Diesel fumes through heater

Don't have a MAF sensor myself, but I've read a through threads about them. If I remember correctly, when the MAF is disconnected the engine management system goes in to a different mode (not quite VWesque) but will run very well. Long term though, you are meant to get it sorted. I can also remember people saying, do not buy the Cheap ones it's false economy. To be honest, if I was you, I wouldn't be looking at the MAF sensor for the rogue fume smell just yet.

Maf may well be faulty but its not going to be the cause of your ex gas smell.

The Landy runs the same with the MAF sensor disconnected!
I will try a new one anyway tomorrow as the unit is under warranty.
And l need to get the missus's 90 sorted as well, now it's had a new clutch. That's not running right either.

lightning said:

Disconnect it and go for a drive. It should run OK.
Then reconnect it and try again, it should be better. If it's no different then the MAF unit is almost certainly U/S

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lightning said:

Isn't that what l said?

Disconnect the MAF unit, if there's no difference....it's faulty

Fit a new one, and it runs better!

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lightning said:

I don't recall posting that.

However my local specialist are pretty good with warranty items, but if not l'm not paying another £90.... I'll buy one of the £30 ones that they also sell.

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Hear this is what you stated about MAF unit diagnostic.
I find it hard to understand how the MAF unit is causing diesel fumes into the cab.
My thoughts are (for what they are worth)
You talk about diesel fumes into the cab but go on to describe exhaust fumes, two different things which have different areas that may be at fault.
Exhaust fumes into the cab should be pretty straightforward to diagnose. The fumes are created in the cylinders and then pass through the cylinder head, exhaust manifold, turbo, exhaust front pipe, exhaust middle box, exhaust middle pipe and on to the rear box.
From this list the easiest parts to check are the pipe and boxes from the turbo if you are sure that no leaks are present there then, exhaust manifold gasket leaking, exhaust manifold cracked, exhaust to turbo gasket, turbo body cracked, turbo waste gate leaking. If all of these are sound then I am pretty sure what you are smelling is not exhaust gasses.
Diesel is something different, neat fuel pumped from the tank to the injectors under pressure the TD5 uses the injectors as a pump to gain the very high pressure prior to injecting into the cylinder but that will not rule out the ability for the diesel to leak prior to the injectors. I understand that the most common point is the fuel pressure regulator sited toward the rear of the cylinder head on the right-hand side as you sit in the driver seat.
Again if you rule out and fuel leaks then its not diesel you can smell.
You have thoughts of the MAS sensor causing this smell, the MAF sensor
The MAF sensor is located in the intake system between the air filter housing and the turbocharger. The ECM uses the information generated by the MAF sensor to control exhaust gas recirculation (EGR).
The MAF sensor works on the hot film principal. The MAF sensor has 2 sensing elements contained within a film.
One element is controlled at ambient temperature e.g. 25 °C (77 °F) while the other is heated to 200 °C (360 °F)above this temperature e.g. 225 °C (437 °F). As air passes through the MAF sensor the hot film will be cooled.
The current required to keep the constant 200 °C (360 °F) difference provides a precise although non-linear signal of the air drawn into the engine. The MAF sensor sends a voltage of between 0 and 5 volts to the ECM, proportional to the mass of the incoming air. This calculation allows the ECM to set the EGR ratio for varying operating conditions.
So in theory the MAF sensor controls only the EGR valve but we also know that false and out of range signals from the MAF sensor can cause the ECU to react to these signals.
If this reaction is to reduce the quantity of fuel the injectors dispense then power developed will be down, you are not looking for reduced fuel injected as this would not cause the smell you describe.
An increase of fuel dispensed by the injectors (which would be more in keeping with smelling diesel) would mean an increase in power developed by your engine.
More diesel injected means more power in a diesel engine not like a petrol engine which if over fuelled would mean and over rich mixture of fuel/air un-burnt petrol and result in a smell of petrol. Diesels can take to some extent additional fuel and use it (not to the point of an hydraulic lock).
After all that I really do believe what you are smelling is not exhaust fumes as you have checked and have had it checked and why should your vehicle be different to any other and the heater be able to suck the exhaust gasses from the rear of the vehicle into the cab.
Diesel it could be if any leaks but you have dismissed this by checking.
Sorry but I am coming back to the brakes and the smell of over-heated pads entering the heater system.
The only other thing I could think of is the axel and gearbox wading breathers but that would be a long shot.
OK one more and I am done do you have the additional heater air scoop fitted on the top of the wing if so has something crawled into like a mouse and died and you can smell the rotting mouse???

An update on this,
Thanks for the detailed reply by the way. I went out tonight in the Land Rover and gave it a good thrashing to 4,000 through the gears, really for the first time ever. (Normally it just trundles around town)
The first time l floored it, there was a (looked like light grey) smoke screen to rival a cooling tower. In fact it pretty much obscured the car l had just passed.
After that it reduced each time l did it until it stopped smoking.
After that the smell seems to have gone when l have the heater on.
So now l need to monitor it, if it does that every time l put my foot down there's clearly something wrong, unless it's burning off oil that's accumulated in the intercooler/exhaust etc.

Are you loosing coolant?
Far fetched but a cylinder head gasket and a small hole in the heater matrix at the top would create the symptoms you describe. Hence only being drawn in when the fan is on.

I have a smell of coolant in mine that only occurs after a blast on the motorway with the fans on. Other than that I never really smell it. I'm gonna whip the matrix out and check.

No, l have kept an eye on the coolant level and it is stable, l have not topped it up in 10,000 miles.
My current thoughts are......l assume this cloud of grey smoke on hard acceleration was oil being burnt. Which means it must be on the intake side as it had to go through the engine.
So my guess is either a build up of oil in the intercooler, or turbo bearings failing.
Or both.
Might it be worth me removing and checking the intercooler?
As l said, there's over 1mm play in the turbo bearing if you take off the inlet hose. But the LR specialist said this was normal when there is no oil pressure.
I don't mind fitting a turbo if that's the fault.

Play in turbo shaft normal
If it only smokes initially I wouldnt worry to much, if it does it each and every time you have something wrong.
But if you pussy foot it around all the time may I suggest Nissan Micra as more suitable.
Its a car drive, it generally abuse it, otherwise whats the point of owing it? and if it blows up well it was obviously flawed to begin with!

Lightning
twot links about smoke
http://www.dieselsmoke.com.au/
http://www.kent4x4offroading.co.uk/smoky_diesel_engines.htm
A reference to white smoke in the one link :- White Smoke will smell of unburned diesel - White ‘Steam’ will not!.

I am still not convinced it is diesel / exhaust fumes you smell I know you said the brakes are not getting hot but is there any lip on the disk at all or are they new disks?
I have come up with a theory for the smell but if the disks are as new and no lip at all then the theory will be out of the window.
Also have you tried starting the engine and without moving the vehicle get the engine up to temperature and check for the smell?
If not try it so that we can rule out all except the engine.

lynall said:

Play in turbo shaft normal
If it only smokes initially I wouldnt worry to much, if it does it each and every time you have something wrong.
But if you pussy foot it around all the time may I suggest Nissan Micra as more suitable.
Its a car drive, it generally abuse it, otherwise whats the point of owing it? and if it blows up well it was obviously flawed to begin with!

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I drive between customer's houses for my business. I am not one for thrashing around housing estates, l bought a Defender because l wanted to get out of the "van driver mentality" and be a bit more laid back in my driving.

Great then you need the micra and surely no one would buy a 4x4 for just pottering around the housing estate?
You would not need to look at it as it would not need fixing a bit like your 90

But l love driving the Defender!

And being a 110 with the side facing seats removed l can carry all my tools plus four passengers.

We've just come back from Norfolk in it. Not sure l could get my dinghy, outboard motor, mountain bike and a week's luggage in a Micra

I found the cause last night of my smelly heater. Strangely I was loosing next to no coolant!

Is that the back of the intercooler? I am going to take mine off and have a look at it.

No its the big black box at the back of the engine bay just in front the passenger. A bit of a swine to remove

Oh the heater matrix.

Mine only smells when stationary. It depends which way the wind is blowing as to whether l smell it or not.

Behind the box there is a foam seal and if gone engine bay fumes will enter cab.

I'm going to look at that too. Can it be checked without taking out the heater matrix?

No,you have to remove the whole heater box.

lightning said:

OK so l have posted this before, last year, but l thought it was sorted.

The exhaust on my 110 TD5 CSW does smell strongly of diesel, but l guess it will....it's a diesel lol

However as soon as l stop moving the smell comes through the heater, if the blower is on.
If the blower is not on l never get the smell even when reversing.

I am at a loss as to how the fumes so readily find their way to the heater intake on the wing, as the exhaust is at the back.

The exhaust has been checked for leaks. The EGR valve has been removed. The MAF unit is new, as is the air filter.
The manifold looks OK and l cannot smell fumes under the bonnet anyway, they seem to be outside.
The ECU has been remapped and no fault codes showed up.
This Defender has had this issue since l bought it a year ago and l have done 12,000 miles.
The engine runs fine and fuel economy is good. The injector harness has been replaced as there was oil in the harness.

I just get this diesel smell in the cabin, unless the wind is blowing it away.

What can l check? I even put some drought excluder along the edges of the bonnet but it made no difference.
Two garages have looked at it and found nothing, one suggested removing the CAT which l let them do, but it made no difference.

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Have you sorted this issue?