B7500 overheating

[edl123]

I have a kubota and its overheating the radator is cleaned and flushed, replaced water pump and termostate after about 15-20 it starts to run hot. The temp gauge goes over to about 3/4 of the way over and it starts coming out of the over flow tube. Any thoughts or ideas on what could be causing this? It never overheated until about 6 months ago I have had it for a while and it has about 360 hrs on it.

 

[85Hokie]

You say that you cleaned the radiator .......... how did you clean it ?

Check oil .......... and water in it?

Have you used a thermometer to measure the temp at top of radiator neck and bottom neck? - should be a good 100 degrees difference .......

off the top of my head - sounds as if you have a head gasket blown..... or worse, a cracked head or block.

IF you have a blown head gasket - when you start it again, have radiator cap off - start engine and look carefully into top of radiator - any bubbles?

 

[BruceP]

It never overheated until about 6 months ago

Overheating an engine is VERY BAD for it. This is why there is guage or light to alert operator before damage is done.

If it has truly "overheated".... the head-gasket may be leaking combustion gasses into the coolant or worse: head may be warped or cracked.

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There is a 'test' which can be done for combustion-gasses in the coolant. (basically dip a test-strip)

Also consider doing a leakdown test. (Replace radiator cap with small bycycle pump and pressurize the system...then wait to see if the pressure bleeds down)

Many autoparts stores will loan to you an leakdown tester for the weekend.

 

[Yogihorseman]

I have a kubota and its overheating the radator is cleaned and flushed, replaced water pump and termostate after about 15-20 it starts to run hot. The temp gauge goes over to about 3/4 of the way over and it starts coming out of the over flow tube. Any thoughts or ideas on what could be causing this? It never overheated until about 6 months ago I have had it for a while and it has about 360 hrs on it.

I had the same problem with my B7500 I could mow for 30 or 40 minutes and it would get hot had a small hole in radiator so replaced it still got hot changed thermostat still got hot, the next time it got hot it melted a hole in the fuel tank neck so I bought a new tank and installed it wrapped the muffler and exhaust pipe with muffler wrap I mowed all summer and it does not get hot

 

[BruceP]

wrapped the muffler and exhaust pipe with muffler wrap I mowed all summer and it does not get hot

This is worth repeating because it is true for all ICE engines. (lawnmowers, motorcycles, equipment...etc)

Keeping the heat WITHIN the exhaust-system has several benefits:

• Cooler underhood temperatures
  • Less heat from exhaust gets into nearby components.
• More engine-power
  • as exhaust gas cools (expands) , it loses energy, flows slower, and reduces turbocharger efficiency
• reduces noise

The main reason street cars do not have 'wrapped' exhaust is due to longevety.... the 'wrap' holds water against pipes and rots them out. Instead, they may use double-walled tubing or less conductive stainless-steel.

NOTE: A turbocharger actually converts HEAT into compressed-air. (not just exhaust-gas flow) This can be seen by measuring EGT (Exhaust Gas Temperature) before/after turbocharger.