The other day i was driving home from work and my temp gauge went through the roof for about 20 seconds then dropped back down to normal range. Not sure if it's the thermostat but i would think that if it were it would be staying hot and not coming back down. i've noticed a strong smell of antifreeze in the cabin and i am chalking that up to a heater core that is probably leaking and needs replaced but i don't think that would be causing this. my fan clutch is working fine but i do here some potential squeaking in the bearing. not sure if it's a bad sensor or something but i'm afraid to drive it until i figure it out. any ideas?

 

by the way brand new radiator, brand new water pump, brand new thermostat.

 

If your heater core is leaking, you should either bypass it or fix it and not leave it like that. You will lose coolant continuously. To bypass it, you can connect the inlet and outlet hoses together or just use one hose and connect the inlet and outlet pipes at the front of the engine.
Have you checked the coolant level in the radiator? Is it low? Could also use a laser/temperature gun on the thermostat housing to see what it is reading. Are the radiator hoses hot?
there are a lot of simple things you can do to troubleshoot yourself.

 

i had no idea you could bypass that!!! With summer coming I need a heater like a spare butt so I'll definitely do that today!! Do you need to drain the radiator to do that?

As for coolant level it's good and the reservoir is good as well. It's almost like the gauge is bad or it's something electronic that's causing it. The fan clutch seems good and the hoses are hot and I can feel liquid running through them.

Any other tips or tricks? I need them!!

 

Air bubble in the system that was working its way out? When did you replace the rad, stat, and pump?

Or maybe a failing temp sensor?

 

No, but you need to go from 3/4" hose to 5/8" hose. Might find an adapter at the hardware store, or cobble something together from various plumbing parts. Don't use the plastic stuff - it doesn't like heat. Use brass.

Just cut your heater hose about 8" or so back from the t-stat & water pump, and plug both ends into your home brew adapter, and clamp. Top up the coolant. Done.

 

I have had to bypass my heater core on the fly and you can get the smaller hose onto the bigger fitting with some persuasion. You will lose a little coolant but not a lot.
If yo remove the hoses from the heater core be very careful. They will be stuck on there very well and those inlets on the heater core are not the most stout things in the world. If they are really stuck on you will be better to slice the hose and unwrap it rather than to force it off. I have some of these from harbor freight and these make old hose removal a snap: https://www.harborfreight.com/3-piec...ers-37909.html

 

just loop the hose from the water pump to the thermostat housing. Like this
I also put a T with a cap to remove the air, works awesome

 

I would not trust clamping 3/4" hose down onto a 5/8" fitting. Should be okay to go the other way - 5/8" hose stretched onto a 3/4" fitting.

 

One thing the OP did not mention was the OD temps at the time could have just got hot then e-fans came on and cooled everything back down quickly.