WTH is this weird, plastic thimble in Radiator Reservoir Hose?!

[Jerome Nelson]

I've had some issues with random overheating in my 2000 Tahoe.

You can see the troubleshooting below, but it seems pretty clear, that the coolant is being blocked.
I've flushed the radiator multiple time, and I'm still getting rusty, coolant water, with little, tiny brown bits coming out of it.

Out of frustration, I started taking hoses off to ensure none of them were blocked. One of the hoses I removed was the hose that expels the Radiator reservoir water to the engine block, right behind the thermostat. This line also "y"s from the heater core hose. When I removed the hose, I tried flushing water through it, but it was blocked. I was finally able to flush out this weird, thimble-sized, plastic "cap". (Please see image)

Is this supposed to be there?!
If so, what is it?!
Is this what is causing the random overheating?!
(FYI - the photo makes it look like it's about 20% bigger than it really is.)


TROUBLESHOOTING:
No oil in the radiator
No water in oil or transmission fluid
The fan is working fine
The water pump seems to be working fine
No heat in the cabin, but I think the actuator needs to be replaced - next on my list.

TRUCK DETAILS:
2000 Tahoe LT
5.3L
2WD
4-Speed Automatic
202,*** miles

 

[89Suburban]

I know there is supposed to be a restrictor in that hose but that baffles me.

 

[03catburban]

Appears to me some blocked off connections most likely during some repair work and left it on when they clamped hose back on

 

[Fless]

I know there is supposed to be a restrictor in that hose but that baffles me.

The restrictor is needed for the INPUT hose to the surge tank. That's the OUTPUT hose. OE radiators have the restricted port built in, but it's in the port for the short small hose from the radiator to the surge tank. Apples and oranges.

 

[iamdub]

I've had some issues with random overheating in my 2000 Tahoe.

You can see the troubleshooting below, but it seems pretty clear, that the coolant is being blocked.
I've flushed the radiator multiple time, and I'm still getting rusty, coolant water, with little, tiny brown bits coming out of it.

Out of frustration, I started taking hoses off to ensure none of them were blocked. One of the hoses I removed was the hose that expels the Radiator reservoir water to the engine block, right behind the thermostat. This line also "y"s from the heater core hose. When I removed the hose, I tried flushing water through it, but it was blocked. I was finally able to flush out this weird, thimble-sized, plastic "cap". (Please see image)

Is this supposed to be there?!
If so, what is it?!
Is this what is causing the random overheating?!
(FYI - the photo makes it look like it's about 20% bigger than it really is.)


TROUBLESHOOTING:
No oil in the radiator
No water in oil or transmission fluid
The fan is working fine
The water pump seems to be working fine
No heat in the cabin, but I think the actuator needs to be replaced - next on my list.

TRUCK DETAILS:
2000 Tahoe LT
5.3L
2WD
4-Speed Automatic
202,*** miles

I think it's a cap or plug for a port on a new radiator or new water pump and someone put the hose over it and it eventually blew off inside the hose from the water pressure. Basically, I agree with @03catburban.

 

[rockola1971]

Yeah that totally looks like a factory seal for a radiator or water pump. One that would be on the part while its awaiting a new home installed on a vehicle. Used to keep dirt and debris out of a new part.
Not supposed to be there.