Cooling issue

[Chris777]

Hi please can anyone help with a coolant issue I am having on a 2014  AUDI A3 1.4 TFSI 122ps S Line
8V1 - 3-door
Had front impact, lost all coolant, looks minor to rad but temp sensor I think it is on lower right juncture had popped out of fitting, cleaned put back in and secure back with snap ring.
Now seems to get to 90 fans are kicking in inlet pipe to rad warm but outlet cold. Not going over 90 but engine got warm and started tapping so turned off. Looked like was taking fluid, was just using neat deionised incase dumped all again.
I never got to put lid on overflow tank and fan seemed to kick on / off but rad and outlet cold.
Could it be thermostat or caved in section of rad or something?
I have since drained just the deionised and put the 50/50 mix
Runs up to 90, fans kick in and off but keep getting to a ticking coming from engine block by sounds but if rev to 2000 it goes fan goes off then fan back and ticks again.
Top pipe hot and bottom pipe cold.
I'm struck
Please help

[cliffcoggin]

Chris.

Please clarify how much damage there is to the radiator. At one point you mentioned minor damage; elsewhere you mentioned it was caved in and had lost all its coolant.

The ticking noise could be the fan contacting damaged radiator fins.

I assume "the lid of the overflow tank"which you left off, is the pressure cap of the expansion tank. To run without it will allow the coolant to boil away because the system can not develope the necessary pressure. 

[Chris777]

Hi 

Thanks very much for reply.

Minor damage I thought,  the crash bar took most, looks like surface to ac condenser and the ac seems to still work. It looked like the fluid had escaped where the lower pipe corners and has the temperature sensor as it was popped out and the wet was on that side of inner belly pan. I put a new o ring on and popped back in place.

The first time I run up with expansion top off but this time put top on when seemed to stop bubbling and had fans running as well as squeezing top pipe. Can't feel the actual rad getting warm but hard to feel, is it the piece direct behind the fan, as seems to be 4 elements making up the rad pack. 

When I mentioned caved in I was thinking if the energy had somehow transferred on impact dislodged the temp sensor and leaked out as well as damaging the radiator? Just the tapping concerns me. I have a video but not sure how to upload

[Chris777]

Hi

I have added the videos into album 

Audi A3 14 - Chris

https://www.audiownersclub.com/gallery/category/3-a3-photos/

[cliffcoggin]

Thanks for the videos Chris. The moving images are confusing, but at one point I did hear the knocking you mentioned above the normal diesel rattle.

I think you will need to remove the radiator to get to the bottom of this and ensure that the fan is not hitting it. Check that its mounting points have not been bent out of position. You may even have to renew the radiator because too many of the fins appear to have been flattened to allow decent air flow.

Note that the AC radiator will be immediately behind the engine radiator. There may also be a gearbox oil cooler there as well. Both will need to be disconnected.

[Chris777]

Thanks Cliff. It's the 1.4 petrol, fan definitely not hitting anywhere I checked. The noise sounds like an air knock of such a thing and is coming from around the oil cap. Did you see the round oil mark on the inside of the bonnet padding I pointed out, could the cap be leaking and a reason for it not building pressure?

Is it normal for that temperature sensor just to blow out of its mounting upon an impact? It seems to still build to 90 degrees on the dash ok so presuming the sensor is still good?

Is the radiator directly behind the fan sorry? So a/c condenser at the front and an oil cooler in the middle?

Is it possible to change the radiator and slam panel without disconnecting the a/c lines?

Heard if disconnected Ac then the fans won't engage until regassed?

My main concern was that oil mark and sound coming from block poss cylinder head issue but oil looks dirty/old but good no milky/frothy.

Is there anyway to check the flow of the radiator before taking the whole front to bits at all?

I am new to this but keen to learn. I did a 67 A3 8v for myself but was only panels and some replacements. Cooling and electrical I am a complete novice

Any help graciously receieved

[cliffcoggin]

I can't answer your questions Chris as I have not done the job myself. Neverthless you ought to investigate further as that knock indicates something is wrong. It may be unrelated to the cooling system, such as a broken engine mount for instance.

No I could not see any oily mark. The videos were too small and jerky for these old eyes to follow so I just listened with my eyes shut.

I did hear you talking about an air lock. That is a real possibility on these cooling systems, and can be a devil to remove. Squeezing the hoses sometimes helps, other times you may need to apply vacuum to expand the air until it reaches the reservoir.

[Chris777]

Ok thanks

Should let you click expand in bottom right of those videos and in 720p so should be clear. 

Is there a bleed nozzle at all ?

Any way to check is radiator before removing?

Can a cracked block or faulty thermostat be eliminated?

The oil mark is on one of the short videos (the title says Oil mark) was like a ring of oil droplets on bonnet padding looked directly above the oil refill cap as if the impact of the crash somehow created high pressure blew oil out of the head and the pressure sensor out of the lower coolant line.

How do I diagnose the knock? Why would it go away when rev to 2k then the fan kick back in and a few secs later starts the knock again

Any help really appreciated as don't want to make a costly mistake

[Chris777]

Is there anyone you can point me to for further advice please Cliff?

Again I really appreciate your time and replies on this 

[cliffcoggin]

Chris. I have looked again at the videos at full screen which has made things clearer. All I would add is:

1/ The knocking is unrelated to the lack of coolant circulation. The knock may be within the engine, or connected with the alternator pulley or bearing, or an engine mount, or the exhaust hitting something. I really can not be any more specific.

2/ The oil ring on the underside of the bonnet indicates the engine has been run without the filler cap at some point. Whether it blew out in the crash (which seems very unlikely) or was not secured after the last oil top up I can not say, but pressure in the crankcase would blow oil spray out of the filler pipe without it.

3/ The lack of coolant flow is likely to be an air lock as mentioned earlier, particularly if it was OK before the crash. However if you want to test the system for blockages you need to drain the radiator, disconnect the hoses, and run water through it from a garden hose. The radiator should easily cope with as much water flow as you can give. You could also do this test on the engine block if you remove the thermostat first. (Test the thermostat while it is out by putting it in boiling water.) Do the same to the heater matrix, though of course the flow will be lower.

[Chris777]

Thanks very much, 

The knock doesn't start until it has been running over 20 minutes doesn't sound like metal on metal tap sounds like a pressure release tap to me that's why I thought was related

Nothing more to try before a tear down and replace radiator then?

I am eager to learn so will give it a shot just hope I don't get out of my depth.... any tips tricks, insights before I have at it.

Appreciate you Cliff. 

[Chris777]

The tap starts when the top pipe is getting too hot to touch and the fans kicked in to try and cool. Temp gauge still on 90 but if I rev it the tick goes away then comes back as it settles it's strange

[Chris777]

How do I give you feedback/thanks/props on here?