I've identified and used every item in this D-series bottom end kit, except for the large o-ring.

At first I thought it was for the oil cooler which some engines had, but it's way too big to be that.

Anyone know what it was for?

 

water pump?

 

Yeah what he said^
Isn't it supposed to be formed tho lol

 

Nope, definitely not the water pump.

 

Well then your kit is missing a water pump gasket and I have no idea what that is XD

I looked up fail pros conversion set seems to have the water pump gasket and timing cover gasket but only one of the water pipe o rings I'd look at oem Honda parts diagram to see if that gasket is present somewhere but I doubt it never seem that in any of the d series engines ive taken apart

 

I'm not missing the water pump gasket, it was in the box with the new water pump itself.

I already looked at the honda parts diagrams for several different year/versions of D series motors and haven't found anything that looks like that o-ring.

I've always hated having parts left over, but I think it's the simple fact of not knowing what it's for which bothers me the most.

 

I looked at a couple of the gasket sets on ebay look about the same but a full gasket set should have a water pump gasket regardless if what you bought came with a new waste pump Imo

 

Here is just the conversion set very similar to what you have there and the conversion set most of time includes a water pump gasket

http://item.mobileweb.ebay.com/viewi...id=12024620466

Here is fel pros conversion set notice a water pump gasket
http://www.amazon.com/gp/aw/d/B000C2...dir_mdp_mobile

 

ohhhh so basically its just a cheap water pump seal that you form to fit.

mystery solved!

 

Off topic, but Ive been on your build thread and damn it looks good. I hope you can make that generic gasket you are using to seal better than what i had. (i bought some off ebay) didnt last too long. probably 25-30k.
My HG went too. The leak came from between the cylinders. sucked but i sure learned that you cant buy good quality with cheap prices. Unless youre getting whole seller price...