Epic coolant leak

[S0updr4g0n]

I'm after some sage advice, hopefully someone can help!

2008 VXR8 no issues apparent until today, after a 40 minute drive.

Pulled into my destination car park and heading for a space when a very loud hissing sound and lots of white steam appeared - temp gauge reading normal. I parked and popped the bonnet to inspect and the rad hose up top has removed itself from the rad and emptied all the coolant onto the floor. Closer inspection reveals the rad 'flange' has broken off in part and the clip is still on the hose.

From a quick run down, I'm guessing the causes can be many including bad rad cap, blown head gasket and dodgy therm. The only other thing (I'm not looking to prove, just want to find out why) is that I had someone look at the air con valve in the same location yesterday and it's possible they may have inadvertently put manual strain on the rad/hose connection.

My questions really are, what is likely? Has anyone had this happen? Are there easy ways of testing to find out the cause?

Any help appreciated!

Edited by S0updr4g0n on Thursday 14th September 22:49

[skinnyman]

If the release spring in the rad cap is knackered then it won't release any excess pressure in the system, which could cause the pipe to blow off, if it was knocked loose by someone before hand. But even then the question would be 'why is the system pressure so high?'

[Bmwbigot1]

Had the same problem on an 08 VXR8 60k miles.Spoke to the two British specialists,never heard of that happening before (yeh right!) started looking on American Pontiac G8 sites and it's a regular happening at about 8-10 year old 60k miles.They replace theirs with a Cold Case 2 row aluminium radiator.I bought mine from :- [e-mail] part number/stock number LMG 5005. Takes the standard radiator cap. Cost $ 379 plus carriage if I remember correctly. Plus £108 import duty and parcel force handling fee. ( Dick Turpins alive and well) I also replaced both hoses (get the gm part numbers off the old ones as I have been told there are two? different top hoses. One final note of caution before fitting fill with WATER check to make sure the drain tap works,mine didn't due to the boss in the radiator was longer than the height of the tap. Meant I had to enlarge the hole in the plastic under tray so that I could remove the tap complete with a spanner.(not an insurmountable problem but a pain in the butt) It's the same radiator for manual/ auto transmissions you just put a plastic cap over the connections on a manual transmission.Hope this helps you.

[S0updr4g0n]

Thanks for the info and help so far!

Pressure wise I don't think it was abnormally high. I can see from the plastic pipe that it's brittle on the end and there are bits missing exactly where the clip was seated. Therefore, I'm guessing, but I think a bit of manual 'pressing' on the pipe would be enough to crumble the edge which meant the clip was no longer over the plastic tube and it just gradually worked loose.

I'll certainly look into the alternative, thanks BmwBigot1 .. I also have a rad manufacturer local to me who might be able to assist who I'll try Monday.

[S0updr4g0n]

Just as an update; the company local to me is able to make them. They make performance cooling systems and I'm told they will be able to make a complete aluminium unit based from a mould of the original. It works out cheaper from what I can see also.

If it's certain and can be achieved I'll see if I can get them to keep the moulding for others should anyone else require it.


Thanks for the helpful replies!

[Shauuuun]

Did you get you’re alloy rad ?

[S0updr4g0n]

Certainly did.

I had a better rad made by a nice chap (other thread) from Advanced Autocooling in Bristol.

[jon1bc]

Same thing happened to me last year. 08 VXR8

I was out in the car and decided to return home earlier than planned as I noticed the water temp gauge was slightly higher than normal. I pulled into my garage, popped bonnet, peered over the engine bay to see if anything was amiss/leaking - after about 30 seconds I went to turn the engine off then bang! the garage turned into a steam room - coolant absolutely everywhere - walls, ceiling the lot. I was so lucky to get away unscathed that day.

[S0updr4g0n]

jon1bc said:

Same thing happened to me last year. 08 VXR8

I was out in the car and decided to return home earlier than planned as I noticed the water temp gauge was slightly higher than normal. I pulled into my garage, popped bonnet, peered over the engine bay to see if anything was amiss/leaking - after about 30 seconds I went to turn the engine off then bang! the garage turned into a steam room - coolant absolutely everywhere - walls, ceiling the lot. I was so lucky to get away unscathed that day.

Oof, lucky indeed! It certainly pumps it out doesn't it?

I recently had another oddity whereby there was a small burst when the rad cap popped (Stant). From a cool point, I tried to do some diagnostics by running the engine to get it up to temp and it did but then carried on climbing. Fans kicked in but continued to climb so I thought it was probably the water pump!

I ordered a replacement and had it changed over; the problem has gone and all is normal. However, with a small camera inspection, the old pump seems fine - no broken impeller or anything and nothing sounds loose.

I can only assume it's either requiring heat / pressure to fail OR there is a problem I've not found out about yet.

[dan mugglestone]

Ive had something similar happen twice where I go for a drive everything is normal . But once i park up coolant drops out on the right side and there is a gurgling noise around the engine .
I top it up once cool and the leak has gone?
Is this something to do with a faulty radiator cap???
On an LS2 in a monaro

[mfp4073]

dan mugglestone said:

Ive had something similar happen twice where I go for a drive everything is normal . But once i park up coolant drops out on the right side and there is a gurgling noise around the engine .
I top it up once cool and the leak has gone?
Is this something to do with a faulty radiator cap???
On an LS2 in a monaro

I'm not sure why but radiator caps on a Monaro are known for failure.

[dan mugglestone]

mfp4073 said:

dan mugglestone said:

Ive had something similar happen twice where I go for a drive everything is normal . But once i park up coolant drops out on the right side and there is a gurgling noise around the engine .
I top it up once cool and the leak has gone?
Is this something to do with a faulty radiator cap???
On an LS2 in a monaro

I'm not sure why but radiator caps on a Monaro are known for failure.

Does it have to allow a bit of pressure relief when working normally?

[mfp4073]

dan mugglestone said:

Does it have to allow a bit of pressure relief when working normally?

The only time the radiator cap will releve any pressure in the cooling system is when things have become way too hot for some reason. During normal use the coolant system needs to be pressurised to work properly.
When the car is cold if you remove the cap there should be some pressure release, that tells you the cap is working as it should.
If the cap is not maintaining any pressure it is faulty and needs to be replaced.

[bigwheel]

Monaro rad caps are known to have weak springs.
They're ok for the first few years but then the spring metal isn't robust enough and loses it's strength and allows coolant out.

[dan mugglestone]

Sussed It!!!!!
The reason its leaking on the right is because the rad cap spring is giving up, then allowing coolant to run through the overflow pipe that leads into the neck of the top up tank on the right. LS2 vxr
It then overfills this and excess pours on the floor!! which is why i cannot find a leaking hose.

Seems its a weak spring as suggested above

[stu vxr]

dan mugglestone said:

Sussed It!!!!!
The reason its leaking on the right is because the rad cap spring is giving up, then allowing coolant to run through the overflow pipe that leads into the neck of the top up tank on the right. LS2 vxr
It then overfills this and excess pours on the floor!! which is why i cannot find a leaking hose.

Seems its a weak spring as suggested above

It may be weak, but the cap is supposed to lift to allow expansion of the coolant into the reservoir tank, once things cool, a vacuum is created to draw coolant back into the radiator, it's a dated system and can be very frustrating.

You need to maintain the correct level in the reservoir tank for this to be effective hence not suffering from coolant loss.

[bigwheel]

stu vxr said:

It may be weak, but the cap is supposed to lift to allow expansion of the coolant into the reservoir tank, once things cool, a vacuum is created to draw coolant back into the radiator, it's a dated system and can be very frustrating.

You need to maintain the correct level in the reservoir tank for this to be effective hence not suffering from coolant loss.

Yes, it's supposed to lift but the developing problem is it lifts at too low a pressure thus over filling the expansion tank.

[dan mugglestone]

bigwheel said:

Yes, it's supposed to lift but the developing problem is it lifts at too low a pressure thus over filling the expansion tank.

At the moment its an intermittent problem so will order another one and keep an i on it , does seem to do it after a run and perhaps radiating heat biulds up with no airflow and steams it open

Cheers for the help

[S0updr4g0n]

Interesting. I, and naively probably, believed he expansion tank was a non-return affair. To hear a vacuum is involved to return coolant has surprised me a little. Thanks for the info.

[S0updr4g0n]

dan mugglestone said:

At the moment its an intermittent problem so will order another one and keep an i on it , does seem to do it after a run and perhaps radiating heat biulds up with no airflow and steams it open

Cheers for the help

I did have the same issue with gurgling after a run, the rad cap was faulty in my case.