oil filter tightness

There is allot of information in the various oil change threads.

 

As Ed quoted, 18 ft.lbs. Which is very little. Those caps don't need much more than hand tightening.

 

Also there's a clip which appears to keep the oil filter housing from loosening. I tighten it and make sure the clip falls into the correct position to block any movement. I will even reverse direction to make sure the clip is just right. No leaks for 1.5 years.

 

I work at Fram oil filters. I would be happy to send you the toyota factory instructions for changing the filter if you pm me. I tried posting them and the forum will not let me.

 

I'm willing to bet you have it tighter than is needed.

 

I just tightened mine hand tight and I do not like to tighten the pan bolt too tight either, but I use socket wrench there. I always use John's instructions from many years ago, it is so good.

 

There's a torque spec on the filter box, I believe it's the 18 ft/lb's mentioned above, or thereabouts. I happened to have an oil filter socket that fit (think it's an industry standard size), so I was ok with my first oil change: torqued it to specification. IMO that's a fair bit tighter than "hand tight".

FWIW, the seal is made by the O-Ring which is a little ways down a machined hole, so even with hand tight, as long as it doesn't rattle loose you should be ok. Also, there's a tricky little clip who's purpose is (I think) to prevent a loose cap from unscrewing.

The cap install instruction says to start the screwing in process with a tab on the cap 90 degrees away from..., well something. I believe the idea is to do this so the clip ends up in the recess at the tab, but not 100% sure on this. I think it's a fairly good idea, but the documentation is confusing. It might help if they explained the intent.

 

I recommend using a torque wrench to tighten both the filter (18 FT/LB ) and drain plug (27 FT/LB ) on the 2010 Prius.

The 2010 Prius cannister/cartridge filter with o-ring has a different feel than the old metal can filters so it is risky to rely on the old school hand tighten feel or number of turns method to tighten it. Also, it is interesting to note that the torque requirement for the metal can type filter on my 2007 Camry is 10 FT/LB, which is typical for such filters and less than the Prius. If one uses the hand tightening method on a Prius after having been used to doing so on metal can filters, it is likely that the Prius filter may not be sufficiently torqued.

We can still change our own oil on the Prius. I know I will be more careful than the junior tech at the dealer. However, I have come to realize that the Prius is much more sensitive to perfoming even routine maintenance/repair operations according to the book than other cars I have owned.

 

I've done both the oil changes on my prius thus far. I do it in the driveway on some ramps, which makes it hard for me to get any real leverage to really tighten anything down since I'm laying on my back when I do it. I typically tighten everything until it "snugs", then give it between 1/4 and 1/2 turn with the ratchet. That usually does the trick for the filter and drain plug.

 

The o-ring in its groove is what does the seal. Once the cap bottoms out, tightening it more doesn't help. Just screw it in until it bottoms out, but no tighter.

 

^ Yes what he said. You can feel the filter cap bottom out in it's housing. The retainer clip will keep it from unscrewing itself.

 

Question: If you only need to "just screw it in until it bottoms out, but no tighter", why does Toyota specify a torque of 18 ft/lb for the oil filter cap?

Answer: Toyota knows that an o-ring requires a certain amount of compression to seal properly, in this case 18 ft/lb. The most reliable method to insure the correct compresion of the o-ring is with a torque wrench. A person who does a lot of Prius cartridge type oil changes may be able to do it reliably without using a torque wrench, but I only change oil in my Prius twice per year, so I use a torque wrench to be sure. Your "no tighter" method could cause the o-ring to be not compressed enough to seal and the cap to leak oil. I don't think you will find any authoritative automotive maintenance manual or publication that prescribes your "no tighter" method.

 

I torqued to 18 ft/lb, but I think it's mainly to ensure the oil filter cap stays secure. That and the little clip, for insurance.

I can't see the torquing changing the behaviour of the O-Ring. It's on the side of the cap, and when installed sits a little distance down inside the cylindrical oil filter cavity. Torquing doesn't compress it against anything.

 

There are actually three things happening when the oil filter cap is torqued to the Toyota specification:

1. The o-ring is compressed against the o-ring seat inside the oil filter bracket. That's how oil rings work.
2. The oil filter element is sealed against its seat inside the oil filter bracket to prevent oil from bypassing the oil filter element.
3. The oil filter cap itself is secured to prevent it from coming loose.

When you are working with plastic and aluminum parts, it pays not to either over or under tighten them. Undertighten them and they leak; overtighten them and they break; professionals know this. Amateurs think they can get away with old outdated techniques but eventually they get burned. Then, they think it is because of a "poor design", or such other lame excuse, when really it is a failure to learn and adapt to the changes in technology.

 

I wonder which "touches down" first: the end of the oil filter element or the lip on the oil filter cap? Can't see them both making contact simultaenously. I would guess the lip of the cap is what's getting torqued, ie: the main faying surface. And the filter element end is just snug.

 

The o-ring is on the barrel of the cap, not the flange. Once the o-ring is past the conical section of the housing, it's compressed fully, and tightening it more doesn't make it seal better:

Here's where the o-ring first touches the conical section:
| |
| \____
--O--

Once in, it's sealed even before the cap bottoms out:
| |
| \____
---O--

Bottoming out the cap makes sure it can't back out, and there's the metal tab-thing that helps:
||
|\____
---O--

Sealing is done by position, not extra torque (like with cartridge filters.

 

cit1991 - Your drawings are probably correct. Did you take measurements? It would be easy to measure the distance between the o-ring and the cap flange and then transfer that measurement to the inside of the oil filter bracket to see exactly where the o-ring resides. Saturday, I changed the oil in my Prius for the fifth time, before I saw your above post. Had I seen your post beforehand, I would have measured. I did notice how little effort it takes to torque the cap to 18 ft/lb, which leads me to the conclusion that tightening without a torque wrench probably leads one to overtighten, rather than undertighten, the cap.