Coolant Level still rising after a ton of work.

This is really starting to get on my tits now.

Recently I bought a rotten 300tdi Manual Disco with 2 days of MOT left on it. I drove that car over 400 miles in the last two days and had no problems with it at all, especially no overheating or coolant pressurizing.

The engine was then removed from that car and fitted it to a good Disco rolling shell I have. Now I am unable to bleed the system due to a constant stream of big fat bubbles coming through the thermostat housing filler hole. Naturally if I put the thermostat bung back in the coolant level rises in the expansion tank, although it doesnt seem to rise much more quickly if I rev the engine for a few seconds.

As I hadn't had any problems with the coolant system before removing the engine I did not touch the head gasket to begin with. Instead I replaced any dubious components outside the engine. These parts include:

Heater Matrix,
Heater pipes,
Thermostat housing,
That little union that screws into the head and joins the heater pipe,
Radiator,
One new core plug behind the turbo,
Water pump,
P gasket.
(There might be more to add to this list, will update if I think of anything.)

After all that I was still having the same trouble so I bit the bullet and took the head off. On removal the head gasket did not look obviously blown. I will admit that I did not give the head the most thorough inspection, definately no pressure test, but I could not see any cracks in it. I then cleaned the block and the head thoroughly and refitted the head with new bolts and an elring composite gasket.

Still the same problem.

Using a "Block check" tool the fluid stays blue and the bulb does not reinflate easily.

What else could be causing this?

As long as a crack was not ruled out with pressure test unfortunately it remains the prime suspect IMO

Thanks for that. I half expected someone to say that but I am simply not as experienced as many of you on here.

Just while we are on the subject, could a porous core plug give these symptoms?

IMO that will leak only not else, a good move would be tp replace the tank's cap with new and tighten it well cos it must keep steady pressure in the system through it's controll valve otherwise it can cause all sort of problems

sierrafery said:

a good move would be to replace the tank's cap with new

Click to expand...

Tis good advice ! Ask me how I know .....

It might be worth doing a sniff test - but I suspect it hasn't run enough to produce any cross contamination. It does sound like a head problem

Good luck.

Disco1BFG said:

Ask me how I know .....

Click to expand...

How do you know?

Oh yeah, I knew there was something else I should have added to the list of stuff already replaced.

I have also replaced the header tank cap and that 2 into 1 overflow pipe from the header tank to the rad'.

+1 For "how do you know?"

jimllshiftit said:

Thanks for that. I half expected someone to say that but I am simply not as experienced as many of you on here.

Just while we are on the subject, could a porous core plug give these symptoms?

Click to expand...

no, just a leak,
if head gasket was blown even slightly it would be pumping coolant from expansion tank, with your symptoms you are looking for staining across fire ring to water way
check rad gets hot all over when up to temp, fill system completely ie thermostat plug removed and expansion cap till both overflow , then refit and go for a run,system needs only to overflow not run clear

Sounds like ill be making a call to Turners in the morning then. I just can't understand how I was so unlucky not to have any trouble during the period I was running around in it and then catastrophic head failure as soon as I put it in the other car. Could it have become damaged while it was on the engine crane?

Also, thanks for the advice but I can't take the car for a run as it is still little more than a rolling shell, definately not road legal. Today though I notice that the coolant in the expansion tank becomes like a jacuzzi if I rev the engine.