Manager Forum

Good morning gentlemen,
I've got a 2004 infinity g35 that we did a thermostat and coolant flush on. Since then, the cooling system works fine while idleing in the shop. Fans come on (low speed) at 203 deg and go off at 190 deg. It will do this all day long until it's driven. After 10 minutes of driving the cooling fans switch to high speed and will not go off until shutting the vehicle off for a couple minutes then re start and works like normal again.While the fans are stuck on high, the air flow thru the rad is warmish to cool and the eng temp will go up to 230 deg, even going down the highway at 75 mph the high fans on and temp rises. Pull over, shut car off for a few minutes, and right back to normal again. I've followed Mitchel's bleed procedure to a tee, 4 times over. It doesnt take any more coolant, no air in system. I was thinking head issue, however, no evidence. I was thinking fans electrically get stuck on high, but the cool air across rad and temp rising tells me no, or else it would run cool, and even 75 mph air flow doesn't help. Anyone experienced a similar issue? I would sure appreciate input on this one. Thanks

Why was a thermostat and flush done? Did it have some kind of symptom before this?

we did a coolant flush for maintenance in mid march 2013. It returned 8 days later for no heat. Had heat when it left. we did t stat at that time for heat and heat came back and everything was hunky dory till the next day when cust said fans were loud (on high) and i've been bleeding system ever since.

These are a SOB to bleed..............................

I heard that Steve. I've thoughroly been thru the procedure 4 complet times and even lifted the fe so the car was at a 60 deg upward angle. The bleed procedure says when you stop having to add coolant it's done. So far it won't take any more. The fact of being able to shut it off for a few minutes, re-start, then works fine till 10 min or so of driving. Arrrrrgh. I guess for now i will continue trying to bleed system. Going for another ride right now, like Arnold says "I'll be back"

Have you tried one of those vacuum fill bleeders? I've had good success with mine.

Ric made a good point about the vac fillers. I love it and it's never failed me. I remember i had a Mazda that I swore was bled. I had that thing jacked way up and raced the engine, lit prayaer candles and hired a witch Dr. Finally it burped. Vac fill from that time on, especially Mazdas and Inifinities. Another thing I do is over the years i've crushed a few of the tellow fill funnel kits. Now I stick a few of the extensions together raising the funell up and it bleeds much better.

Another idea, see if the heater hose has been replaced abd it's looped wrong. I've seen hoses that are routed wrong and wuill always hold an air pocket.......

Vaccuum bleeders are great, I have one, also have one of those yellow jugs that attatch to the radiator cap from lisle, those work great also. Good luck.

i do have a vac bleeder, so i will try that first thing in the am. Its actually my last resort. Ive checked ALL the coolant hoses and they are all routed correctly, no kinks, good thought though Steve.

Thanks for the insight on this one. I vac bled it today and it was much better. Still not completely right so i adde coolant thru the bleed port on the heater hose and all set now, wshoooo. Thanks again

Thanks for posting the fix.

Well, just got a call from customer. He took it for a 100 mile ride over the weekend and a little while into the ride he heard the cooling fans come on high and stayed on the whole time. Temp guage in car stayed right in the middle, but fans never shut off. I guess I'll re-post a/the fix again later. Going to be looking hard towards possible head gkt issues. Tune in later, same bat time, same bat channel..

Before you jump to conclusions the sensors for the fans may have been damaged by the constant overheating. If the gauge stayed in the normal range throughout the trip, driving at speeds or at idle, I would look into the possibility of a bad sensor. This vehicle may have two sensors so look at it with your scanner. Another possibility is a bad relay. It also may have been overworked and once triggered won't release, although this usually will cause a fan staying on after key is shut off. Well, all i can say is a few times in situations like this I've shot myself in the foot by assuming. Good luck.............