98 GTX oil pump

[PDCII]

About to finish up an install on a SBT replacement engine on one of my two 98 GTX Limiteds. This is the second engine failure on this ski and they really don't get used much. Other ski still runs great. I did a drill test on the pump and it is pumping almost no oil, even at high RPMs so I don't think it's working properly. I was going to replace the pump but am having a ridiculous time finding one. My questions are, 1. Does anyone have a source for a new oil pump? 2. Pro's/Cons on doing away with the oil injection completely (other than the obvious greater oil consumption)

Thanks in advance!

 

[riding high]

If you can't find a new one you may want to contact a fellow on here about a used one. I think he goes by the name on minntonka4me or something close to that. For his exact title you could possible contact LouDoo on this forum.

 

[Dr Honda]

Did you test the pump properly?

The oil pumps don't put out much oil. You have to remember... it takes several hours to burn a tank of oil. In the book there is a REAL test. You spin the pump at 1500 RPM, and measure the output for 30 seconds, and then the output is less than one ml. (on an 800 it's around .8ml)

 

[SabrToothSqrl]

I have an oil pump from a 98 951 GTX LTD. $40. Free shipping.

 

[PDCII]

Dr Honda,
I have the manual and was attempting the "Real" test. The Dewalt drill I used has a max RPM of 1800. I had to approximate the 1500 rpm that is required but after 30 seconds. It did ok at the idle setting but as soon as I rotated to the max oil position it quit pumping completely.

 

[PDCII]

SabrToothSqurl,
a little worried about a used pump. Did you check the flow per manual specs?

 

[SabrToothSqrl]

I honestly don't have time to test, but if if you get it and it doesn't work, I'll refund you. (paypal).
I usually use a cordless, spinning counter clockwise, holding the pump 'open', but it's a messy test... and I don't know what my DeWalt 18v does in "2"... but I know it's not 7,000 RPM lol.

I'm starting work on a 01 XP, have to decide if I can salvage it or if it goes to the dumpster... (after removing the good stuff).

 

[Dr Honda]

You can run it at full speed of your drill. (1800) Then... just do a liner ratio to figure out the flow. (do you remember than from high school trig?)

If not... I guess I won't let my Physics degree go to waste.

OK... 1800 RPM is 120% of 1500 RPM.... so 120% of the flow would be 0.96 ml per/30sec.

Just to verify... lining up the marks is idle. If you let go of the pump arm, the spring will roll it back, and give you "Full" oil. Also... the measured volume is from each hose.

Try it again, and let us know.

Last thing... the pump is gravity fed. It will not SUCK the oil up the hose. SO... when you do the test... make sure your oil tank is above the pump.

 

[Robj]

You also have to remember on the emgine at say 3000 rpm the pump is turning something less than that due to the difference in geat sizes between the rotary valve gear and the oil pump gear. My guess it is a ratio of 2:1, but you need to check. Something to remember when using the drill.

 

[SabrToothSqrl]

the GTX LTD has no rotary valve... it's a 951. however the 787 is also driven from the driveshaft, not the RV gear...?

 

[Robj]

Sorry I do not know that engine so thanks for correcting me. I have a 720 and the gear ratio from the drive gear to the oil pump driven gear should be considered. In some case it may be 1:1, but in my case it appeared to be 2:1. So that drill spinning the pump at 1500 rpm has the same output as if it were on the engine revving at 3000 rpm. The point that I wanted to make is that the oil pump may not spin at the same rate as the crankshaft.

 

[PDCII]

The oil pump test is actually out of the manual and doesn't even reference the engine RPMs. It states using a drill, 1500 RPM in a counter clockwise rotation.

 

[PDCII]

yes, figured it must be a gravity feed, so covered that. Like I said, flow volume passed in the low RPM test, but when I open the valve, it stops flowing completely?

 

[mrpickles2000]

I just did this test on my 787. Just make sure pump is below oil supply and bleed oil pump fully. I had oil pump lever hooked up to throttle so I had just rubber banded throttle open. I measured how far the oil traveled in the oil line and did a volume calculation based on cross section area of 3/32 line. Came up with around .69ml in 30 secs. Multiply by 1500/1400 and came up with .74, which is in the range for the 787.