Oil return problem

About 2 years ago, just before heading off to France for a fortnights holiday, I fitted an Oil filter (proper original type) into the return line on my '71 750.
Whilst checking the level & looking for returning oil etc I was'nt convinced that the oil was returning properly but after a short run the level was OK so I assumed all was OK.

About a week later, sitting in a traffic queue in mid France, the exhausts were smoking badly, but after a short run again all was OK. Upon closer inspection I decided that the oil was'nt returning to the tank when the engine was at idle, but collecting in the crankcase to be blown into the tank through the breather hose at higher revs.

So, I bypassed the filter with a piece of hose & continued my holiday, with the oil returning as it should, even at idle.

When I got home, I removed the filter unit & pipes, expecting a restriction but was easily able to blow through by mouth.

Now I am preparing the bike for another trip to France & Spain I thought I had better have a closer look.

I have removed timing cover & oil pump, no issues there.

The central port in the crankcase oil pump mating face (return port from pump) seems clear to the pipe outlet on the rear of the crankcase, but also links to a drilling back into the timing case.Is this correct? Maybe the added restriction of the filter was making the oil follow this path rather than go through the filter to the tank?


Any advice would be very much appreciated

Bob

My first guess would be the oil lines crossed up, but I'm sure that would be catastrophic.

A bad filter is a huge possibility. I'd try another brand, if possible. Another filter at the very least.

Bobolink said:

The central port in the crankcase oil pump mating face (return port from pump) seems clear to the pipe outlet on the rear of the crankcase, but also links to a drilling back into the timing case.Is this correct?

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The timing case (recirc. from the oil pressure relief valve) drilling should connect to the FEED side?

Verify that your new filter is a FreeFlow type with a 7 to 9 psi bypass.
For what it's worth, these bikes ran originally without a filter so if you wanted to play it safe for your trip, you could just eliminate it for now, as in, bypass it for safety sake.

A spin-on type filter should offer practically no restriction at all, as the rate of flow in this application is quite low, although do I seem to remember somebody having problems in the past-because if I remember correctly, the pipes had been connected to the filter housing the wrong way around, and the filter didn't work with the oil flow reversed.

Seems like I've heard what LAB states. Connected backwards and a check valve that did not like flowing until high RPMs bypassed it.

Cookie said:

Connected backwards and a check valve that did not like flowing until high RPMs bypassed it.

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Apparently, some of these spin-on filters have a built-in non-return valve which will stop oil flow through the filter if the lines were to be connected up the wrong way?
post26454.html

In a word, yes. When I adapt a filter to an application that has not had one I check the type very carefully for check valves and how they will work in my application. I used to have to cut one open to be sure, but information is available on the net now.
I like it best if I find someone who has used a type for a while as they will have done some development for me.

FWIW NAPA power Sport PS7013 Chrome Under 10 bucks.
http://www.napafilters.com/filterlookup ... art=PS7013

pvisseriii said:

FWIW NAPA power Sport PS7013 Chrome Under 10 bucks.
http://www.napafilters.com/filterlookup ... art=PS7013

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Pretty.

I was at napa last month trying to cross my 9 buck waldridge filter to something more economical. They crossed it to a 14 buck filter. I think it was a wix. For a buck over my 9 dollar job I'll opt for the chrome. Thanks for the link

rgrigutis said:

I was at napa last month trying to cross my 9 buck waldridge filter to something more economical. They crossed it to a 14 buck filter. I think it was a wix. For a buck over my 9 dollar job I'll opt for the chrome. Thanks for the link

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The NAPA chrome job is for a Harley (go figure), Sportster if I recall. It has been mentioned on this forum before.

NAPA ps7013 is primarily a Ducati filter along with a very few Harleys with 16mm thread.

pvisseriii said:

NAPA ps7013 is primarily a Ducati filter along with a very few Harleys with 16mm thread.

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You could also install an adaptor and then use a FRAM 3614 (3 models to choose from).

+1 on that, Then you can chose from a dozen different filters. http://www.coloradonortonworks.com/catalog/engine.asp Just scroll down.

Thanks for the replys.

I dont think it's the filter as when I got home I was able to blow through it & the pipes by mouth. Also checked it was connected the right way by comparing to my wifes Mk111.

The real question I think is, should the return outlet from the pump (crntral port) go anywhere but to the pipe to the oil tank or should there be, as appears to be in my case, an internal link back into the timing case? If I squirt oil from an oil can into the central port in the cranksase it appears from the return pipe at the back of the crankcase but also from a hole in the back of the timing chest behind & above the oil pump mounting face.

Regards

Bob.

Bobolink said:

The real question I think is, should the return outlet from the pump (crntral port) go anywhere but to the pipe to the oil tank or should there be, as appears to be in my case, an internal link back into the timing case? If I squirt oil from an oil can into the central port in the cranksase it appears from the return pipe at the back of the crankcase but also from a hole in the back of the timing chest behind & above the oil pump mounting face.

Click to expand...

As I said on page 1, the timing case gallery should connect to the FEED side, and not the return (scavenge) side.

Yes, LAB, you are correct, the "gallery" does connect to the feed side.

What I have is a connection between the return drilling from the pump to the connector on the rear of the crankcase and a drilled hole about 3/4 of inch below the timing cover gasket face, behind & above the oil pump mounting face.

I will try to post picture later to explain clearer but work in now calling..........

Any ideas?

Bob.

L.A.B. Could he be talking about the return from the head?