: $8ish peace of mind for summer

04-19-10, 10:57 PM
So I had a gurgling noise coming from the overflow hose/t-joint above the radiator when coolant temps were above 210 and getting a "low coolant warning" on sharp curves. It's getting warmer so I should be getting the opposite effect with expanding coolant. Thought it could be the water pump, but its cheaper to try a new surge tank cap and see if that works. BAM, $8 dollars later no gurgling. On a side note, I'm on my 3rd radiator and they've gone bad on the upper seams with gelling dexcool. Maybe there's too much pressure in our cooling system or our tank caps go bad too early/often (I'm on 3rd cap @64,000 mi.). Anywho, if you're in SoCal, PHX, or Vegas this is good preventative maintenance for the summer IMO.

04-20-10, 06:48 AM
where did you get the cap? dealer or parts store?

04-20-10, 03:12 PM
I got it at Checker auto parts AKA Oreilly for our midwest brethren.

04-20-10, 03:56 PM
This made me think. I know mine leaks at high RPM. So I guess your saying that the cap doesn't let the pressure out, so it bleeds from the radiator.
I don't have a big problem with it. Just get the smell sometimes, and add fluid once or twice a year. But I think imma try this.

04-21-10, 03:28 AM
yeah the price is right for this..lol. It absolutely cannot hurt.

05-20-10, 08:37 AM
Replaced my radiator last week with an aftermarket. Filled the system and started the car with heat set to max. Fluid level did not go down and the air was still cold with the coolant temp showing 232. It took a while, but I finally heard a moan (like a cow getting boinked in the wrong hole). Fluid went down, I top it off and the heat is working inside the car. Went out that night, checking the fluid level and adding as needed every time I stopped.

This was last week and everything seemed fine since then. I got a burnt coolant smell last night, but wasn't sure if it was from last week when it leaked all over the motor (only drove the car a couple times).
So when I get home I decide to remove the cap and leave it off incase the system still has some air in it. Twisting the cap off and POP. A bit of fluid splashed out (not much really) but there was quite a bit of pressure built up in the system. Much more than I feel comfortable with. Safe to say the cap was not letting any pressure out.

I guess with all that pressure constantly pushing out on the crimps of the radiator, it has to give and let some fluid out.


05-20-10, 10:35 AM
do these cars have a bleed screw?

05-20-10, 01:37 PM
Is it a certain brand of cap or just some OEM replacement from Oreilly's?

05-21-10, 08:07 PM
do these cars have a bleed screw?

I assume you mean a petcock to drain the radiator? If so, no they do not just pull the bottom hose off.

05-21-10, 09:12 PM
I assume you mean a petcock to drain the radiator? If so, no they do not just pull the bottom hose off.

no - my bmw has a bleed screw on the top of the rad that I can loosen slightly to bleed off air and coolant while the system is pressurized. Doe the CTS-V have one?

05-22-10, 08:37 AM
Not on the radiator. I'll look for a spot on the motor, but I doubt it.

05-22-10, 09:05 AM
this thread has gone on to long without a pic of this pressure release cap and a part #..

05-22-10, 02:08 PM
I was just thinking I was on bimmerforums, all this talk of radiators etc.
Couple of things, there should not be air in the system except above the fluid level in the coolant reservoir. Our cars will typically, purge air on their own. All one needs to do when replacing a rad or doing a flush is to fill with coolant and run the engine through a few heat/cool cycles making sure the coolant level is correct adding as required. If the pressure cap is faulty ie too low, you probably will get fluid bubbling out the cap because it is boiling in the engine. This will seem like there is air in the system. If the cap has too much pressure, then the rad could let go....whatever is the weak link in the system.
Actually, now that I think of it no one replaces rad caps on BMW's when they have "issues", maybe that is a fix that is needed. (If you are wondering, I have a couple E36 cars for hobby wrenching)

05-23-10, 07:01 PM
I'm sick of GM radiators. I am on my third in 2 years! Ron Davis for me next time...