My new Lemon S3! Gurgling coolant system….

[Stickystuff]

Morning all,
I’ve been a member of the forum for quite a few years but I’ve been on and off…
I had an A3 QTS about 10 years ago and for the last 7 years I’ve had(still got) my trusty 2005 A6 2.7tdi. Currently on 257,000 miles and climbing!
Anyway, I picked up a cheap S3 this week d, the interior condition is awful and the exterior is not much better. However not too much corrosion considering its condition or age, 151,000 miles.
When I went to view it the guy said it’s not taxed or insured so I only was able to take it for a short spin around the block and check it drove. Drove ok picked up ok as much as I could rev it, EML on(homemade decat) and traction control light on.
I picked it up Friday on a trailer (courtesy of my wife’s car)and Yesterday I drove it a little further but only doing 2-3 miles, when I got home I thought I would check everything was ok and I could hear a gurgling noise from the cooling system… after thinking about it the temp gauge didn’t reach 90° so I’m guessing first they took the thermostat out…. Or it’s stuck open. I took the tank Cap off and I could hear it bubbling and the coolant level started to rise… I put the cap back on before it went all over the place.
Before I immediately go to start changing the head gasket, is there anything else that might cause this and I’m not as unlucky as I think….?
Oh and the guy said that he changed the cam belt 300 miles ago but didn’t mention nor did I ask if he also changed the water pump. I want to catch it before it gets any worse… I suspect it might have already gone over the threshold though as he never mentioned it….
Thanks in advance

 

[s3mad_dude]

Definitely worth replacing the thermostat as you say but I’d also do the coolant temperature sensor as well. That’s the sensor located on the top of the coolant flange which is situated on the gearbox side of the engine. After that, refill and bleed the cooling system and go from there. Head gasket is rare to go on a S3 lump so that would be a last resort for me. Is your cooling fan kicking in? One should always run if the air con is on (fan closest to battery), and the other comes on when the car gets a bit warm. Not sure when though. After a while! Finally, the after-run coolant pump (or auxiliary water pump it’s sometimes called) shoukd run after engine shut down always. In fact even if you turn the ignition on two clicks and then off, the pump will run. It runs for about five mins. It’s located on top of the radiator within some cooling pipes. Check yours works too. Let us know how you get on. Also might be worth scanning with VCDS, clear old codes out and then start investigating your new car with the mind set that any new codes are relevant.

 

[OsterForever]

Burbling after shutting off the engine might be caused by air trapped in the system, or the reservoir cap not being airtight (or the reservoir itself might be cracked), if the system is not airtight it won't be able to properly pressurize, and if it's not pressurized its boiling temperature is going to be lower, hence the burbling (coolant is just water with anti-freeze and anti-rust additives, so it behaves pretty similar to water when it comes to temperature and pressure)
If it was the head gasket you'd get constant bubbles or coolant rise.
However, since the coolant started rising when you took off the cap, that'd indicate that the system does pressurize. Removing the cap depressurized the system, and the coolant started expanding, which is perfectly normal. So I'd start with bleeding the cooling system (or, since the cars apparent sketchy history, change the coolant altogether to a fresh G12coolant)
You can check the thermostat without taking things apart, just start the car when it's cooled down (the hoses are at the ambient temperature), start it up and see if the hoses that go to the radiator remain cool until the gauge goes up to 90 (might take a bit after that point for the thermostat to open up). If they do, and only start warming up after the engine is at 90-100 degrees, it means the thermostat is good. If they gradually heat up together with the car, then the thermostat is probably bad. Be careful though, don't just grab and hold them because you can burn your hand if they're hot, just place your hand on it for half a second and remove it. Make sure to turn off the AC so the fan doesn't spin, will make heating up the engine a bit faster, and also you won't get hurt by accidentally touching the spinning fan.

There is a thousand theories on the internet when it comes to bleeding the VW cooling systems, each slightly different than the other. Since the older VW engines don't really have bleeding valves/nipples, we usually just pour it until it's at the MAX mark, start the engine up, pour some more when it suck it up a bit, then close the cap, wait until it's properly warmed up while keeping an eye on the coolant level, then give it a couple revs, wait a minute, shut down the engine. Leave it be for a couple hours until it cools down, then open the reservoir and top off if needed. Never had problems with air locked this way. Not saying this is the best option, but it's the option that works for us.

 

[Stickystuff]

So I think that the coolant temp sensor is actually quite new, it’s the green type and looks pretty clean especially compared to the surroundings on the engine etc.

I’m pretty sure the thermostat isn’t working as it should have gotten up to 90° on the dash and it was sat idling for a while before I drove it too. I need to give it a bit more of a check over as I noticed annoyingly after I got back that the MAF sensor was unplugged and there is an after market TIP, the after market dump valve wasn’t actually clamped into it and was loose. So lucky it hadn’t sucked any crap in.
I’ll see if I can spend a little time on it tomorrow evening and plug it in and start fresh like you said.

 

[Stickystuff]

Right, so I didn’t manage to take it for another drive to test the cooling system tonight but I did have a look at the intake because I was concerned with the noises. So I’ve found the dump valve sits at an awkward angle with the rest of the pipe work. The pipe from the breather valve to the TIP is mushed so needs to be replaced but it doesn’t make any unwanted woosh noises.
Can anyone help with the correct routing of the vacuum pipes on top of the rocker cover. Currently it all looks like the attached photos and doesn’t look Right.
I put the dump valve back in place and actually clamped it in place but the N75 valve plug sits right on top of it again not sure it’s the right position.

 

[Stickystuff]

I forgot I also plugged it in and it had a multitude of lambda sensor faults… unsurprising as someone has cut the cats out and put some pipe in.
But with the traction control system it has a permanent fault for the yaw sensor. Before I look to find a replacement sensor can anyone suggest anything I can do to test it first?

 

[S3AMJ]

You can do a basic settings “calibration” of the Yaw sensor on VCDS. Other things to check for that sensor is that the mounting bracket is straight and not bent, while your looking at that you can also check the wiring to make sure that’s ok. They are known to go randomly these sensors, but those are the things I’d try first before spending £100+ I do have a known working sensor as well if you were interested and you couldn’t get it to work.

 

[A3SLine2014]

Was it a good price - the car?

 

[Stickystuff]

So I only managed to get a few minutes on the car last night. I took it for a short drive to get it up to temperature, it was still a little slow but got to 90° I sat it on the drive for a little while and watched the system, no gurgling sounds on or off. But one thing I noticed although the temp gauge in the car didn’t go above 90° the cooling fans only kicked in for a matter of seconds and not fully. In fact the air con fan kicked in harder than the actual cooling fan. Do you think the rad switch is faulty? It kicked in a few times and under pressure it was all good, and as Osterfoerever said the only reason I got that was when I released the pressure by opening the expansion cap. It does still concern me that the coolant starts to boil at what is essentially 90° so I’m going to change the thermostat and look for a new fan switch.
do you know if the fans are controlled by canbus or if it is good old fashioned anologue wiring?

 

[Stickystuff]

Was it a good price - the car?

I think so, but I’m starting to wonder now lol I’d say depending on how you value them now but between a 1/4 or maybe a 1/3 the price of a decent one.
It really needs a good clean inside and out and dehumifigation if that’s a word it’s got a strong Smokey smell in it which as a non Smokey is pretty disgusting.
At the moment I’m focusing on getting it running right and then I’ll worry about the asthetics and aromas.

 

[pj123]

I've chased a similar problem in the past and have found anything but genuine audi thermostats to cause issues.
Using the hidden display in the climate control is really helpful for diagnosing. (Press bottom right and top right buttons together, then use temp control to go up to channel 49, then press bottom right button). This displays actually temp. My car sat in traffic gets quite hot before second fan kicks in, maybe 102 degs, so now I keep air con switched on which keeps 2nd fan permanently running.

I saw you had an issue with yaw sensor. I removed mine, dug it out and resoldered all the connectors from chip to the board and it fixed it.

 

[Stuart B]

It's unlikely to have a failed head gasket, the head would crack before the gasket fails, it is two sheets of pressed steal. As you're changing the thermostat, maybe drain all the current coolant at the same time, when the thermostat is off stick your fingers in the hole and make sure the water pump isn't foo-bar.

Personally I would delete the n249 jungle on top of the cam cover and just run some 4-5mm silicon from the n249 nipple under the inlet manifold directly to the top of the DV..

650 £ ?

 

[Stickystuff]

Not had chance to work on the car this week, other than gave the outside a quick wash over the weekend. I started to sand the headlights with wet and dry to remove the UV staining. You can see the colour difference in the left hand light much clearer.

But I’ve been on a bit of a spending spree. The exhaust down pipe blows and sounds awful, I looked into replacement aftermarket and genuine. But I actually found a cheap stainless steel 3 inch down pipe and decat section that drops to 2.5 inch to fit with the standard exhaust system. It arrived today. I have heard that alignment issues can happen with these running against the prop shaft. I will look into that hopefully ‘tweak’ it if need be to avoid that.

I did also buy a cheap 3 inch Cat to weld into the ‘decat’ pipe should I need too.

I also bought some new floor mats, a new coolant expansion tank to go with the new thermostat and I also purchased a new headlining kit as the previous owner decided to rip the old material off I’m guessing because it was hanging off. The weathers meant to be nicer over the weekend and the wife is taking the kids to some birthday parties so I’ve pretty much got the whole of Sunday to try and get at least the down pipe done. I think the easiest thing to do is just drop the front subframe rather than faffing about trying to squeeze it through etc. so I’ve got the car up on my lift blocks to make it easier to jack it up and support on axle stands. I’ll take it for a proper wheel alignment once I’ve got all or most of the mechanicals done. Once I’ve got it running right I’ll be looking at new bushes and or suspension links etc. going to check the rear arms to make sure they are in good enough condition. If they are I’ll likely remove them clean them up and spray paint them to give them a bit of added protection. Or replace where necessary.

The brakes are in good condition so I think I’ll split them down sandblast the calipers and carriers and paint them. Not sure what colour to go for though. I did think about getting some LCR front brembos. But making sure the car is mechanically sound first.
Oh and I’ve moved it back and forth a few times and noticed that the traction control light has gone out… I did fit a new battery last week as the old one was a little dead so I think the low voltage may have contributed towards its fault.

 

[Stickystuff]

It's unlikely to have a failed head gasket, the head would crack before the gasket fails, it is two sheets of pressed steal. As you're changing the thermostat, maybe drain all the current coolant at the same time, when the thermostat is off stick your fingers in the hole and make sure the water pump isn't foo-bar.

Personally I would delete the n249 jungle on top of the cam cover and just I’d run some 4-5mm silicon from

650 £ ?

It's unlikely to have a failed head gasket, the head would crack before the gasket fails, it is two sheets of pressed steal. As you're changing the thermostat, maybe drain all the current coolant at the same time, when the thermostat is off stick your fingers in the hole and make sure the water pump isn't foo-bar.

Personally I would delete the n249 jungle on top of the cam cover and just run some 4-5mm silicon from the n249 nipple under the inlet manifold directly to the top of the DV..

650 £ ?

Do you have any photos of what it should look like? I’d like to tidy up the vacuum/boost pipes not only to make it look nicer but also I can’t get the engine cover to fit properly because of the little box thing.

 

[Stuart B]

Do you have the bracket over the cylinders 3 and 4 coil packs?

 

[Stickystuff]

Do you have the bracket over the cylinders 3 and 4 coil packs?

No brackets over any of the coils. Does that make a difference?

 

[Stickystuff]

So managed to get a few hours in over the weeekend. I’m pretty sure the gurgling coolant it’s nothing to worry about and it was just me. But I have still got a new thermostat to fit and a new expansion tank.
I tackled the harder job yesterday doing the exhaust.

I dropped the front subframe to get access to the exhaust. At first I didn’t drop the steering rack from the column but in the end the initial bend straight off the turbo is too big to get through.

You can see the original downpipe and previously made decat. The flexi pipe had split basically 99% of the way round, I just had to twist and pull to snap the last little bit off. I didn’t get any photos of the underside but will add to the photos.

The turbo is looking ok, other than one little crack between the valve and turbine I guess it won’t reach it’s max boost with a little leakage but from some previous photos of peoples turbos I’ve seen before it’s not the worst. Having said that on the cold side there’s a fair amount of oil in the boost pipes so it could be looking time for a rebuild or replacement at some point.

Annoyingly I knew the front antiroll bar bushes were worn and I had plenty of time to get new bushes but I forgot to in the end. So I added some electrical tape for now, the red alone adds 3HP! Haha

And I only got one photo of it fitted but from above so you can see it too much. I have to admit despite it being a much bigger pipe it doesn’t hit on anything, now. I had to bend the support rod up as it was too low, I only had a soldering gas bottle so it took quite a while to heat the rod up and it was so close to the subframe it was awkward to bend. And the heat shield above the down pipe was rubbing causing an annoying vibration noise at certain revs. I had to remove the heat shield to bend it as when I pushed on it with my lever bar it just sat back on the down pipe.


I’m going to drain the coolant and replace the thermostat and expansion tank hopefully this week so will post updates as and when.

 

[OsterForever]

While the crack doesn't seem like a big issue, I also had just one small crack on my K03 in almost identical spot and it wasn't able to provide enough boost at higher RPM, so much that the ECU was going into a soft limp mode (you had to let go of the accelerator for it to start boosting again). Granted, it was a flashed ECU and was asking for 100% of what the turbo should be able to give. I guess if you don't experience such problems then it's OK for now, but if it started cracking then it's going to crack more and more, so be prepared to put new one in. The K03 on my second 1.8T car had so many cracks I was surprised it was generating any meaningful boost.
I have to applaud you for the dedication tho, I rarely remove the subframe even on the lift, I don't think I'd be patient enough to do it on jacks at the side of the road.
Hopefully the car sounds great now with a proper downpipe

 

[Stuart B]

Don't use those gaskets, they will last a week...

You usually use a reciprocating saw and cut the top of the downpipe off and bring through the wheel well. But as you have it off now you can paint it

Steering rack bolts and subframe bolts are expensive but should be replaced, especially the sub frame bolts, otherwise you might start getting a clunk when you reverse off your driveway.

If you don't have the bracket above the coil packs then there's nothing to for the n249 jungle to...I expect the previous owner bypassed it and just chucked it on for the sale...

 

[Stuart B]

You usually see cracks on the inside of the hot side eg where the manifold meets the top of the turbo and around the lump... is this a crack or broken off carbon?

 

[OsterForever]

Well, this is still the hot side, and a fairly common place for K03/K04 turbos to crack, you can see that the crack goes all the way to where it meets the wastegate flap. I'm pretty sure you can also see one small crack to the left of the wastegate. I've had two different K03 turbos that cracked around the wastegate in a similar fashion. If you google K03 or K04 cracks you'll see quite a few examples of them cracking in the same spot.

 

[Stickystuff]

Don't use those gaskets, they will last a week...

You usually use a reciprocating saw and cut the top of the downpipe off and bring through the wheel well. But as you have it off now you can paint it

Steering rack bolts and subframe bolts are expensive but should be replaced, especially the sub frame bolts, otherwise you might start getting a clunk when you reverse off your driveway.

If you don't have the bracket above the coil packs then there's nothing to for the n249 jungle to...I expect the previous owner bypassed it and just chucked it on for the sale...

Funny you should say that. I took it for a quick drive yesterday up the road and had to park it across the road to work on my neighbours van. And it clunked up and down the curb. I tightened the bolts with my impact gun but it might need a tweak with a bar. I’ve had that before on a Renault traffic many years ago.

You usually see cracks on the inside of the hot side eg where the manifold meets the top of the turbo and around the lump... is this a crack or broken off carbon?

View attachment 270270

Well that’s the gaskets I was supplied with, I did think about refitting the original metal one but worst case I can replace it if need be. It’s not being driven daily yet so I’m sure I’ll find out the more o use it.

And yes as Oster has pointed out the crack extends to the otherside of the valve so it’s certainly slowly on its way out.

I’m not 100% sure what I’m doing with it now. I think it’s more of a lemon in its current condition than I realised when I first picked it up.

The interior is shocking so I’m starting to think it’s going to be better off turning it into a Track car rather than a road car.

The seats are meant too be a white leather but they're so dirty with oil I’m not sure I’ll be able to clean them

 

[Stuart B]

You'll see on the inside of the hotside they'll be cracks which have swelled the lump and that machines the turbine wheel... essentially to fit.

I have seen 3 turbos 2 k04s from my s3 and tt, and one from ttshop examined by their engineer as perfect condition, (all cracked) which once split was foobar too... I got back my money and sent it to AET as my exchange unit for a vt262c hybrid... total junk

 

[Stuart B]

The replacement stretch sub frame bolts, require a lot of torque then a further 180 degrees.. I could barely manage that with a 3foot breaker bar with an axle stand tube as extra extension.. I wouldn't advise that with the same bolts as you may strip the threads as the bolts are already stretched..

 

[Stickystuff]

I've not had chance to do anything to the S3 recently, I've been busy building my wife a home office.

But I figured out that the knocking noise embarrassingly was that I hadn't fully done up one side of the subframe... once that was done the noise dissapeared strangely

I spent a few minutes on it the other night, I had to jump start it because the battery was flat, but I got it running and 'up to temp', well I had warm/hot air pumping out of the vents. I noticed that some coolant/water was slowly flowing down one of the fans, as I looked at it properly it was clearly the Auxillery water pump as S3Mad_dude suggested. So I've got a new one on the way and I also ordered some silicone vacuum pipe to carry out the N259 delete too.

If they arrive before the weekend I will try and give myself an hour or two to drain the coolant, changed the thermostat finally and the Aux pump. I'll take it for a proper drive and hopefully the temp gauge will rise correctly and the fans will kick in without it over heating.
Next will be some tyres as the ones on it are knackered.

I have a company van so will only be driving it at weekends or the occasional evening during the week. Does anyone have any suggestions on a decent tyre that wont break the bank?
I've got Mich PS5s on my A6 but at £150ish per corner I could get some more track/fast road tyres...

 

[S3AMJ]

I’ve heard bad things about the PS5’s so much so one of our tyre suppliers refused to sell them to me! How are you finding them?

 

[Stickystuff]

I don't know of anyone else experience but I had them on my A6 and I havn't a bad thing to say really. I had to get one replaced but that was because of a pothole so can't blame that on the tyre. Otherwise they have been good a reliable for me. My wife has PS4's on her Tiguan and I had PS4's before these. But in all honesty they are similar price to the PS5's and so far been very similar. The only thing I will say is my daily drive(before I got a company van) was 16 miles each way on back roads with plenty of bumps and certain areas that got quite wet in the winter and they performed well for me. Granted I don't really push my A6 like I would the S3.

What bad things had they said?

 

[S3AMJ]

Deforming, flat spots and cords coming through randomly. These are things that have happened within 5000-6000miles. As a result I’ve decided to go with the tried and tested PS4’s which are more money than PS5’s….. which also makes you wonder….. why!?

 

[Stickystuff]

Oh well so far I’ve done about 6-8k and they’ve been fine for me!


I managed to get a few hours on the car today!
I got set sorting the cooling system, I managed to change the coolant reservoir so now I can actually tell what the coolant level is. Changed the thermostat, it’s an original Audi one so I suspect that it’s possibly the original. And also the auxiliary water pump as it wasn’t working and it was certainly leaking.

I got the car running topped the coolant up and it gets up to temperature all good. Much quicker than it did before.

 

[Stickystuff]

I went for the Bosch pump as it was nearly half the price of the Febi one but Bosch is still a decent one.

I also picked up some cheap Coilovers.

I just didn’t get chance to install them today.
I’m thinking about taking the Touareg calipers off my A6 and putting them onto the S3! I’m not 109% sure if I want to get rid of the A6 yet though

 

[OsterForever]

I went for the Bosch pump as it was nearly half the price of the Febi one but Bosch is still a decent one.

Bosch and Febi make parts of similar quality. Don't forget that Bosch is a supplier of OEM parts for quite a few manufacturers, and the parts they sell on aftermarket are usually exactly the same as the ones they send to VW etc., just without the OEM markings.
Of course Febi makes some great parts, but If I have a choice between the two I always go for Bosch, especially when it comes to electronics.

I also picked up some cheap Coilovers.

Don't forget to sort the rears out as well. I installed a pair of KYB Ultra SR shocks and the rear's been behaving very nicely since, even with stock springs.

 

[Stickystuff]

Yeah, I am aware of that but I often feel that the Febi stuff comes better packaged.

And Yes indeed, I had a quick look at my rear shocks at they have certainly seen better days. They've got a metal guard/cover and thats pretty rotton. I will need to give myself some time to get the rear up and check the rear arms too!!

Looking to get maybe some Bilsteins for the rear so they are slightly uprated similar to the fronts. I don't want it to be too harsh but I'm setting it up mostly for Track use as I have a company van so won't be driving it as a daily thankfully. Although looking at the prices one shock is more than I paid for these cheap coilovers.

I might get some cheaper ones for now just so I can get it driving safely. I won't be doing any track days this side of Christmas no doubt so if I get into it seriously then I'll start to buy some decent stuff. I just need to get some tyres for it now get some of the other parts I've collected fitted and then good to go