Oil pump out put

[Mr. Ed]

I've been working through and adjusting my '92 70hp. This evening I checked the oil pump out put, as per the instructions on the Yammaha service manual. Well ... I'm a little confused at the outcome. The book says I should have between 2.02 and 2.46 ml of oil discharged in 3 minutes. I had 4.9 ml in 3 minutes. Had this same reading on the top and middle cylinder ... didn't bother to check the bottom.

Engine RPM was at 1500, oil linkage was disconnected and all the way open ... just as specified on the shop manual. Temp was 60 degrees (calls for 50-86 in the book).

The only thing not as per the book (at least that I can see) is my oil is fresh Pennzoil Premium Plus (TCW-3) instead of Yamalube.

Anyone have any insight? Could it be the oil? Time to replace the oil pump?

I've thought since I bought this unit (last year) that she smoked a little more than I thought it would/should ... better extra oil than not enough I guess!!!

Ed

[boats.net]

They usually go over the specs but not twice over which would mean your engine is running on a 25:1 mix at full throttle. if thats the case there would be heavy smoke at full throttle. If your test are correct then replace oil pump.

[Mr. Ed]

Thanks, I will run the test again in a few days (after the rains clear).

I have noticed a little smoke at idle. But, have not noticed it at WOT ... the motor is used mainly to get from one fishing hole to another. I have not been fouling plugs and when I do open her up there is no lack in preformance.

Somehow this is not making sense to me. At 25:1 I would think I would be laying out an effective "mosquito fog"! If the pump is failing ... wouldn't it pump less oil volume?

I'm wondering if somehow my test could be flawed. After warm up I set the idle speed to 1500 rpm on the console tach (could the tach be that wrong to make a difference?). Linkage to oil pump had been previously disconnected (running on 50:1 aux tank). Oil pump lever was moved to WOT position. Top oil line was removed at intake and attached to 6cc syringe for 3 min. Repeated same steps for center cylinder, except disconnected oil line at check valve. Could the use of Pennzoil Premium Plus instead of Yamalube be causing that much of a difference? Does my test procedure sound correct?

Thanks for your help,
Ed

[Ken]

Ed,
Your oil pump has no idea what kind of oil you are using - Pennzoil is fine. Any TCW-3 oil would be ok. I use Pennzoil synthetic blend TCW-3 myself, and it is good - less smoke than the other brands.
Good luck [img]smile.gif[/img] ,
Ken K

[boats.net]

That is the way you test it. That engine has a varable ratio oil pump(200:1 to 50:1) so it's hard to say how much oil it will use but at the normal mixture at full throttle it should use a 50:1 oil mixture which would be 12 gallons gas per 1 quart oil, at the results of your test it would burn 6 gallons gas per 1 quart oil at full throttle.

[Mr. Ed]

Thanks guys ... I'll order one today.

I'm just having a hard time comprehending this one. Generally, if any type of pump is failing ... the efficiency goes down, not up. Although not ever having one of these apart before, I suppose it could be something in the variable ratio part that has gone bad.

Better too much oil than not enough!!

Ed

[Mr. Ed]

Just a thanks guys. Got the new pump today, installed tonight. Pumping about 2.8 cc in 3 minutes now ... a little higher than spec ... but much better than the original 4.9 cc!!

Ed