Expansion Tank Still Filling Up!

[murph]

Hi all,
was hoping if anyone could shed any light on this for me. My mechanic has had the surf for nearly a month & can't work out why it does what it does?

Had the head replaced, (milners) the rad replaced, the stat & rad cap replaced. Surf seemed to be running better. The batts then died. (both of them.) I noticed the expansion bottle was getting full & rad getting low, using about a ltr of coolant per 15 mile trip to work. Got the car back on a thurs evening. Was concerned on the friday checking the coolant level found it had left the expansion bottle & was wet all over the batt.

Gave it back to the garage over a week ago. The mechanic ran the car for the week & can't find the reason why the expansion tanks keeps overflowing. He says the gas tests on the rad came back neg. Which to me suggests nothing wrong with the head, but why the pressure then?

Any help would be appreciated.

[BUSHWHACKER]

There's either an air lock in the cooling system, or air is getting in when the engine cools.

Is your heaters set to hot when you top up?
When the engine is cold, top up coolant and leave the rad cap off over night if possible to expell any air.


Is it a Milners radiator?

[murph]

Expansion Tank Still Filling Up!

Hi Vince,


don't know about the rad? Only that it is a new one,(£235) at the second attempt of acquiring one. But I will ask, & ask I will. He disregarded any blockage on the rad as it was new. The thing i'm thinking is, he didn't know of the 2nd heater in the rear. Or am i hoping too much?

[BUSHWHACKER]

Hi Vince,


don't know about the rad? Only that it is a new one,(£235) at the second attempt of acquiring one. But I will ask, & ask I will. He disregarded any blockage on the rad as it was new. The thing i'm thinking is, he didn't know of the 2nd heater in the rear. Or am i hoping too much?

The rear heater works directly off the cooling circuit and not through the thermostat, so if it wasn't set to hot then it could be causing the air-lock.

There were some poor quality rads from Milners a while back, so I would give it a thorough check over and flush.

[Bobby Doc]

Are you putting too much water in the expantion tank?

If there is too much water in the tank and the engine gets hot, the pressure cap releases the expanded water into the tank. but if the expantion tank is already full of water it overflows, causing it to syphen the water out of the system including the radiator & engine.

[murph]

Expansion Tank Still Filling Up

Thanks Vince, I'll email these replies to him, fingers & everything else crossed.

Thanks for your help.
Mike.

[murph]

Expansion Tank Still Filling Up!

Cheers Doc,

I've been emptying the expansion tank back into the rad untill i get it back to the full line mark about 1/2 way on the tank. I was doing this from cold in the morning before going to work. 20 mins & 15 miles later at work when i check again, the expansion tank would be 3/4 to full with splash'es over the batt.

When it was time to go home the level would be remaining at 3/4 to full.

Damn annoying when I've already paid out thinking it was fixed.

Mike.

[andycook]

Have you made sure the new radiator cap is working correctly and not faulty ?

[murph]

Expansion Tank Still Filling Up!

Yep, the cap has been replaced & a original one as that as well. You did mean the one on the rad, not the one on me shoulders?

Mike

[davemaxx]

my rad is not a genuine toyota one although it is a good one (touch wood) the genuine toyota rad cap will fit but the inner guts of it will no way let any water by or back in when cooling, i asked a bloke in a car spares for a cap for my old rad and he insisted that i showed him the rad so he could check that he was selling me the right one, he couldn't emphasise enough how important it was. i suppose if they changed the name to safety relief valve the price would go up.

[NiftyNev]

i'm not sure how it allows the water back in, it must be to do with atmospheric pressure and siphonage working against the seald system pressure opening the cap and water gushing in, in a series of burps.

http://www.are.com.au/feat/techt/imp...diator_cap.htm

Nev

[davemaxx]

oh thanks for that niftynev, i edited the post because i thought i was waffelling on a bit.

[legendgamesmaster]

if water is getting into the expansion tank, you have air in the system.
As the engine temp increases, the air expands, pressurising the system and pushes the water out into the overflow.
Go for the burping technique (do a search here on burping the coolant there are some pictures somewhere) and ensure the heaters are open when you do it.

[davemaxx]

heated water also expands, fresh heated water creates air bubbels, but for the amount of water in the system it wouldn't be much of an air pocket, which i would have thought would be let by the rad cap on a 15 mile trip. he also says there is no evidence of exahst gas in the water and hasn't mentioned oil or sludge contamination on the dip stick.

how about the thermostat being jamed shut.
because its a new rad, does this mean the old one was leaking and as an attempt to stop it, it was codged with bottle after bottle of rad weld stuff and the system hasn't been flushed.

is the dip pipe on the inside of the expansion tank cap present.

[Tallyman]

The whole system should have been flushed through when the head was replaced. If it wasn't then that could be part of the problem. Did the mechanic refill with the Toyota red coolant or did he use some branded stuff, as the Toyota red and other UK stuff don't mix well.

Best bet is to get him to drain and flush the system with both front & rear heaters set to hot and the thermostat removed, to allow water to flow easier around the engine and heater pipes. It's also not unknown for the rear heater feed pipes or matrix to be blocked. You can test that by removing the hoses from the small feed and return pipes, connecting a hosepipe and testing if water flows freely around the rear system. If not then the rear heater matrix may need removing and cleaning or replacing/rebuilding. Also replace the thermostat again (if not already) as it's not unknown for them to be faulty from new.

Then when everything is flowing clear and clean, refill the whole system but with the heater hose outlet disconnected from the valve in the engine bay (about the highest part of the system) until it starts to overflow, then reconnect it. Continue slowly filling until the rad is topped right up and about 1/3 in the expansion bottle (to minimum mark). Then run the engine on tickover without the rad cap on, topping up the rad if the level drops. Replace cap once it gets hot and it stops needing a top up.

Take it for a run (with the heaters still open and on hot) then allow to cool and check the levels again. Once all the air is out then, unless you have a leak somewhere which is allowing air to enter, it should be OK. If not then there may be another problem, possibly a knackered water pump.