Erratic cooling

My problem is why today and not yesterday? Same load, same road, same air temp, same driver. That radiator core came out of my ‘06. It looked good 250,00 miles ago. I need to check on the impeller on the water pump. Just because the water appears to be moving slowly through the radiator, it isn’t necessarily the radiator slowing the flow. If it is the radiator why the change from day to day. I doubt the core is plugging and unplugging itself. I need to put a camera in a capsule and send it through the cooling system. Don’t I wish.

 

That had crossed my mind and I was going to call Detroit. I would hope by this day in age people would have quit coming up with stupid ideas related to pump impellers. But but but we can save $.07 per impeller by doing this. I will check it for sure.

 

Case closed. Joke is on me. I NEVER would have believed it. I disassembled all the cooling system possible. Back flushed and flushed everywhere. Put a hose in the top of the radiator. Top tank filled asap. I can pee a bigger stream than what came out the bottom. AARRRRGGGGHHHHH

 

Yes. I put the water pump on a while back (1 year maybe). I just got off the phone with Russ. He tells me there is a baffle between the top tank and the core. He had a core issue and the water hose test looked good but the core was still partially plugged. So the garden hose test isn't a good one. Good to know. Next I told him that one day the truck is 100% ok cooling. Another day it won't cool. or cools half right. He hadn't yet read post #22. Now he and I both believe the water pump impeller is slipping. Russ informed me that even today water impellers can go to slipping. So I have my answer on the top tank and the impeller. So back to work.

 

Next update. It positively isn't the water pump. I removed the snap ring and plate and found the impeller to be ok. Next I removed the water pump to put it down on blocks so I could get the snap ring back in. I don't own any Paul Bunyan size snap ring pliers. Checked the bull gear for wiggle while I had the opportunity. So a core it is I guess.