When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The cap comes off counter clockwise, like any other cap.
If im having trouble getting a cap off, like the oil filter housing cap i'll put on work gloves with the rubber grips.
Then I have a big set of channel locks to use, put a towel over the cap to protect it from damage.
But that cap shouldnt be on that tight. Can see where the plastic nub went past where its supposed to stop (red circle), now its up over the ridge. Just have to force it off now.
The venting coolant cap is on "two-fingers tight" only. **
The seal is done by a large o-ring that does not need to be put on tight.
Did the plastic cap survive or split up ???
** in case you're missing coolant, its not the venting cap causing leakage.
It's likely caused by high heat - Inspect your radiator seams for cracks and signs of wetness.
Last edited by CaliBenzDriver; Sep 10, 2025 at 07:40 PM.
I looked on mine and there are 2 nubs on the cap. May have some trouble getting the cap off due to the 2nd smaller nub, may need to use something like a small screwdriver to pry upwards on the cap as you spin it off to clear the stop part on the reservoir.
Can just barely see the 2nd nub in your photo. (red square)
Ok, yea.
100% some doofus over-tightened this thing. Bought it back in May and I'll be doing most of the work on this car from now on.
I appreciate the cross reference pictures. Now I know that I need put on some rubber gloves, get a buddy, and see if I can lift that tab and turn it at the same time.
@CaliBenzDriver
No overheating issue nor do I suspect any leakage. The cap is not split or warped in anyway. If/when I get this thing out, you said there is an O ring in there. Should I just get a new one seeing as this one was crushed on for quite some time? Not sure if anyone else experienced issues with their caps. I see these things are like $10 on FCPEuro.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
