Temperature Spike on 4.0 V6

First time asking a question but have read several topics on here. Great forum! I recently bought a 2006 4.0 v6 Tacoma for my son. The engine was completely overhauled at 300k due to a blown header initially. New timing chain, water pump and several other items. I had my mechanic friend ask the previous owner about the overhaul and the previous owner gave me all receipts and very open to everything he did. I stay in contact with him asking questions here or there. We've had no issues until this week when I was getting two new tires. No temp issues on freeway but I noticed it rising a bit in traffic. When close to home, temp really starting rising when I was at a light. When getting over 30 mph, temp would go back to normal. Water pump is new, when I try to spin the fan, it has the resistance that I think it should have so don't think it's the fan clutch(I could be wrong). I've done a detailed engine clean to see if anything leaks as I'm losing radiator fluid at a very low pace somewhere. I seen head gasket, water pump, air pocket issues in other forums so just trying to figure out where to start. Any help is very much appreciated!

 

It's a good sign that it seems to be cooling properly when it's moving so hopefully not a head gasket or other serious issue. Two things come to mind that could be the issue 1) is the fan clutch 2) the water pump may not be moving enough water at low speed.

If you have a strong fan or two you could idle it in the driveway with the fans blowing air through the radiator to see if it's an airflow issue (fan clutch) or a water flow issue (water pump or possibly radiator).

You can also check with it idling to feel if there is ample air moving from the fan as it is.

 

Step 1 is check the coolant level in the radiator (not just the bottle) with the engine cool.

 

I have radiator fluid. I just took these pics after doing my engine cleaning. This is right above the power steering pump.

 

Sorry for the large pics...still new to this.

 

You’re certain it’s coolant leaking? It “looks” like oil. Id do a cooling system pressure test. You might be able to rent a pressure tester from an auto parts store.

$131 Stant Cooling System Tester, Metallic

https://www.amazon.com/Stant-12270-...automotive&sprefix=Coolant+pre,aps,143&sr=1-2

This is the one I had. I think for a backyard mechanic it would be fine. Mine kept taking a crap so I sprung for a snapon one.

https://shop.snapon.com/product/Cooling-System-Testers/Cooling-System-Pressure-Tester-Kit/SVTS272A

 

It’s a little unlikely the water pump isn’t moving enough coolant. The fins are metal and should not lose shape as long at the belt isn’t slipping. I looked for any mention of the thermostat and hope I didn’t miss it. That’s an easy check to make sure it’s not stuck half closed. No collapsed hoses? Air pockets in the 4.0 are somewhat more difficult to remove. I use a dedicated radiator full funnel to get the coolant level higher than the highest hose. You then stop up the funnel and dump the extra back in the bottle. Good luck.

 

The fan clutch should have resistance but it's also a component that when bad, will cause it to run hotter in traffic and when idling and going slower speeds.

https://www.youtube.com/results?search_query=testing+a+tacoma+fan+clutch

 

Thanks for everyone's feedback and I wanted to close the loop on my situation. I replaced the fan clutch, thermo, OEM radiator cap, did block test(blue liquid) and coolant pressure test. Ultimately, still had bubbles in overflow. Ended up a head gasket issue. 4 and 6 cylinders. Had a mechanic friend replace all gaskets and head bolts with OEM gaskets and bolts. Runs like a champ now. Now I'm replacing vapor canister to get rid of that code. I also have Icon 2.0 shocks that I need to try and rebuild. I called a place and they wanted $275 per shock so was going to try and buy the rebuild kit and fluid and do myself. I'm sure there's a thread on that somewhere in here.