Polo AMF engine in an A2

M

macandy0

Member
Hello
I am in the middle of replacing the engine on my 1.4 TDI. I have a replacement from a Polo and thought I had swapped all the relevant bits until I noticed the oil level sensor. The Polo doesn't have this although the casting is essentially the same on the front of the engine as on the Audi but they haven't bored the holes for the sensor and mounting bolt. Of course I have only seen this after changing the cambelt etc. and in any case I don't think I can get the toothed wheel on the crankshaft off. How tight is that?The casting is behind this wheel.
So firstly, has the Polo 9N an oil level sensor, it seems not but if so where is it? Secondly could I just continue and not bother with the sensor or bridge the terminals so it doesn't operate the alarm and warning light? ( is this going to happen?) Or another possibility is to drill a bolt mounting hole for the sensor, fit the engine see if it works and if I have an issue with warning lights and buzzers, I could take off the sump and drill a hole fr the sensor from below. Is this a stupid plan? I'm not sure which is the best and or quickest route. Some people think the issue is only the sump being different and it being a matter of simply swapping the A2 sump over, but it isn't. The casting containing the oil sensor is separate behind the crankshaft toothed wheel
Can anyone advise?
Thanks
 
The oil level and temp switch was in the sump, just below the filler tube but after some research found they changed this to a front mounted sensor in mid 2002.

Which system did your A2 engine have and which does the Polo replacement engine use ?

Cheers Spike
 
My A2 engine has the sensor on the front of the engine, not on the sump but a separate casting. The Polo engine doesn't seem to have one. So could I just bridge the terminals on the wiring to stop the warning light coming on? The oil pressure sender is just below the filter I assume.
 
If both are AMF engines, you should be able to swap sumps. If you can't, they are probably different engines. We have two ANY engines, one has an oil sensor (A2) and one doesn't (Lupo 3L).

RAB
 
RAB said:
If both are AMF engines, you should be able to swap sumps. If you can't, they are probably different engines. We have two ANY engines, one has an oil sensor (A2) and one doesn't (Lupo 3L).

RAB
Click to expand...

Hi Rab, yes I agree, one thing though, if you change sumps remember to check the pick up pipe, a differrent shaped sump may well mean that you might have to swap the oil pickup pipe too (just to make sure that it is positioned correctly in the sump)

STeve B
 
Bridging the level sensor wires may work but there could be an issue with the oil temperature part of the sensor. The engine ECU is expecting a varying signal which may be used for fuelling / injection timing adjustment as the engine warms up. I don't know how the engine will be affected if this does not happen.

Cheers Spike

PS. RAB, strange that the parts book does not show the different sensor locations. I only found it while looking at the Lubrication System exploded view in the workshop manual.
 
The sumps on both engines appear to be the same, as said the sensor position, and absence of on the Polo engine, is the thing. The point about the oil temp part of the sensor perhaps signalling the injection is a worry. Could this not be from the coolant temp sensor?
 
What's the problem then? Just swap the sumps over and connect up as before.

RAB
 
Don't think anyone can predict if bridging the level sensor wires but leaving the oil temp part of the sensor disconnected will cause problems.

As neither of the sumps has the sensor mounting, in my view the options are to either transfer the front oil seal carrier casting (which is where the sensor plugs into on later engines) or modify the sump to take the sensor and lengthen the wires if necessary.

Cheers Spike
 
So I have finally got the engine in and started it today once the fuel had pumped through. Finally I decided to pierce the hole for the oil sensor in the front engine casting just to be safe that I wouldn't get funny signals if I simply bridged the wires on the connector to the sensor. It all seems to work once I had enough coolant in the system, this caused the electric fan to run continually. Otherwise it runs much smoother than the old engine. Still have to try it on the road.. The only worry is a slight noise from I think the timing belt. This I renewed with an SKF kit and I checked everything about 4 times. This is a worry because this story began because of timing belt tensioner failure. I renewed the belt on my previous engine with a kit bought on the internet and when I saw the tensioners included which were obviously not OEM quality, I hesitated about fitting them but finally did. There I also had a noise at first but seemingly worse. Then 10'000km later the alternator pulley failed and a week after replacing this, the timing belt tensioners failed but I can't imagine why these should be related. Has anyone else had timing belts making noise after replacement?

So if anyone wants to or by necessity has to fit a Polo or Lupo AMF motor to an A2, you have to remember to swap over a few things:

1. The already mentioned oil level sensor. Either you do without which may cause some issues, and bridge the wiring. Or you swap over the front castings but this entails removing the toothed wheel on the end of the crankshaft which must be very tight. Or you can do as I did, make holes in the Polo casting for the sensor and its mounting bolt. The depression is already in the casting which you have to pierce then finish off with a file. Better to remove the sump so it isn't full of swarf afterwards.

2. The oil filler on the Polo engine is taller so may not fit under the A2 scuttle/screen. The A2 still has an oil filler in this location on the cam cover but it probably never gets used.

3. The oil filter /oil cooler hosing is slightly different because the external oil filler is plumbed in here.

4. The dipstick tube has to be swapped over because of the external filler on the A2.

5. Slight differences in the turbo but don't seem to be important.

Everything else ( I think) is identical. Hopefully mine will function beautifully!
 
The noise might be from the alternator.
The freewheeling mechanism can often fail, especially if the engine has been sitting for a while.

Steve B
 
The alternator came off my original engine and the freewheel pulley was replace recently. I think I will disconnect the belt and run the engine to verify.
 
Yes it is the cambelt making noise. I looked at the clearance on the hydraulic tensioner which seems to have slipped abit. It's meant to be 4mm+/- 1mm ( according to SKF) but was at least 5mm. Don't really understand why as I checked everything thoroughly before fitting the engine to avoid another gynecological type operation through the wheel arch, but it looks like I will have to. I think the belt was slightly too tight so overloading the rollers etc. hence the noise. Does anyone know how critical the 4mm measure for the clearance of the hydraulic tensioner is? Would it be advisable to re-tension from scratch ie. removing the auxiliary belt pulley and all the covers (again) Any knowledgeable comments would be appreciated thanks.
 
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