[cmxi]

Hi.

Just rebuilt my crf250r 2008 with new crank, piston and cylinder.

replaced all gaskets.

started her upp an she ran just fine.

but i notised the coolant level was sinking.

drained the filter side oil and it was full of coolant.

stripped the head and cylinder. Gaskets ok and cant find any obvious fault. .

what have i missed? ? If I fill the coolant and leave The engine oil drainbolt open i have a constant flow of coolant going from the radiator to the oil even with the engine off. It will drained all the coolant in just a few minuter. .

[cmxi]

Also i have 4 dowels for the cylinder/head. Two on the right side between case and cylinder, and Two between cylinder and head.

Is this correct?? I only find 3 in the parts diagram...

[mossman77]

Possibly a warped head. The old gasket was conformed to the head but the new one is not. Could be wrong.

[cmxi]

Shouldent ive seen White smoke If The head is warped and The engine is running??

[JimDirt]

Also i have 4 dowels for the cylinder/head. Two on the right side between case and cylinder, and Two between cylinder and head.

Is this correct?? I only find 3 in the parts diagram...

Correct for the bottom between case and cylinder , 2 dowels on Clutch side , then between the cylinder and head , one dowel should be at the front of the engine on the timing chain side , the other on the clutch side to the rear

The leak would have to do with the head/cylinder assembly unless your water pump seal/shaft is bad , that's about the only way you are getting coolant into the oil that i know of

Unless like mossman77 mentioned and you have a warped head (check it with a straight edge to confirm) , but you should see coolant on the gasket when you disassemble the top end (it should be dry if the coolant was drained before dis-assembly)

[cmxi]

Also i have 4 dowels for the cylinder/head. Two on the right side between case and cylinder, and Two between cylinder and head.

Is this correct?? I only find 3 in the parts diagram...

Correct for the bottom between case and cylinder , 2 dowels on Clutch side , then between the cylinder and head , one dowel should be at the front of the engine on the timing chain side , the other on the clutch side to the rear

The leak would have to do with the head/cylinder assembly unless your water pump seal/shaft is bad , that's about the only way you are getting coolant into the oil that i know of

Unless like mossman77 mentioned and you have a warped head (check it with a straight edge to confirm) , but you should see coolant on the gasket when you disassemble the top end (it should be dry if the coolant was drained before dis-assembly)

I removed The cover by The flywheel and The coolant makes it way inte The motor by The oil passage from The cyl to The oil filter. It weeps coolant from The small passage above The flywheel. ..

[cmxi]

Also i have 4 dowels for the cylinder/head. Two on the right side between case and cylinder, and Two between cylinder and head.

Is this correct?? I only find 3 in the parts diagram...

Correct for the bottom between case and cylinder , 2 dowels on Clutch side , then between the cylinder and head , one dowel should be at the front of the engine on the timing chain side , the other on the clutch side to the rear

The leak would have to do with the head/cylinder assembly unless your water pump seal/shaft is bad , that's about the only way you are getting coolant into the oil that i know of

Unless like mossman77 mentioned and you have a warped head (check it with a straight edge to confirm) , but you should see coolant on the gasket when you disassemble the top end (it should be dry if the coolant was drained before dis-assembly)

I removed The cover by The flywheel and The coolant makes it way inte The motor by The oil passage from The cyl to The oil filter. It weeps coolant from The small passage above The flywheel.

[JimDirt]

To get into that passage , i would say it has to do with the front dowel on the timing chain/ignition side , but either way , i would say it has to do with the head/base gasket/s , have you confirmed there is no dampness on either gasket (head/base) ? , have you confirmed that there is no old base gasket remaining to compromise the sealing of the base gasket ?? (even a slight amount might allow it to leak) , have you tried draining the coolant , and holding a rag over the radiator opening and slightly pressurizing the system with air ?? ,(this may require 2 people) , if there is a breach in the gasket , the air will tell you where it is coming from , you should be able to hear where the air is going and trace it to the leak

Unless by some odd issue , you have a crack in the case , the gaskets or the dowel would be my guess as to the breach location

[cmxi]

To get into that passage , i would say it has to do with the front dowel on the timing chain/ignition side , but either way , i would say it has to do with the head/base gasket/s , have you confirmed there is no dampness on either gasket (head/base) ? , have you confirmed that there is no old base gasket remaining to compromise the sealing of the base gasket ?? (even a slight amount might allow it to leak) , have you tried draining the coolant , and holding a rag over the radiator opening and slightly pressurizing the system with air ?? ,(this may require 2 people) , if there is a breach in the gasket , the air will tell you where it is coming from , you should be able to hear where the air is going and trace it to the leak

Unless by some odd issue , you have a crack in the case , the gaskets or the dowel would be my guess as to the breach location

I tried to put sealant on the gaskets and just assembler the top and cyl.. connected the coolant hoses and filled the radiator.. same problem.. that should present the gaskets from leaking.. goding to try the old cyl to se if it is the new cylinder that is faulty..

[cmxi]

Is there a difference in the gaskets and cylinder between 04 to 09??

checked the head with a Steel straight. It seemed Ok.

no gaskets residue and everything cleaned prior to assembly. .

will order new gaskets and hoper for the best...

but strange that a gasket can leak over 1L / 5 min without the engine running. ..

[JimDirt]

According to this , they are the same
http://www.crfsonly.com/catalog/product ... cts_id/960


What about the dowels , were they where they were supposed to be ??

Did you try blowing air like i mentioned ?? , it might tell you something , and it would have been nice to do that when it was all together , it could have told you where the leak was originating from , also , make sure there is nothing wrong with the case surface itself , unless the case itself is cracked somewhere , i don't know of anywhere else it could pass water like that , with the exception of the water pump seal or shaft leaking

Maybe someone else can make a suggestion as to what it might be , as this is all i can come up with , you could also PM Ken , the owner here , he might have run across this situation in his shop , just look for the user name crfsonly in any post on the main forum page and go to his Profile and PM him

[cmxi]

According to this , they are the same
http://www.crfsonly.com/catalog/product ... cts_id/960


What about the dowels , were they where they were supposed to be ??

Did you try blowing air like i mentioned ?? , it might tell you something , and it would have been nice to do that when it was all together , it could have told you where the leak was originating from , also , make sure there is nothing wrong with the case surface itself , unless the case itself is cracked somewhere , i don't know of anywhere else it could pass water like that , with the exception of the water pump seal or shaft leaking

Maybe someone else can make a suggestion as to what it might be , as this is all i can come up with , you could also PM Ken , the owner here , he might have run across this situation in his shop , just look for the user name crfsonly in any post on the main forum page and go to his Profile and PM him

Hi.

Thanks.

Ive orderd new gasket of a different brand. During the weekend i will clean everything and prepare for a new try...

I did not pressurise the system unfortionatly. But will do first thing next time ive assembled it again.

The dowels where in the correct place.. and all 4 the same size..

If I have time i will do a mockup with the old vs new cyl to see if there is an differance..

[cmxi]

Problem located. It is the NEW cylinder that leaks coolant internaly.. triad the old cylinder and it was fine...

[JimDirt]

Hmmmmm , well , glad you got to the bottom of the issue

Where did you get the cylinder ??? (Cylinder is bad , not Head , correct ??)

Was it NEW ??

If it was new then you should be able to return it as Defective if its a reputable place ...

[cmxi]

Yes finaly!!

Brand new cylinder!!

Fitted the old one with the same gaskets.. no problem!!

Yes cylinder was bad.. It must be a internal casting fault that lets coolant pass between the cooling chanels and The oil chanel.

The cylinder will be returned and a new till be sent to me after it has been pressuretested by the dealer. I do not want to spend more money investigating faulty products..?

100$ in gaskets and oil poored out in the drain so far... not including the price of the cylinder.