Head gasket symptoms with dry sump?

MarkJ · World Chat Champion Joined: 11 Apr 2006 Karma :

Hi all, I've got a very intermittent problem with my 1999 Aprilia RSV. Every now and again (as in, one morning every three weeks or so) I'll get the bike out of the garage in a morning and notice a small puddle of about two tablespoons of coolant under the bike. The coolant overflow bottle has coolant in and doesn't seem to be leaking, it seems to be coming from the area where the water pump and pipes are, however I can never trace the leak to an exact location because the coolant seems to spread everywhere.

The bike always starts up fine even when it's just dumped this little bit of coolant, the bike gets up to temp fine but doesn't overheat, it doesn't even overheat in slow moving traffic. The only white smoke I get from the exhaust is when it's cold after starting. Once up to temp it's fine.

The thing that concerns me is that the radiator cap gets a bit of the mayonnaise gunk on it after a few hunderd miles, it's only a very small amount but it's there. Thing is there isn't any mayo in the oil tank so I'm not sure if it's the head gasket or not.

Apparently the water pump has two seals - one for oil and another for the coolant so they should never mix. If either gets past the seal it should just come out of the weep hole.

Last night I had a decent run on it and gave it the beans - every day when I commute it never gets put under any stress. Could revving the bike high cause an increase in pressure, making something blow that doesn't normally under low load?

Has anyone had these symptoms before? I don't know where to start as it's so intermittent.

TLDR; bike drops a small bit of coolant, little bit of mayo on radiator cap but no white exhaust smoke or mayo in oil.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

From your description it is possible it is the head gasket, but to be honest it wouldn't be my first choice (even accounting for wishful thinking when finding a problem). That said oil in the water and no water in the oil (or vice versa) is not unusual.

It takes very little oil to cause a gunky mess. I would be tempted to drain and flush the cooling system. Connect a hose pipe up to one of the bikes cooling system hoses and run the bike for a while with the hose pipe running.

Could the water be coming from the weep hole?

All the best

Keith
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RIDINGforKICK... · Scooby Slapper Joined: 06 Oct 2011 Karma :

Things to check

Is it/has it been overfilled? Try letting the level drop to the "low" level, and see if it still sheds coolant.

Does the system need bleeding, could be air trapped in a pocket.

Do you do a lot of short journeys, where the engine doesn't get up to full working temperature about 6 or 7 miles?

Have you got the correct coolant in the bike?

Have you got the correct oil in the bike? ( it can make a huge difference, if you put the wrong grade in some engines)

Drop the oil, and see if there is any water/gunge in there.

RIDINGforKICK... · Scooby Slapper Joined: 06 Oct 2011 Karma :

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

https://www.arrowheadradiator.com/head_gasket_or_combustion_leak_test.htm

MarkJ · World Chat Champion Joined: 11 Apr 2006 Karma :

Thanks for the suggestions Thumbs Up

Keith, the weep hole is around that area. If it were to be leaking from the weep hole, that would mean the water seal has gone wouldn't it? If so, why would it only leak every so often?

RfK, res level is in the middle, so not overfilled afaik.
I do do short journeys on it - work is only an 8 mile trip through town and last night I went to my parents which is only one mile away.
Coolant is correct - ready mixed 5 year stuff.
Oil is correct - 10W40 semi.
I changed the oil two months ago when I first noticed this problem and there was no mayo in the oil then, I may do another change though for piece of mind.

When I did the oil change I also part stripped the bike down to give it a clean as the engine was coated in muck, it's possible I could have got a bit of oil in a coolant pipe I suppose (although I did tape them up pretty well) which might explain the small amount of mayo.

Combustion leak tester is a good idea Thumbs Up

although I did a normal compression test when I stripped the bike down and all was normal (180psi).

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Not sure why it would only leak occasionally. However if the leak is from that area it would be the first thing I would try.

All the best

Keith
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RIDINGforKICK... · Scooby Slapper Joined: 06 Oct 2011 Karma :

MarkJ · World Chat Champion Joined: 11 Apr 2006 Karma :

I thought that was only for condensation in the oil?

RIDINGforKICK... · Scooby Slapper Joined: 06 Oct 2011 Karma :

Nah

Overcooling engines causes all kinds of problems, the oil goes like treacle, the anti-freeze turns acidic, the ECU gets wobbly because it never gets any clean running data, you get corrosion inside the engine etc etc...

Anyway, try giving her a good thrashing for a week or two, and see fit it helps

Has for the leak, get a pressure tester on the radiator, pump it up to the value on the rad cap, and watch for leaks. If it is the water pump, don't change it until you have tried the thrashing thing, because they do settle with use.