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Arjan van Druten

WR400 Coolwater level drops too fast. How to best Isolate the cause of leakage?

11 posts in this topic

Hi All,
 

I experience a fast lowering of coolwater level, Circa 0.5 cm (in the resevoir) per ride (of 1 hour).

I also noticed very small levels of coolwater drips under the bike - bleu water. Often there are a few drips of oil of the valve cover / engine breather hose also, but guess that is normal....

I can not find the leakage location of the coolwater however.

 

* Does anyone has experience with this. What is the best way to Isolate the probable cause of failure?

 

- e.g. Start with cilinder leakage test and check the head gasgets (by checking for bubbles in the radiator)?

 

* What is the most likely cause, any ideas?

 

Many Thanks

 

Arjan

 

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sounds like it is leaking from the waterpump drain hole which is on the under side of the waterpump castings

 

A new seal in the water pump should fix it

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sounds like it is leaking from the waterpump drain hole which is on the under side of the waterpump castings

 

A new seal in the water pump should fix it

 

Thanks!

You could just be right. I am going disassembly it tomorrow. 

 

I just spotted some cooling water on the frame, just below the waterpump.

 

 Does it also mean that the water system cannot build up pressure or could this be the reason that the water level in the radiators is so low (as I remove the plug from the radiator i do not see any cooling liquid).

 

 

2 more questions:

 

- There is not a over pressure / overload valve in this pump area, is there?

 

- there is no filter in the cooling water circuit somewhere? Which could be blocked by debris and it is causing this issue.

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no filter. Over pressure valve is the radiator cap

they start leaking when engine is just started but tend to stop when the engine warms up

if its been like it a while then this is why you have no water in your radiators

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no filter. Over pressure valve is the radiator cap

they start leaking when engine is just started but tend to stop when the engine warms up

if its been like it a while then this is why you have no water in your radiators

   

Oh, thats interesting!, that it only leaks when cold....!! ? But why? seems like a fragile function than....

 

 

Please check picture attached. I just replenished all the coolwater, and re-torqued the drain bolt with the copper washer (seal).

I started engine, and when trhottled it into some higher RPM, i spotted Coolwater leakage from this hole...

 

I cant find any info about this in the manual. I have not disassemble the pump yet. Does anyone nows how this works. Is this normal...

I am almost sure that the leakage is comming from here...

 

Thanks!!

Oh, thats interesting!, that it only leaks when cold....!! ? But why? seems like a fragile function than....

 

 

Please check picture attached. I just replenished all the coolwater, and re-torqued the drain bolt with the copper washer (seal).

I started engine, and when trhottled it into some higher RPM, i spotted Coolwater leakage from this hole...

 

I cant find any info about this in the manual. I have not disassemble the pump yet. Does anyone nows how this works. Is this normal...

I am almost sure that the leakage is comming from here...

 

Thanks!!

water pomp leakage.JPG

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Oh, thats interesting!, that it only leaks when cold....!! ? But why? seems like a fragile function than....

 

 

Please check picture attached. I just replenished all the coolwater, and re-torqued the drain bolt with the copper washer (seal).

I started engine, and when trhottled it into some higher RPM, i spotted Coolwater leakage from this hole...

 

I cant find any info about this in the manual. I have not disassemble the pump yet. Does anyone nows how this works. Is this normal...

I am almost sure that the leakage is comming from here...

 

Thanks!!

  

 

So, Just reading first reply again -->

 

Is this the "drain hole" as said before; and a new seal in the water pomp should solve it...?

 

This is referred to as O-ring: number 8 on IPL....

 

Thanks

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Oh, thats interesting!, that it only leaks when cold....!! ? But why? seems like a fragile function than....

 

 

Please check picture attached. I just replenished all the coolwater, and re-torqued the drain bolt with the copper washer (seal).

I started engine, and when trhottled it into some higher RPM, i spotted Coolwater leakage from this hole...

 

I cant find any info about this in the manual. I have not disassemble the pump yet. Does anyone nows how this works. Is this normal...

I am almost sure that the leakage is comming from here...

 

Thanks!!

  

 

So, Just reading the earlier post...Is this the "drain hole" as said before, and a new seal in the water pomp should solve it...?

 

 

**********

 

Just removed the cover of the pomp (see attached pic), and looking at what the O-ring is covering, the replacement of this O-ring will not solve the leakage from that hole, for sure...

 

_ I cant remove the impellor, as there is no resistance (blue nut cannot be removed). Is this a kind of free-run system...?

 

I am stucked for the moment...or have to remove the complete side cover of the engine... :-(

 

***********

 

Any Ideas?

water pomp leakage 2.JPG

water pomp leakage 3.JPG

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Just found a vid on Youtube that makes the issue clear...

https://www.youtube.com/watch?v=vZMiiO4RCiQ

 

-->>> There is just one thing that I really do not understand...

I just checked with another engine, and the impellor SHOULD NOT BE FREE ROTATING...Mine is...  :(

Still dont understand why I saw the leak getting more when I run the motor on HIGH RPM (neutral shift). If the shaft was broken, than it should not matter...

 

It also means that I (may) have been riding with a bike with no water pump for some time...!!!   :jawdrop:

Is the shaft broken ? I will have to find out... Big issues!

 

 

Guess I have a lot of work to do :-)  :rolleyes:

 

 

 

Cheers

Edited by Arjan van Druten

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This is how a normal pump should look like...I guess I have been running the bike a long time without a water pump...  :jawdrop:

 

Maybe it shows how reliable these engines are....

 

Its time for a new bike: WR450F 2016 :-)  :ride:

yamaha.JPG

Edited by Arjan van Druten

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If you have tried to remove the impeller without removing the cover to hold the back of the shaft then you have probably round off the drive flats where it locates in the end of the balancer shaft

 

You need to take the clutch cover off to see whats going on with it

 

Yes they leak when cold when the seal needs replacement, as an early warning sign

 

The seal in question is number 4 in the parts diagram you posted

 

The drain is there to stop the water getting into the engine, by giving an easy path to escape

Edited by GuyGraham

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If you have tried to remove the impeller without removing the cover to hold the back of the shaft then you have probably round off the drive flats where it locates in the end of the balancer shaft

 

You need to take the clutch cover off to see whats going on with it

 

Yes they leak when cold when the seal needs replacement, as an early warning sign

 

The seal in question is number 4 in the parts diagram you posted

 

The drain is there to stop the water getting into the engine, by giving an easy path to escape

Thanks Graham,

 

I do now understand the smart way of the construction; a double (redundant) seal with a leakage hole in the middle. I believe the water should normally not get out (also not with a cold engine...). If it does, than it is a indication that the 1st seal has a failure and quick repair is needed to prevent the second seal from failing and water getting into the oil / core of engine...These seals are dynamic seals, very prone to failure, specially the one on the water side (NO oil lubrication!)

 

I will check it, but i am very afraid that much damage has already been done. Look at the brown, baked  color of the internals...!!!   It shows that the water has been boiling hot or something or mixed with oil already..and the shaft likely was already disconnected.....Its not normal.

See other pic I last attached!

 

I am going to look for a new bike - wr450 2016..-. in the mean time :-) Was already planning to do this..,.

This one, which has never really let me down, is at the end of his life...

 

Will give a update when I figured out wat the cause was of the impellor disconnection (because that is really weird i think)....

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