cooling system dye show up in the oil in a GM 3.1 with the famous intake gasket issues. Slight UV was detected, UOA confirmed the leak.
I apologize for just now seeing this. I may have to give this a try too.

Do you just add to coolant depending on coolant capacity and shine a light after use?
 
I apologize for just now seeing this. I may have to give this a try too.

Do you just add to coolant depending on coolant capacity and shine a light after use?
Yes, most kits included a UV flashlight. And dye refills are usually available for oils, coolant, A/C, etc. The dye will find the tiniest leaks.
Dye in and run it so it circulates and goes through a heat cycle, so system gets a full hot/cold expansion cycle.
 
I have a 2022 Kubota ZD1211 with ~80 hours on it that is randomly losing coolant all of the sudden. It has a diesel 1100 cc liquid cooled engine.

It was fine all last season, but up until now it’ll loose around 1” of coolant from the reservoir after every other use or so. The radiator is full and the machine isn’t overheating… the coolant just has to be going somewhere so I am concerned. Also, the oil is fine and I’m not seeing any obvious leaks when it’s parked and running.

I should really take it to the dealer, and likely will, but I am hoping to diagnose/ fix it myself to eliminate the hassle and downtime.
I assume the unit is still under warranty. If not, Kubota is a very genuine quality company who takes great pride in their products. There is a chance that even if the unit is slighty out of warranty, they will fix it. This card of course could be played if it is a head gasket.
 
It’s still under warranty, but I’m trying to avoid downtime at the dealer. I might talk to them though if I can’t figure it out.

Usage has slowed down a lot after messing with the cap. It lost about 1/4” in the reservoir a few uses ago and has been steady.

My next step is a UV kit.
 
It’s still under warranty, but I’m trying to avoid downtime at the dealer. I might talk to them though if I can’t figure it out.

Usage has slowed down a lot after messing with the cap. It lost about 1/4” in the reservoir a few uses ago and has been steady.

My next step is a UV kit.
at least let then know and get it on paper. could prove to be an expensive issue.....do you use the thing for business?
 
+1

Downtime sucks, but machines are expensive and if this is a bigger issue you want documentation of it being checked by the dealer while within warranty.
You’re absolutely correct. I’m going to give it a few more uses and if I can’t figure it out, it’ll go in to the dealer.
 
I bought the same machine a couple years ago and had the same problem. After 3 years I finally found where the very small leak was coming from.
After it sat the winter in my conex when I checked it prior to starting the coolant was low and a spot was on the floor.
I put mine on an auto lift to see underneath and I found all radiator hoses were weeping. I removed all hoses (real pain) cleaned inside of hose and neck and reassembled with some permatex and new clamps. Level is now steady.
90cummins
 
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