Don't want this to come off the wrong way, but you know it's spinning when there's coolant circulating through the system.

All jokes aside, there have been past threads on this forum where members have sheared off the "ears" of the supercharger (which interface with identical ears on water pump) whilst wrestling with removing it, or the water pump, or both.



I'm with you! As I stated earlier, there are only so many things that this could be, so if the thermostat checks out, and the heater core is good, and the water pump installation and connection to s/c is good, it comes back to whether the system hasn't bled properly for whatever reason.

Stupid Question: Your drive belt is still intact and spinning the supercharger pulley, correct?

 

It's working then, as fluid is moving through the system, just not through the heater core as far as I can tell. That would rule out the PTO gears being bad. I changed out the serpentine belt last week Everything spins as it should. Once I rule out the thermostat again tonight, I am going to try and bleed the system a few more times. If that doesn't do it, I am going to breakdown and have it towed to a shop to let them try and figure it out.

 

+1 thats a good test to rule it out, i have seen new ones stick, rare but it happens even with the OEM MINI one.

 

Just two thoughts:

It would not hurt to attach a garden hose direct to a heater hose, just to be sure it's not blocked in some manner.

Is it possible to connect the heater hoses upside-down or back-to-front or inside-out or downside-up or in such a way that through flow is not possible?

 

Tested the thermostat and it opened at 195 as it should. I bled the system again after it was all back together. It took it longer to overheat, but still did. I watched the fan as well. So, the low-speed fan isn't turning on. All I got is the high speed fan turning on at 233f. What are the odds that not having the low speed fan working would cause the problem?

 

Your finding is exactly what I expect given the odds.

You should get the low speed fan fixed. As a temporary fix you can wire the low speed to the high speed if you know what you are doing so at low speed the fan will run at high speed. Much better than no low speed.

You should stop trying to second guess your problem and proceed to check the PTO gear unless you find it too difficult to perform.

 

I don't know if you have the tool to remove the belt from the supercharger. If you don't you can only try to spin the PTO, and if you can spin it with your fingers it is conclusive the gear are toasted. If you cannot spin it it is not conclusive as it could be toasted and seized in a mess inside. The conclusive check is to spin the pulley side of the SC and see if the PTO spin in unison.

Still if you have very high miles the best is to open the PTO and check the condition of the gears as well as top up the oil if all is well.

 

My low speed fan doesn’t work and I never overheat. I will repair it when I replace the AC compressor that blew out when the fan quit. Is there some way that you can disconnect the top heater hose and poor water directly into the heater core?

 

To OP. One more fruit for thought. If your car ran fine and rather suddenly it overheats and given all the steps you have done, it is almost certainly is the coolant not circulating through the radiator. Corrosion that cause a radiator to clog is very rare nowadays. The only thing that remains that you haven't confirm is if the SC PTO reliably turns the water pump. Additionally you have no heat from the heater which is another strong evidence the new water pump is not pumping water.

 

I'm going to pull the watsr pump back off this morning, along with the belt to check the PTO gears. I'm actually hoping they are bad so I have a smoking gun on what's causing all of this.

 

Welp, that did the trick. PTO gears are shot. Thanks for all the help guys! At least I know I have a completely replaced cooling system once I swap out the super charger.

 

Great that you’ve finally uncovered the cause of your overheating problem.

So we’re talking about the internal gears inside the s/c PTO end, and not the ‘ears’ that interface with the water pump, correct? Maybe post a pic of the point of failure?

I’d also make it a priority to fix your fan, whether you replace the entire unit, or swap out just the failed low speed resistor. FWIW, if you do end up replacing the fan, hold onto the faulty one, as you can throw on a new resistor and have a backup ready to go if you have a resistor fail again in the future.

Let us know how you make out after the s/c has been replaced.

 

My 2005 MCS has the same problem.

 

My apologies for chiming in, but I have the same issues and results as Darik67u.

 

It is possible that the radiator is clogged, from someone using stop leak. If this is the case a new radiator will be needed! (about $120)
If it is building pressure and blowing out the cap, the head gasket may be blown. Use a cooling system pressure tester to find where the leak is. You will have to remove the spark plugs to see if water is getting into the cylinders! An inspection camera, to put down the holes will be helpful. Don't go over 15 psi for the pressure test!