FSI Owners, Never Ignore An EML.

PlasticMac

PlasticMac

Member
United-Kingdom
Serious engine damage has recently resulted from overheating in two FSIs.
The cause of the overheating, in both cases, was failure of the heater element in the thermostat housing.
This heater element is used to lower the engine temperature, from the normal 110C, to around 85C, by opening the thermostat early when the engine load is high, to dissipate the extra heat through the radiator, and keep the engine at a safe temperature.
When the heater element fails, the EML will tell you, but the thermostat will now only open at 110C, so no additional cooling at high engine loads. At these higher loads, the engine will overheat, causing engine damage, most likely head gasket failure.
Sadly, when the EML is on, it's not unknown to hear "Yes I've got an EML, but the car runs fine, so I ignore it ..."
Yes, it will run fine ... until it doesn't, but it'll be too late by then. If you see an EML, scan it, don't leave it.
If the heater element is the problem, a scan will show:
<17704/P1296/004758 - Error in Mapped Cooling System>
Best not drive the car, until the part is replaced, or risk the of the engine overheating is high.
Although this heater element failure applies to all FSIs, perhaps it is, potentially, more likely when the engine is running the ProBoost ECU.
This is because the ProBoost map runs the engine at the lower temperature, (85C), at all times, and does this using the heater element to open the thermostat at the lower temperature. This will mean that the heater will be on much of the time, so it's very likely it's life will be shorter in a Proboost engine, than one with the OEM map.
EML is your friend, not your enemy. It could very well save your engine from destruction.
Mac.
 
Hi Mac,

First of all, thanks for all your contributions to the forum especially on the FSI, which I’ve gained a lot of knowledge from.

Your post above comes at a poignant time as I’ve been planning on getting the Proboost for my FSI for a while as a preventative measure lowering the coolant temperature - but the above info makes me reconsider. Maybe it would be worth a new post on the Proboost thread asking how everyone is getting on and how many have had issues similar to the ones you mention above.

My FSI is actually is in very fine fettle and I believe it to have been treated well in its life in Germany before I imported it to Spain this year. From reading many of your posts I’m sure your advice would be “If it ain’t broke…” which is often proves to be good advice.

Probably more of a question for PM but given now my FSI living in a hot country - is there anything specific from a preventative maintenance point of view you would advise?

Thanks again,

Stuart
 
Forgive my ignorance as I have never been brave enough to venture into the fsi world despite the word on the street is seemingly suggesting it's the best engine of the bunch for an A2 as a "drivers car" taking into account the information here is it possible to run without a thermostat??
 
Howey said:
.......... is it possible to run without a thermostat??
Click to expand...
Good Evening Howey,

Actually not a daft question. I am no expert but common sense says yes, in fact you could remove the thermostat from any car, it is just the consequences. The immediate physical consequence must be the average coolant temperature will be lower than normal, I suspect most of the time the ECU will consider the engine cold and adjust fuelling to match with large mpg increase. Okay, theoretically remap the ECU for no thermostat but the average coolant temperature will still be lower than what we consider normal which leads to the main question of engine efficiency with coolant temperature. I did read the reason the FSI runs at 110℃ is the the higher than normal coolant temperature is more efficient whatever that means. Probably other consequences and questions.

Sorry I started to waffle.

Andy
 
VonB said:
Hi Mac,

First of all, thanks for all your contributions to the forum especially on the FSI, which I’ve gained a lot of knowledge from.

Your post above comes at a poignant time as I’ve been planning on getting the Proboost for my FSI for a while as a preventative measure lowering the coolant temperature - but the above info makes me reconsider. Maybe it would be worth a new post on the Proboost thread asking how everyone is getting on and how many have had issues similar to the ones you mention above.

My FSI is actually is in very fine fettle and I believe it to have been treated well in its life in Germany before I imported it to Spain this year. From reading many of your posts I’m sure your advice would be “If it ain’t broke…” which is often proves to be good advice.

Probably more of a question for PM but given now my FSI living in a hot country - is there anything specific from a preventative maintenance point of view you would advise?

Thanks again,

Stuart
Click to expand...
As long as the EML is taken seriously, as I've outlined, going ProBoost does not increase the risk of engine damage. All FSIs are getting on a bit, so electrical parts that are constantly cycling will wear out.
I have tried to understand the theories that drove the FSI design, and from what I've learned, (and often re-learned too), it makes sense, maximising engine efficiency, and minimising emmissions by tight control of engine temperature.
Mac.
 
Excuse my ignorance, but if the failure is as described, would the temp gauge not rise as a warning to impending problems?
 
EdinA2 said:
Excuse my ignorance, but if the failure is as described, would the temp gauge not rise as a warning to impending problems?
Click to expand...
The temperature gauge in the FSI, as in all A2s, (and most other cars), is only an indicator, not a temperature gauge that directly indicates the temperature of the coolant. It is electronically weighted to indicate 90C, over a range of actual temperatures, so as not to worry the driver.
I don't know the exact characteristics, but I think that by the time it showed a really high temperature, it would be too late
The EML will be active immediately the ECU detects a fault in the heater element circuit, regardless of the heater being activated or not.
Mac.
 
Howey said:
Forgive my ignorance as I have never been brave enough to venture into the fsi world despite the word on the street is seemingly suggesting it's the best engine of the bunch for an A2 as a "drivers car" taking into account the information here is it possible to run without a thermostat??
Click to expand...
If more, seemingly, daft questions had been asked, many a disaster would have been avoided, so ask away.
Have a read of this extract from an Audi SSP, that gives an overview of cooling systems, including the background to the FSI version.
Mac.
 

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PlasticMac said:
If more, seemingly, daft questions had been asked, many a disaster would have been avoided, so ask away.
Have a read of this extract from an Audi SSP, that gives an overview of cooling systems, including the background to the FSI version.
Mac.
Click to expand...
Nice document that is! Would be interesting to see real world comparisons on how the engine performs with and without the thermostat if removal is indeed possible.
 
Hi Mac,

Yours is a timely post, as far as I am concerned. My FSI recently overheated towards the end of a 50 mile motorway cruise. Steam was visible at the edge of the front engine cover, but there were no overheat warnings or abnormal temp gauge readings, also no evidence of a leak in or under the engine bay. I left everything to cool during a work shift and, again, found no evidence of a leak but the water level was way down. I did a top up and started on the journey home, but after 20 miles I had the coolant level light come on, shortly followed by the red overheat and low oil pressure. Luckily I was able to peel off into a service area and call the AA. They diagnosed a hose leak and ferried my A2 home.
My local car service business verified that the leak was in the 8Z0121056A pipe ( 13 in the attached photo) but said a replacement part was unavailable. After much searching around the heritage parts dealers I also had no luck at all finding that part. However, by contacting A2steve of A2OC fame, he was able to supply a stock of FSI coolant parts, including the one needed, and fitting and pressure testing will proceed tomorrow.
My garage is going to fit a brand new ‘ death pipe’ ( No 30 in the attached system photo) and also, in the light of Mac’s post, a new thermostat. The latter item is now my problem . The new thermostat they were supplied is not correct and I have had no luck sourcing the correct part. I have attached a second photo of the part numbers from the original thermostat in the hope that someone might be able to point me towards a supplier of this part. As it is, I will have to refit the old thermostat and hope for the best, but I would much rather fit a new part to eliminate the chance ( repeat?) of the potential engine wrecking scenario.

Any advice very gratefully received.

Colin
 

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To run at anything close to efficiency, an internal combustion engine needs a means to regulate it's temperature. Too cool and it's very inefficient at turning fuel into rotational energy, too hot, and the rotating parts will seize.
Engine temperature control is only possible with a device to regulate how much heat is dissipated at any one time.
One of the two ways this can be done, is by regulating the flow rate of coolant around a circuit of fixed volume. Circulation at high speed, when the engine us under high load, and at lower speed, under lower load. That would need an external, variable speed, electric pump, with a closed circuit feedback loop. Failure of any part of such a system would result in, (virtually), instant engine destruction.
The alternative way is to vary the volume of the coolant system, so a large volume, (the radiator), is available when high capacity cooling is required, (high engine load), but a much smaller capacity, (ni radiator), is sufficient for lower engine loads. This allows an integral, engine driven coolant pump to be used. Conveniently, the engine driven pump runs slowly at low engine loads, (speeds), and faster at high engine loads.
An integral pump, a radiator, and a thermostat to switch the radiator in and out of the coolant circuit is the simplest of the two.
Not got the character of my, (long gone), 500cc single cylinder Velocette Thruxton though.
Mac.
 
A2A2 said:
Hi Mac,

Yours is a timely post, as far as I am concerned. My FSI recently overheated towards the end of a 50 mile motorway cruise. Steam was visible at the edge of the front engine cover, but there were no overheat warnings or abnormal temp gauge readings, also no evidence of a leak in or under the engine bay. I left everything to cool during a work shift and, again, found no evidence of a leak but the water level was way down. I did a top up and started on the journey home, but after 20 miles I had the coolant level light come on, shortly followed by the red overheat and low oil pressure. Luckily I was able to peel off into a service area and call the AA. They diagnosed a hose leak and ferried my A2 home.
My local car service business verified that the leak was in the 8Z0121056A pipe ( 13 in the attached photo) but said a replacement part was unavailable. After much searching around the heritage parts dealers I also had no luck at all finding that part. However, by contacting A2steve of A2OC fame, he was able to supply a stock of FSI coolant parts, including the one needed, and fitting and pressure testing will proceed tomorrow.
My garage is going to fit a brand new ‘ death pipe’ ( No 30 in the attached system photo) and also, in the light of Mac’s post, a new thermostat. The latter item is now my problem . The new thermostat they were supplied is not correct and I have had no luck sourcing the correct part. I have attached a second photo of the part numbers from the original thermostat in the hope that someone might be able to point me towards a supplier of this part. As it is, I will have to refit the old thermostat and hope for the best, but I would much rather fit a new part to eliminate the chance ( repeat?) of the potential engine wrecking scenario.

Any advice very gratefully received.

Colin
Click to expand...
Good Evening Colin,

Unfortunately as you have found many parts are no longer available from Audi/TPS for our A2's (NLA) particularly coolant parts for our FSI's. This is compounded that the FSI is somewhat unusual running at a higher temperature than normal leading to failures in coolant parts, basically not up to job of prolonged higher temperatures.

As to the thermostat, it is news to me it it is now NLA (I checked) and will probably appear on Audi Tradition in the future but you need is more pressing. However I do not understand your difficulty in sourcing, still seem plenty of aftermarket around...


Or ebay...

Audi 032121121N for sale | eBay

Find great deals on eBay for Audi 032121121N. Shop with confidence.
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Which you buy is a difficult question, I think there is some confusion around by sellers not connecting with the FSI thermostat being quite rare and being 'electronic' and turning out not to be compatible as it sounds in the case of your garage. All I can say go for a reputable brand but these generally are more expensive (getting more towards £100), but I can say I fitted Mahle as I had some evidence they were Audi's supplier at some time.

Andy
 
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Hi Colin.
Reading your post, it seems you had a coolant leak, from a hose, and lost some coolant as a result. That's about all that I get from your account.
You need to get the engine scanned, to find out if anything else has failed, either before the leak, (possibly causing the leak), or afterwards, (as a result).
Without that knowledge, you may be replacing parts that are not faulty. Or fixing a fault that isn't there.
Probably too late now, but I'd have just replaced the hose and clips that's leaking, and go from there.
A scan is still the way to go, essential in my opinion, the data should still be there.
Post the results here. If your mechanic is not able to scan it, give me a shout, I'm only a couple of junctions down the M3.
Mac.
 
Hi,

I think I used a Mahle or Mayle thermostat in the past and you could clearly see the VW logo had been ground off. Have a look on the forum and you will find which one of the two it is.

Evros
 
PlasticMac said:
Hi Colin.
Reading your post, it seems you had a coolant leak, from a hose, and lost some coolant as a result. That's about all that I get from your account.
You need to get the engine scanned, to find out if anything else has failed, either before the leak, (possibly causing the leak), or afterwards, (as a result).
Without that knowledge, you may be replacing parts that are not faulty. Or fixing a fault that isn't there.
Probably too late now, but I'd have just replaced the hose and clips that's leaking, and go from there.
A scan is still the way to go, essential in my opinion, the data should still be there.
Post the results here. If your mechanic is not able to scan it, give me a shout, I'm only a couple of junctions down the M3.
Mac.
Click to expand...
I've assumed you did not get an EML at any point, is that correct?
Mac.
 
The car has had a permanent EML since I bought it 3 years ago, only temporarily cleared to get through the MoT. The EML tester always shows either a cat sensor or coil pack issue, but nothing related to cooling. I must admit the I haven’t checked it recently.
 
A2A2 said:
The car has had a permanent EML since I bought it 3 years ago, only temporarily cleared to get through the MoT. The EML tester always shows either a cat sensor or coil pack issue, but nothing related to cooling. I must admit the I haven’t checked it recently.
Click to expand...
Ahhh OK, ignore most of my previous post, but I'd still get it scanned.
At this moment, no one knows what started the chain of events, that lead to the hose failure and coolant loss. A scan might tell you.
Unless you, and your mechanic, are sure the head gasket is not blown, then a CO test is the first thing to do.
Once you are 100% sure the head gasket is OK, then refurbishment of the cooling system is sensible. But only when you're sure.
Mac.
 
is this it? A Mahle part replacing the 032121121N original. I've bought from vwspares before and they have been good, but I'm not an FSi owner and I don't know the part by eye to be able to verify.

 
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