June 1990 VN - Coolant Surge Tank

[JetJackson]

The surge tank is the highest part of the cooling system and if all the small pipes from the inlet manifold are clear then as long as there is coolant in the surge tank then the block and radiator are full. The surge tank does not need to be full 100% and any air in there does not mean there is air in the system (engine, radiator etc), if your air bleed pipes from the inlte manifold are blocked then you will have air trapped.
Any trapped air will flow out of these small pipes into the surge tank as you fill the radiator. As far as a design for bleeding the air out it's actually a better idea than a radiator cap and bleed screw.
So as long as the surge tank caps with and without the overflow bottle are the same all you need to do is fill the surge tank to the seam and take the overflow recovery off. At normal operating temp the coolant will NOT expand to fill the surge tank and escape from the cap.

Thanks wortus for your input. My next step is to check the vapour pipes for blockages. After reading the other posts and of these pipes, it makes sense that they're most likely blocked. This will mean draining off some of the coolant, so when I have done that check I will only fill the surge tank to the seam line as suggested.
On my surge tank there are no "level" marks or indicator lines or sticker to show correct coolant level so I have always filled near to top. The overflow/recovery bottle does have upper and lower coolant level lines. I'm fairly confident there are no coolant leaks (now) and hopefully after I check the vapour pipes, there still won't be any leaks.

Cheers. :beer chug:

 

[Jonah 101]

I remember Ferrari tractors use a similar system, so do ford transits and Falcons. You could try adapt one of these bottles to your car.

 

[wortus]

Thanks wortus for your input. My next step is to check the vapour pipes for blockages. After reading the other posts and of these pipes, it makes sense that they're most likely blocked. This will mean draining off some of the coolant, so when I have done that check I will only fill the surge tank to the seam line as suggested.
On my surge tank there are no "level" marks or indicator lines or sticker to show correct coolant level so I have always filled near to top. The overflow/recovery bottle does have upper and lower coolant level lines. I'm fairly confident there are no coolant leaks (now) and hopefully after I check the vapour pipes, there still won't be any leaks.

Cheers. :beer chug:

I am pretty sure the cars without a recovery tank had a sticker, mine did not however. I remember seeing photo's of these stickers but I am pretty sure the correct level is up to the seam.
One thing you should do is take the surge tank out and check it. Mine developed a zig zag fracture/strain mark along the seam on the rear side. I was lucky I checked it just before a big trip out west.
If you have a syringe just suck the excess coolant out of the surge tank. Also if you need a few surge tank hoses I have 2 of them genuine NOS, the one for the air bleed pipes and the one that goes down to the stainless steel pipe. Send me a PM if interested.

 

[JetJackson]

I am pretty sure the cars without a recovery tank had a sticker, mine did not however. I remember seeing photo's of these stickers but I am pretty sure the correct level is up to the seam.
One thing you should do is take the surge tank out and check it. Mine developed a zig zag fracture/strain mark along the seam on the rear side. I was lucky I checked it just before a big trip out west.
If you have a syringe just suck the excess coolant out of the surge tank. Also if you need a few surge tank hoses I have 2 of them genuine NOS, the one for the air bleed pipes and the one that goes down to the stainless steel pipe. Send me a PM if interested.

My surge tank is in good nick, but I found another in similar condition at my local wreckers, so I got it,,,just in case. Now here is the bit that cheesed me right off. I cleaned the inside (using degreaser) and had it bright and clean, put it up in a shelf (out of harms way) and the damn thing fell down and cracked the small outlet to overflow bottle pipe.
Some surge tanks (like mine) have a sealing land for O ring, while other similar tanks don't, must be for the later model.

Cheers. :beer chug:

 

[wortus]

My surge tank is in good nick, but I found another in similar condition at my local wreckers, so I got it,,,just in case. Now here is the bit that cheesed me right off. I cleaned the inside (using degreaser) and had it bright and clean, put it up in a shelf (out of harms way) and the damn thing fell down and cracked the small outlet to overflow bottle pipe.
Some surge tanks (like mine) have a sealing land for O ring, while other similar tanks don't, must be for the later model.

Cheers. :beer chug:

I thought all surge tanks had 3 hose connections and the connection to the recovery bottle was part of a clip on attachment to the cap?
There are 2 small hose connections on the surge tank, one oes to the bleed pipes from the inlet manifold, the other goes to the radiator and the large one goes down to the stainless steel pipe?

 

[JetJackson]

I thought all surge tanks had 3 hose connections and the connection to the recovery bottle was part of a clip on attachment to the cap?
There are 2 small hose connections on the surge tank, one oes to the bleed pipes from the inlet manifold, the other goes to the radiator and the large one goes down to the stainless steel pipe?

Yes, you are correct, my mistake. The outlet that cracked when the "spare" tank fell, is the small one at front right corner that goes to top of radiator.

In this pic you can see the sealing land for the O ring.

Other tanks I have seen at my local wreckers don't have that sealing land. I actually managed to score another cap with overflow pipe connector but was slightly different at the base of the cap to my original. It's difficult to explain the differences, so I won't go into that.

Cheers. :beer chug:

 

[Cheap6]

On my surge tank there are no "level" marks or indicator lines or sticker to show correct coolant level so I have always filled near to top.

Cheers. :beer chug:

With the recovery bottle tank in use the surge tank should be filled completely with liquid coolant, as should the space between the cap over the surge tank cap and the hose to the recovery bottle. They should self bleed anyway with any air between the surge tank and the recovery bottle being pushed out through the recovery bottle with the engine up to operating temp. and the vent valve in the surge tank cap open.

Thanks wortus for your input. My next step is to check the vapour pipes for blockages. After reading the other posts and of these pipes, it makes sense that they're most likely blocked. This will mean draining off some of the coolant, so when I have done that check I will only fill the surge tank to the seam line as suggested.

A little higher than that will be OK too. (The level will be different hot vs cold anyway).

Some surge tanks (like mine) have a sealing land for O ring, while other similar tanks don't, must be for the later model.

Cheers. :beer chug:

Other tanks I have seen at my local wreckers don't have that sealing land. I actually managed to score another cap with overflow pipe connector but was slightly different at the base of the cap to my original. It's difficult to explain the differences, so I won't go into that.

Cheers. :beer chug:

That's interesting. My recollection was only of a larger 'O' ring that sealed against the top surface of the surge tank as distinct from around the surge tank neck. It has been a while since I have seen a SI VN so not unsurprising though. I'd say you're correct and there was a change in the design of the surge tank and the cap that connects to the recovery bottle as well at some point.

Now we can all be complete anoraks about VN SI cooling systems .

 

[wortus]

Wha does your cap look like? Mine was a round cap with a lot of German writing on it, the cap off the surge tank I got from the wreckers was smaller in outside diameter and had vanes on the outside like some bathroom tap handles. You could always check with Holden to see if the part number for the surge tank was updated during the production of VN's, a sure sign it was modified.

 

[Jxfwsf]

i purchased a new cap from bursons a couple of years ago, the original cap's 1 way valve was faulty and continually let coolant escape (no pressure, so it would continually overheat and boil), the new cap was $25ish i think from memory.

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[Lamo]

Stupid suggestion.

Have you asked Toyota about this? Maybe they still have spares as well?