Club 80-90 Forums

P.S. = Thinking about it, I have never actually looked to see how full the top up tank gets with a well hot engine

I wouldn't have thought it would get as full as you describe, someone (likely Ian ) will be a long soon with that info

ghost123uk wrote:P.S. = Thinking about it, I have never actually looked to see how full the top up tank gets with a well hot engine

I wouldn't have thought it would get as full as you describe, someone (likely Ian ) will be a long soon with that info

Our's gets to about the top of the cap if not a fraction higher when you pull up after a good run.

Ian

That sounds ok then. I filled by tank up when cold to the max mark. When hot it is over this mark. When revved it appears to go down a bit. When hot an turned off it goes to the bottom or just past the filler cap. Then returns to mas as it cools.

At present this has all been done stationary. I'll Tax her tonight and then road run. Now wheres my AA card

This all sounds good for you then

I have to go for a drive today (to delivery a FlyMo I just sold) so I will check how much my top up tank level rises too.

silly question but if the top up tank is sealed how does the air escape?
As there is a rise and falling of the fluid in the top up tank surly air needs to escape?

It isn't sealed there's a hole(s) at the top somewhere.

Ian

Ok, the system works like this......
When the engine is cold the top up tank is at the max ( full to the filler) and the header tank is also full to the brim.... As the engine heats up, the coolant expands, but it's under pressure ( the darek cap is a pressure cap) which raises its boiling point, but as it expands it forces itself out through the darlek cap into the top up tank, which has three small hole in the top to allow air to get out and coolant too if it gets that high ..... As your engine cools down, the pressure drops and the coolant is sucked back into the header tank as the coolant contracts , hence the top up tank level drops whilst maintaining the full to the brim level in the header tank......

Thanks Mocki,

Cold, there is next to no air in my expansion tank and top-up tank is at MAX. When hot the top-up tank rises to halfway across the filler cap (very hard driving). I see no holes on the top of the top-up tank. If these are blocked will this be enough to cause the water to come out the top-up filler cap?

pfield69 wrote:Thanks Mocki,

Cold, there is next to no air in my expansion tank and top-up tank is at MAX. When hot the top-up tank rises to halfway across the filler cap (very hard driving). I see no holes on the top of the top-up tank. If these are blocked will this be enough to cause the water to come out the top-up filler cap?

No, the header tank is thick, the other is very weak.

The holes are up at the top out of sight when the tank is fitted, in the half inch wide "tab" shaped bit . But don't go ripping things to bits, from your description they are not blocked, as if they were the lid would be pushed off when the hot under pressure coolant was pushed in, and the tank would be sucked in when the vacuumed exit of the coolant took place on cooling down..... Just trust us!

If you have coolant coming out of the header tank cap ( darlek on late bayonet on early ) then you either have a duff cap, or a cracked tank around the threads , but your description suggests it is working ok

Thanks.

You can just see the tab with the holes at the top of this photo.

Well I thought we had success but.....

went out today (in the cold-0C) and we have a leak from right hand head seal

Is this head gasket territory?

This is exactly what happened to the first engine in our TinTop. The excess pressure caused by the boiling water in the left hand head, in turn caused by similar blockages to the thin pipes you had, and a duff Dalek cap, caused the (likely already weak) head to case seal to leak and fail.

You likely know the ins and outs of replacing them. It is a big job, fraught with dangers.

If it happened to me again, I would go and get an Elite re-con

Sorry mate

pfield69 wrote: Is this head gasket territory?

No, it's the 'water jacket seal' if you do a search they have been covered a great many times The 'head gasket' itself is a narrow annealed ring between each of the barrels and the heads.

Ian