strange coolant loss issue and smoke

[Stephen Hyde]

hello all,

recently got myself a 2005 b7 a4 1.9 tdi (115) which seems to be in excellent condition and i have an invoice for an engine replacement in the last couple months (car has 154k on but engine apprently has about 55k.)

but in the last 2 days i have started having major issues with coolant loss and white smoke, smoke seems to be worse when engine is cold but also can be when car is ticking over at running temp. but not every time car is running. car has still got full power and NEVER overheats.

now this would normally suggest a head gasket issue to me but from what i know that usually means overheating and a constant smoke rather than just when cold/idling

im wondering if it could be egr cooler maybe ? if the 115 tdi even has one.


should also mention car is sometimes slow to start and lumpy but i think thats due to glow plug relay fault.

i do have access to vcds if anyone has any suggestions to look at on their to point me in the right direction

thanks

 

[Stickystuff]

Best idea would be to do a scan with a diag reader, this would probably cover the sluggish starting more than the coolant loss.

But I think you’re probably in the right ball park with the EGR cooler. It will have one but where exactly I’m not too sure.

I would suggest once you’ve found it to remove the coolant pipes going to it and connecting them together to bypass the cooler itself. This should stop the smoking. Potentially you might be able to feel some exhaust pressure from the cooler inlet and outlet coolant ports putting your thumbs over each one being sensible and wearing decent nitrile gloves or similar to avoid any initial heat.

*please make sure you are confident before doing this, it’s only advice and if you injure yourself or anything from following my advice I take not responsibility *
I’ve not worked on your engine before so I do not know how exactly how it is set up. It’s just a generic diagnosis idea


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[Stephen Hyde]

Best idea would be to do a scan with a diag reader, this would probably cover the sluggish starting more than the coolant loss.

But I think you’re probably in the right ball park with the EGR cooler. It will have one but where exactly I’m not too sure.

I would suggest once you’ve found it to remove the coolant pipes going to it and connecting them together to bypass the cooler itself. This should stop the smoking. Potentially you might be able to feel some exhaust pressure from the cooler inlet and outlet coolant ports putting your thumbs over each one being sensible and wearing decent nitrile gloves or similar to avoid any initial heat.

*please make sure you are confident before doing this, it’s only advice and if you injure yourself or anything from following my advice I take not responsibility *
I’ve not worked on your engine before so I do not know how exactly how it is set up. It’s just a generic diagnosis idea


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thanks for the reply, as for slow starting i get absolutely no codes except for 4 glow plug ones.

i did bypass the egr cooler and all the smoke has stopped, it did smoke for a bit after doing the bypass but i am assuming that was residual mosture in the system as it has cleared and not smoked since. other than grey smoke when cold (which i know from experiance with my previous e46 320d to be glow plug related.

 

[Stickystuff]

Well if you keep it by passed for too long you might end up with other problems so it worth’s worth getting it changed sooner than later.

As for the glow plug issue make sure again you get them changed sooner than later cause it’s un-burnt fuel going through the system, that can be part of the issue with the cooler.

There’s always some sort of knock on effect from one thing to another


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[Stephen Hyde]

Well if you keep it by passed for too long you might end up with other problems so it worth’s worth getting it changed sooner than later.

As for the glow plug issue make sure again you get them changed sooner than later cause it’s un-burnt fuel going through the system, that can be part of the issue with the cooler.

There’s always some sort of knock on effect from one thing to another


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yep im going to get a new cooler asap (or just remove the egr entirely),

as for the glow plugs i suspect the relay over actual plugs as engine only has about 55k on it, whereas car has 155k

 

[Stickystuff]

It’s difficult to prove the engine actually has that low mileage on. So expect the worst.

The easiest way to test the glow plugs is with a test light, or if you don’t have one you can make one. Get a working headlight bulb with a couple of wires attached to each terminal. you need to then put one end into the glow plug ‘plug’ and the other end need to be earth onto the engine or if need be the battery earth. Then cycle the ignition on, if it lights up for about 5 seconds then goes out then the glow plug relay works, you need to do this for each glow plug though to make sure there are no problems with one of the wires etc.

Then once you’ve confirmed that’s all working properly you can repeat the process but earthing it on the head of each glow plug not the body. You are still likely to get the light to work on each glow plug but that doesn’t conform of the glow plugs failed or not that just confirms you’ve got good continuity.

The reason it’s best to use a test light and ideally a headlight bulb because it draws a similar current to a glow plug. Using a multi metre you might still get a connection but that doesn’t show up a broken or partially broken wire.

If you find one or two of them don’t work on this way round then it’s likely that you have a faulty glow plug. I would still remove the glow plugs and test them individually.

You basically power them up directly from the battery using jump leads. You only need to do this for a few seconds and see if they glow. Earth the body using the negative lead and then using the positive lead gently touch the head, there will be a little spark initially but once on properly the glow plug should heat up and after a second or two glow. But allow it about 5-6 seconds before disconnecting.

I would like to think that by doing all of the above you will have identified an issue.

I hope that helps anyway


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