[Los_Serpent]

F650 funduro 97'

I've had this very small coolant leak for a while now. Around 100-200ml every 1000/1500km

What do you guys suggest? Sealer? Any cons?

 

[stevedixey]

Is it coming from the head gasket or through \ under the bolt head (or both?) It isn't unknown for the temperature switch to leak so just wanted to be sure....

Difficult call.... If the gasket leaks you risk water contamination of the oil as well. Checked the bolts are correctly tensioned? The Clymer manual (page 105) does say that if there is a coolant leak, you can loosen slightly then retighten certain bolts. It also says do not under any circumstamces use a sealer on the head gasket.

If you fully loosen the head off then you'll likely need a new head gasket anyway... and since the head is off you might as well check the gasket face is flat \ undamaged.

 

[Los_Serpent]

Is it coming from the head gasket or through \ under the bolt head (or both?) It isn't unknown for the temperature switch to leak so just wanted to be sure....

Difficult call.... If the gasket leaks you risk water contamination of the oil as well. Checked the bolts are correctly tensioned? The Clymer manual (page 105) does say that if there is a coolant leak, you can loosen slightly then retighten certain bolts. It also says do not under any circumstamces use a sealer on the head gasket.

If you fully loosen the head off then you'll likely need a new head gasket anyway... and since the head is off you might as well check the gasket face is flat \ undamaged.

It's definitely the gasket, it is visibily worn where the leak is.... Its coming from the right side corner of the gasket, and i can see the gasket in that area is very brittle/worn
If the oil is contaminated I'll look milky correct?

Does the engine need to be taken off the bike to replace that gasket?

Gonna look up the torque figure on those bolts and tighten them....

 

[stevedixey]

Hi

I've got a feeling you can do the head in the frame but may have to create a bit of space by dropping the front engine mount. To be honest, by the time you have removed all the gear needed to get at the engine top end it's not much more of a job to drop the engine fully and have plenty of space to work in with less risk of dirt or anything else falling into holes

 

[Los_Serpent]

Hi

I've got a feeling you can do the head in the frame but may have to create a bit of space by dropping the front engine mount. To be honest, by the time you have removed all the gear needed to get at the engine top end it's not much more of a job to drop the engine fully and have plenty of space to work in with less risk of dirt or anything else falling into holes

Can't it be sealed from the outside? I've seen some engines with a weird epoxy like stuff around the gasket....

What about rocking with it? It's not that annoying, the leak is small.

If the only way to fix it is taking the engine apart I'd rather leave it until it becomes a big leak

 

[stevedixey]

Difficult to seal if the surfaces are contaminated.

Potentially, the leak might cause some localised damage to the metal over time even though the coolant is supposed to be "alloy safe". The engineer in me says fix it as leaks rarely get better and you still don't know if the coolant is also finding its way into the oil inside the head cover

If I knew the leak was purely towards the outside, I might run with it but I'd have that nagging doubt in my mind (the downside of being an engineer, lol)

 

[Los_Serpent]

Difficult to seal if the surfaces are contaminated.

Potentially, the leak might cause some localised damage to the metal over time even though the coolant is supposed to be "alloy safe". The engineer in me says fix it as leaks rarely get better and you still don't know if the coolant is also finding its way into the oil inside the head cover

If I knew the leak was purely towards the outside, I might run with it but I'd have that nagging doubt in my mind (the downside of being an engineer, lol)

Quite sure it's a gasket rubber, you can see it in the pic,

Would it be possible to seal the outside of the cylinder with some sort of epoxy?

Contaminated oil will look milky correct?

 

[Godoh]

Los , the danger of trying to seal the head gasket from the outside is this.
If the gasket is leaking , it is damaged, if there is a leak from the combustion chamber into the coolant galleries then you could end up blowing the radiator.
At worst the leaking gasses will damage the cylinder head and barrel seal areas and make getting a good seal impossible without machining.
Really the only way to do a proper job is to take the head off and put a new gasket in.
Pete

 

[Los_Serpent]

Los , the danger of trying to seal the head gasket from the outside is this.
If the gasket is leaking , it is damaged, if there is a leak from the combustion chamber into the coolant galleries then you could end up blowing the radiator.
At worst the leaking gasses will damage the cylinder head and barrel seal areas and make getting a good seal impossible without machining.
Really the only way to do a proper job is to take the head off and put a new gasket in.
Pete

Pete! Hello my friend, do you have any idea what happen to the chain gang forums? they've been. Down for a while.


What do you think about those products you put in the radiator that fix small leaks? Would what you said about the risks still apply like sealing it from the outside??

Also you think i could ride another 2000-4000km without doing damage in this state as long as the leak doesn't get bigger? It's just a bit of a big job for me so I'd rather wait until im on holiday from work so i can take my time doing this.

 

[Godoh]

Los, it seems like the F650 US site tried to migrate to a new server and somehow it went wrong. Other than that no ideas about whether it will be recovered.
Some radiator leak stop products work but there is always a danger that they clog things up, such as radiator cores.
Putting some sealant on the outside of the head/barrel seal will most likely do two things.
First it will make changing the gasket later harder and will glue the head to the barrel.
Second the leak will just work its way around where you have sealed it.
One more thing make sure that if you ever take the spark plug out you clean the debris and rubbish from around it first, if that stuff were to fall into the cylinder it would create lots of problems.
You may get away with a radiator leak sealant for a while, it would be worth a try, but if you do the head during your holidays make sure the clean the radiator and coolant galleries well.
Good luck
Pete

 

[Los_Serpent]

Los, it seems like the F650 US site tried to migrate to a new server and somehow it went wrong. Other than that no ideas about whether it will be recovered.
Some radiator leak stop products work but there is always a danger that they clog things up, such as radiator cores.
Putting some sealant on the outside of the head/barrel seal will most likely do two things.
First it will make changing the gasket later harder and will glue the head to the barrel.
Second the leak will just work its way around where you have sealed it.
One more thing make sure that if you ever take the spark plug out you clean the debris and rubbish from around it first, if that stuff were to fall into the cylinder it would create lots of problems.
You may get away with a radiator leak sealant for a while, it would be worth a try, but if you do the head during your holidays make sure the clean the radiator and coolant galleries well.
Good luck
Pete

Sounds good! Will definitely use the sealing product until holiday arrives.

About cleaning the galleries, how would i do so?

 

[Godoh]

Hi Los, to clean the galleries just flush clean water through them.
Make sure to flush the radiator out.
The head coolant galleries
The radiator hoses
and
The water pump hoses.
Just use a hose and wash them out until they run clear.
There may be some build up or oxidisation depending on how good the previous owner was at changing coolant.
Be careful cleaning the cylinder head and barrel. Use something soft so you don't scratch the mating surfaces.
Pete

 

[Los_Serpent]

Hi Los, to clean the galleries just flush clean water through them.
Make sure to flush the radiator out.
The head coolant galleries
The radiator hoses
and
The water pump hoses.
Just use a hose and wash them out until they run clear.
There may be some build up or oxidisation depending on how good the previous owner was at changing coolant.
Be careful cleaning the cylinder head and barrel. Use something soft so you don't scratch the mating surfaces.
Pete

sounds good!

one last thing - before even trying to take the head off or using a sealer, i wanna try tightening all bolts, it's been a while since i've done so, but the marks i made with paint are still there so the bolts didn't loosen up any.

should i just try to torque all of them to spec? or should i loosen them a bit and the torque down again? i've seen some people on forums advising to loosen them first - others saying if you loosen them and re-tighten them might make things even worse.

 

[Godoh]

Los re torquing bolts depends on a few things.
If the bolts were put in with antisieze then it is often ok to just re tension them.
If they were put in dry then they often sieze in the threads and will give a false reading.
I suggest checking the torque settings first, see if they move.
Gaskets can flatten with age or vibration, you may get away with it for a short while, but as the gasket is already leaking it will most likely keep on doing so.
Be careful. Bolts that are stuck in the threads can snap very easily. Go steady and if they don't move with the right torque setting try backing off a little first.
The last thing you want is a snapped head bolt.
Pete

 

[Los_Serpent]

Los re torquing bolts depends on a few things.
If the bolts were put in with antisieze then it is often ok to just re tension them.
If they were put in dry then they often sieze in the threads and will give a false reading.
I suggest checking the torque settings first, see if they move.
Gaskets can flatten with age or vibration, you may get away with it for a short while, but as the gasket is already leaking it will most likely keep on doing so.
Be careful. Bolts that are stuck in the threads can snap very easily. Go steady and if they don't move with the right torque setting try backing off a little first.
The last thing you want is a snapped head bolt.
Pete

Hey man, so i noticed my right side head bolt was a bit loose, at 50nm it screwd in a bit.

Now my issue is with all the other headbolts. My torque wrench cant reach em. I can only reach with a normal spanner.

Im gonna do it by feel and be very careful not to overdo.

But im guessing on head bolts a torque wrench is almost a must right? How do people reach in such tight spots with their torque wrench?

Pretty sure these bolts have antisize in them, they go in wayyy too smooth to be put in dry for 20 plus years

 

[Los_Serpent]

After much trying and taking off parts, i managed to tighten all the head screws and nuts, they were all a bit loose. No idea on the torque i got on them and my torque wrench could only reach one bolt.

Will see what happens next ride.

 

[Godoh]

Good luck Los, hope it all goes well and that the gasket holds.
If you can get a feel for how tight a properly torqued bolt is, it is not too hard to use a spanner to do the rest.
Some tight spots are reached by a universal joint on the end of the tension wrench or socket handle.
Pete

 

[Los_Serpent]

Good luck Los, hope it all goes well and that the gasket holds.
If you can get a feel for how tight a properly torqued bolt is, it is not too hard to use a spanner to do the rest.
Some tight spots are reached by a universal joint on the end of the tension wrench or socket handle.
Pete

hey pete, sadly it didn't work and it's still leaking. looks like i'll be taking the engine apart this summer - do you recommend dropping the engine or you think i can do everything with the engine on the frame? this is probably the biggest "bike job" i've done so far - so the less components i take apart the better.

while i'm at it, are there other gasket's/o-rings etc i should replace while i'm at it? bike is old so eventually, some other stuff will give up with rubber and silicone degrading with age, so might as well do it now rather than taking the engine apart again in the near future.

and until holiday's come around, you think i should use a stop leak product (and deal with the potential side effects like clogging etc) or just leave it as is? the leak hasn't gotten worse the last 3000km

 

[Los_Serpent]

 

[anthony]

Replaced my head and base gasket in the frame , but you have to drop the engine forwards.