Radiator Cap Replacement

I am reasonably convinced my Radiator Cap is leaking.

Can anyone confirm that this is the right part to buy for my 2021 TRD ORP?
16401-31830

I had read that Toyota changed the P/N for the radiator cap in 2020 or 2021. I just want to be sure I'm ordering the updated part.

If there is an aftermarket cap that is of higher quality, I would certainly value your input.

 

Stick with OEM.

 

You have the right part number. I am happy enough buying Gates brand radiator caps - think they are just as good as OEM and cheaper. Gates part number is 31412. Certain things I buy only OEM or OEM Supplier (i.e. Denso, NGK, etc) like sensors and fuel injectors but radiator caps is not in that category.

 

imo, id get an oem from the dealership. But first, why do you think its leakign

 

I've been smelling coolant after I pull in the garage lately so I popped the hood and found coolant residue on the hood liner (which ive now cleaned off). It looked centered above the cap. Nothing on the engine and water pump, thermostat housing, and hoses looked fine without evidence of a leak. Pulled the garnish panel and found a drip of coolant below the cap. Under cap was some dried coolant on the edge outside the seal.

 

It would take more evidence than that to convince me to replace the cap. I'd clean that off and look at it again is a few hundred miles. Is the resivour full?

 

The overflow is down about 3/8" since my last oil change 4k miles ago. It's about 1" below the full line. Don't think it loses a lot, but enough to leave deposits on the whole front and sides of the hood liner.

 

You are right to replace the cap - no brainer. They are cheap and a frequent source of coolant leakage. I replace mine every few years as PM. Beyond that, I do the cap and thermostat whenever I drain the coolant.

 

Just ordered the cap from a local dealer.
I agree @Buckaroo . For under $22 shipped to my door, it is worth it to see if the cap is indeed my issue.

For future reference, I ordered part number 16401-31830. Will update this post to verify 100% that is the correct part one I receive and install it.

 

im surprised that it has failed. I still have the original on my 2011 Sr5 with 168k. Have you pulled the cap and checked the gasket?

 

I'm surprised as well. My 06 had 165k on it w the original cap. I kind of feel like it has been problematic from day 1. Would smell coolant periodically and had a little residue on the hood liner. Just starting to get a bit worse so I decided to dig in last night.

I did remove it and clean it. The gasket seems fine - no tears or visual defects. However, I did notice it doesn't quite have the tightness of other radiator caps I've had in the past when locking it down to the radiator. Perhaps the metal plate that acts as a spring behind the gasket is just weaker than it should be and when there is pressure in the system, it allows a tiny bit of coolant to escape. Hopefully, it isn't the sealing surface on the radiator itself, but that looked fine and felt smooth as well.

For less than $22 and 10 minutes of my time, I think it's worth trying a new one to see if it actually is the problem.

 

i agree. Let us know how you make out.

 

If the replacement cap doesn't resolve the issue, don't throw more parts at it. Pressure test the system first.

 

Agreed. If it doesn't resolve it, I will pressure test. Cap was a cheaper option to start with.

I haven't received the cap yet but since cleaning the original cap, I haven't had any leaks or coolant smell.

 

OP, I just ordered the same part # cap as you for my 2019. I'm changing coolant and main hoses this winter.

 

How many miles on it? I am big on proactive maintenance but 5 years seems overkill on hoses. OEM Toyota hoses last a long time from my experience.

 

4Runner spent its 1st 3years in AZ and now it has 105K. Getting it ready for Spring roadtrips for my girls senior season of college softball.

 

Doesn't hurt I have replaced early before for peace of mind. AZ heat I am sure is tough on rubber.