L3800 radiator cap

[Jim L.]

I could use some help.

My used L3800 has a radiator cap with no markings, other than ".9", which I take to be .9 bar or 13psi.

The part number is supposed to be TC422-16090 (Kubota).

Is a Kubota cap marked?

Are the caps a 2-valve design; do they allow coolant to move back from the overflow tank to the radiator?

Thanks for walking out to look at your tractor!

 

[gpreuss]

My L3200 also says 0.9, stamped on one of the grab ears. It has a large top rubber gasket, and a smaller spring driven rubber seal down below, with the overflow tube between them. I can only assume it allows back feed - it has never been hot enough to blow coolant out, and I haven't the courage to suck on the cap to see if it allows flow.

 

[Bluegill]

I've never had any issues with the radiator cap on my L3800. What's the problem?

 

[Jim L.]

Thanks for eyeballing your tractor and the information.

The radiator cap on mine turns out to be a 2-valve. So maybe it is original equipment.

What's happening is that coolant is not getting sucked back into the radiator from the overflow tank. Maybe the radiator cap is the right part, but now to isolate between the radiator cap, the overflow hose(s), or the plastic cap on the overflow tank for air leaks.

 

[North Idaho Wolfman]

The hose should be free of leaks and the cap should vent to the outside.

 

[Jim L.]

The good news is that the hoses work and coolant comes out of the overflow container when vacuum is applied to the hose.

The bad news is that when I start from cold, with the radiator cap off - - looking into the radiator neck I see bubbles and frothing.

Oh Wow Bad News. Likely a leaking gasket or worse.

One month left on warranty. Anyone had experience on warranty claims?

 

[Jim L.]

My service guy says that on a 2012 model the new radiators will show bubbles.

That if there is no coolant in the oil, and no overheating, then I am likely OK.

Derned newfangle machines.

 

[ShaunRH]

Bubbles can be from pump cavitation while cold. The thermostat is closed so the pump is just churning away. If there is a path for that churned fluid to get back into the radiator, you'll see bubbles. They should go away once warmed up and the T-stat is open, but then you're looking at a very short timeframe before it starts coming out of the radiator... to quote Homer Simpson... "DOH!"