I have a 2004 acura tl that just hit the 190K miles and service light came one to replace trans fluid, oil and radiator coolant. I drained and re-filled coolant as per service manual (https://acurazine.com/forums/third-g...0/#post8600501). I am sure i followed the instructions to the T. Then after going to the store about 10 miles, i thought i would check my trans and coolant fluids. I noticed that my radiator reservoir cap was broken. It could just be coincidence that it was time to replace the cap but i thought i would ask if there could be anything else like to much antifreeze?

 

They crack.

I noticed mine cracked after my mechanic did my timing belt/water pump.
He didn't even fill up my coolant reservoir and it was super low (from fluid lost during the service job) so I don't think too much coolant would cause it.

The cap is super cheap.

 

I wasn't sure if the reservoir was pressurized or not, i was think it was but just thought i would ask.

Thanks for the reply!

 

slight pressure, not huge
i drove around with a cracked cap for a few days and asked the dealer while i ordered the cap, they said no harm

 

What's the deal with the reservoir anyway? I can see it bubbling over and filling it up, but can it really drink coolant from it when needed? Doesn't look like it to me. If not than why the min/max lines?

 

IMO it's old and brittle and you snugged it up too tight. A couple others posted the same recently. Its a pretty typical kind if break you'll see with all kinds of plastic caps as there can be quite a bit of force put on the cap's inner top when tightened.