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DannoXYZ · October 29th, 2020, 08:59 PM

Hi Malique and welcome to Ninjette!

There’s multiple paths you can take to recover, depending upon your mechanical skills. Headgasket can be replaced in less than 1/2-day if you’ve got the skillz and tools. Otherwise, replacement used engine would be easiest. Make sure you get compression-test done; otherwise you may be buying another engine with blown headgasket as well. Best to see and hear that engine in operation before buying.

Bubbling coolant overflow tank is due to blown headgasket allowing combustion pressure into coolant passages. That’s literally exhaust bubbling in your coolant tank. Note that blown headgasket is just effect, result of real problem which caused overheating. You should track that down otherwise your replacement engine will also overheat and blow headgasket. TEST and repair/replace:

- radiator, backflush and clear out. Verify it flows plenty of liquid in forward direction

- radiator cap... need pressure-tester to measure pressure when it opens. Might be easier to just replace it

- coolant hoses, test and verify they all flow cleanly with no cloggs

- thermostat, verify opening temperature by bringing to boil in pot

- fan, disconnect and apply power & ground directly and verify it’s operational

- fan thermoswitch, again, test in boiling pot and verify temperature where switch closes contact

- fan circuitry, re-connect fan, key ON, jumper terminals at thermoswitch connector and verify fan turns ON. If not, you’ve got blown fuse and/or bad fan wiring. If fan doesn’t run in this test, find out WHY and fix it! DO NOT skip past this test until you CAN ABSOLUTELY 100% for sure manually trigger fan to run!!!

- water pump, hardly ever causes overheating due to lack of flow. Most of time, shaft seals wear out and they end up leaking well before fins wear out. Last place to look for overheating issues. Most likely one or more above is cause of overheating problem.

When you’ve got it all back together, warm up bike by letting it idle. Temperature will increase to point where cooling fan turns on at about 2/3rd way up temp-gauge. If not, turn off engine before it overheats and blows headgasket. Go back up to top of list and verify everything is operating correctly and measures within specs.

Good luck!

October 29th, 2020, 08:59 PM	#2
DannoXYZ ninjette.org certified postwhore Name: AKA JacRyann Location: Mesa, AZ Join Date: Dec 2011 Motorcycle(s): CB125T CBR250R-MC19 CBR250RR-MC22 NSR350R-MC21 VF500F CBR600RR SFV650 VFR750F R1M ST1300PA Valkyrie-F6C Posts: A lot. MOTY - 2018, MOTM - Nov '17	Hi Malique and welcome to Ninjette! There’s multiple paths you can take to recover, depending upon your mechanical skills. Headgasket can be replaced in less than 1/2-day if you’ve got the skillz and tools. Otherwise, replacement used engine would be easiest. Make sure you get compression-test done; otherwise you may be buying another engine with blown headgasket as well. Best to see and hear that engine in operation before buying. Bubbling coolant overflow tank is due to blown headgasket allowing combustion pressure into coolant passages. That’s literally exhaust bubbling in your coolant tank. Note that blown headgasket is just effect, result of real problem which caused overheating. You should track that down otherwise your replacement engine will also overheat and blow headgasket. TEST and repair/replace: - radiator, backflush and clear out. Verify it flows plenty of liquid in forward direction - radiator cap... need pressure-tester to measure pressure when it opens. Might be easier to just replace it - coolant hoses, test and verify they all flow cleanly with no cloggs - thermostat, verify opening temperature by bringing to boil in pot - fan, disconnect and apply power & ground directly and verify it’s operational - fan thermoswitch, again, test in boiling pot and verify temperature where switch closes contact - fan circuitry, re-connect fan, key ON, jumper terminals at thermoswitch connector and verify fan turns ON. If not, you’ve got blown fuse and/or bad fan wiring. If fan doesn’t run in this test, find out WHY and fix it! DO NOT skip past this test until you CAN ABSOLUTELY 100% for sure manually trigger fan to run!!! - water pump, hardly ever causes overheating due to lack of flow. Most of time, shaft seals wear out and they end up leaking well before fins wear out. Last place to look for overheating issues. Most likely one or more above is cause of overheating problem. When you’ve got it all back together, warm up bike by letting it idle. Temperature will increase to point where cooling fan turns on at about 2/3rd way up temp-gauge. If not, turn off engine before it overheats and blows headgasket. Go back up to top of list and verify everything is operating correctly and measures within specs. Good luck! Last futzed with by DannoXYZ; November 3rd, 2020 at 09:57 PM.