Leakdown Test Needed?

[copycutter]

Hey everyone,

Just looking to get some other opinions on my car's issue atm.

Car is a 96 GTST with Pod, Exhaust, FMIC and EBC.

When I bought the car 6 months ago, it had not been driven for a long time and was quite muddy in the radiator, so I had the system fully flushed and a hose changed when I bought it.

So the other day I was at the dyno having a PFC fitted and tuned, and as we were loading the car up and doing the start of the tuning process, the tuner had to stop as the car was starting to overheat.

When we undid the air bleed bolt there was plenty of bubbly brown water coming out in spurts. We then checked the radiator core, which seemed fairly empty. Over 1L of water put in, then both the cap and bolt put back on and started again after 10 mins, still looking like overheating.

From here the radiator was pressure tested, and we noted that when pressurised to 15psi, after about 6 mins + the system would lose about 1.5-2 psi, without any visible leaks on the ground.

The whole cooling system is stock to my knowledge, and the radiator cap itself looks pretty ancient, which I was told could also have contributed to opening easier, allowing overflow to dump fluid then suck back in when the car is switched off gradually lowering the coolant levels.

Because of the pressure loss without visible leaks, it was suggested to have a leakdown test to determine if the head gasket is allowing water into the motor, which makes sense. However, is it not more likely that the standard radiator or cooling system is to account for the 1-2 psi loss over that period of time and the water level being down with a hairline crack or something?

Add to this the fact that the car has never run as though there is water in the combustion chambers which I thought was an early symptom of head gasket being gone?

I've got a new aluminium radiator, cap and thermostat on the way to me now, and I'm having that fitted plus a complete flush of the system on Monday, but I'm unsure as to whether the leakdown test is needed too.

What do you guys think? Unlikely to be head gasket or a fair chance?

Edited November 16, 2011 by copycutter

[Bsa]

why mot just wait till you get your new toys and see if it still leaks if it does then get one done might save some money

[r33_racer]

Do the radiator system test with the chemical to see if there is combustion gases in the coolant. Mental blank, cant recall the exact name of the test.

[StevenCJR31]

Do the radiator system test with the chemical to see if there is combustion gases in the coolant. Mental blank, cant recall the exact name of the test.

Yes ^^^ do this after you have fitted the new parts . . be aware that flushing the cooling system can dislodge particles off the inside of the block etc and block up the tubes in the radiator making the overheating worse

[copycutter]

Anyone know the name of this chemical test?

If I am replacing the radiator can I not just have the cooling system fully dumped before anything new is put on to prevent this dislodging and blocking of the new radiator?

[pipster11]

pk test i think

[SargeRX8]

You don't need to do a leak down test, a compression test will tell you if you have a leaking cylinder.

[The Dan]

The chemical test is called a Teekay test. Only accurate if there are visible bubbles coming up to the filler neck as it senses hydrocarbons and changes the dye colour.

[copycutter]

Thanks for the information everyone.

I suppose what I'm getting at is that if I replace the cooling system which is obviously not up to the job of even beginning loading a car up on a dyno to start a tune, am I not better to simply get the car tuned, and then monitor closely over the coming months for more symptoms of head gasket failure like oil in cooling system, rough running and start-up etc? Even if the head gasket is gone I would still need to replace the cooling system anyway, because no-one would put a fresh head gasket behind an untrustworthy radiator.

Is there any bonus for catching a head gasket leak early?

I was under the impression that a bad head gasket failure was the same as a little head gasket failure. You still have to rip the head off, buy a gasket kit and pay for machining and labour anyway. Am I not just better to run the car with proper cooling and wait and see?

Thanks again.

Edited November 18, 2011 by copycutter

[pipster11]

If you leave it too long the over heating will warp the head which will cost more to fix