Audi A2 1.2Tdi Coolant overflow

Hello there,
I currently have a problem with my A2, where the coolant systems is being pressurized, which on long trips make a lot of coolant escape out the overflow hole. I really want this problem fixed because its quite annoying.
I'm suspecting that the head gasket is leaking, but it doesn't show any symptoms other than the pressurized cooling system. There are no signs of coolant in the oil or vice versa. The temperature never goes above 90C, and the cabin heater works as it should, it doesn't take long to warm the cabin.
I have tried changing the cap on the coolant tank, but it didn't help.
Have anyone else had the same problem?
I have ordered a block tester to test for combustion gasses in the cooling system, and maybe that can help diagnose the problem.
I haven't changed the thermostat or the water pump but plan on changing them, in hopes that it may solve the problem.

If the gasket is the problem, is it even possible for me to change it? I have read the workshop manual where they describe the procedure and it doesn't seem too difficult. But the studs that hold the head, don't they go all the way through the block and keep the bearing caps in place? Because in the SSP 223 manual it says that the bearing covers should not be removed because it will warp the engine block from my understanding. So can i remove the head without removing the bearing caps.

I hope someone can help, Have a great day

-Simon
 
If this only happens on long trips I would suspect that the water side of the water pump has disintegrated and that you have no circulation. That would explain why the indicated temperature is not excessive. That's the place to start, certainly easier than removing the head and if it's not the water pump, you would have to remove the timing belt anyway to remove the head. If you have to, there shouldn't be any problem removing the head (at least no more than any similar car) but you are correct about removing (or not) the crankshaft.

RAB
 
If this only happens on long trips I would suspect that the water side of the water pump has disintegrated and that you have no circulation. That would explain why the indicated temperature is not excessive. That's the place to start, certainly easier than removing the head and if it's not the water pump, you would have to remove the timing belt anyway to remove the head. If you have to, there shouldn't be any problem removing the head (at least no more than any similar car) but you are correct about removing (or not) the crankshaft.

RAB

Thanks
Yeah, im going to order a new waterpump and thermostat and try and replace that first of all.
 
i have changed the waterpump and the thermostat, the pump was intact so i don't think it will solve the problem, but i will do some long drives and see if the problem is gone.
 
Were you able to check if the plastic impeller was still 'tight' on the shaft. Some come loose and can spin on the shaft when the pump gets hot

Cheers Spike
 
i just tried to spin the impeller, but there is no movement. I can see that the coolant tank is still letting out pressure from the overflow port after a 20km trip, so i don't think it has solved the problem. I tried pressurizing the coolant system when i changed the parts and it holds 1.5bar no problem, the same with the tank, it hold the pressure it should.
I don't know what else could cause the problem since i can't measure a headgasket leak, but i will try to check for co2 in the cooling system with one of those cheap kits you can buy.
maybe its the radiator? i don't really have a clue anymore.
Thanks for the help so far
 
I had simular issues with my TDI last year , although it was not losing much coolant i tried everything and continued driving her for several thousand miles before i finally gave in and pulled the head off , the multi layer head gasket was intact but you could see where compression was being forced into the coolant ports under high load id imagine where there was corrosion between the multilayered head gasket and cylinder head ..
IMG_1466.JPG

the fault itself was the oposite cylinder but just out of shot and cant find a better photo at the moment but ive put a red ring around the same port and you can see the corrsion although not as bad as the side that caused the leak
 
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well i hope the co2 tester can show if that is the fault, it could very well be. If that is the problem i was thinking of fitting a larger coolant reservoir so that only pressure escapes and not coolant, only temporarily.
I still don't know if it's possible to remove the head on the 1.2Tdi without warping the block, but i do have an extra engine for my car that i'm currently renovating which i could swap to when its done.
 
I was only losing about half a pint on a 100 mile journey, and coolant level getting low in the reservoir id probaly leave things as they are if i were you as its not hurting anything as such losing coolant if its not a huge amount and just letting off pressure and youv still got the low coolant warning if it does get low , so you can stop and wait a little while too cool and top up again, may be worth having a look see on the german forum as theres more 1.2s owners than hear in the uk and even have a shout out there and see if anybodys ever done a headgasket as like you say about warping the block , i may be totally wrong but i thought it was just the bottom end ,that couldnt ever be dismantled as i read it in one of the self study pdfs and replacing head gasket could be done

1.2 tdi.PNG

i can not add the self study pdf as too large a file size but i just took a snippet for you , if youd like the full pdf pm me your email and ile send it to you

Regards Gary
 
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Yes it is the crankshaft bearing covers that mess with the engine, but from my understanding the studs on the picture, the ones that hold the head, go all the way through and hold the bearing caps in place as well. i don't know if the studs are fixed to the block so you can take the head off, it would be stupid if taking the head off ruins the engine. I don't know of the 1.4tdi also uses the threaded rods as well, or if its normal bolts.
 
Ref page 8 and 9 of this SSP - http://www.volkspage.net/technik/ssp/ssp/SSP_223.pdf

As RAB eluded to in an earlier post it looks like it's only the bottom end which can't be touched but it sounds like the head can be replaced using a special procedure for the head nuts.

Back to the cooling issue, I don't recall anyone having success with a co2 'sniffer' test even though the gasket eventually proved to be at fault

Cheers Spike
 
Ah thanks, it says on page 9 that the studs are glued in place, so i don't think it should be a problem to remove the head,
yeah i know the co2 tester probably isn't the best way to test it, but why not try, if it shows sign of co2 then i know that the gasket probably is the problem, its just to be extra certain.
 
Well, late update.
The co2 test didn't show anything, but i decided i wanted to change the head gasket by myself, and might as well change the timing belt when i got it all apart anyway, since it needs changing within the next 6 months. I started by taking the whole front of the car, it was pretty easy, and it made the whole procedure a lot easier and less frustrating. I started by trying a compression test on all cylinders and i got a reading of 27Bar on all three. The workshop manual states that 25-31 Bar is "new/good" and 19Bar is the wear limit. So all good. You just remove the injector plug so the car doesn't start.
I drained all the coolant, removed the front, disconnected battery, removed alternator and bracket, locked the crank and cam gear, removed the belt, removed the left engine mount, put a jack under the engine to hold it, removed all intake pipe, i loosened the egr cooler, took off the egr/anti shudder valve off the manifold and shoved both of them it in the back of the engine compartment. I removed the intake manifold completely. I loosened the nuts on the exhaust manifold that held the turbo. I removed the fuel lines from the tandem pump, and loosened the rails on the valve cover, and shoved them to one side. I let the tandem pump be attached to the head since i didn't have the gasket that sits in between the pump and the head. There are two bolts that hold a piece of plastic that sits behind the timing belt, one is a hex screw that sits below the cam gear, and a bolt sits on the back of the engine, i think the whole piece can be removed if the water pump is removed, but i didn't want to remove it, since i changed it not too long ago. It is also a good idea to remove the thermostat since that guarantees that no coolant is left in the channels in the head. You also have to remove the cam position sensor. The turbo oil feed is also attached to the head with a single bolt right underneath the tandem pump.
When i was sure that all things that are connected to the head were removed i loosened the 8pcs 12 point hex nuts that hold the head onto the block. It is a very good idea to get a longer 12 point than normal, because the short ones can't reach the nuts when the cam is installed, and it more work if you have to remove that part, so i highly suggest getting longer 12 point bits. I bought mine on ebay, something similar to the one in the picture.
s-l1600.jpg
The nuts are very tight, and a breaker bar is probably the best tool for the job, i loosened them all and was able to pull the head up, over the head studs, the head is pretty heavy so make sure you have somewhere to put it, don't place it on something hard, the injector tips protrude from the bottom, so don't slam it into the floor. When i had the head off, i looked for any sign of leaks, one of the cylinders were a bit black around the edge, it will post some picture later, so that might have caused it. Remove the old gasket, and i used some acetone to clean off the old gasket residue, both on the block and on the head. I inspected the cylinder walls while i was at it, and the look really good, i could still see the cross hatch hone in the cylinder wall, even after 350.000 km, that's pretty impressive. I took the new gasket out of the packaging for the first time and put in in place without getting dirty hand on it. If you want a gasket between the exhaust manifold and the turbo, make sure to put it in now, you can't get in in after the head is on, i forgot, but from what other people have told me, the don't have a gasket there anyway, there was no gasket on mine, so i was not going to take the head of because of that. I Put the head back on and torqued it down. Got the manifold, timing belt, all the necessary stuff, so that i could perform a new compression test. And it read the same as last, so that's a good sign. So i put the whole car back together. Easy as that ;P You get the idea. I installed a pressure sensor in my cooling system when i was troubleshooting it, so when i took the first trip with it, i could see that it looked a lot better. Usually the pressure would rise when the engine was under moderate load, to about 1.4Bar where the Over pressure valve would open. Also when i would start up my car in the morning the pressure would rise to 0.5Bar, but that is all gone. So it's fixed, only took 14 hours of work including 3 meal breaks, and a lot of help from a friend. If anyone has questions feel free too message me about the procedure, maybe i can help.
-Coro
i will upload some more picture, when i get the transferred from the camera
 

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You make it sound so easy! I spent 5 hours building a flat pack cabin-bed for a child. You rebuilt an engine in little over double that! Amazing! You are luck that you don't live near me or I'd be round like a shot for help!


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