Topic: oil filter cover nut size

[crashmaster]

PO hacked up the nut on the face of the oil filter cover that you use to turn it on/off. I plan to weld on a new nut. Can anyone tell me what size nut/bolt head they used from the factory, so I can use a socket on it? like 15mm or whatever - see attached - part #8 Thanks

[Bodi]

The original was, I think, 10mm. That didn't last too well so a lot of aftermarket bolts were installed, usually 17mm.

[bryanj]

The original was 12mm hex and was that size so you couldnt hamfistedly strip the thread out of the crancase thearby ruining the cases, aftermarket are frequently 17mm and can strip the threads out, why piss about with welding all the fours up to F2 use the same bolt and they are not expensive

[crashmaster]

Thanks. I am a welder at work, so no big deal to weld it. A new bolt is like $40. It will take me 10 minutes to do it. I will stick a 12mm on there.

There is a check valve inside the bolt. Does anyone know if it is it metal? Don't want anything getting to hot that shouldn't. Thanks

[bryanj]

Rally? Put in google and got this

[newday777]

Vintagecb750 has the bolt for $23.40 with free shipping

https://vintagecb750.com/collections/engine

[dave500]

I welded a 19mm nut on one and cost me zero,just dont wind em up real tight it aint a wheel nut!

[crashmaster]

I was looking at South Sound Honda last night for other stuff and saw the price there for OEM. I didn't shop around cause I can fix it. Thanks

[Deltarider]

I welded a 19mm nut on one [...]

That's what I did, be it a 17mm nut. Personally, this is the kind of part you want OEM, not aftermarket. It's long ago, but I remember reports on such an aftermarket bolt where the valve moved the other way or not at all...
Damaging the OEM bolt can be prevented. Tap it with a hammer before loosening it, ideally with a socket on a T-handle. Don't overtighten it ofcourse.
Tip: especially O-rings that come with aftermarket oilfilters can resist staying in the groove during reassembly. When you buy an oilfilter, have that O-ring under a heavy book in the months before you need it. I have had good results with the Encyclopedia Brittanica.

[crashmaster]

I was just looking and 12 mm is a little small. I agree, 17 mm is a pretty good size. The PO left some meat on the existing bolt that I want to utilize so I have to have a big enough size to swallow that. Thanks for all the help

[kerryb]

A new small pipe wrench will grab what’s left and remove the damaged bolt.  Chuck it in the lathe to make the stub match your nut.  Weld on new nut, clean the overpressure valve in the bolt.  Cost, fun time.  You’re only squeezing an oring for the seal.

[crashmaster]

A new small pipe wrench will grab what’s left and remove the damaged bolt.  Chuck it in the lathe to make the stub match your nut.  Weld on new nut, clean the overpressure valve in the bolt.  Cost, fun time.  You’re only squeezing an oring for the seal.

Yup 👍

[CycleRanger]

Just don't do this.
As found on my K5 when I got it.

[crashmaster]

Just don't do this.
As found on my K5 when I got it.

That's so you can get a big crescent wrench on it and stand on it for max torque...

[Don R]

 What Dave said, ^ just because it's a got big nut doesn't mean you need to tighten it with a breaker bar. Jeez.

[bryanj]

Now i know this is anathema to you us cousins but awhitworth size socke( cant remember if 3/16 or 1/4), is a nice hammer on fit to a knackered 12mm hex and the hammering on usually loosens the bolt

[Bodi]

The valve is a steel piston and a steel coil spring, held in with a steel split pin. No rubber. I doubt you would heat it up enough to affect the spring temper.

[piefairy]

My bike came with a 17mm from the PO. I've always just gone hand tight plus a little with the wrench. Like others said, just compressing 2 gaskets.

[dave500]

I took mine apart to weld it,also gotta lotta gunk out.

[BenelliSEI]

Just don't do this.
As found on my K5 when I got it.

I like this one. May have to make one of my own!

[spotty]

another option, which i've seen done before, is rather than welding a new nut on, weld a 3/8" drive socket on.

[Don R]

 I gotta get a pic of my aftermarket one, it's got a nut as big as a, well it's pretty big.

[crashmaster]

The valve is a steel piston and a steel coil spring, held in with a steel split pin. No rubber. I doubt you would heat it up enough to affect the spring temper.

Thanks Bodi

[HondaMan]

When the Kawi 903 came out with their oil filter bolt, it was in 17mm size. This made lots of Honda home-wrenchers (who had rounded oil filter bolts from using the Honda toolkit wrench ) go get one of those instead.

Here's an important thing to know about this oil filter cover: use ONLY Honda's own O-ring on the outside of the cover. Theirs is thicker (always was) than the other ones that come with a lot of oil filters today. The oil filter bolt gets stripped (and the cover cracked) from someone overtightening them to try to stop the weeping because they used the too-skinny O-ring in the oil filter's box.

Honda's O-ring is:
91316-425-003
O-RING (89X4.5)

[MauiK3]

By the way, nice GL engine up there!