Logo

John Deere 6404 Overheating

rlsmart

New member
" My port John Deere 6404 &#40

" My port John Deere 6404 (1976, normally aspirated) overheats at anything over 1450 rpm. Before the onset of this problem it ran about 10 deg F hotter than the starboard engine. Now (until it overheats) it runs about 30 deg F hotter.
I've tried the following:
1) Replaced thermostat
2) Removed & rebuilt raw water pump
3) Cleaned through hull
4) Removed & rebuilt coolant pump
5) Removed & cleaned heat exchanger
6) Removed head & cleaned passages (some corrosion)
7) Checked coolant for CO (None)
8) Heat gun shows no hot spots, just generally 30 deg F hotter than starboard engine.
Have tried mechanics and John Deere reps. So far nothing has helped. Just ran across this site & thought I'd see if anyone out there had any advice.

Thanks "
 
Did you check the guage or se

Did you check the guage or sending unit to see if the reading is off.
 
I have heard of rubber hoses

I have heard of rubber hoses delaminating inside and acting like a flapper valve when water flows through. When there is no flow the piece hides back where it came from and when looking through it appears completely clear. Is the flow the same on both motors?
 
What about coolant level and

What about coolant level and proper closure of the coolant inlet? what about the exaust line?

ciao from italy
 
When you took out the raw wat

When you took out the raw water pump impeller were any blades missing?I came across the same problem on a Yanmar and found 6 blades from the impeller detached and got themselves stuck on the lub oil cooler end cap.This abviously restricts the flow rate with incresed RPM.
Good luck
 
Back
Top