Mk2 2.3 Auto - Head Gasket

[philclemo]

Hi SK

 

I understand your query. The niggle is that the chain and sprocket marks are as per last assembly, where we didn't have any performance problems. Looking at the arrangement at the crankshaft sprocket end I find it quite impossible for the chain to move as there doesn't appear to be any space for it to jump a tooth, I may be wrong though.

 

With regards to Sparkpaul's comment relating to excessive water on the sensor, the car wasn't running brilliantly just before the second H/G replacement, and as it was drawing in more water (especially into cyl. 3) so from those symptoms it stacks up.

 

Believe me I would have been happier to find that I had put it back with a sprocket one or two teeth out but it was as it had been dismantled. If, and it's a big if, the timing is out how much sway has or does thengine have to accept a variance in the valve timing, as on assembly, at rest the head is pushing valves down on to the piston top, that is why you must turn the crank to drop the piston 25mm from TDC, there doesn't seem to be much allowance to get this wrong.

 

Perplexed!!!!!

 

Phil

[sparky Paul]

So it could be a suspect pre-cat sensor?

 

It not impossible, but from the lambda activity you describe, I would say it's unlikely. The lambda voltages are only slightly odd, probably not far enough out to be a concern. Even if you presume that it is significant, it could be a lambda fault or it could be accurately reporting that the engine is running lean due to some other problem.

 

Probably the easiest way to check if the lambda sensor is doing it's job is to get an emissions test done. Whatever other problems the engine has, the ECU should use the lambda reading to do it's best to maintain correct emissions.

 

When you say you have previously done H/G were they on your Gal?

 

If so your life would have been a misery if I had known!

Fortunately not! The old Galaxy has been the model of reliability in the engine department. :D

Edited May 27, 2012 by sparky Paul

[philclemo]

So it could be a suspect pre-cat sensor?

The old Galaxy has been the model of reliability in the engine department. :D

 

That is our frustration! The Mk 1 was tough as old boots but this incarnation does seem to attract problems! I remember when for what soon turned out to be 3 months, the Mk 1 ran on minimum coolant, minimum oil ( on the dipstick) and a dicky coil thus watering down the oil with petrol and never complained!

 

The problems with this one stem from a dealer who was crooked, he knowingly sold this with this problem and has squirmed his way out of responsibility for it.

 

Hey ho!

[philclemo]

Hi Sparky

 

I had the Gal today and carried out some more checks on the O2 Sensor.

 

This reading was in the space of a minute from a rolling start at approx. 30mph accelerating (well trying to) up an incline, we did get to about 50 mph at the top by the way!

 

O2 sensor 1 bank 1 Sensor 2

0.020v @ -9.4% stft 0.715 v

0.025v @ 0.0% 0.700 v

0.025v @ 0.0% 0.000 v

0.800v @ +6.3% 0.105 v

0.845v @ +7.0% 0.160 v

0.745v @ +1.6% 0.160 v

0.745v @ +1.6% 0.210 v

0.750v @ -3.1% 0.265 v

0.180v @ -0.8% 0.380 v

0.075v @ 0.0% 0.610 v

0.360v @ -7.8% 0.610 v

0.360v @ -7.8% 0.820 v

0.700v @ -3.9% 0.765 v

0.285v @ +1.6% 0.680 v

0.290v @ +3.1% 0.640 v

0.810v @ +5.5% 0.445 v

0.840v @ +6.3% 0.570 v

0.060v @ 0.0% 0.675 v

0.860v @ +14.8% 0.675 v

0.875v @ +14.8% 0.900 v

0.870v @ +14.8% 0.900 v

0.880v @ +14.8% 0.900 v

0.880v @ +14.8% 0.905 v

0.870v @ +14.8% 0.905 v

0.825v @ -3.9% 0.815 v

0.000v @ -9.4% 0.010 v

0.000v @ 0.0% 0.000 v

0.000v @ -9.4% 0.000 v

0.845v @ +3.9% 0.095 v

0.875v @ +5.5% 0.130 v

0.870v @ -0.8% 0.145 v

0.865v @ -1.6% 0.160 v

0.865v @ +3.1% 0.195 v

0.790v @ +3.1% 0.230 v

0.315v @ +0.8% 0.565 v

 

I also tried disconnecting the Pre Cat O2 sensor, no effect whatsoever, on idle, or acceleration. On second start up the MIL came on. Personally I thought the ECU would have invoked limp home mode.

 

What effect would disconnecting the battery and shorting the cables to reset the ECU have?

 

I am going to try to get an emmissions test next week if possible.

[sparky Paul]

Those lambda figures do look a bit all over the place, but as I said earlier you can't tell if the sensor is kaput or if it's accurately reporting emissions problems stemming from other faults... an emission test may confirm. A fixed or slow output from the sensor is obviously a duff sensor, but anything else is a grey area.

 

I've never had limp mode with a lambda fault, the engine defaults to a lean running mode but otherwise runs quite normally, although it would be down fractionally on power. You often don't realise there's a problem until the emission test for the MOT.

 

Something else to consider after headgasket failure is a partially blocked cat, which would make the engine struggle to breathe at higher revs. Also, I reckon I mentioned this earlier, but are you sure there are no manifold leaks, inlet and exhaust?

 

Removing the battery for a few minutes then reconnecting resets certain learnt parameters, but I don't think it would account for the sort of power loss you seem to be describing. In any case, I assume the battery would have been disconnected during the HG work.

[philclemo]

Right!

 

I had access to the Gal once more this weekend, because after reading another section of the Haynes manual for the Mk1 (timing chain replacement) it showed quite clearly that the chain could come off the crankshaft sprocket (you were right SK!) and this could have certainly happened due to the three persons necessary to get the head back on (two to lift the head and one other keeping the chain under tension!).

 

Anyway, looking at the directions of setting TDC on No1 the Haynes manual refers to that if the timing marks are pointing directly at each other this means that No4 piston is at TDC not No1 - this is at odds with the TIS as it suggests, as a check after setting the timing, to turn the engine to No2 TDC and these timing marks would point to each other. When I checked this after SK's suggestion I could not get the timing marks to point at each other with No2 at TDC (in fact inlet was at 12 o'clock and exhaust was at 8 o'clock). So, yesterday I took the rocker cover off once more. Turned the engine until No1 at TDC and then another revolution to get No4 at TDC and the timing marks were out by two teeth!

 

As a further check I turned the engine until I could get the copper links to match up with the factory marks on the sprocket, I couldn't as both sprockets wouldn't 'catch' the copper links. So obviously the chain had moved. Without not having access to the crankshaft sprocket, i was forced to time the engine from first principles (eg No1 at TDC, cam lobes on each cam at exactly the same position but horizontally opposed) - the result is an engine with it's guts back! Only one problem is that on tickover it appears to be a little lumpy, almost lean in fact. No problems in starting, everything back to normal. I haven't OBD'd it yet, that may pull some codes up perhaps. I would like to sort the lumpiness though, perhaps the O2 sensor after getting wet sparky Paul ????

 

Finally, thanks to one and all for your guidance and suggestions!

[sparky Paul]

At least you found something definitely wrong in the end, it sounds like you have it cracked. The chain certainly can slip on the crank sprocket, that's the main reason I was quizzing you about the position of No.1 TDC when aligning the marks - as. The best way for sure is to align the three sets of copper links on all three sprockets.

 

As for the rough idle, I would eliminate the idle control valve first, it's a simple job to clean it and it's worth eliminating as a possible cause. They can go sticky when the car has been stood.

 

I would guess that the lambda sensor is probably okay from the sensor output above, but the quickest way to tell for sure would be to get a emissions test. You don't usually see any fault codes unless the sensor heater is burnt off.

[philclemo]

Hi Paul

 

Thanks, but Re: Idle Control Valve, the car hasn't stood. It has been used daily despite the lack of power, could it have picked something up?

 

I do have a spare gasket for this part in one of the Gasket sets I have purchased though!

 

Phil

Edited June 11, 2012 by philclemo

[seatkid]

Reset the ECU by removing the battery for a minute or two. Its possible that the ECU has been trying to adapt ignition/fueling based on your incorrectly timed engine. Another possibility, could be burnt valves or deposits on the valve seats again due the timing error - cylinder pressure test would confirm.

 

Not sure of your "timing from 1st principles" procedure. Do the marks point at each other with no.2 TDC now?

Edited June 11, 2012 by seatkid

[philclemo]

Bit of an update, I think?

 

I took the idle control valve off to clean it. It was a bit grubby but I cleaned it up and tested it. No difference, whilst the engine was ticking over I disconnected it and the engine really spluttered so I would assume its working. I then disconnected the MAF and no difference at all. When I last did that the engine stalled. Is it possible that the MAF has a problem?

 

Never really experienced problems with this type of sensor, so is this indicative of a fault?

[mikej]

For what it's worth my own 2.3 will not allow me to disconnect the maf without rough idleing, coughing and spluttering etc so it's possible yours is duff have you tried cleaning it at all? excuse spelling Stella has it's own effects lol

[philclemo]

Ah, good old Stella, I know her well!

 

I haven't tried to clean the MAF but I did have a mess around with it yesterday. Is it possible to clean them?

[seatkid]

Ah, good old Stella, I know her well!

 

I haven't tried to clean the MAF but I did have a mess around with it yesterday. Is it possible to clean them?

To clean it effectively, remove the actual sensor from the MAF housing (2 torx screws). Less than 25% chance that cleaning will have any effect as I think its usually the embedded thick film heated sensor in the unit that "burns off" and causes calibration drift and failure.