I recently bought a used Kubota RTV900 with a plow attachment to take care of a long, steep driveway this winter. I think it’s a 2006 and it has about 460 hours on it. The previous owner told me when I bought it that it needed an oil change but I know nothing else about how well it was maintained over the years. While going through the items in the maintenance schedule I discovered a problem with the coolant system. The coolant reserve tank was completely empty so I filled it and soon after noticed a spot of antifreeze on my garage floor. I had never noticed a leak before. I took the protective panel under the radiator off the bottom of the RTV and could see that the radiator itself, the drain valve, and all hoses and connections were dry and tight as far as the hose going into the engine block. I then took off the next protective panel that is right under the forward part of the engine. The engine-facing side of this plate was covered with a mess of oily debris that had to be scraped off and the engine itself was pretty dirty also. I cleaned things up with some paper towels and ran the engine to see if I could spot any leaks. After running the engine for only a few minutes, I saw a drop of coolant on the side of the crankcase right behind the starter motor. I wiped it dry, started the engine again, and the drop re-appeared after a few minutes. I was expecting to find that maybe the water pump was leaking, but I don’t see how that would cause the coolant to appear so far back on the side of the engine block. I can’t see anything else that might spray coolant onto this area. If the cylinder block actually has a hole in it I would expect I would see a lot more problems than just a slow leak of coolant. I am fairly handy but as I’m sure you can tell I’m new to engine work so I thought I’d see if anyone could help me diagnose this problem. Thanks.
2006 RTV900 coolant leak
- Thread starter dennardo
- Start date
aurthuritis
Well-known member
yup the freeze plug is leaking. could be corrosion? they are EZ to replace? just google freeze plug in videos. as another fix you can use an expandable rubber plug in it's place but you sacrifice a little protection.
We use the expandable rubber freeze plugs to seal the pipe tops in out cattle panels. They tap right in and tighten up with a socket or boxed end wrench. It looks like a round rubber piece and a washer on each flat end with a bolt /nut in center.
They keep water out of the cattle panel vertical pipes and so they don't freeze and crack in the winter. (another good use for them.)
collie
They keep water out of the cattle panel vertical pipes and so they don't freeze and crack in the winter. (another good use for them.)
collieThanks for the help
Thanks for the replies. I am also afraid that this may be the start of many problems. The machine has low hours but some of the corrosion is significant. I've been watching a few videos and it seems like it is worthwhile to try to replace that plug myself. It looks pretty straightforward once the starter motor is out of the way and that looks pretty easy, too. I'm going to research replacement plugs, gather my materials and give it a go.
Thanks for the replies. I am also afraid that this may be the start of many problems. The machine has low hours but some of the corrosion is significant. I've been watching a few videos and it seems like it is worthwhile to try to replace that plug myself. It looks pretty straightforward once the starter motor is out of the way and that looks pretty easy, too. I'm going to research replacement plugs, gather my materials and give it a go.
Did you get replacements from Kubota? Some folks seem to prefer brass plugs and I thought I might look for those and replace the one right beside it at the same time. I got the Service Manual for the RTV900 but I can't seem to find an engine diagram with part numbers, so it's difficult to go looking for specs. Or to be sure exactly how many of these plugs there are on this engine and how many are relatively accessible.
aurthuritis
Well-known member
don't use brass. u will get an electrolysis and something in the system will become an anode and rot away. drill a small hole in the old plug and put a pan head screw in the hole so you can pry on the screw or best use a slide hammer. use a little sealer on the new plug and drive it in with a socket that matches it's OD.
fixed it
Just in case anyone was interested, I fixed it and it was pretty easy. I got the plug from the local Kubota dealer. After removing the starter motor I used a mallet and blunt piece of metal to tap one edge of the old plug. This made the opposite edge come forward until I could grab it with a pair of vice grips and pull it loose. After cleaning the edge of the hole, I put a bead of high temperature sealant around the new plug and hammered it in using a socket to distribute the pressure and avoid deforming the rim of the plug. I did a radiator flush and got back up and running with no leaks. The pic is the new plug before the starter motor was re-attached.
One potential problem is that the cooling system is supposed to have a capacity of a little over a gallon, but on all flushes and the final fill I could only put in about a half gallon. Also, when I removed the old plug there was a bunch of sludge behind it the color and consistency of mud. I assume it is mostly rust. Is my coolant system running with half the amount of fluid because it is half-full of sludge?
Just in case anyone was interested, I fixed it and it was pretty easy. I got the plug from the local Kubota dealer. After removing the starter motor I used a mallet and blunt piece of metal to tap one edge of the old plug. This made the opposite edge come forward until I could grab it with a pair of vice grips and pull it loose. After cleaning the edge of the hole, I put a bead of high temperature sealant around the new plug and hammered it in using a socket to distribute the pressure and avoid deforming the rim of the plug. I did a radiator flush and got back up and running with no leaks. The pic is the new plug before the starter motor was re-attached.
One potential problem is that the cooling system is supposed to have a capacity of a little over a gallon, but on all flushes and the final fill I could only put in about a half gallon. Also, when I removed the old plug there was a bunch of sludge behind it the color and consistency of mud. I assume it is mostly rust. Is my coolant system running with half the amount of fluid because it is half-full of sludge?
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aurthuritis
Well-known member
was the old plug rusted or pitted?
Yes I replaced with a Kubota part and had no issues with the plug sealing. I just replaced that one freeze plug.
Sounds like my coolant system, I replaced the radiator which was full of rust.
Personally, I'd remove the thermostat and both radiator hoses from the radiator. I hook a garden hose to the lower hose and flush the engine until the water runs clear. Hook the hoses back up and use something like this to flush the system until the rust is gone.
https://www.amazon.com/Thermocure-Coolant-Remover-Removes-Cooling/dp/B00R74I5UY
Add good antifreeze and drive the wheels off of it.
https://www.amazon.com/Thermocure-Coolant-Remover-Removes-Cooling/dp/B00R74I5UY
Add good antifreeze and drive the wheels off of it.
I followed this advice yesterday. When the water first ran out of the engine block it was kind of rusty but not nearly as bad as I thought it would be. I let it run clear and then took the hose to the radiator again. After getting everything put back together it still only took about a half-gallon of coolant before it was full. I'm just going to keep driving it and see what happens. I recently got the temp gauge fixed, so at least I'll be able to tell if I'm getting too hot.
I'm not looking forward to taking the seat and seatbelts and plastic panels off to get to the radiator again if I have to. Some of the bolts were extremely hard to get out. The first step was to remove the rear seat cushion, and even that was a problem. The bolts had rusted to the threaded pieces that are hammered into the wood seat back and I had to cut them out to remove the seat. The wood (maybe chipboard?) it is made of is too thin to hold a screw so it is not too secure right now. Also, the head of one of the hex-head bolts holding down the center panel stripped when I was putting it back together, so that'll be a job and a half to get out.
I would elevate the front with radiator cap off and run a bit and see if it would burp any air out. There may be some air trapped .
The newer seats have a plastic base instead of untreated wood. Those bottoms don't rot thankfully. collie
The newer seats have a plastic base instead of untreated wood. Those bottoms don't rot thankfully. collie
aurthuritis
Well-known member
take out the thermostat and drill a small 3/32 hole in it then reinstall. the air will work it's way out.
This brings back memories. Used a sawzall to cut the screws along the floor. What a PITA.
I hadn't even thought of air trapped in the system (shows how much experience I have with engines). I actually elevated the rear wheels when draining coolant to help it all drain out, and I left it that way when filling. D'oh! I did then re-check the coolant level after putting the rear wheels back on the ground and it was still full. I'll give this a try, though - thanks.
There is no problem with a hole in the thermostat? Does this just mean that a small amount of coolant goes back to the radiator even when the engine is not hot?
Yes it does mean a small amount of fluid by passes the stat all the time but the fix has been around for years as a way to get air out of the system.
The air in the system will effect cooling much more than a small hole. When the air is gone, you could replace the stat to see effect it has, but my guess is it's not dramatic.
It's a excellent suggestion.