328 cooling fans, still a challange

Followed all advice so far. Fans for colling are still not comming on. Changed the temp sending unit in front, checked the fuses.....When I jumper the temp sensor, both fans kick on. Thought it might be the relay, but if the fans kick on when jumped then the relay is working right?.

Also checked the level in the resovior and filled it to 3-4 inches from top.

What Am I missing.

Was wondering, what is actually sensing the temp? Is it the sending unit. what if my water pump was failing and the coolant was not circulating, therefore the sensor would not be picking it up the high temp????

When I changed the sensor there was definately coolant present as some was pouring out during the quick swap of the sensor.

Help please, want to drive it but too affraid

 

"When I jumper the temp sensor, both fans kick on. Thought it might be the relay, but if the fans kick on when jumped then the relay is working right?." -- Yes, that result indicates that the relays and the associated wiring are all OK.

"Was wondering, what is actually sensing the temp?" -- There are really two independent sensors -- the thermoswitch in the radiator (to switch the relays "on) and a thermister at the engine (to run the temp gauge).

Are you sure your thermostat isn't stuck closed (i.e., coolant just recirculating in the engine)? When temp gauge reads ~200 deg F (and the fans aren't on, but they should be) are the main lines at the radiator also very warm to the touch?

 

When my Boxer did that it turned out to be a bad fuse box connection. I just bought a new OEM fusebox, soldered all the rivet connections and installed the new fusebox. That solved that problem.

 

Also- "3 or 4 inches" from the expansion tank top is too low. Fill to 6mm (at least on a 308 QV- are they the same?) or about 2" from the lip. That extra inch or two of fluid is more than you would think. My QV fans were inop and I was low on coolant. I was about 2" low and ended up putting in about 2 liters to get it up to the correct level. If you put in too much coolant/water- it will overflow through the expansion cap as it gets to operating temperature. No big deal.

FWIW-A top off of the coolant, and a thorough bleed procedure couldn't hurt. Maybe you already did this, so please disreguard if you have.

Good luck

 

Actually, it is 6 CM from the tank neck...but like you said, if overfilled, it will spit or boil out the excess in short order...

I'm falling in line with Steve Magnuson's thought that he may have a stuck thermostat.

 

Sorry- typo. I meant to type "6cm", but put "6mm". Correct you are.

Back to the problem- It sounds like there is not enough coolant- either it's low, or the thermostat is stuck closed, or there is crud in the system which is blocking the travel.

When mine was low, the temp guage was reading very warm, but the radiator wasn't getting enough coolant to the radiator temp swich to turn them on.
Sounds similar to your problem.

Please keep us posted on what you find. Thanks