t25 over heating

[d245jke]

Hi all-can anyone help
I have a 1900cc t25 1986 than keeps overheating. It runs okay around town but I only have do about 25 miles on the motorway and small bubbles appear in the expansion tank, these build up and force water out of the filler tank. I have checked the radiator which is working fine, fitted a new thermostat, fitted a new expansion tank with new cap, and bled the cooling system as per manual instructions.I have had the cooling system tested for carbondioxide in the water but this was proved to be negative, there is no water in the oil or oil in the water. Has anyone got any suggestions what it could be.

[kevtherev]

there must be a blockage/gas leak somewhere if the coolant is being forced into the top up tank.

fitted a new expansion tank with new cap

that's the top up tank... did you mean the header tank?

small bubbles appear in the expansion tank

again do you mean the header tank?

after a bleed, these bubbles will appear in the header as the water moves around after the thermostsat opens.
then they will stop.
if you continue to get bubbles then the header tank is being pressurised by gas from the head

[d245jke]

Hi
The manual states it is the expansion tank. This then condenses in the overflow top up tank and forces water out of the small hole.

[kevtherev]

so you call the header tank the expansion tank.

OK
the small bubbles are coming into the header/expansion... do they stop?
I might add that's normal after a coolant change untill the air is all gone.

does the top up tank fill right up from the header/expansion then?

if it does thats a cracked head, blockage or faulty cap.

where did you get the cap from?

[Ian Hulley]

Where are you buying your 'new' parts from ?

Ian

[d245jke]

Hi
Let me tell you a little about the history of the engine. The original engine had done 150,000 miles of trouble free ?

[Ian Hulley]

You need to speak to their manager and politely point out the fact you've reported the same fault over and over (giving dates) and if necessary mention the fact you'll seek a legal remedy if it comes to that.

You need to keep this OFF the forums though as they will feel the damage may already be done. Ask the Mods to delete this thread if you feel it will help.


Ian.

[kevtherev]

From day one the new engine was a dissapointment. There was a disturbing knocking noise from the tappets when starting the engine from cold

Not uncommon and unrelated to overheating
hydraulic tappets are like that..if they are old