Coolant reservoir cap - correct one?
 

Hi, so I just bought a '95 Disco and there's something amiss with the coolant reservoir cap - it doesn't fit correctly. It starts out as if it is the correct one, but then it binds up and goes cockeyed to the point of beginning to cross thread; yet the tank doesn't appear to be cross threaded as of right now. The previous owner said that this (new) tank supersedes the original one that split a while back, but the cap is for the original one (that split). In essence, he changed the tank but not the cap.

Does anyone have any insight to this? All the ones I see to order look just like the one I already have, and I'd rather not buy the same one over again. As it is, this cap will not hold pressure since it's not able to seal properly.

No visible part numbers to go off of, but the owner believes the tank to be part number PCF101590. He also mentioned that the cap I need is part number NTC7161 as listed on Atlantic British. NTC7161 looks exactly like the one I already have.

Any ideas??

Pics attached.

Looks like the right cap. Both the OE black and newer translucent tanks take the same cap.

Check your tank and cap threads again. Something's got to be wonky. Or maybe the plastic on the tank isn't rigid enough and it distorts when the cap starts to seal.

Yeah, I'm going to give it a closer look. Maybe it's cross threaded but hard to tell. Someone might have gorilla-fisted it from day one I don't know. I was afraid to do that myself because I wa told it was the wrong cap but sounds like it might be the right one after all. I noticed the D2 caps look like the BMW ones...

you can see in the first pix the threads are crossed just after it starts










































































7

I figured it out. Thread on the tank were fine, as was the cap. I popped out the center pressure valve disk and the cap screwed right on with no issues; however the disk wouldn't fit inside the hole on the tank. The problem was that there was excess plastic (as if left over from the manufacturing process) on the inside lip of the tank opening which prevented the pressure portion of the cap from seating, thus not allowing the cap to be threaded onto the tank. Glad I didn't buy another cap.

FWIW - since the round disk inside the cap itself just pops right out, I suppose you could rig something up to pressure check that it actually opens at 15psi if you were to feel so inclined.

You're going to cut off the excess tank plastic and reinstall the part in the cap, right??

Already done - fits like a glove. The excess plastic was just enough to keep the disk inside the cap from being able to fit inside the hole. Absolutely zero loss in structural integrity as a result of this trimming out of the hole. It's like they forgot to do it at the factory or something.

Do not mess with a junk cap, buy a new one and prevent the possibility of toasting your engine, they are about $17 at NAPA.

The cap was never the issue, but for posterity sake I might change it anyway. I prefer not to shop at Napa...