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-   -   Overflow tank (https://www.fjrowners.com/forums/9-fjr-technical/147817-overflow-tank.html)

Rustedpalm 08-09-2019 06:54 AM

Overflow tank
 
On a gen 1, what is the orientation of the inlet and outlet hoses to the expansion tank? I would think the hot overflow coolant would be pushed into the top of the tank and then be pulled back to the radiator from the bottom.

Mine is trying to push the coolant from the radiator into the bottom of the expansion tank.
Someone may have switched them at the radiator neck.

RaYzerman 08-09-2019 08:12 AM

1 Attachment(s)
There are two hoses at the filler neck, top one goes into the bottom of the reservoir, and coolant only flows when rad cap releases it to that hose. The lower hose is a bypass hose where coolant is circulating all the time. There will also be a drain hose from the top of the coolant reservoir, in the event too much coolant is in the reservoir.
See attached.

N4HHE 08-09-2019 09:52 AM

I don't know the specifics of your FJR but the overflow hose from radiator cap area correctly goes to the bottom of the reservoir no matter the water cooled vehicle. This hose blows and sucks. Hot steam has to bubble through cooler liquid in the reservoir. When engine cools liquid is sucked back into the radiator.

Rustedpalm 08-09-2019 10:45 AM

Quote:

Originally Posted by N4HHE (Post 1221147)
I don't know the specifics of your FJR but the overflow hose from radiator cap area correctly goes to the bottom of the reservoir no matter the water cooled vehicle. This hose blows and sucks. Hot steam has to bubble through cooler liquid in the reservoir. When engine cools liquid is sucked back into the radiator.

Ok so mine is connected to the bottom, however, the spout it's attached to is totally sealed up. It looks like it melted. And no fluid will pass through. So at about 4 bars on the gauge it starts to lose fluid around that hose and then runs hot. Gets up to the last bar flashing.

N4HHE 08-09-2019 11:39 AM

Quote:

Originally Posted by Rustedpalm (Post 1221163)
Ok so mine is connected to the bottom, however, the spout it's attached to is totally sealed up. It looks like it melted. And no fluid will pass through. So at about 4 bars on the gauge it starts to lose fluid around that hose and then runs hot. Gets up to the last bar flashing.

Crud will accumulate at the bottom.

The reservoir should have one hose out the top running somewhere safe to vent under the vehicle. Normally this breathes air. If disaster strikes it can blow steam.

Generally there is a space in the neck where radiator cap installs which is routed to the bottom of the reservoir. The radiator cap has two seals, one spring loaded at the bottom. Another larger in diameter at the top. When pressure overcomes the spring hot steam vents out the hose to the reservoir.

When engine cools coolant contracts it produces a vacuum. In the center of the spring loaded plunger of radiator cap is a smaller metal plate which is very lightly spring loaded. Vacuum opens this plate and draws liquid from the reservoir. You can open it with your fingernail to verify it is not stuck.

For the system to work the top seal of the radiator cap must be good else the vacuum will suck air. The hose to reservoir must not collapse under suction. And the fitting at the reservoir must not be blocked.

I think you have two related problems. A blocked reservoir will not overheat your engine. When coolant is changed a working reservoir is necessary to burp air out of the engine. Every heat cycle vents to reservoir and whatever air is in the system tends to be at top of radiator so the first thing out is air. Cooling draws liquid back. If there is any more air the next heat cycle will vent air out, liquid in. Repeats until all air is gone. Then heating vents hot liquid coolant.

Air in the cooling system results in lower cooling capacity. But not huge losses in cooling as seems to be your problem. Not unless your engine coolant level is significantly low. Start by checking quantity at the radiator cap. And fix the reservoir.

red 08-09-2019 12:28 PM

Overflow tank
 
Quote:

Originally Posted by Rustedpalm (Post 1221163)
Ok so mine is connected to the bottom, however, the spout it's attached to is totally sealed up. It looks like it melted. And no fluid will pass through.

Rustedpalm,

A new OEM coolant overflow tank is not expensive. If yours is toast, just replace it with new parts.
Amazon is quick and convenient, if your dealer is not.
Once that happens, we can go from there if you have any more problems.
.

Rustedpalm 08-09-2019 12:32 PM

Quote:

Originally Posted by N4HHE (Post 1221171)
Quote:

Originally Posted by Rustedpalm (Post 1221163)
Ok so mine is connected to the bottom, however, the spout it's attached to is totally sealed up. It looks like it melted. And no fluid will pass through. So at about 4 bars on the gauge it starts to lose fluid around that hose and then runs hot. Gets up to the last bar flashing.

Crud will accumulate at the bottom.

The reservoir should have one hose out the top running somewhere safe to vent under the vehicle. Normally this breathes air. If disaster strikes it can blow steam.

Generally there is a space in the neck where radiator cap installs which is routed to the bottom of the reservoir. The radiator cap has two seals, one spring loaded at the bottom. Another larger in diameter at the top. When pressure overcomes the spring hot steam vents out the hose to the reservoir.

When engine cools coolant contracts it produces a vacuum. In the center of the spring loaded plunger of radiator cap is a smaller metal plate which is very lightly spring loaded. Vacuum opens this plate and draws liquid from the reservoir. You can open it with your fingernail to verify it is not stuck.

For the system to work the top seal of the radiator cap must be good else the vacuum will suck air. The hose to reservoir must not collapse under suction. And the fitting at the reservoir must not be blocked.

I think you have two related problems. A blocked reservoir will not overheat your engine. When coolant is changed a working reservoir is necessary to burp air out of the engine. Every heat cycle vents to reservoir and whatever air is in the system tends to be at top of radiator so the first thing out is air. Cooling draws liquid back. If there is any more air the next heat cycle will vent air out, liquid in. Repeats until all air is gone. Then heating vents hot liquid coolant.

Air in the cooling system results in lower cooling capacity. But not huge losses in cooling as seems to be your problem. Not unless your engine coolant level is significantly low. Start by checking quantity at the radiator cap. And fix the reservoir.

Yep, this is what I'm thinking. I just bought this bike. PO said he flushed and filled the system. I believe he only idled it for a few minutes. As I rode it it warmed up enough to open the cap and push fluid to the tank. But since the tank is blocked it simply leaked out onto the ground. At this point the system was low on coolant which could make it run hot. I doubt he burped it properly so it probably also had air trapped. Does that sound logical?
Any way I'm replacing the tank because it's obviously bad.

N4HHE 08-09-2019 12:39 PM

Quote:

Originally Posted by Rustedpalm (Post 1221181)
Yep, this is what I'm thinking. I just bought this bike. PO said he flushed and filled the system. I believe he only idled it for a few minutes. As I rode it it warmed up enough to open the cap and push fluid to the tank. But since the tank is blocked it simply leaked out onto the ground. At this point the system was low on coolant which could make it run hot. I doubt he burped it properly so it probably also had air trapped. Does that sound logical?
Any way I'm replacing the tank because it's obviously bad.

Sounds good.

Usually a good burp can be had warming the engine with radiator cap off. Fill as the level falls.

Rustedpalm 08-09-2019 01:15 PM

Thanks N4HHE.
As you can tell it's been awhile since I've had a liquid cooled bike lol.

But I did get some burping experience working on my son's Nissan 350z. What a pain🤪

RaYzerman 08-09-2019 02:08 PM

That blocked port is the root cause of your problmes. It pissed fluid out elsewhere, which leaves it low when it cools off. Lose enough and you'll overheat. Yes to replacing it if you can't "drill" it out. Many neglect to empty and flush that reservoir when doing a coolant change, and the crud accumulates at the bottom, as the previous owner seems to have done. It is inconvenient to get at after all.


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