No coolant flow from overflow pipe

[fourteen8]

My D2 Td5 has been having coolant leak which due to over (not much) pressure I suspect.

It was first leaks from the top radiator hose that goes to radiator. I thought the clamp was not clamping the hose evenly so I changed it to new one.

then it was fine for a few days and it started to leak from the top radiator hose that goes to the engine and I did the same. Changed the clamp.

Now it is leaking from the top radiator hose that goes to the thermostat. I havent change the clamp yet. and this morning I run the engine and open the overflow tank and ddidn't see any coolant from the overflow pipe to the tank which there should be coolant flow to it when the engine still cold.

Any idea why is this happening? I did changed the coolant few weeks ago before the problem started.

Do you think I didn't bleed the system properly or radiator is blocking? (engine temp still fine)

Do you think overflow pipe, radiator or thermostat blocked causing extra pressure on the system when the engine is off?

Thanks.

[turbopsi]

How did you go with this one? Any updates?

Seems that I'll be going through the same process of chasing the next leak down the chain and it seemed to start after I fitted a new expansion tank cap.

The new cap resolved the issue of coolant blowing out of the expansion tank purge pipe, but then it started weeping out of the top coolant hose at radiator, head and thermostat ends.

Cheers
Tony.

[onebob]

oh dear - been there......

Head Gasket:(

[clubagreenie]

Yep, welcome to Team B.H.G.

[turbopsi]

Always thought the B.H.G was the most likely cause but was in denial. Appreciate the reality check.

Would it be worth going through the whole pressure test route, check for exhaust gas in coolant, etc or start preparing time and parts for a new H.G job?

2001 Disco TD5 with 220K and no record of it being done before.

Edit: Just thought I would add, the engine runs, starts and sounds perfect. Doesn't overheat, maintains constant temp one warm (temp guage half way) and has dropped around 200ml over 2000kms.

Cheers.

[fourteen8]

How did you go with this one? Any updates?

Seems that I'll be going through the same process of chasing the next leak down the chain and it seemed to start after I fitted a new expansion tank cap.

The new cap resolved the issue of coolant blowing out of the expansion tank purge pipe, but then it started weeping out of the top coolant hose at radiator, head and thermostat ends.

Cheers
Tony.

I did another check by unpluging the small hose that goes to overflow tank and could see coolant flowing.

Mine did the same like your. Weeping on top radiator hose as you describe. Before going to HG i did change the thermostat today and now I can hear HISHH sound from overflow tank cap and the cap is alao new.

It had HG replaced 2 years ago. Could it be HG again? Should I ask to change from plastic dowel to steel one this time? Anyone recommend a mechanic around western suburb of melbourne? I did the first one at Romsey LR.

[onebob]

As i understand it the plastic location dowels disintegrate and with the warming and cooling of the engine through normal use the head and gasket start to "walk" (my mechanics techo term :D). The gallery openings etc in the block/gasket/head get out alignment and you variously get constriction and/or blow by and the early symptom of this happening is over pressure in the cooling system. For peace of mind replace the plastic dowels.

onebob

[gazk]

Is the coolant system losing fluid through the expansion tank over-flow every time you drive a reasonable distance? As mentioned above posssibly a head gasket leak pressurising the system. Run the engine with the cap removed and look for small bubbles.

Fixed mine recently with a new head gasket - the plastic head dowel damage indicated about 1mm of movement which was enough to cause a small leak into the coolant gallery beside the #3 cylinder.

[fourteen8]

Is the coolant system losing fluid through the expansion tank over-flow every time you drive a reasonable distance? As mentioned above posssibly a head gasket leak pressurising the system. Run the engine with the cap removed and look for small bubbles.

Fixed mine recently with a new head gasket - the plastic head dowel damage indicated about 1mm of movement which was enough to cause a small leak into the coolant gallery beside the #3 cylinder.

The coolant went through top radiator hose. Now i had change the thermostat with 3 new hoses for it I couldnt find any leak but I can hear a hishing sound from the expansion tank cap.

Did you replace the plastic dowel with steel dowel?

[gazk]

The coolant went through top radiator hose. Now i had change the thermostat with 3 new hoses for it I couldnt find any leak but I can hear a hishing sound from the expansion tank cap.

Did you replace the plastic dowel with steel dowel?

When the system over-pressurises the coolant will leak from the "weakest point" this can be any of the hoses joints, the screw in plug in the exhaust side of the head, coolant pump seals etc or the pressure release valve in the cap.

You will find that when you open the cap (even with the system cooled down) that there will be a hissing as the pressure is released and the coolant level in the tank will rise.

My coolant loss got progressively worse over about 3 months before I changed the gasket. I did however check and top up the coolant system regularly and I have a low coolant alarm fitted for insurance - it has saved me once before when I had a major leak.

When I fitted the new head gasket I replaced the two plastic dowels with steel ones. 2000km later no coolant leaks.