David Lively

Anyone got any ideas on what this stuff is? Car runs fine. It's not really a sludge so much as... gunk, for lack of a better term.
A month or so ago, the engine got pretty hot (260ºF) when the fan controller harness melted. Just changed the oil, no sign of coolant / milkshake.

(2011 base.)

Dano523

Normal, and at the 5 year mark each time when its time to flush the Dexcool and replace it with new, make sure to pull the tank to use crushed ice in it with the cap on, to do a lot of shaking to get all the dried crap on the side walls out of the tank as well. The flush part of the mix at the 5 year Dexcool replacement takes car of the motor and most of the lines (done about three times until the water is coming out clear with not tint), but the fluid in the tank does go stagnant/not part of the recirculating distilled water flush, so tank need to be cleaned by hand instead.
Also, make sure to pull the heater core lines after the flush is done, to reverse flow it with a garden hose, to get the crap out of it as well.
Note, go both way a few times with the hose, to make sure to get what every is trapped before the coils, back out during is separate flush.


And no, dealer will not go to this length to make sure all the system is clean, like the tank and the heater core. They just dump the old dexcool out, put some water in to let it flush with the motor running for a few mins, drain that water out, add in the New Dexcool/burp the system and call it good. If you wanted them to clean the tank, they would just install a new tank on your dime instead. As for heater core reverse flush at the dealer, would be like pulling hens teeth most of the time, and would be an additional charge over the top (since it not show to be done this way in the GMSI).

Other items on the list, replace the T stat when doing a flush and leave the T stat out while doing the flushes.
Also, pull the top plastic cap for the Radiator/A/C condenser, push the condenser forward, and get in between the two with a long 90 wand garden hose tube to flush the condenser out from the back side, the radiator out from the back side as well.

if you need to see what you are making to use on the garden hose to flush out the two from thier back sides.
http://www.watersaber.com/


And at some point, will need to have the Ac system Freon vacuumed out, replace the in line filter and use a new O ring, and then have the system recharged, if the A/C is not working efficiently/ not a problem of blocked air flow through the condenser.


So yes, this is a reason that most of use wrench on our own cars, since can go into more detail of when doing the work ourselves/Don't have to fight with the dealer with them seeing such as addition work above and beyond the normal service and charging extra for it.

David Lively

@Dano523 Wow! That's an epic amount of detail. Thank you!

Dano523

No Worries, and the reason that the fan harness connector melted, is someone way over clocked the PWM controller to bring the fan on sooner. You can bring the fan on slightly faster, but there is no way in hell that the stock radaditor and fan is going to hold the temp of the motor below 210 when you are getting on the motor.

So oem stock fan tables, and as stated, you can bump them a touch in the tune to bring the fan on/start ramping it up at slightlly lower temps, but just trying to do a melt down of the entire system (PWM and all), adjusting the tables too far bring the fan on too low to try to hold the temp of the motor below 200.
Attachment 48335485

If you are on the stock tune/no one has played with the fan temp settings,the radiator/condensers have been sprayed cleaned, and you did melt the connector, then with the car off, reach in and spin the fan by hand. It should free spin when you give it a whirl, and it if does not, then either time to pull the fan apart to re-grease the fan motor bearings, or just replace the fan. When the fan bearings go dry, it starts to bind up the fan, which causes it to pull more power from the PWM to spin it and causes the increase temp problem in the connector as well.

David Lively

The car had a tune that, as far as I can tell, is for a supercharger. Fuel maps were super aggressive, timing changes, every downstream O2 sensor DTC disabled, idle set to 850rpm... good times. When I bought the car, it had been put back to stock (and the engine had been replaced). The next time I buy a used car, I'm taking my laptop and HP Tuners interface with me. :/

The fan tables were set to 99% over 205º. I'm not a professional mechanic, but I think whoever did that doesn't understand the "P" in PWM.

I'll climb in there this weekend and check out the radiator and condenser. Ten years and 56k miles; I'm sure it's not exactly pristine.

Thanks again for the advice!

Dano523

Don't need to pull them, just pull the top plastic cap, and this will allow you enough room to flush the raditor, then condenser forward from the back to blow the gravel/crap out with a garden hose wand type cleaner that can collect in the veins and can only be cleaned out back forward the way they entered.


Or store bought if you don't want to make one.
Note, the store bought set comes in handy for other things, since I use the air wand yearly to blow blow out my gas hot water heater filter/chamber section when I pull the burners to clean them. Same goes for servicing my heater and AC coils yearly at the same time, plus any other thing that I need a long reach wand off the air compressor.