I just had a friend stop by over the weekend to have his reservoir replaced and while he was at he stopped off at an Auto Zone and grabbed a brand new reservoir cap.


The reservoir was in an OEM LR box and looked very nice, and that was a quick install. I then slapped on the Made In China Motorad Reservoir Cap that had a black center vs the OEM Yellow center found on the original cap.


He took off and it wasn't even 25min later when I got the distress call that he was on the side of the road due to it suddenly starting to overheat and he saw steam from under the hood. I hauled butt and got to him just at the bottom of a bridge under construction (in a very bad spot IMHO). He popped the hood and the dang reservoir cap was no where to be seen!!!! I eventually found it down under his SAI pump.


I was like I know I threaded it on properly, so I tried it again, and when you went to really tighten it down it popped and then you could pull it right off!!!! At first I thought maybe it was the threads on the new reservoir, but when I used his OEM (he was keeping it as a spare) it tightened down properly. His original had nasty looking seals on it so I carefully swapped them out with the Motorad unit, topped off his coolant, burped it the best I could on the side of the freeway, and I followed him for 10 miles. We inspected it once more and no more problems were found.


He will be taking that Made In China Motorad reservoir cap and getting his 17.00 back. Then he's going to order an OEM unit online. My friend asked who made the cap when he bought it and the Auto Zone dude said all their caps, thermostats are made by Motorad. I believe him as most of the stuff I've ever bought there was stamped Motorad.


I'm not saying they're all crap, or that Motorad makes bad thermostats, but I'm SO glad I didn't swap out the cap on my 02 (was thinking about it as it's the original cap) before I went on my 800 mile trip or I'd have been truly pissed off had it done that to me with my family in the car with me! Something told me to hold off on that inside my head and I'm sad it happened to my friend, but at the same time I'm glad it wasn't me lol.

 

Sucks for the cap, but why did he overheat?

When our head gasket failed I took the cap off so we could drive it awhile without pressure. Driving it awhile turned out to be 5 months until i redid the head gaskets.

 

 

Yep the cap blew off once the system got any pressure. Purely the caps fault as I tried to install it again and when tight it popped (think the plastic is thinner and the cap flexes) and the cap could just be pulled off.

When he saw temps of 207F (went from 193F very quickly) he pulled over, when he came to a complete stop that is when he saw the steam from the engine bay.

By the time I got there it had cooled down enough that I was able to top it off with 1.5 gallons of coolant & I gave him the rest I had in case he needed to top it off. After swapping the cap he was back in the 193-195F range on the rest of his 90 mile trip.

I had that issue with crappy caps during my H3 days. Had to use an OEM vs the cheap auto part store units.

 

I know that... I guess I read the OP comment wrong. I thought the cap popped from his initial turning it too far.

 

Nice save!

 

Yeah it was on fully like it should have been & when the system got up to temp it popped off completely. I truly thought I must not have threaded it on properly, but when I re-installed again I found it wouldn’t fully tighten down without popping the threads every single time. It would not properly seal. Seriously I think it’s just thinner plastic vs the OEM cap & it’s flexing. He took it back today and got his $$ back.

And yes I am glad he’s aware of his LR vs just driving it until the red light of death pops on! He said he saw 193F then 205F and when he finally came to a stop it was at 207F upon shutdown.