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Discussion Starter #1
I had a problem early on with a coolant leak where the coolant leaves the water pump and goes into the head, which I think was resolved (I don't see coolant pooling or leaking there any longer).

I just looked and my expansion tank is empty even though I know it was at the full line a few days ago. Still had coolant when I took the radiator cap off. Where should I look to figure out where this may be leaking from. I don't see any pools on the ground or anything dripping when I fill it. The last few times I would drive to and from work a few times and it looked like there was always coolant in the expansion tank and I assumed fluctuations were based on temperature and normal heat cycles.

I'd rather find it and fix it than try something like one of those stop leak additives that you pour on as I'd be concerned it would clog something I wouldn't want it to.
 

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Read Lapping the head to cure overheating
ie: you have a warped head that blowing high pressure gas into the cooling system and forcing coolant out the overflow

FOG
 

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The last few times I would drive to and from work a few times and it looked like there was always coolant in the expansion tank and I assumed fluctuations were based on temperature and normal heat cycles.
Yes, that sounds like normal fluctuation. What you really need to look for is a net loss over a longer period of time. Often with minor leaks the coolant will evaporate on the hot motor and won't leave a puddle on the ground. A crusty yellow stain can be a good clue; also a burnt smell when you park it after a good hard run.

Mine developed a small leak on one of the coolant tubes on the head after I had adjusted the valves without replacing the o-rings on the tubes. The coolant ran down next to the spark plug and from there down the weep hole. I knew I had an issue because of the tell-tale smell, but couldn't I figure out where until I finally spotted the yellow crust on the outside of the cylinder head.

And you are right, stop leak type additives are not recommended but if you do decide to go that route, Aluma-seal is the best of the lot. Its a fine aluminum powder which doesn't clog things. For a motorcycle engine, a quarter teaspoon would be plenty. Consider it a temporary fix only.
 

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Discussion Starter #4
Read Lapping the head to cure overheating
ie: you have a warped head that blowing high pressure gas into the cooling system and forcing coolant out the overflow
While I would say that this is worth investigating at no time (that I noticed) did the temp gauge read hot, or even in the upper 20% of the normal.

Mine developed a small leak on one of the coolant tubes on the head after I had adjusted the valves without replacing the o-rings on the tubes. The coolant ran down next to the spark plug and from there down the weep hole. I knew I had an issue because of the tell-tale smell, but couldn't I figure out where until I finally spotted the yellow crust on the outside of the cylinder head.
I will take a look at that area this weekend.

I am not entirely ruling out that the leak is in the same area as before with the tube that exits the water pump area. just because I do not see it pooling there anymore does not mean it is entirely cured. I have new bolts,both gaskets, just dont have the 14mm rubber o rings or the pipe (I did have a new pipe and o rings but cannot seem to find them, I am wondering if the o rings were used on the coolant tubes on the head).
 

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Discussion Starter #5
Read Lapping the head to cure overheating
ie: you have a warped head that blowing high pressure gas into the cooling system and forcing coolant out the overflow
Upon re-reading this Im wondering if you may mean it was overheated in the past and the symptom is the high pressure feeding back into the system causing the overflow.
 

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there are 3 main areas where coolant leaks of course it can leak anywhere from pipes at the clipped ends for example but you can usually see those. the 3 that are harder to trace is the mechanical seal in the water pump this leak exits via a little hole in the case under the pump water runs into the belly pan and held there until it evaporates or runs out while riding. second is the tubes that go into the head these have O rings on the tubes and can leak coolant from here. it runs into the plug wells and out down the cylinder wall through a little hole in the side of the jugs. this also evaporates on the hot engine and may not be seen if the leak is small.
the 3rd is a warped head or leaking head gasket this pressurises the coolant and chucks it out of the over flow pipe from the expansion tank. before stripping anything down check all these places you can see if it is the head gasket by pulling the expansion bottle over flow to outside the engine case and keep an eye on it next ride out if chucks coolant out it is the head as Fog suggests. if you do not check you will never know.
by the way for information purposes you have the flow the wrong way round it exits the pump into the cylinder block then out through the head into the thermostat housing then the rad top hose cooler it exits the rad btm hose and into the pump.
 

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Upon re-reading this Im wondering if you may mean it was overheated in the past and the symptom is the high pressure feeding back into the system causing the overflow.
Did the previous owner give any indication that it may have overheated in the past? Hopefully it's not the head but if it is I have a very heavy, thick piece of 18"x18" plate glass you can borrow if you want. I've been saving it for something like this, just in case.
 

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Discussion Starter #8
I looked this morning and think it's still the same place, looking closely it appears as if the o ring in the water pump pipe is peeking out on the back side (towards the engine) and there is a little bit of coolant showing. I'm sure as it heats up and pressure bolts a bit that increases as I let the engine runs for a bit to get up to temp.

51553
51554
 

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Discussion Starter #10
Yeah, I ordered another set just to be sure from partzilla just waiting for them to be delivered sometime in a week or so ....
 

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It's much better to pull the pipe out of the block when taking the water pump apart, and easier to re-fit a straight pipe back in than the curved end into the pump casing....just saying,;)
 

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Discussion Starter #12
Ok so I drained the coolant and took off the cover and found a few things. One was a broken bolt, luckily I was able to get the stud out with some vise grips.

I also noted that it looks like some coolant was leaking behind the plate.

Looking at the coolant tube I am going to replace it along with the o rings. Not sure if it needs to be, but one less thing to be a possible cause, the area where it seats into the cover looks as if it's a little irregular, not sure if maybe if was whacked or something but in case that is the reason it wasn't sealing the o ring correctly I'll replace that too. What are the chances the issue is actually in the cover where the pipe seats?

51577
51578
 

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Discussion Starter #13
So interesting turn of events.... Got the new cylinder pipe in and it is noticably different than the one that I took off. A little longer on one leg and the angle is a little different as well, this may have been the issue all along...
51631
 

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Discussion Starter #14
In reviewing the steps I am reading

"Inspect the rubber seal on the backside of the impeller"

Is this the rubber/plastic piece that comes with the mechanical seal?
 

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Discussion Starter #15
And the oil seal on the back side says to install the seal until it is flush with the housing. Is that the lip of the housing or it is seated completely in the housing?
 

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the face on the back side of the impeller is ceramic (very hard stuff) the black face of the seal is a carbon compound (very soft stuff) it is spring loaded to maintain contact with the impeller and to take up wear of the carbon.
The oil seal is the lip thingy the lips grip the shaft of th impeller and are held there by oil pressure be sure to install the seal (oil) lips facing the engine (oil pressure) .
exact distance for either ,not critical , flush as I remember

FOG
 
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