Coolant overflow.

**rapserv** · 23rd February 2022, 12:55 AM

Noticed that the coolant header tank in the D2 was excessively high today and is actually overflowing.
I checked the level a week or two ago and all was well, but for some reason now, its filling up and overflowing.
There doesn't appear to be any oil in the water or water in the oil and no blow back from the oil filler cap.

My 'engine saver' sensor in the top hose is not alarming yet .. and yes .. it is working.
Anyone have any suggestions as to what might be causing this?

**biggin** · 23rd February 2022, 01:37 AM

Sounds like head gasket failure, I’m sorry to say.

**laney** · 23rd February 2022, 05:43 AM

x2

**Pedro_The_Swift** · 23rd February 2022, 07:21 AM

First up, refill the system properly, make sure the overflow res is at the right mark, drive till warm/hot, check levels...
there is a D2 hack where you tape a 600ml coke bottle to the overflow, the more inside the coke bottle the quicker you need to fix it--

**discorevy** · 23rd February 2022, 08:33 AM

Does the top hose feel like it has lots of pressure after a short drive ? ( rock hard hoses ) can you see bubbles coming up in the reservoir with engine running ? ( remove cap slowly if pressure in the system )
If no noticeable pressure after a long run, ( there should be some ) have a close look at the cap ( 2x O rings and the rubber top seal as well as the sealing surface on the reservoir )

**rapserv** · 23rd February 2022, 10:29 AM

Originally Posted by discorevy

Does the top hose feel like it has lots of pressure after a short drive ? ( rock hard hoses ) can you see bubbles coming up in the reservoir with engine running ? ( remove cap slowly if pressure in the system )
If no noticeable pressure after a long run, ( there should be some ) have a close look at the cap ( 2x O rings and the rubber top seal as well as the sealing surface on the reservoir )

Took it for a short drive .. just about up to temp .. can easily squeeze the top hose .. so little pressure.
The reservoir bottle level has dropped to just below the full mark now (I haven't added any additional coolant) and I can see a few little air bubbles inside the reservoir but this could be due to coolant dribbling from the return hose. There certainly isn't a good stream returning as I think there normally is.
Could this mean a failed/faulty water pump?
I replaced it about 5 years ago with a non-genuine pump.
I might drop the fan belt and check if the impeller is turning freely for starters.

**discorevy** · 23rd February 2022, 05:43 PM

Originally Posted by rapserv

Took it for a short drive .. just about up to temp .. can easily squeeze the top hose .. so little pressure.
The reservoir bottle level has dropped to just below the full mark now (I haven't added any additional coolant) and I can see a few little air bubbles inside the reservoir but this could be due to coolant dribbling from the return hose. There certainly isn't a good stream returning as I think there normally is.
Could this mean a failed/faulty water pump?
I replaced it about 5 years ago with a non-genuine pump.
I might drop the fan belt and check if the impeller is turning freely for starters.

there will be some resistance from power steering pump. I have seen an impeller with no blades left but check it's not a partial blockage in the tank section of the rad return hose ( common )
Assuming the cap is ok ( without test equipment, it should hold pressure after a good run ) have you got any means of measuring coolant temp?

Edit: RE, the bubbles, get a torch and shine it into the resevoir, if it's getting combustion gasses into cooling system the bubbles will be seen coming from the bottom of the tank , get someone to give it a short rev ( pedal flat for 1-2 seconds ), you can block the return for the test

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