Alfa Romeo 156 jts oil Mystery

[GabAlfa]

Hope someone can help or maybe I can help someone. I have be an Alfa driver pretty much all my life. I have recently acquired a 2004, 156 jts (74,000 kms) and discovered the following;
Down on power, burning oil, burning fuel excessively as proven by the spark plugs with black carbon build up in base, core and arch (not oily).
carried out compression test - 150 psi (dry) and cold engine. 250psi (wet). I think that is good compression, please let me know otherwise.
took cam cover off and hold and behold discovered Cam lobes worn - replaced them with 147 TS, had a spare set lying around...yes, they are the same, and they work !. just need to have a thread machined on the end of the exhaust cam shaft for the HP fuel pump spindle.
Also replaced the variator and variator half bearings (intake cam) and half bearing for exhaust cam, they were scored.
Also replaced all 16 valve lifters/tapets.
Re-assembled. Put fresh Castrol Edge 10-60W oil and bang ! Power is up, fuel consumption is better, no noisy tappet sound from the lifters but still blowing out smoke under heavy revving, doesn't seem blue, more like black.
Oil consumption seem excessive to me (100 ml to 100km's) this is city driving, short trips. Noticed the temperature does not rise quickly, possible thermostat issue (open all the time). Can take about 20 minutes to reach 70-80 degrees.
Checked spark plugs and burning right to me, slight black grey on base but grey white in core and arches (NGK twin arch spark plug).
Also discovered that the Cat Converter core (honey comb material) has been damaged as I discovered bits in the muffler (assuming due to excessive fuel burning and heat from inadequate intake and exhaust aperture). Have not experienced the Motor control system failure alert and checked the codes with the ECU Multiscan and only error code is P0443 - Evaporative Control Valve which I replaced (had one lying around) and still get the error. This one beats me, not sure but I'm not too worried about it.
So... my mystery is where is the oil going ? If it was the valve stem seals leaking surely I would see oil build up on the spark plugs. Compression is good as I can see, again I would see oil build up in the spark plugs. Is it the Cat converter causing issues ? Anyone have any suggestions or silver bullet ?? and no, there is no oil on floor, engine base squeaky clean for a change..
Alfa forever !! "Your not a true petrol head until you own an Alfa"
 

[LaStregaNera]

Sort out the thermostat - our BMW had a similar issue with the thermostat hanging open and was running on the warm up map the whole time - dumping excess fuel in and in our case, not triggering DPF regeneration.
Exhaust valve seals being knackered would see oil dissappearing out the exhaust - you wouldn't see it on the plugs. 100ml/100km is 1l/1000km - which alot of OEMs will tell you is "within tolerances" for oil consumption. I'd suspect it's the rings - all the running on the warm up map would was down the bores and accelerate the wear (Compression coming up 100psi between dry and wet suggests it's not at all happy).

[simmi1983]

That is a big difference between wet and dry compression readings which definately suggests rings to me!!
This would explain oil consumption and power loss. As for the black smoke , fuel consumption and the cat being damaged this could very well be leaky fuel injectors-so it seems like you may have a couple of issues here. First thing I would do is get those injectors checked out-there are mobile guys that can come around and test them if you already have them off the car.  If that gets you some answers I would replace that cat and monitor your oil consumption (I think the black smoke from over fueling could be masking your blue smoke).
Over fueling could also be caused by a few other things like Coolant temp sensors, fuel pressure regulators or a faulty ECU.

Unfortunately there aren't alot of ways to fix your compression issue without taking your pistons out, it could very well be that your compression rings could be carboned up and stuck in the piston groove and not allowing it to seal on the cylinder fully.  If this is the case I have heard of guys fulling the cylinders up with diesel or ATF to free the rings up and allow them to move freely again-but this method is usually reserved for lower tech engines.
But I would do another compression test with an accurate tester as I have never seen a jump of 100psi between wet and dry.
Hope this helps.

Luke

[GabAlfa]

Hi all,

An update for anyone who was interested in this and may be interested for future reference. I am an Alfa enthusiast, I think.., so I persevered with this issue and mystery...
I decided to dig deeper so pulled the heads off, as you do. Upon inspection of the rings found them worn, pistons looked to be ok but evidence of oil flowing into the cylinder and into heads. Cylinder bores looked pristine, shiny with cross hatching visible. Pulled apart the head and upon inspection found massive amount of oil and gunk build up behind the valves and face of the valves. Also pulled the main bearing caps and inspected the main bearings which were ok, no sign of excessive ware or marks. Pulled the big end bearings off and found them to be excessively worn with score marks (not good) The bearings have a coating which was missing. Crank shaft had no signs of ware, luckily ! So.. decide to buy new head gasket set, piston rings and bind end bearings. This was actually quite reasonable price wise (about AU $ 400). Note I took a bit of a gamble with the rings as I ordered from a supplier in UK who could not supply the Goetze brand so supplied Nippon rings. Much can be said about this but you can ping me with questions, if you wish after reading...
I cleaned all pistons and installed the new Nippon rings. Used piston ring pliers and compressor (eBay $30).
Disassembled the heads, degreased cleaned with brass brush and high pressure hose with combination of degreaser and soapy water then high pressure aired it out. came up squeaky clean. Cleaned all valves and then reinstalled them with new Valve stem seals. Installing is a fun job. I think I spent a whole day just working on the head. Double sprung valves are fun... need a specific tool for this from eBay ($40).
I did all this work while the engine was in the car, removing sump was fun... oil pick up gets in the way as drive shaft block the sump from moving around. like wise re-installing had to loosely git the oil pick up to allow movement then once in place the sump, you can tighten the oil pick up and then fit the sump. You need a person to help with this, got my son to help with this. anyway just a tip here ...
Installed the head following the torque procedure as per manual, that was fun and worked up a good sweat. I really love my torque wrench now !
So... cut a long story short. I installed the remainder of the camshafts, belts and exhaust components, installed all fluids (cheap 15-40 oil) and fired it up !
This was scarey ! first time I rebuild an engine ! (essentially) so I was freaking out a bit so many steps and so many parts !
She started up beautifully ! got it to running temperature and then took it for a drive to ware in the rings (I took the quick burst and engine compression braking approach) much can be said about this.... After about 100 ks I changed the oil and I am running 10-60 full synt. The car has now done 1000 kms since rebuild and has used up zero oil ! not a drop ! niente !   , no smoke, no smell no pollution and no oil consumption !!! yeayyyy !!
So the mystery is no more ! Luke, you were right, It was the rings and possibly the valve guide seals. Luckily I salvaged this engine before it was too late but boy what a journey !!!
Hope this helps some one out there in the Alfa land !

[Colin Edwards]

G'day GabAlfa,

Great description on restoring the 156 JTS.  Being a 159 3.2 owner, your experience with regard to the valve stem seals has me curious. 
Do you believe the stem seals were worn enough to cause the carbon build up in the valve heads?  Was this build up on both inlet and exhaust?  Given Direct Injection / JTS can't wash gunk off the top of inlet valves, if the engine was a Twin Spark, do you think these valves would have been kept clean?  Critics of Direct Injection claim fuel washing provided by "conventional" inlet tract injection keep inlet valves clean. 
I've stuck a borescope down the manifold of my 3.2 JTS and the valves look close to brand new - only done 100k however.

Do you think previous poor (none!) maintenance / oil changes have caused cam wear, big end wear and stem seal wear? 
I understand in the past low phosphor oil was specified for engines with cats.  However, this low phosphor oil is not ideal for lubricating sliding surfaces like cam lobes - and maybe big end bearings and stem seals!?!  Apparently current oils feature slightly higher phosphor plus other friction modifiers that these early oils missed out on.