Questions about my oil pump

[Mailman]

I’ve got my right cover off right now , and I wanted to take the opportunity to poke around in there and see how things look.
Everything looks clean and free from any damage.
My questions are:
1. The screws that hold the oil pump together. Locktite yes or no? And anyone know the torque values for those screws?

And also my tach drive mount where it passes through the case, is leaking.
Do you think I can replace that red colored seal with a regular o-ring?

Mucho Gracias
Roberto

 

[XSLeo]

A new or-ring would help if you found one the right size. Also inside that piece in your hand is an oil seal. I doubt you can find one of those at the local hardware store.
If you properly tighten those mount screws you won't need any thread lock. 90 inch pounds / 7.5 foot pounds.
While you have it apart, check the clearances. I don't recall the specs but side clearance is important. With the rotors in the pump body, place a straightedge across the rotors and body, use feeler gauge to check clearance between straight edge and rotor. On my 75 I could just barely get the thinnest blade in on the inner rotor and just in on the outer.
An excessive side clearance allows oil to slip out past the sides of the rotors and this decreases oil pump efficiency.
Leo

 

[gggGary]

Yes the (available) seal inside the drive is usually the culprit and the shaft is usually pretty worn there getting that threaded insert out can be fun. XSleo makes good points but I don't worry much as long as the pump ain't beat to crap from debris passing through it. .

 

[MaxPete]

If you use Loctite - I'd suggest the removal "blue" grade rather than the (permanent) red variety.

As for torque on those screws - if they are 6mm dia. (I don't recall) then the manual calls for a standard torque of 7 ft-lb on that size fastener. The difficulty is getting a good reading on torque values using a screwdriver bit. For that reason, I'd suggest switching to SHCS fasteners (i.e. socket head cap screws - Allen head screws) if you can get some the same size. That way, you can get a good solid read on how tight you are making them.

On the seal question, I'd defer to the gurus but there won't be too much heat there so a good quality o-ring should be OK if you cannot get an OEM replacement part. I just looked on the Boats.net parts schematic and there are actually two sealing components on that assembly: an o-ring and a seal. It appears that both are still available at very low cost.

• 2) O-RING 93210-11313-00 List: $3.34 Boats.net: $2.14 req'd: 1
• 3) OIL SEAL, SO-TYPE 93104-07036-00 List: $4.62 Boats.net: $3.22 req'd: 1

So, unless the housing is scratched or otherwise damaged, it appears that you can renew the entire sealing arrangement of the tachometer drive for around $6.00 USD (plus, of course, the usual shipping charge). The unfortunate thing is that the seal does not appear to have been used on any other Yamaha models after the final XS650s were built in the 1983-84 timeframe. Having said that, the fact that the part number is still good means that the part is still available from Yamaha and that suggests that your friendly neighbourhood Yamaha dealer may have it, or be able to bring it in, for no shipping cost.

Your seal, in the photo above, simply looks worn to me so I'd try a new seal and see how she works.

 

[5twins]

That red o-ring is silicone. There are a few more used up in the head area, which I can understand because of the higher heat. A normal o-ring should be fine in that lower heat area on the case. This is one I tried to find a substitute for. My 1st attempt at measuring an original (difficult at best) and ordering some was a bust. The 1mm thick x 12mm I.D. size I got was totally wrong, not thick enough and too big on the diameter. Next I tried a 1.5mm x 11mm and that seems to fit/work.

 

[MaxPete]

You could also take it into a hydraulics parts supplier (look for "Parker-Hannifin" or "Sundstrand" in the yellow pages) and get them to match it with a high temp viton or silicon o-ring. They'll have a very large selection of o-ring diameters with many different cross-sectional dimensions.

 

[Mailman]

Ah yes, a closer look with a flashlight reveals the seal INSIDE that I missed seeing before.
I DO have a couple manuals, I should’ve looked at the diagrams before asking. Hmmm
I’m already waiting on some other parts , and it IS all torn apart now. I’ll look into it.
Thank you all for responding.
And Pete thanks for doing the legwork , looking up part numbers and such.
This forum really is THE BEST!
Bob

 

[Jim]

Do you think I can replace that red colored seal with a regular o-ring?

Use a nitrile rubber o-ring. Theyr'e oil and gas compatible...

 

[MaxPete]

Yup - not all o-rings are created equal.

 

[5twins]

It looks like the replacement Yamaha is now selling is no longer the red silicone type. Looks like just a plain black rubber one. They may also list the size in the description (1.3 x 11.8)? That is an oddball, lol.

 

[MaxPete]

True - but I'd bet that a 1.5 x 12 would fit OK with some gentle persuasion...

 

[Mailman]

Both seals have been ordered from Boats.net. They are racing across the continent as we speak!

 

[Mailman]

Am I screwed here? This is really bugging me, I reassembled my oil pump today. I hate running a screw into aluminum without any kind of lubrication, so I put a little motor oil on the thread of the screws and ran them in snug and then I started working them up to torque. I was shooting for 85 inch pounds. I was going slow, up 5 pounds at a time going back and forth on the screws. Then I got scared, I had my wrench set to 70 pounds and a couple of the screws just seemed to be turning a bit too much. I was afraid of stripping the housing threads, so I stopped and removed the screws, took a look at the threads and they looked ok.

Now I'm thinking, maybe oiling the threads wasn't a good idea, maybe it's messing up my torque reading. So I wipe the oil off the threads, both the screws and the threaded holes, and I start over. Same result, I can get right up to 65 pounds and everything feels solid, but go for 70 and it no longer feels like it's tightening. It just feels like it's stripping. So out they came again, another look at the threads.

This time I put some blue locktite on the screws , ran them to 65 inch pounds, and walked away. But I can't help worrying if things will be ok.
Btw Pete I should've taken your good advice and swapped the Phillips head screws over to Allen heads. I was being stubborn.

So did I screw up here?

 

[Jim]

Bob, Bell Helicopter did some testing a long time ago and determined that lubricated threads will tighten 30-50% more than dry threads for the same amount of torque. Caused several helicopter crashes. Unless otherwise instructed, threads are always torqued dry.

 

[Mailman]

One more little update, Gary warned me that getting the threaded insert out of the tach drive mount could be difficult, so heeding that warning, I placed that peice inside a small ziplock bag and sprayed it liberally with penetrating oil and zipped it up and just let it soak for a couple days. Popped loose first try.
My new seals arrived today, three days after ordering. Not bad.

 

[Mailman]

Bob, Bell Helicopter did some testing a long time ago and determined that lubricated threads will tighten 30-50% more than dry threads for the same amount of torque. Caused several helicopter crashes. Unless otherwise instructed, threads are always torqued dry.

You don't use anti seize on bolts going into aluminum? I am so paranoid about galling threads , I butter everything up! Yikes!

 

[Jim]

Nope. When a book sez ...torque to.... it's always assumed the threads are dry.

If they want the threads lubricated, they will use the phrase ... lubetorque to....

 

[Mailman]

Ok thanks Jim, so applying what you said, you think that my screws may indeed be higher than the 65 inch lbs that I have them currently set at?
I would think that even blue locktite would have some lubrication value.

 

[YamadudeXS650C]

Consistent with Bob's paranoia ))), I lubricate bolts going into aluminum, prioritizing the integrity of the threads. One can always compensate for the torque differential.

 

[Jim]

I would think that even blue locktite would have some lubrication value.

Some... but very little. My concern would be that, based on you description of your initial torque, you may have started to pull the threads loose. I know you don't want to hear that, but that's what your description sounds like.