H G 'sniffer test'..on a diesel ?

[varesecrazy]

We are probably all familiar with the 'sniffer test'

Checking the coolant expansion bottle for exhaust gasses..

But..

Is it a 'petrol thing'

Or work for diesels too..??


Opinions and experience please

 

[jackwhoo]

We are probably all familiar with the 'sniffer test'

Checking the coolant expansion bottle for exhaust gasses..

But..

Is it a 'petrol thing'

Or work for diesels too..??


Opinions and experience please

Works on any internal combustion engine

Ok Charlie yes not if it's air cooled

Detects co2

 

[varesecrazy]

But is it LESS effective on a derv.. or basically the same..?

 

[chris3234]

It will probably take longer leaking to detect due the the lower co2 volume of a diesel's exhaust

But should still work



That being said diesels don't tend to blow head gaskets half as much petrol's due to lower heat produced

 

[varesecrazy]

I have a friend chasing odd issues on a VAG 4 cyl..

Sniff test was negative.. despite the expansion bottle being contaminated..
Is losing coolant too

 

[chris3234]

Oil in the coolant?

I know a few vag engines suffer from oil cooler cracking and leaking

 

[jackwhoo]

I have a friend chasing odd issues on a VAG 4 cyl..

Sniff test was negative.. despite the expansion bottle being contaminated..
Is losing coolant too

Contaminated with what?
Which vag engine?
What odds issues?

 

[jackwhoo]

Oil in the coolant?

I know a few vag engines suffer from oil cooler cracking and leaking

Beat me to it Chris if it's oil in coolant

Coolant tends to migrate into oil at a much slower rate if oil cooler crack

At least the oil coolers are readily available and not too costly.

 

[jackwhoo]

Simple test to oil cooler is to disconnect both coolant pipes to oil/coolant heat exchanger, joint the two coolant hosed directly together with a short pipe and hose clips.
Run engine, if oil is evident in the now open coolant ports on oil cooler there is a crack between the oil side and coolant side. You may have to get the engine oil properly warm for it to show if caught it early and crack small.

 

[AndyRKett]

I believe these kits are not looking for co2 but actually hydrocarbons, it’s a relatively basic chemical test co2 doesn’t react anywhere near as easily as hydrocarbons which should not be present in the coolant and if it’s petrol or diesel there are still going to be the same sorts of hydrocarbons present in the coolant if the head gasket has blown

 

[varesecrazy]

Thanks all

Had both coolers replaced.. its a TDi..

Leak 'might' have slowed :stopped.. but appears to have higher oil temps now

Time will tell..

I was just wondering if an inconclusive sniff was due to being a diesel..
could just be the hg is failing..

On a £10k daily driver its just got to be sorted..

( the cheapest HG quote was the cost of my 1st grande diesel..)

 

[jackwhoo]

I believe these kits are not looking for co2 but actually hydrocarbons, it’s a relatively basic chemical test co2 doesn’t react anywhere near as easily as hydrocarbons which should not be present in the coolant and if it’s petrol or diesel there are still going to be the same sorts of hydrocarbons present in the coolant if the head gasket has blown

That is what I used to think

https://pmmonline.co.uk/technical/blown-head-gaskets-how-to-detect-them/

This one is definitely detecting co2

 

[jackwhoo]

Thanks all

Had both coolers replaced.. its a TDi..

Leak 'might' have slowed :stopped.. but appears to have higher oil temps now

Time will tell..

I was just wondering if an inconvlusive sniff was due to being a diesel..
could just be the hg is failing..

On a £10k daily driver its just got to be sorted..

( the cheapest HG quote was the cost of my 1st grande diesel..)

Hi Charlie,

Both coolers? I can think of coolant/oil
And fuel to air cooler and intercooler, egr and radiator.


Really hard to get consistent oil temps as there are a lot of variables to the cooling.

Is it tdi pd , or tdi cr?

Cleaning oil out or cooling system is soooo time consuming. May I reccomend Lidl own brand Landry detergent sir?

The oil will keep popping up in header tank for quite a while even if source has been fixed.

If very very very unlucky hgs can fail between coolant and oil passage without involving combustion seal. That would be super rare .

 

[AndyRKett]

That is what I used to think

https://pmmonline.co.uk/technical/blown-head-gaskets-how-to-detect-them/

This one is definitely detecting co2

Actually a lot of these detect acidity. its nothing more than a simple litmus test.

CO2 dissolved in water is slightly acidic, and so to make sure the test is accurate you need to replace all the coolant in the system with water to make sure that the starting acidity is already known.

However if you fill the car with water from a source that is acidic or alkaline, Such as a hard water area, then the CO2 in the water can give a false negative.

Basically lime scale in hard water areas is very alkaline and so an acidity caused by the CO2 ends up cancelled out.

But also these kits will only tell you if the gasket is blown to a coolant channel. For example The old Mondeo V6 used to always blow to the outside atmosphere. Alot of fiat 1.2's will blow between cylinders. some can blow to oil channels.

So really testing the coolant isn't a reliable way of checking for a blown head gasket anyway, But looking for hydrocarbons is infinitely more reliable than CO2 kits, as there should not be any hydrocarbons in the coolant..... Unless someone poured oil in there by mistake.

 

[AndyRKett]

Thanks all

Had both coolers replaced.. its a TDi..

Leak 'might' have slowed :stopped.. but appears to have higher oil temps now

Time will tell..

Recent Hot weather?

The oil cooler still has a thermostat, so if this has been replaced then it might have a different opening temp from an old one? Or a new oil to coolant "cooler" might be more efficient so transferring more heat to the oil.

 

[varesecrazy]

I think the oil being of an elevated temp

110 ..up from 100.. is a trend these replacements hasnt changed

Oil cooler in front..and turbo cooler too

Its a GTD ..Yes these seem to be relatively common failures

 

[AndyRKett]

Its a GTD ..Yes these seem to be relatively common failures

Interesting. Which GTD is it.


My 2015 2.0 Euro 6 TDI (150 bhp rather than the 180 ponies in the GTD of the same year)

yet my car is based on the Mk6 the GTD in that was only 167hp.

So mine isn't massively down on power by comparison but runs at a steady 85'C

 

[jackwhoo]

Recent Hot weather?

The oil cooler still has a thermostat, so if this has been replaced then it might have a different opening temp from an old one? Or a new oil to coolant "cooler" might be more efficient so transferring more heat to the oil.

Are you sure this oil to water heat exchanger has a thermostat controlling oil flow through the heat exchanger?

My understanding is : as the coolant flow through the heat exchanger is from the primary engine circuit it doesn't require an oil flow thermostat,
Due to: if the oil is cooler than coolant the coolant will bring the oil up to ideal operating temp more quickly,
if the oil temp is higher than coolant temp the coolant will cool the oil.
The above arrangement does away with the need for an oil flow control thermostat and associated bypass pipework.

Jack

 

[AndyRKett]

Are you sure this oil to water heat exchanger has a thermostat controlling oil flow through the heat exchanger?

My understanding is : as the coolant flow through the heat exchanger is from the primary engine circuit it doesn't require an oil flow thermostat,
Due to: if the oil is cooler than coolant the coolant will bring the oil up to ideal operating temp more quickly,
if the oil temp is higher than coolant temp the coolant will cool the oil.
The above arrangement does away with the need for an oil flow control thermostat and associated bypass pipework.

Jack

Seems you’re trying to pick holes here or catch me out for some reason, But you’re not really reading and understanding the tone of my posts

I’ll explain... I don’t know what Charlie has so if it’s an air cooled oil cooler then it will have a thermostat, if it’s a water to oil exchanger then maybe not, I have to be honest I’m not committing myself 100% whole heartedly to sort out why the oil might be now running a little hotter.... I don’t know what the set up of the engine in question Or exactly what has or hasn’t been replaced. I’m throwing out suggestions, just trying to give Charlie some ideas, he’s been around the block long enough to sort these things out, I don’t need to sit here and give him a class on all the different ways of cooling oil. Both Charlie and I know our way around a car.

 

[jackwhoo]

Seems you’re trying to pick holes here or catch me out for some reason, But you’re not really reading and understanding the tone of my posts

I’ll explain... I don’t know what Charlie has so if it’s an air cooled oil cooler then it will have a thermostat, if it’s a water to oil exchanger then maybe not, I have to be honest I’m not committing myself 100% whole heartedly to sort out why the oil might be now running a little hotter.... I don’t know what the set up of the engine in question Or exactly what has or hasn’t been replaced. I’m throwing out suggestions, just trying to give Charlie some ideas, he’s been around the block long enough to sort these things out, I don’t need to sit here and give him a class on all the different ways of cooling oil. Both Charlie and I know our way around a car.

Oh dear,

No Andy I'm not try to pick holes or catch you out.

I'm trying to keep an open mind , learn and where possible help other members.

Other people may have been interested in the function of an oil to coolant heat exchanger and how it doesn't over cool the oil.

Your posts are read very carefully.

Being informed that sniff testers that detect co2 are not fit for purpose and the instructions for use are incorrect has been very enlightening.
Please post a link to sniff test kit that 100% detects hydrocarbons in the coolant that would be very helpful.

Thanks

Jack