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#1 Punisher

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Posted 17 July 2018 - 09:45 AM

Totally new to triples; now have a 1997 and a 1999 Mach Z.

Would like to keep them both oil injected if possible. What would be required to refresh/renew to accomplish this?

Thanks!!

#2 pma1123

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Posted 17 July 2018 - 04:18 PM

Congrats on your Mach Z's!!! 

 

I see no need to eliminate the oil injection and have to add the stuffer gears, etc. so long as this is something less than an improved race sled.  But I'm sure others have their reasons.  

 

As far as what to look at; I've had a pretty good streak of buying Mach Z's and any one of the water pumps I've ventured into has needed a re-do or I caught mag cylinder that was drinking coolant because of the water pump.   I think others will agree on this being a pretty common early failure/preventative item.  The pump shaft seals are included in the gasket kits and if you search threads, I know GPT listed the bearing numbers for the water pump if you wanted to get bearing supplier pricing instead of dealer pricing.  

 

I pretty much have come to the conclusion that if I want to ride these and be able to have some degree of trust in the machine, I better dig in and at least do a once-over and re-seal on the engine.  And inevitably, I end up finding other stuff along the way...

  

 

 

 


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#3 XCR583

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Posted 17 July 2018 - 09:02 PM

Like mentioned, I think unless racing, keeping the oil injection isn't a big deal. Personally when I fully disassemble and rebuild a motor, I replace all of the oil injection lines. I think that's about the only thing you can do. Some have done some work on the pumps somehow but not many. Generally speaking, I dont think the pumps fail to much. When the do fail, they are supposed to pump oil as if the throttle is wide open. Sometimes the pumps stick or are slow to return closed, some have put a little spring on to assist them to close. I think at this point, it might be time to replace the pump if you can still get them.

2018 Polaris Switchback XCR 800

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1999 Ski-Doo Mach Z "Mike Houle" #72

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1998 Ski-Doo Mach Z (needs some major work also!! lol)

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1997 Ski-Doo Mach I 700 (Grass Drag Sled)

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#4 Daag44

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Posted 17 July 2018 - 11:07 PM

Oil injection has the advantage of smoking a lot less at idle. Premix is still used by many to complement the oil pump for the obvious benefits of premix.

The oil pump should get a teardown similar to what we do on twins. It's not often discussed with the triples as many favor full premix after having lost engines due to oil delivery which is most often caused by the oil lines.

There are very good threads about the oil pump on the triples with explanations and pictures. The google search below is a good example but you can play with the keywords and handle names to look for more. I chose ilovemyskidoo because he fixes the wear using a tig and he's right to only attempt this with a tig. This is exactly the type of work I get my local shop to do on just about anything including welding cases which I should add needs a fair amount of life experience to do well as the cracks can extend a fair way further then we can see.

ilovemyskidoo oil pump tig site:dootalk.com
 
Thumbdoctor with any keyword site:dootalk.com

TwoRevs oil pump site:dootalk.com



Some of the best stuff on the oil pump for triples can be found in a thread started by Gaboon and contributed by Thumbdoctor. I should note that there is no dead zone where it pumps no oil. The minimum oil delivery is in the middle the arm complete travel. So the reference line is not the minimum, and the maximum is not at at either end of the full travel. The maximum oil delivery is 90 deg in either direction from its minimum position.

One last thing, take a very close look at how the oil is delivered to the gears and the coolant pump shaft. This is not as simple as the twins hence why so many have converted to premix. Once you see how it works it will give a better understanding why many feed oil each season to the coolant pump case body on the oil side.


Oil injection pump
Started By gaboon, Jan 06 2014 10:42 AM
https://www.dootalk....ion-pump/page-2


https://www.dootalk..../#entry20470802

#5 Daag44

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Posted 17 July 2018 - 11:46 PM

Both pumps are driven by the mag crank end through gears, so it is additionally important for the crank to turn as true as possible. The same reason goes for all of the crankshaft seals. The PTO end may have an oil mod as this is common for the triples, but if you have working experience with twins then Isoflex with an added seal is a good bet. I believe your 1999 already has the Isoflex which is I think how it all started and spilled over to the twins. The added seal has the benefit it making it twice as unlikely to get an air leak and suffer a pto side failure. The end bearing cavity sees a constant positive and negative pulses, but the dominant pulse is pressure hence how a leak will allow the oil and even grease if it is hot enough to be pushed by the seal. Loose seals from wear and high runout makes this problem worse.



#6 Punisher

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Posted 18 July 2018 - 02:11 AM

Oil lines for sure, no different than twins. Just wondered if the triple systems had any inherent weaknesses. These are mostly collectible, but all my sleds have to run, and hopefully be reliable. So an engine resealing and crank check might be in the works. I've never had a pump fail in well over 100 2-strokes.

Thanks all for the info. Can you elaborate about oiling the coolant pump body? Why, how often, etc.?

Thx!

#7 Daag44

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Posted 18 July 2018 - 03:43 PM

In the first two pictures you can see the oil channel machined at the bottom of the MAG side crank chamber and the hole that it connects to on the gear side.

 

In the third picture you can see the coolant pump assembly comprising of (from Left to Right), a drive gear that is turned by the crankshaft, two support bearings for the shaft, an oil seals to keep the oil from reaching the impeller, a set of seals to keep coolant from the impeller from reaching the oil side, and the impeller. Between the seals that separate the oil from the coolant, is a weeping area  with a hole at the bottom to allow any fluids that pass the seals to drain through the weeping hole.

 

Note the coolant pump shaft is located considerably higher than the oil conduit, so the oil won't reach the shaft unless the engine is running to turn the gear and sling the oil. And of course once oil has reached the two bearing then there is enough residual oil to continue lubricating until the oil is slung back into motion.

 

When the engine isn't running, there should always be oil pooled at the bottom of the crank chambers, so there should always be oil in the conduit. The moment the engine starts, the gears sling oil to the closest bearing on the pump assembly, and with the help of the crank pulses the oil circulates to both bearings. If you take a closer look at the coolant pump shaft housing, the half that is part of the crankcase, there is a cavity for the two bearings, hence there should always be residual oil in this cavity for startup.

 

Also note the rust in the housing that is next to the two bearings. The corrosion is from coolant seeping by all 3 seals to then reach the bearings. When disassembling triples or looking at the parts on eBay you can see how many of them have rust in this area from coolant seepage. The pressure that builds behind the impeller is what pushes the coolant against the seals, hence the hole that pierces the impeller to equilibrate the pressure, and the use of two seals on the impeller side. On later engines - twins - there are more holes in the impeller.

 

This is main reason many will suggest to inspect and rebuild this area when a top end is done, and also to add a quantity of oil through the oil fill screw hole as preseason maintenance. The odd bolt/screw that is used to refill the cavity is seen on the cover for the coolant pump assembly.

 

 

Case Half - Bottom - showing oil conduit to gear side cavity from crank chamber side.jpg

 

 

Case Half - Bottom - showing oil conduit to gear side cavity from gear side.jpg

 

 

Crankcases showing coolant pump assembly and oil fill bolt.jpg


Edited by Daag44, 27 April 2020 - 10:06 PM.


#8 pma1123

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Posted 18 July 2018 - 04:46 PM

Great post Daag44!!  Very clearly shows that path for coolant drinking on that Mag cylinder.  The water pump guts and rust staining in that 3rd picture are nearly identical to what I have seen on my sleds also.  

 

I also added a picture of the stator housing from mine showing the corrosion stain on the water pump idler gear bearing area.  (I didn't think anything was wrong with this engine before I tore it apart, but never actually rode the sled)

 

The fill for the water pump bearings is the large socket head cap screw (8mm allen?) in the middle of the water pump cover.  

Attached Images

  • statorhsg.JPG

Edited by pma1123, 18 July 2018 - 05:18 PM.

Fleet of Doo triples, couple twins too.


#9 Punisher

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Posted 18 July 2018 - 07:36 PM

Thanks for the info boys. Completely different setup than the old water pumps on RV twins.

Is it just old/worn seals in the pump assembly that allow coolant to reach the crankcase?

Much difference between a 1997 800, and a 1999 800?

Edited by Punisher, 18 July 2018 - 07:47 PM.


#10 ilovemyskidoo

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Posted 14 August 2018 - 10:39 AM

Ya that’s pretty much it, they just wear out. 97 and 99 engines where mostly the same only real difference was seal and bearing set up on the pto side.

I'd rather be looking at it, instead of looking for it.


#11 Daag44

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Posted 14 August 2018 - 06:50 PM

The 800 triple brought Isoflex to sleds with the use of a greased outer PTO bearing. The 800 triple also brought a more sophisticated electrical system with DC powered accessories. The SDI being fully DC in 2004 held onto the same notion of dual circuits for the Engine Management and another for the Accessories. The ETEC took the electrical design even further with the ECM/ECU controlling the output voltage for the various Engine Management circuits and still keeps the Engine Management and Accessories separate. There is a surprising amount of tech derived from the 800 triple that we learned to love or hate  :laugh_old:


Edited by Daag44, 24 August 2018 - 01:11 AM.





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