Every time I remove my engine that same thing happens. What I think is that areas inside the engine are prevented from filling with that first fill of coolant because of air pressure. Think of the gas tank vent in reverse. I use one of the coolant hoses as a bulb to force the coolant beyond the air traps inside the engine. It takes awhile for the coolant system to stabilize and pressurize......I saw it described on the forum as a burp. You did the fill the coolant system using the 'radiator cap' type cap and NOT the overflow tank, right?

 

Just thought i'd answer everyone before i go on.
I did fill it in the radiator cap as you mentioned yep.

 

Check to make sure your not getting any coolant in the engine oil, it will get thick, and muddy looking.
by ticking over do you mean idling?
how long is the bike running b4 it starts to push the coolant out?

if you have no coolant in the system the temp light will not come on.

the only thing that should coming from radiator filler is some bubbles, and you should see the coolant drop some in the fill neck as the bubbles surface.

sounds to me like you have a bad head gasket, but I wouldnt condem it just yet.

 

The bike is running for just under 10 mins i think before it starts pushing coolant out. I just read on another thread about a boiling noise, like the coolant isn't circulating. This is the case with my bike also. When i bled it the first time i filled up the filler neck, gave it a couple of snaps of the throttle and topped it up but didn't seem to work.

 

Just my two cents, a head gasket is usually known when coolant is mixing with the oil. So check that.
Second, let it run for a few seconds, or let it set over night with the radiator cap off (it's the highest point) just in case an air bubble needs to surface. Good luck

 

If the oil and coolant are not getting mixed and the oil and coolant are not leaking out of the H-Gasket, either externally or internally. I would NOT suspect the Head gasket.
I would suspect air trapped in the coolant system or waterpump or stuck T-stat.

 

There are a few diff ways a headgasket goes bad, and not always do the coolant and oil mix. you'll only get that went the gasket goes bad or gets pushed out between the water jacket and the oil return. oil in the coolant would indicate the pressurized oil to top end is getting into the water jacket.

1 the cylinder pressure goes into the water jacket, creating air and excess pressure in the system, causes the coolant bottle to fill, and overheating cause the t stat doesnt open, or simply air in the system doesnt cool the engine properly.

2 coolant can seep into the cylinder on cool down, or sucked in on the intake stroke, the later you ussually get white smoke while running. but in either case the piston will look steam cleaned, cause it was.

3 if the gasket rots, or the blow out is severe enough, head gets warped, you will get coolant in the oil, or an external leak, and it could have low compression and not fire at all

 

Should I start with a compression test before doing anything else and if so would low compression in the cylinders be an indicator that the gasket has had it?

 

Low compression could be alot of things, but it may be a good place to start if you have a compression gauge. not nessicarily looking for low compression but a difference between the front and rear, there may be some diff, but shouldnt be much.

but an idication of a bad gasket would be constant air comming to the top of the filler neck while the engine is running ( with the cap off )you may have to blip the throttle.

is the t stat in correctly?, I dont think you can put that one in up side down.

and is the water pump working correctly, possibly a problem with the impeller, havent seen it on a bike, or a Honda for that matter. but have seen the impellers spin freely on the shafts, in VW's and Dodges, seen them rot rite off on GM's and Fords.
when you blip the throttle with the fill cap off and see the cooland drop , that would be an indication that the water pump is working.
run it with the cap off watch for continuios bubbles, take notice as to whether all the hoses get hot, and hot coolant is flowing through the radiator, that would be any indication that the t stat opened and you have flow.

 

You have to remove the engine to access the water pump on these bikes. The reason for that is because water pumps on Shadows don't quit. Sure, sometimes you get a back gasket that leaks, but the impeller is cast aluminum and as long as the engine is turning, you can be assured the impeller is turning. Look somewhere else; the water pump isn't your problem.

--Justin

 

Thanks. That'll save me some time.

 

I don't have the manual for this bike. Does anyone know what the compression should be for this model. It's a 94 vt600.

 

Given the compression ratio, I'd say that anything above 120PSI is fine. It's not so much the number you're looking for though, it's the percentage difference between them. The engine will run with just about anything over 75PSI. However, if one is 80 and the other is 140, you have a problem. If one is 87 and the other is 92, then that's a bit low, but still mostly okay since they're the same. You want them within 10% of each other. Remember to hold the throttle at wide open for testing the compression. A lot of people get horrible numbers because they forget to hold the throttle open.

--Justin

 

Given the compression ratio, I'd say that anything above 120PSI is fine. It's not so much the number you're looking for though, it's the percentage difference between them. The engine will run with just about anything over 75PSI. However, if one is 80 and the other is 140, you have a problem. If one is 87 and the other is 92, then that's a bit low, but still mostly okay since they're the same. You want them within 10% of each other. Remember to hold the throttle at wide open for testing the compression. A lot of people get horrible numbers because they forget to hold the throttle open.

--Justin

+1 on that one. deffinetly looking for the difference between the 2.
dont think I Would ever see a honda pump fail as far as the impeller goes, but have seen it on other stuff, they do leak due to bad bearings from time to time. but I am not entirly familar with the design of the water pumps on these bikes.it is one of the last things I would look at.

But I also believe any component is capable of failure no matter how small the probability.

 

Here's the compression results guys. I've drawn a diagram just to show it easier.

 

that looks good, I am surprized at the different pressures from one side to the other on the same cylinder, but all in all, from side to side and front to rear there pretty close.
but just cause it looks good,doesnt mean it is.
with the ignition of the air/fuel mixture the cylinder pressure is much greater, then you get the cylinder gases leaking into the coolant jacket.
They do make a kit the detects exauste gases in the cooling system, may be pricey, we use them at the shop.
heres one thats simalar to what we use.
Head Gasket or Combustion Leak Test Procedure (Gasoline Engines Only)

 

using a differential pressure gauge is a far better way to test the compression of the cylinder. This process uses 2 gauges one measures the pressure going into the cylinder and the other measures the pressure IN the cylinder. This measures the leakdown of the cylinder and also will give you an indication of what has failed if anything. You should be able to find the setup at an auto supply store.
When you pressurize the cylinder you will be able to hear exhaust valve leaks or intake valve leaks and will also be able to tell if the cylinder pressure is leaking into the water jacket. If you have the rad cap off and pressurize the cylinders you would see bubbles or the rad would just start overflowing as the air replaces the fluid.

This is a far better test that the compression tester and cranking the engine method and is a more accurate indicator of cylinder health.

 

Iv'e noticed that there's a blob of some kind of black filler type stuff on the top corner of the rad. I'm not sure if it's covering a hole or crack or whatever but would this cause the problems i'm having? I refilled the coolant system just to take a close look at this and from what i can make out there seems to be steam coming from underneath the filler stuff.. I don't know is this because of the pressure that already exists in the coolant system that the steam is coming out. What do you guys think. Could this be the origin of the problem. Any help appreciated as always.

 

Iv'e noticed that there's a blob of some kind of black filler type stuff on the top corner of the rad. I'm not sure if it's covering a hole or crack or whatever but would this cause the problems i'm having? I refilled the coolant system just to take a close look at this and from what i can make out there seems to be steam coming from underneath the filler stuff.. I don't know is this because of the pressure that already exists in the coolant system that the steam is coming out. What do you guys think. Could this be the origin of the problem. Any help appreciated as always.

Yes , could be the origin. with the raditor filled, and the bike running, do all the hoses get hot? and are there constant bubbles comming to the surface of the filler neck?

 

i'll have to check the hoses to see. probably get round to it in the morning. as for air bubbles i'm not quite sure whether i'm overfilling or not. i filled the reservoir and then filled the rad filler neck and left both caps off and idle the bike for a few minutes giving it a few snaps of the throttle. there were some initial gushes of coolant coming back out the neck but then it seems to settle and i top it up. the whole system takes over a litre anyway i'm sure. this has been discussed in the beginning of the thread however so time to focus on this rad!:mrgreen: thanks. i'll let ye know the updates.