Leaking head gasket woes

[zorroz]

Pulled my pipe of today on my 84 RM250 to have a look up the exhaust port and saw water in the bore and manifold. Only small drops but still in there. I haven't ridden her yet was going to run it in tommorow. I was thinking new head gasket, lap head and maybe some Hymolar on there to make sure. Anyone else had this prob? .

[Lozza]

I would most certainly lap the top of the barrel,I found a persistent leaky gasket from that not being flat.Warps when it gets hot like the head.

[Nathan S]

And right now, I wish that I hadn't deleted the photo that I took at the Nationals of Lozza's leaking head gasket...

[Rosco400]

And the institutes long walk back to the pits, that was sad to

[Lozza]

Yes wondering when that little hiccup would come to light Oh well wanna make an omlette some eggs get broken

[zorroz]

Well I took your advice Loz and pulled the barrel off and studs and found that where the steel part of the head gasket sits,it was worn a bit so after about 20 min of lapping, it all looks straight now. I lapped the head which seemed good compared to the cylinder.

[Rosco400]

Did you put head and barrel together and run thin feeler gauge around the join just to double check or rub a thin bit of the Prussian blue on the head and see where high/low spots are on barrel before putting back together

[suzuki27]

Was the mechanical seal behind the water pump impeller replaced-these were a fairly common failure in older engines and would let coolant flow back into the crankshaft. I have also found, after a rebuild that the anti- freeze/boil additives increase the permeability of the coolant- a lot more than just distilled water for example- ie, it is more able to leak through small gaps/spaces. On both occasions I found by running the bike to allow things to "seat" in,and re-tensioning the head nuts solved the problem-then change the oil of course.Both times,this was 83 & 84 RM's.

[VMX Andrew]

speakin of leakin head gaskets....ive just rebuilt the motor in my Yz250G  and went to put the pipe springs on ...what do you think i forgot to put back on during the rebuild.the bloody o ring that goes underneath the bottom nut that holds the cylinder where the springs hook up...shit..would it hurt to take the nut off and put the oring on and risk a leakin head gasket..or just start all over again with new gaskets all around....

[Nathan S]

You're talking about one of the four nuts that holds the barrel onto the cases? Then go ahead and take it off - it won't be a problem provided you retorque it properly.
If you're really paranoid, you can remove the head and barrel complete, and save you upsetting the head gasket when you replace the base gasket.

[VMX Andrew]

i think ill just go ahead and take the nut off and put it back on and retorque it..thanks..

[LWC82PE]

i highly recommend using that blue Hylomar/Aero brand gasket cement and coat both sides of the gasket with it ( if your using one). i believe its one of the best on the market and i have never had any problems since switching ot it. it works very well.