02 tahoe overheating

[dbtahoe01]

A few days I noticed while sitting in traffic that my truck temp was getting close to 260. O turned the heat on and got home. The following day I drained the antifreeze and changed the thermostat. It seemed to be fine but today while waiting in line at a fast food spot it went over 210 and started climbing more...
I have a brand new 187 degree thermostat on the truck and have dex cool in the truck.
What else can be the issue?

Radiator, water pump?

 

[OR VietVet]

If you are not low on coolant I would expect the radiator may be clogged and not allowing coolant temp dissipation. I would also be aware that the 260 degrees likely damaged head gaskets and maybe heads. That is if in fact the temp gauge reading is correct. Get it checked by a qualified tech.

 

[dbtahoe01]

If you are not low on coolant I would expect the radiator may be clogged and not allowing coolant temp dissipation. I would also be aware that the 260 degrees likely damaged head gaskets and maybe heads. That is if in fact the temp gauge reading is correct. Get it checked by a qualified tech.

It's not low on coolant at all its full. It's never got as high as 260 but it was working it's way up. I have no leaks in my driveway so I wouldn't expect it to be the water pump. Last bad one I had it was leaking from the weep hole.
It is the original radiator, so perhaps thas the issue. The fan is belt driven to I know that can't be the issue.

I travel for business weekly and my mechanic isn't open on the weekend anymore so I have to wait til modal to drop it off to my mechanic and leave it there for 2 weeks til I get back in town.

Other than radiator what else would you recommend be replaced?

---------- Post added at 05:45 PM ---------- Previous post was at 05:44 PM ----------

Is there a quick way of testing to make sure it's not a head issue? I just replaced this engine in January

 

[dbtahoe01]

Attached are a few pics I just took.
I touched my intake tube and it's rather hot at the moment considering the truck has been parked for a hour.
The front of the radiator does have quite a bit of gunk and bugs built up on it and in the bottom a lot of debris. How can I clean it or should I just get a new one?

 

[dbtahoe01]

A friend mentioned the fan clutch to me and he's sure it's the issue...
Question is how can I figure our of the fan clutch is bad or not

I just tried turning it. Trying to spin it fast it stops very quickly. So I don't think that's the issue but I don't know a damn thing about the fan clutch. Maybe it's to stiff and needs to be replaced

 

[southboundchicken]

This is what i would do... Pull the grill off ( its very easy) and clean as much junk off the radiator and wash with water to flush any junk caught between the cooling fins then run to your local auto parts store and buy a fan clutch most likely thats your problem if your not losing antifreeze if thats not it it could be a bad impeller in the water pump or clogged radiator.... The fan clutch is cheaper than a radiator or water pump

 

[dbtahoe01]

I'll go ahead and wash it down today and try to replace the clutch fan. I'll go ahead and order a radiator too since it's only $80 and it's 14 years old. Last thing I'll replace is the waterpump..

engine swap was done in January b/c I had no compression in cylinder 7 and it cost more to fix that 1 cylinder vs swapping the engine to an engine with less miles. I had 256k on the engine the new engine only had 88k on it.
I find it odd that I swapped the thermostat a few days ago and it 100+ and didn't overheat yet it was only 88 yesterday and began to overhead again...

I don't have high pressure water at my house. Should I go to a car wash and use the high pressure hose to wash the radiator down? My dad lives 20 minutes from me and he has a 2800 psi pressure washer too...

---------- Post added at 08:04 AM ---------- Previous post was at 08:03 AM ----------

Btw, I used pure dex cool I didn't add any distilled water, should i?

 

[Sasquatch]

Dexcool is supposed to be a 50-50 ratio with distilled water.

 

[dbtahoe01]

Dexcool is supposed to be a 50-50 ratio with distilled water.

O ok so it's fine then. I kinda remember when I took the thermostat off the fluid being green which makes me think when I had the engine swap done they didn't use dexcool

 

[dbtahoe01]

Dexcool is supposed to be a 50-50 ratio with distilled water.

This is what I used