Head Gasket or Airlock?
 

I was driving today and noticed the heater took a little longer than usual to heat up. No overheating at all. When I got home tonight I popped the bonnet to check the coolant, and noticed the lower hose was cool. I took the header tank top off carefully and there was a stream of bubbling (not too vigorous though). I squeezed the top rad pipe to free any possible airlock, and there was some air released, which indicated there was some airlock. I topped up, closed the top, started the engine, the car heated up, fans kicked in when it was hot enough, then stopped when it had cooled enough. There has been no coolant at all pumped into the overflow tank.

Any ideas?

Thanks

Myles

from what ur saying id go with airlock

Thanks for the reply, I hope so. The thing that concerned me was the bubbling. I could only explain it as the airlock stopping the coolant getting round to be cooled, therefore geting over hot round the header.

What does everybody else think?

Classic by per chance?
If you have an airlock then you need to ask yourself why its got an airlock in a pressurised system as it shouldnt let any air in, so you either have a leak or you have changed the coolant recently and not bled the system properly (or whoever did the change).
Other options are (if the car is a classic) dodgy rad piping (hardened plastic/cracked or deteriorated rubber pipes).

Tony:)

I had the front end repaired in Oct,and the coolant was replaced during the work. I removed an airlock just before Xmas, but could still hear the rushing water behind the dash. I presume there was still air in there somewhere.Its a newage by the way.

air lock

Thanks bighead, Ive been blighted with the old airlock since the front end was repaired!

try and do a pressure test on ur coolant system, u pressurise it and it should hold pressure, if pressure start to fall on gauge then u can a leak somewhere allowing air in.

I just got home and had a look at the overflow(plastic) tank, when I revved, it pumped a little coolant into that tank. The bottom pipe feels no warmer than very luke warm.
Ill have to have a pressure test. Tomorrow, Im going to try and milk the airlock out of the system properly. Anyone give me the definitive guide to doing this?

Update. Had a look down the drivers side of the radiator and it is all wet down the plastic part, and the leaves that gathered at the bottom are doused in warm water, coolant I presume.The car still isnt overheating so from this can I presume the rad is leaking and introducing air into the system? There was a stream of bubbling in the header tank from cold.

Guys, I reaaly need some advice here, does the fact that the drivers side of the rad is wet, with fluid pooling at the bottom mean that the rad is nadged? Would this mean that there is air being dragged in and showing itself as a stream of tiny bubbles?

All help really appreciated!

i know its sounds mad, but taste it, dont drink it obviously, just a small tap on tongue n spit. ul taste the coolant and ul know. if so, change rad, shudnt b coolant there. and if water is getting out, air will get in.

Ill take a good neckful in a mo!! Im hoping it is the rad, not an HG problem popping rads!

As an aside, when the front end of my car was damaged, it was repaired by the other guys insurance company. The garage that did it didnt replace the rad, and the problems with a poss airlock have happened ever since. Im going to tap them up on Monday, and speak to them about possible damage to the rad in the accident.

Im a panel beater, and whenever a car has a tap on front end, we change the rads as standard. its doesnt take alot to damage them. id put money on it the damage was done in accident. contact the insurance company and tell them. they should then have it bk in. the work should be guaranteed for 3 - 5 years aswell. well ours is as its vauxhall approved repairer. and paint is for 1 year.

There is also duty of care. if they didnt change damaged bits and it caused engine to blow, its their fault. they didnt estimate car correctly and check all components that were damaged and / or could have been damaged due to the shock of the accident.

Thanks for all your help with the issues mate, I will get right on to the insurance company. Ill keep you posted.

You shouldn't have any wetness on the drivers side of the rad (obviously!), etc. Suspect a split/pinhole in the driver side plastic end tank. Or it could be a perished hose that goes forn the header tank to the nipple on that end tank. Or the big top hose split or not on correctly.

Start car, idle, pop lid, stand there watching driver's side area whilst engine gets up to temp. As the temp increases, hopefully, you'll see the source of the leak - as it starts to pee out under pressure. Even a small pinhole can be detected! You may have to look further down in and around the bottom of the end tank, so get your head over that area and use a good powerful torch or the light on your cameraphone, etc...

Thanks, Ill have a look. I couldnt see where it was coming from before, but might have another try.

Another update. The car is going back to the garage that repaired the front end and decided not to replace the radiator. They are going to check the car over. I need to get a few things straight.
1. If the radiator is leaking and introducing air into the coolant system, would it create enough pressure to push the head gasket through?
2. Could a headgasket going and introducing exhaust fumes into the coolant system create enough pressure to push a hole through the radiator?
3. And most importantly, what checks should I make sure the garage do tomorrow, Im thinking coolant pressure test, sniff test for exhaust fumes, compression check? Not sure on these but I dont want to drive away not having the car checked completely.

Many thanks, Im going tomorrow, so any quick but accurate answers are truly appreciated!

1) I'm sure it's possible, yes.

2) Very much so! It happened to me. I had HG failure and the extra pressure in the system when on boost (and also because it introduced an airlock) caused my rad's driver side endtank to develop a pinhole failure. The excess pressure in the system will always expose the next weakest link in the system... sooner or later.

3) Sniff test not necessarily conclusive on the turbo'd EJ flat-4 - can still show negative at idle. This is because significant pressure/combustion gases invariably only gets introduced when you are driving using boost. Exactly this happened to me, too. Instead, after a run using boost... park up... turn engine off... let cool for 10-20mins... carefully remove pressure cap, slooowly releasing pressure... are there any horrible combustion gases in the header tank (stick your nose in there - it'll be obvious)... has the coolant level gone down significantly too...

Update. Took the car to the garage who repaired the front end today. They started by poo-pooing the idea of a holed radiator sucking air in, until I started to explain that it has been seen, and i was 'concerned' about a HG problem if the leak gets worse. Their ears pricked up then, and are speaking to the insurance company who authorised the front end work, to get them to ok a new rad, or investigation at the very least.

They couldn't see any leaks, but accepted that the residue from coolant spray was around the drivers side of the engine bay, and the rad looked damp round the top seal. They also agreed that these leaks manifest themselves randomly.
Waiting on a call now.

Keep a record of all that has gone on. As if the car does throw a head gasket soon you could use it as evidence that the initial job was not done right. With the garages oversight causing the HG faliure and then they have to sort it out.

Thanks dude, I will.

good job mate, ur intitled for u car 2 be repaired correctly, and leaks on rads dont just spring up, caused bu shock damage from impact if not directly hit

Once the hot system starts to cool then a vacuum is set up. Normally the water in the overflow tank will be sucked back into the system. If there is a pin hole then air will be sucked back instead.

There shouldn't be ANY cause for wetness on the drivers side of the rad other than from its failure or a hose failure.

Thanks for the comments guys. I dont know why the guys didnt know this from the outset, but to be fair I think they just wanted to get the car in and find something obvious. It wasnt, so they were a bit flummoxed. I told them there were bubbles in the header tank straight from the key being turned. To me that points to air being dragged right in from......wait for it.......a compromise in the coolant system. Weakest part is the rad, I would have thought, and they agreed.

Funny thing was, they did a coolant pressure test, then told me how the test is not 100% reliable. Why do it then?

Myles - this is not necessarily the case mate. When you start from cold with the header cap off and rev the engine; you will get bubbles in the water - turbulance from the pump. I have two impreza and they both do this - both problem free too :thumb:

I wouldnt lend too much weight to this theory mate.

There are a number of things you can get checked if you want to eliminate the HG failure - sniffer test is one. disconnect overflow pipe from overflow resevoir and hook up a long rubber hose to it and lash up to the screen - if you get water coming out then this may be indicative. As someone else said - go for a thrash and remove the header tank cap after 10 mins or so and have a sniff - should be just the smell of sweet antifreeze and no fumes.