Faint fuelsmell from coolant

Hello, I was checking in on my VFR750 which is stored for the winter, i was checking the coolant (which was green?) and it had a faint fuel smell. I drove it all summer maybe 4000 km and there was no problem, except for that it had a hard time getting warm. Should i be concerned? The oil is fine and there is no white smoke.

 

I can not think of any way gas would get into the cooling system. Cooling system is a closed system which operate under pressure when hot. I would suggest to flushing cooling system and replace thermostat which sounds like it is stuck open (easy on old bikes) and get a new radiator cap for good measure. Not an expensive maintenance item. Be careful with draining old coolant, don't leave any puddles around, pets like the taste and it will kill them.

 

I heard someone talking about the head gasket, but you dont think so? I thought it was wierd that the oil was fine and i haven't lost any fluid. God knows how old the fluid is tho, but the green color, is this suspicious? I have heard of it but never seen it.

 

Head gasket (most common), hairline crack(rare if your bike is running well), or water pump seal (plausible but unlikely if you're coolant 'looks' good and isn't milky looking) is how it could infiltrate into the cooling jacket of the cylinder.

Those are your 3 main points of contact where fuel / gasses can infiltrate the coolant.

I would suggest the OP start with a leak-down compression test to be safe.

 

What is a leak-down compression test? And how bad do you think it is to ride with it?

 

You test the compression of a cylinder over a period of time to see how much compression it loses. Just do a quick Google search on the subject. You'd need a tester for this, they can be picked up for a reasonable cost.

No idea - could be nothing at all. If it is something, it could snowball into something bad. I couldn't tell you until I got my hands on it or you can do some tests like the leak-down.

 

I understand thank you. If its one of the aforementioned problems, is this something that evolves over time? Because i bought the bike last spring and have driven it at least 4000km during that summer and there where no sound, no weird smells, smoke or loss of fluid.

 

I was thinking of something less catastrophic than a head gasket, but definitely could be from the compression stroke. Since it is faint, do the maintenance and keep checking it for increased odor. If it is a head gasket, it will probably get worse with time.

 

How hard is a head gasket to change on these bikes? I have been working on cars larger part of my life, but dont have to much experience with bikes. Does the engine have to come out?

 

How long have you owned this bike? Has it sat for a long time before you got it? Best to do compression and leak down tests to properly determine problem. Being an overhead cam engine, not an easy task replacing gaskets, make sure you can get them first! Some one else here that has done it will give you the answer.

 

I have had it for a year, i dont know how long it has sat actually. Theres only been two previous owners. I thought of something that i have experienced with old beatles, that when the car/bike sat for a while, the gaskets shrink and needs some time to expand, could this have caused that a small amount of fuel has leaked for example by the water pump?

 

It can if the gasket deteriorates ... all seals and gaskets will deteriorate over time.

Kind of a PITA on these bikes as there's not a lot of a room in the frame. The job itself is pretty easy with knowledge and tools, just very little room to work with. If you've never done one before and don't have the right tools, I would recommend having a professional do it (provided that it's required).

 

Oil would leak past the water pump (with fuel in it) but your coolant would be milky if this was the case.

 

I understand, this would be visuable on the dipstick correct? The oil i dark brown as it should be?

 

I thought we were talking about coolant ... it should be translucent. If it's whitish / milky, you may have gotten oil into the coolant.

Vice versa with the oil.

 

We are, the coolant is clear green and the oil is dark brown. The oil doesn't smell like anything out of the ordinary. There are no visual leaks and there has never been (in my possession) a puddle or a drop under the bike. Its just the smell. The coolant may be as old as the bike for all i know tho (hope not).

 

Do a compression leak-down test. If it looks good, then flush and replace the coolant.

Check the coolant regularly for smell and keep an eye on it and the oil colour.

 

I have never done a compression test, is it difficult?

 

before jumping into the deep end, why not just change all the fliuds & then make your mind up from a known good..

 

I would send the coolant in for analysis and make sure it actually has any fuel in it. They also make test strips that can quickly determine if there are any hydrocarbons present in the coolant. There is a product called block check that works good too.