Overflow bottle cap
 

Hi. 69 144s B20b. I have overflow bottle 673624 123. with a lip at 2cm deep, I am using pressure cap TVS 10. Is this correct?

Basically, there are long and short reach caps. If the bottle should use a long reach it will obviously fit but a short reach cap will go on but won't seal. If the bottle should have a short cap, a long one almost certainly won't squeeze down to fit.
I think there are 2 bottles, one for late B18 and one for B20. I think only the B20 one is available now. Not sure if they both used what I think is a long cap but Brookhouse says that if using the B20 bottle with a B18 you have to use the B20 bottle cap. I suspect that you have had the 144 long enough to have always used the correct cap but they are easy to measure and check.

I actually have the two caps and both can fit. The short reach cap goes on easily and the long reach can co on with some pressure.Will post photos of bottle and caps.

Your description echos my comment and the long one should suit your bottle. The 10 = 10psi, which is fine.

As a follow up I haven't been able to find bottle #673624 in the catalogues. There is a reference to that number in the Volvo Competition services catalogue where it says that it should be changed to a #686833 (standard B20 type) but that's all.


B18 bottle #676588 with cap #673336
B20 bottle #686833 with cap #673233


As I write I have a 686833 in front of me and that has the following measurements. Top down to sealing ridge 2cm. the hole into the bottle 3cm. Difficult to see from your pic but yours might have a slightly bigger hole? maybe Volvo made it smaller by thickening up the section to make it more rigid? Then changed the number? Looking again at your pictures, awkward when you have two threads, I see that your bottle has no strengthening rings around the neck, so my hypothesis might be right. This one also has a ring around the area the blow-off holes are. Pic attached.


Make sure that the two tabs on the cap slide properly down to the lock position. I had a Saab bottle which is the same as the Volvo one where the top had distorted and one of the tabs would pop off the ramp. That meant the seal only partially pressed against the ridge in the bottle. The result, boil over when coming to a halt after a fast run.

I’m guessing you need the higher pressure cap. On mine I need to remove the bottle from the mountings to apply adequate pressure to the cap and screw it home.

It's OK to tweak the tabs on the cap slightly to make it easier to fit and take off the cap. Don't bend so they are at an angle. I've not done it but polishing up the plastic and applying a very light smear of silicone grease would probably help smooth things a bit. It uses a constant pressure spring so there won't be any difference to the seal performance.