Block test - exhaust present gases in coolant

[NiceCupOfTea]

Anybody ever tried one of these before?

A friend of mine used an ebay block test kit on my Saab today - get the engine running and warmed up, take the top off the expansion tank, seal it with plastic tube filled with blue liquid, suck air from tank through it, and if the liquid turns yellow your HG's kippered!

Mine turned greeny I assume this means there is a leak somewhere but not full on HGF just yet. Did try it on another car and it stayed blue. Oil is fine, no excessive steam from exhaust. I am losing a bit of coolant but too much to be going into the bores and not noticing steam (if that makes sense!)

How reliable are these block tests?

ETA:

http://cgi.ebay.co.uk/Block-Tester-Kit-leak-cracke...

Edited by NiceCupOfTea on Saturday 11th April 22:03

[Furyous]

Fairly common way of initial diagnostics.

Comp test also helps.

[stevieturbo]

was it a very mild colour change, or a quite substantial one ?


They are very reliable if used correctly.

[Iain328]

NiceCupOfTea said:

Anybody ever tried one of these before?

A friend of mine used an ebay block test kit on my Saab today - get the engine running and warmed up, take the top off the expansion tank, seal it with plastic tube filled with blue liquid, suck air from tank through it, and if the liquid turns yellow your HG's kippered!

Mine turned greeny I assume this means there is a leak somewhere but not full on HGF just yet. Did try it on another car and it stayed blue. Oil is fine, no excessive steam from exhaust. I am losing a bit of coolant but too much to be going into the bores and not noticing steam (if that makes sense!)

How reliable are these block tests?

ETA:

I've got one, definitly works - try sticking it just in front of the exhaust pipe & drawing some air/exhaust fumes through it - it'll go yellow real quick!

I think the key to using it is to take some coolant out of the expansion tank so there is a good big air gap & then run the engine for a few minutes before you start pumping the tester. That way if there is a leak you allow a reasonable quantity of exhaust gases to build up before you start the test.

Edited by Iain328 on Sunday 12th April 00:52

[NiceCupOfTea]

It was a definite change to a green colour, but not yellow. There were exhaust gases in the air (other cars running in workshop) but there was a good gap in the expansion tank and the engine was good and hot. Did it on another car and it stayed blue.

[Simon Says]

stevieturbo said:

was it a very mild colour change, or a quite substantial one ?


They are very reliable if used correctly.

NCOT if its changed color and your sure you carried out the test correctly then the fact the color as changed is a positive indication of gasses present in the cooling system,if no problem exists then the dye will remain blue,clean and dry the tester again and re-check just to confirm,the kit i have says Diesels change the blue dye green if gasses are present and yellow on petrol but that's cobblers most failed headgaskets i have checked with this kit on petrol cars sends the dye green(diesel fail)regardless,i have had this kit for many years now so i am used to this now,and as i have said already if the headgaskets fine the dye just stays blue.

Edited by Simon Says on Sunday 12th April 15:56

[(steven)]

I had one turn green on me when testing a old petrol BMW 535. Turned out to be a cracked head.

To be fair, one garage told me the car was fine and another told me the head gasket had gone so it was a very small leak as even the pro's couldn't make up their mind.

Go and get a compression test.

Edited by (steven) on Sunday 12th April 22:04

[NiceCupOfTea]

Did a comp test 6 months ago and it was good.

For now I will monitor it - got a service due in a couple of months so will get them to check it out then...

[Tony Charente]

Hello NiceCupofTea,
Just wondering what the outcome was, please, as I have the same symptoms?

Also, (general question to all), the instructions talk about sucking the gas through for a minute - I did it for much longer before it turned green. With an engine with no leak, should it stay blue even if you suck the gas through it for ages?

Many thanks,
Tony

[stevieturbo]

You dont suck anything through anything !!!!


You attach it to the header tank, and if there is any pressure or gas present, it will expel itself through the chambers with the test fluid in it.

[NiceCupOfTea]

Hi Tony.

If it's good it should stay blue indefinitely as I understand it.

The outcome was that as I was getting some other work done during the service last summer (core plug had corroded and I was losing a lot of coolant) I decided to get the head gasket done as a preventative measure). It hadn't got any worse but it was weighing on my mind a bit. Could see steam from the exhaust after a dyno run.

Can't remember what the garage said now but I think there was evidence of some seepage on the old gasket. Still, not bad for 20 years and 170k miles!

[perdu]

I used to use these kits at work

I'm afraid that if it went green it shows an exhaust gas leak into your coolant, it doesn't have to go yellow

Maybe it shows only a slight leak but that won't get any better will it?



Head off soon, sorry

I never knew the colour test to fail