power loss once engine gets hot?

[Kubota Dave]

B7800 with 600 hours once the tractor gets hot it will have a power loss as to where even driving it you have to take it easy as the RPMs drop if you push the peddle with nothing running. Take your foot off the peddle RPMs go back up.

This B7800 has always ran hot once it gets close to the red mark i stop bush hogging let it cool and it will run fine for 30min or so the outside temp seems to factor in on it.

I have checked the air filter housing, oil, hydraulic fluid, cleaned out the radiator and screen, radiator is full.........something i need to check still is the radiator fan.

Is it normal to have a power loss when a tractor gets hot?

 

[dodge man]

How are the fuel filters?

 

[Kubota Dave]

How are the fuel filters?

Dealer replaced them the last time it was there.

 

[oldnslo]

Is this something that happened gradually over time or a sudden change?

Does it sound like missing on one cylinder or just engine RPM’s drop?

 

[Tinhack]

Have you checked for a broken belt to your fan and water pump? Or even a loose belt will do it.

 

[rScotty]

For the best cooling, check that there is not an air gap between the fan shroud and the radiator. A lot of times there is a gap that is gasketed when the tractor is new, but the gasket goes away over time.

If you can see light there between the back of the radiator and the fan shroud, seal the gap with caulk or weatherstripping so the fan cannot pull air in from the sides behind the radiator.

The goal is to force fan to pull air past the radiator fins where it can do the most cooling.

 

[dodge man]

I’d check and make sure you are getting fuel to the engine when this happens. I know you said the dealer replaced the filters but that doesn’t mean you still don’t have a problem. The easiest way is with the engine off take a fuel line off and see if diesel flows out by gravity. When I’ve had plugged filters you could tell it wasn’t right when taking the line off after the filter.

The reason I’m bringing this up is that unless you are overheating the engine the heat alone shouldn’t make it run bad. Some tractors will pull power when the get hot but I’d think yours is old enough it wouldn’t be computer controlled.

 

[rScotty]

It might not be engine cooling. But that is simplest and has to be put right anyway.

I agree that most cases where RPMs drop means that it isn't getting enough fuel. But what if it is?

Then another possibility with a hot engine losing power would be an engine intake or exhaust valve is not sealing or doesn't have enough clearance....diesel owners rarely check valve clearance like they should.

Or the engine could be getting hot simply because it is being asked to do more work than it is built to do. That is not uncommon either - particularly when plowing or mowing where the load is high and continuous. The easy test is to ack off a gear or use a lower range, so it is going slower at full RPM and see if that will ease it enough to make it cooler and the RPMs stay up. If so, time to slow down or get a larger tractor - or smaller implement.

rScotty

 

[careyo63]

You can rent a Radiator pressure gage at any local big chain Auto Parts store. If it was mine I would leave it hooked up so you know what the Cooling Sys. doing. Getting Pressured up! Crack, Warped head, Head gasket etc.. Then you can pretty much rule those factors out. My Guess is one of the above Problem/Problems.

 

[SPYDERLK]

An overheated injector pump can do this. The reason I know is that my L3450 has a separate output from the bottom tank on the radiator leading directly through the pump. The tractor developed a symptom of losing power and missing when the temp registered about 2/3scale and up. Turns out the radiator fins were pretty clean, but there was some blockage in the vertical section feeding straight down to the tank in the place were that separate output was. Cleaned that set of rad fins and the tractor was back to normal.

I had thought the pump was failing but it was being "cooled" by too hot water.