Losing coolant/overheating but no visible cause

[king1042]

My 2004 1.8 75 saloon has been losing coolant for a year or so now. Two local mechanics have looked at it and can't find the cause - one advised me to just live with it and keep topping up; which I have been doing. However lately it's started to overheat on longer journeys: i.e. 30 + miles, and I fear the worst. Anyone had a similar problem? My next move is to introduce food dye into the coolant then get underneath to see if I can spot where it's coming out. I love my old Connie and want to hang onto it for as long as possible so any advice would be more than welcome...

[Wayne2015]

Originally Posted by king1042

My 2004 1.8 75 saloon has been losing coolant for a year or so now. Two local mechanics have looked at it and can't find the cause - one advised me to just live with it and keep topping up; which I have been doing. However lately it's started to overheat on longer journeys: i.e. 30 + miles, and I fear the worst. Anyone had a similar problem? My next move is to introduce food dye into the coolant then get underneath to see if I can spot where it's coming out. I love my old Connie and want to hang onto it for as long as possible so any advice would be more than welcome...

Does the coolant bottle have an overflow outlet?

[kaiser]

You are loosing or using water.
Typical places to check

Outside:
T Piece
Crack in expansion bottle
faulty radiator cap (replace, cheap)
any plastic connection, tube or pipe, including the radiator
Inlet manifold gasket.

Inside.
head gasket
Crack in block or liner
leaking liner seal at bottom
water pump

I would do the following.
1. Check for mayonnaise under the oil filler cap with a hot engine. If water or mayo, then you have water going into the engine, that would be liner, crack, head gasket or inlet manifold gasket.
2. If the oil filler cap is dry, I think you are loosing to the outside. Here I would carefully check the T-piece. They can open and let water out, and later close again. Almost impossible to see. Look for marks.
also heck the water pump. That will drain near the engine pulley, running down along the cam belt. Can be difficult to see.
3. A new radiator cap is in-expensive, and they can start leaking, Difficult to check, but I would just replace it, BMW issue. Don't worry if it says 200 in stead of 140.
Park on a piece of cardboard, to see if there is any dripping from the engine.

[ProfDave]

Rad cap rings a first start as far as I am concerned.

Is your cooling fan OK?? Do you use your air con? Could be the low speed fan is US too which is often just the resistor!

[roverbarmy]

I thought that mine was losing coolant until I stopped overfilling it! Are you sure that you know where the max mark is because it's a lot lower than you might think (waaaaaaay down in the header tank). Mine just kept pushing out of the cap (also replaced) until I stopped overfilling it.

[roverbarmy]

Correct coolant levels shown in posts 7 and 8 HERE
Mike

[SD1too]

Originally Posted by ProfDave

Is your cooling fan OK? Could be the low speed fan is US too which is often just the resistor!

Martin,

This is what you should check first and it's easy. Start the engine from cold, press the windscreen demist button then get out of the car and walk to the radiator grille. Is the electric cooling fan running?

Please report back and we'll take it from there.

Simon

[chrissyboy]

your saying coolant lose with no signs of where the car is losing it from .it can only be an internal leak then hgf,remember you dont always have iol and water mixing it all depends on where the gasket is leaking

[DMGRS]

The first thing to try (after making sure the level is in fact correct) is the coolant cap - you can change the whole cap, or just the O Ring seals.

Both are here:
Coolant Cap - 75/ZT
Coolant Cap O Rings

[courtman]

How tight should the radiator cap be ???????