Radiator espansion bottle questions.

Hello,

My white plastic expansion bottle isn't white it's filthy ( inside and out ) and I really don't see how I could ever tell what level the coolant was at so I want to take it off and clean it, but...

I can't see how it's attached, where are the bolts hiding and how do you remove it ?

At the top, apart from the hole where the cap screws on, I've got another hole with nothing in it, what's missing, is it relevant or was it just some sort of plug ?

How does it work or do anything ? Because I can only see the thin hose from the thermostat area going into the top cap, is there another hose hiding and if not how is there ever any water flow ?

I've probably got this all wrong so please enlighten me to the expansion tank mysteries.

Thank you.

ps. 1993 Cruising Cabin 3L engine, sorry, I forgot the important part.

Hello NickZ

The expansion bottle was in pretty much the same state on my van and was one of the first parts I removed as part of my refurb. I can imagine exactly the problem as I faced the same issue.

Without wishing to sound like a broken record the EPC (part 16470- on the radiator page) shows exactly how the bottle is attached to the vehicle and how the hoses are attached.

Also, without wishing to sound like a broken record I explain how the expansion bottle works in my very detailed post on the cooling system. You can read this post on my show us yours section posts. It’s just after the rear brake pictures. I also describe the fan clutch in the same post.

I also describe there the best way I’ve found to clean it or any plastic bottle or demountable tank on any vehicle (and I’m not recommending an ultrasonic cleaner by any means).

Sound like you have some homework to do.

After cleaning mine looks like this:




which I’ve also posted in other places; before it was much more than half full of sludge and the sensor was all gumed up. If yours is anywhere near as bad I’d suggest a comprehensive overhaul (flush and back flush, see the post) of the entire system. Just because you have a refurbished radiator (I seem to remember you writing) does not mean your entire system has been overhauled. I’d act with an abundance of caution as the cooling system is often neglected and fixing one part does not fix the lot.

The expansion bottle is not part of the pressurised system so it’s not like used on typical modern vehicles and is plumbed and operates quite differently. The in water flow (down the tube) is purely by expansion displacement but as this happens when the system is hot it can also transfer sludge. Return is by cooling contraction. Nothing more as fas as I can tell. The other hose is a vent to atmosphere. Sound like you might be missing this, but again it’s on the EPC.

I'd suggest you take a look at all the coolant elements, and a lot of this is in the electrical section (I might have mentioned this before).

Please read my post!

HTH!!

Hello LH1i9V,

Thanks for the information, I have read your post before about the cooling system but it didn't explain much about expansion bottle removal or what it does. From your picture it looks like there are four bolts, I'll just have to find them ! I did look at the parts picture but thought that bits weren't showing because it made no sense.

At least now I know how it works or doesn't as it seems a bit useless because a breather hose would prevent pressure and with the hose that runs to the main system attached at the top nothing that goes in it will ever go back unless you drive upside down and my van's not fast enough to loop the loop.

Maybe it's just a pressure relief thing or a rubbish collector and when you see it on high that means you should top up your water level, I don't know. But it seems like there can't be a flow when there's effectively a hole in it. It goes against what you learn in a junior science class. Perhaps I should've done my homework then too as I don't understand how the water returns when it's cold because as it cools/ shrinks doesn't the air follow the path of least resistance and go out the hole leaving the water. If I blew in the breather hose that would be a different matter. Has the breather got a one way valve ? That would make more sense.

Anyway it must be there for a reason and mine's dirty, when they fitted the rebuilt radiator the system was flushed and it was done before that when something was done to the rear heater. I think this was when it got disconnected and I'm never going to use it anyway.

I will investigate further, but it'll definitely be coming off at some point.

The expansion bottle works like this , as the heat builds in the cooling system there is expansion, fluid is forced into the bottle there should be a dip tube to the bottom of said bottle, as the engine cools there will be contraction thus pulling fluid back through the dip tube back into the cooling system. If this did not work we would loose fluid every heating cooling cycle occurred.

JT69... Thank you so much, that explains the mystery I think I'm missing the tube from the cap, it's probably in the bottle as it's unlikely to have gone anywhere else !

I thought it was all a bit wrong and you probably just saved me some serious problems and hunting for leaks that didn't exist.. Awesome !

JT69.. I found the hose in the bottle and fished it out

Awesome glad to help we learn every day