Hi All,

Sorry about the long post, but trying to diagnose if my bike has a blown head gasket or something else wrong.

I have a 1998 CBR600 that suddenly started dumping coolant from the overflow bottle. It has only done about 29,000 km's and im running NGK iridium plugs

I pulled the radiator cap off and started the bike. There were loads of bubbles coming up through the opening. (but not foaming) The amount of bubbles increased as you increased the engine revs.

There was no cross contamination of oil/coolant. Coolant was changed about 6months prior.

On stripping the engine down, the exhaust ports (exhaust side not valve side) had white deposits ontop of the normal carbon deposits on cylinders 1,3 and 4. #2 cylinder was a "wet black carbon" look and there was loads of carbon build up on the tops of the pistons (too much riding too-from work and not enough working the engine).

The gasket looked ok with only a slight "dimple" on the top side of the gasket between #3 and #4 cylinders, but the head and block looked fine and on inspection with a steel ruler appears to be flat.

The only other thing is that about 3 or 4 tanks before the coolant dumping, I had a tank full of really bad premium unleaded (98 ron) fuel. It was extremely hard to keep the bike running, with it spluttering, pinging and running hotter than it normally did. It took a couple of tanks after this one for the bike to come good.

Basically, is there any thing else I should be looking for to help with the diagnosis?

Any help greatly appreciated.
Thanks

 

Could have separate issues. I dunno squat about head gaskets but I did replace the radiator recently.

Did you try flushing and bleeding the radiator?

 

No i didn't try flushing or bleeding the radiator as it had been running fine since I had replaced the coolant about 6 months prior to it all, but thanks for the suggestion

My normal routine is drain coolant, then flush with running water (to check for sand/grit caused by coolant going bad), then with the bike on the centre stand, fill up with new coolant. start bike letting it run and get up to temp, then let coolant level settle. Put bike onto side stand and check coolant level again (the angle should allow any air trapped at the top of the radiator to escape), then top up as required.

 

I'm gonna say you def have a vacuum \ air leak problem going on somewhere, but I can't say exactly where. I'm fairly certain it's not the head gasket. The white deposits are usually from the cylinders running rich, and the fact that #2 was still wet implies that it wasn't firing at all, which would give you a really rough ride.

I'd clean the pistons and replace the rings and gaskets, just cuz of all the mess in there, and see what it does.