Refilling the coolant

So I've drained what looked like ordinary coolant from my '96 4th gen while replacing the stuck open thermostat. Removed the front cylinder drain bolts and gave it a good flush.

However, it's supposed to take 3.6 L of coolant but I only got about 2.1 L in there. After starting the bike, warming it up, and then letting it cool down, it's sucked in another 250 mL from the reservoir. I've done that a second time and it's not sucked in any more. Is there something I'm missing? My KTMs have bleed screws in the cylinder head to release trapped air from the cooling system when refilling. It seems really harsh to warm up the bike with only half the coolant it ought to have, hoping it will "self bleed" 1.5 L of coolant.

Tomorrow I'll take it for a ride and see what happens - but I'll carry coolant and not stray far from home.

 

Did you remove the drain bolt on the water pump also--if not then that's where you left the extra fluid.

 

Yes did that one, too. Reckon I got nearly 3 L into the bucket, and flushed out some more, and spilt some

 

Update... after that first start-up and 'burping' it hasn't needed topping up any more. It has 2.4 L of coolant in it.

I did a 550km ride last Sunday which was a hot day. That's gotta shake loose any air pockets, surely! It is still showing as full on the reservoir.

It's also weeping a little, and a lot, out of the front cylinder drain bolts, so I need to snug those up a bit tighter and/or replace the copper sealing washers.

 

Did you drain your rads?
Im coming up on first coolant replacement and flush, been 5 yrs so its time. The book says 3l but doesnt say if thats also including the reservoir.

 

I think you should anticipate this when changing your coolant. Your cooling system is a tightly sealed pressurized system so when changing your fluid, you open this up, and are bound to get an air pocket in there. The thing is though, fix that. It is not going to hurt ti run your bike a bit with lower coolant in it until you work that air out. Just don't let the bike get hot. The bike will be fine. Coolant is not a lubricant.

Now the crush washer. You can get away without changing the oil plug crush washer because the oil is not pressurized. But the cooling system is so put a new crush washer on every time you remove the plug. It is a small cost that should be factored into the coolant flush.

Any time I have flushed my car or truck, I went through this same thing as well. Air pockets will develop. Actually, on the cars, I would drain the coolant, then stick the garden hose in there and run the car for a while and give the system a real good flush. Not environmentally correct these days. Especially with animals around. Coolant is just nasty stuff for animals. A very painful death.

 

I would drain the complete system Zen. I don't see the benefit of adding good coolant to old worn coolant. But I guess, even a partial coolant change is a benefit if the coolant is old and worn. Just not cost efficient.

 

I was actually thinking about the fact that the rads are above the engine, so the air would get up there, to properly drain the rads we have to take them off, not a big job but still.

I know that I and going to flush my rads thoroughly so they will come off....maybe make that fan mod too but the short of it is I will need to fill from both sides and burp it then top it up. Then get it up to temps/pressure and let it suck in more.

I have always burped my car engines with the cap off so I can add as needed. The vfr cooling system is very much alike so I plan to do the same, unless someone can tell me why thats not a good idea/practice?

 

Yes, singular on the 4th Gen.

I followed the book procedure.

 

That's why I'm asking. The KTMs have a bleed screw on the head to remove the air pocket, and another on the radiator without the cap. But this bike has 2.4 L when the books say 3.6 L - and it's had a day-long thrashing on a hot day and still indicates it's full & happy. Books must be wrong - but it would be nice if someone could confirm that.

Mea culpa, and I have plenty of crush washers on hand. Generally you don't have to use a new crush washer each time, ideally yes, practically no, but yes on some finicky fittings. I appreciate the sentiment but I don't agree with the example, at least not completely. The cooling system is only 1.1 bar (says so right there on the pressure relief cap) but the oil system can go to a lot more than that, IIRC. Maybe not in the sump, but all the other oil feed junctions with crush washers will have that pressure.

That's what I did, but without the engine running because it was apart to change the thermostat. Perhaps I should have started with a coolant drain & flush, and then pulled the bike apart! :smile:

Still reckon I could change the thermostat with the carbs in situ.

 

Then if you have a chance, open the fill cap and see if the level has dropped, the siphon system does work but can take forever to purge the system as you have to go through many pressure cycles. Burp it with the cap loose and run it until warmed up, then top up and tighten the cap. Make sure the reservoir has enough in it and get it hot, then let it cool down. And its done, like all good riders, watch your reservoir and add as needed.

and always put a new crush washer on when taking out plugs, your oil washer is a ribbed washer, not a crush washer so it can be reused a few times. Crush washers are found on the spark plugs if you nees a good example of one. They are designed to seal once, you may get a second or third out of them but thats borrowed time. It will fail at some point.

 

Do you have a service manual for your bike Zen? If not, PM me with your address. I will burn you a copy and send it in the mail. Too large to email. When I did mine, I think I followed the instructions in the Haynes book. Its for the 02 - 05 but same rules apply for the 06 and 07 for this purpose. I can copy and send that portion off to you as well if you wish.

 

Same to warewolf. Just PM me and I will send them off to you if you want.

 

Randy, I actually bought the service manual, then they gave me the Honda general service manual and a couple other documents that are hard to get, all on paper but still valid. especially where the vfr800 book says "follow instructions as in general service book" and that's all!

somewhere on this site is a pdf for each vfr gen.....I found it once and downloaded it, but that was 5 or 6 hard disks ago and now is probably lost in my 10TB storage array......

 

Those links for the manuals here are broken. I don't know if they are going or even can fix them at this point. I think they are still available over at that other place where all the stuffy beeches hang.

 

I tried the other place, too stuffy and hard to understand. I like it here.

 

Me too. Maybe I will post a little more often.......just to show my appreciation you understand.

 

Of course. Always nice to be appreciated

 

I've seen that other place, I was scared to go in, thought it might be like Hotel California, you know, once you check in you can never leave!

 

Oh you leave alright, but they always make sure you know why your leaving. Here its like an engineering forum, everbody puts there two cents in and we take the best, there they treat you like your an idiot for asking a question that needs to be answered to help another querent. Or if you dont have the right tool or its not the right brand of tool. I lasted about 2 weeks and got fed up.

Enough about the other side....depressing