Where is the coolant going?

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katos

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Oct 5, 2015
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hilliards, pa
I love my 1999 mountain max 700 triple but I have been losing coolant. I started it this weekend and ran it for 30 min, it was 65f outside you would think it would leak, NOT A DROP. On several rides last winter the reservoir was almost empty (short rides). Something related to higher pressure, just more heat when riding for real. Head gasket causing it to burn off coolant/more at high speeds? Any input?
 
betting on the water pump mechanical seal. jam your hand under the water pump housing and feel for the weep hole. when mine went i would loose coolant but would never see a drop...it was only when it was running. lay a wet rag on the manifold and gently put your hand under there while its running, or shut it off. you almost have to be a gymnast to avoid burning yourself. that's what i had to do.
 
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roudyroy1 said:
betting on the water pump mechanical seal. jam your hand under the water pump housing and feel for the weep hole. when mine went i would loose coolant but would never see a drop...it was only when it was running. lay a wet rag on the manifold and gently put your hand under there while its running, or shut it off. you almost have to be a gymnast to avoid burning yourself. that's what i had to do.
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I tried to look there, seemed to be no liquid at all even while running 30 in but pretty much all at idle or close to it. I understand the "weep hole" leaking is supposed to be a sign the water pump is failing (I think). I will try to feel for it, as you did, that is tricky.
 
roudyroy1 said:
betting on the water pump mechanical seal. jam your hand under the water pump housing and feel for the weep hole. when mine went i would loose coolant but would never see a drop...it was only when it was running. lay a wet rag on the manifold and gently put your hand under there while its running, or shut it off. you almost have to be a gymnast to avoid burning yourself. that's what i had to do.
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Is it best to replace the impeller and mechanical seal once in there, anything else?
 
katos said:
Is it best to replace the impeller and mechanical seal once in there, anything else?
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If the impeller is tight on the splines you don't have to. , replace the mechanical seal and the washed that goes under the bolt. Put some loctite on the splines and be carful not to touch the ceramic mating surfaces with your fingers as it will not allow them to seat properly.
 
Thanks all for the head torquing advice (they all seem spot on) and for the water pump advice. I will add a post when I figure it out for your edification. I am going to inspect that weep hole again, thinking maybe the coolant was hitting a cup and the frame or something. I guess if I even see a drop under full throttle it might be dumping. I work on everything myself because of budget restrictions, but am definitely backyard level, ANY tips always cherished!
 
Just ran it with white paper plates under the motor and especially the water pump, not a drop. almost thinking about pulling the heads maybe doing rings and gaskets just because it looks like the worlds easiest head to work out (till I snap/strip a bolt)
 
Have you detected bubbling in the overflow tank. No matter how slight. Check while revs are more than just at idle.

Have you ran your finger around the inside of the exhaust pipe and gave it a good sniff.

You could always take a bar of colored soap(Coast & Irish Spring)and work a good layer into the head gasket area. That way if there is a leak of hot fluid around that area, the colored soap will get washed away by the hot fluid and there should be a "clean stream".

What are the color differences of the Pistons/spark plugs?
 
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A couple of bucks said:
Have you detected bubbling in the overflow tank. No matter how slight. Check while revs are more than just at idle.

Have you ran your finger around the inside of the exhaust pipe and gave it a good sniff.

You could always take a bar of colored soap(Coast & Irish Spring)and work a good layer into the head gasket area. That way if there is a leak of hot fluid around that area, the colored soap will get washed away by the hot fluid and there should be a "clean stream".

What are the color differences of the Pistons/spark plugs?
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I cannot smell anything in the exhaust but the smoke is a bit white. Definitely no leakage around the head gasket externally, if anything it is burning it off. I am going to order a compression gauge, I should have long ago anyway. I did torque the head nuts, btw. Also no bubbles in the tank. I did rev it was much as I could. I took a real close look at the plugs and they all seem identical, tried to look at the piston domes, nothing. I suspect it is just a slight leak between the head gasket and cylinder wall and when I run at high RPM the “burn off” noticeable. I’ll see what the compression is. THANKS!
 
Now is the time to do the head gasket mod.
1. Take the head off.
2. Take the three(3) layer gasket off and drill out the two opposing rivets.
3. Dispose of the one(1) that looks the worst.
4. Warm up the two layers and spray COPPERCOAT on two of the sides. Wait between coats to let it flash-off and dry.
5. Take spray HIGH TACK permatex and coat the sides that have nothing on them and that will be in the middle. Kind of like a "HIGH TACK" sandwich.
6. Assemble and enjoy the newfound power.

100s of members have done this with ZERO issues.
 
A couple of bucks said:
Now is the time to do the head gasket mod.
1. Take the head off.
2. Take the three(3) layer gasket off and drill out the two opposing rivets.
3. Dispose of the one(1) that looks the worst.
4. Warm up the two layers and spray COPPERCOAT on two of the sides. Wait between coats to let it flash-off and dry.
5. Take spray HIGH TACK permatex and coat the sides that have nothing on them and that will be in the middle. Kind of like a "HIGH TACK" sandwich.
6. Assemble and enjoy the newfound power.

100s of members have done this with ZERO issues.
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Tryin to wrap my brain around this,, So you are eliminating the center head gasket and causing a flow thru, what does this do? (or am i not getting this?)
 
The blot thickens (gets more boring) I got a pressure gauge, exactly 120 on each cylinder cold, warmed u a slight drop but exactly the same across each cylinder. I had a mechanic over, we inspected the plugs again and pistons. No pronounced antifreeze on plugs, etc..... Keep in mind this ski will lose it whole reservoir when out on a 5 mile ride, so strange. He and others are thinking perhaps a cracked cylinder or something spreading apart with heat. We are going to measure the coolant for combustion contamination and going to pressure test the system and the cap. He also said some skis leak coolant back into the motor instead of out the weep hole, horrible on bearings, Ever heard of this? Is their a motor drain behind the pump to test for coolant in the block? He said many polaris skis have one.
 
A couple of bucks said:
Seeings how it seems like your going to taking the head off, I figured this is the perfect time to do this mod.
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Yes! And I get it now, it's almost like Yamaha designed the head to be for Premium gas then added a shim between the gaskets to allow for 87 oct. Seems like a very safe mode. Very interesting!
 
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