TDi75 coolant leak - advice please

Pinkythelabrat

A2OC Donor
Good afternoon,

I’ve been having to regularly top the coolant up about once a week for the last couple of weeks. I thought it might be a loose cap but a replacement doesn’t seem to have fixed it. I’m looking for some advice please.

5606b1f3343b10d8de7e47d0f5d3b58c.jpg


The header bottle doesn’t appear to be leaking. It was dry. The picture with arrow indicates the general area where I found coolant. The undertray was wet only underneath the near side edge of the gearbox. I can’t really feel any moisture anywhere apart from on top of that area underneath the arrow - it seems quite contained. The wishbone maybe...

The coolant tube with the arrow touching it feels like it should have a clip at the engine end where it Ts but it doesn’t. Am I missing something?

All advice welcome (and needed) - I’m off to look at fluorescent dye kits.


Sent from my iPhone using Tapatalk
 
Not clear from the picture, but if that is the heater inlet pipe going through the bulkhead then yes there should be a clip on it. Check the bottom hose on the expansion tank as I have seen them perish just below the tank ant the tank spigot crack both can cause leeks when hot and under pressure.
 
Not clear from the picture, but if that is the heater inlet pipe going through the bulkhead then yes there should be a clip on it. Check the bottom hose on the expansion tank as I have seen them perish just below the tank ant the tank spigot crack both can cause leeks when hot and under pressure.

The picture is taken showing the near side of the tdi engine cover at the top of the pic, the front is to the left, th gummy mess near the middle left is the gear selector tower.


Sent from my iPad using Tapatalk
 
Or just fit a non oem jubilee clip of suitable size, and probably quicker to get and easier to fit, just do not over tighten it.
 
An update...

I did find a clip on the pipe - it was just rotated to the side and covered in yuk.

I did also find the rough area of the leak and got some better pictures. Unfortunately it's a bit awkward an a bit deep - hopefully someone can identify the bits involved.

51773


This area to the right of the engine block

51774


And further in - the drip is visible through this little metal bracketed area circled... (annoyingly this pic has rotated for some reason - it's 90degrees clockwise to the others).

3 - close plug and drip.jpg


The drip is coming from here. It's a pretty steady amount of bright pink and seems to be coming from around the area of this sensor or plug with wires coming from it.

Wild guess but is this a temperature sensor or something and is there a gasket which might have failed? Or is there a pipe or similar around the back that I can't quite see?

All input very welcome :)

Alex.
 
I think it has a rubber ring seal which may have perished although it would be unusual. ?
 
Apart from the hoses that connect onto the plastic manifold, there is the temperature sensor which has a rubber seal and also where the manifold connects onto the block there is another O ring rubber seal. Could be one ore more of these at fault. Dry everything completely, then run the engine until hot to see if you can find a leak. You may not find a leak statically unfortunately but hopefully it will show up using a bright light and some paper towel under the area. There is also the chance diesel has attacked some rubber but lets hope not.
 
Thanks Mr Special Edition.

I think you are correct. The lovely new pink liquid is drizzling steadily out of the little green four pin ****.

The retaining clip still has a bit of travel on it but I can’t see that it can be forced any higher and the sensor itself is very mobile and wobbly in its slot - it feels like there is no rubber seal at all.

I’m not brave enough to pull it out without a spare clip, ring and a couple of days in case I pull a ‘Dave’. Time to order a replacement... gah!

Typically this happened when I ran out of little blue rubber gloves...


Sent from my iPhone using Tapatalk
 
Thanks Audifan.

It didn’t leak on standing but a torch, a dentists mirror and a running engine (and some real fear sticking my arms down around the lump) and I can see the coolant piddling out around the green sensor plug.




Sent from my iPhone using Tapatalk
 
In that case get a new sensor with a new seal AND a new clip. Tie some string or fishing line around the old clip and pull with pliers to release. Make sure the old seal comes out, fit new sensor and seal, then with the string /fishing line tied to the clip insert it. If you omit the string you can spend hours trying to find where the clip disappeared to. Remember to top up the coolant afterwards.
 
Ordered and the recommendations bookmarked.

String or thread on clip noted! That would be an utter pain! I’ve dropped a socket set before and that was bad enough...


Sent from my iPad using Tapatalk
 
Incidentally my Bad Garage allegedly ‘replaced’ this sensor three years ago so perishing shouldn’t be a problem.

I wonder what joy awaits...


Sent from my iPad using Tapatalk
 
Finally got around to changing the coolant sensor and O-ring today. Hopefully that’s it sorted.

Took about 20mins of fiddling with the clip. The new clip lasted about 12 seconds before snapping in half so the old clip had to go back in. It still feels a bit mobile but hopefully it’s a bit more watertight than the last set up.

Definitely second the advice to get a spare clip and add thread when fitting. Very fiddly. I didn’t drop but it was on the cards and snapping the new clip so easily was a surprise.

Anyone know where to source a metal clip or just the clip on its own? I found a few for other models so maybe had the part number wrong.


Sent from my iPhone using Tapatalk
 
Clips fit to most temp sensors in VAG range. All are plastic so they do not corrode and fall out.
 
Back
Top