Alfa romeo 156 JTS oil Mystery - Alfa Romeo Forum
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Question Alfa romeo 156 JTS oil Mystery

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 minute 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. Is it the Cat converter causing issues ? Anyone have any suggestions or silver bullet ??
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Not heard of someone fitting TS cams to a JTS. They aren't the same (actually I think one of them is, but timed different) and if you're interested you could google Alfa JTS development or similar to understand the theory behind the high compression ratio and cylinder scavenging. I would be worried that the more traditional timing of the TS cams in combination with the very high static compression of the JTS could lead to very high dynamic compression and so under load you might get a cylinder meltdown. But then again it might work. As an aside, when you fitted the TS cams which camlocks did you use, TS or JTS?

As for the oil consumption I would use the car a bit and monitor it to see if it settles or gets worse. The worn cam lobes suggest the oil was not changed very often (if at all) through the car's life. So maybe run it for a bit then change the oil and filter again and see where you're at. 100ml per 100km is right on the limit of Alfa's recommendation for 'normal" usage (1 litre per 1000km).
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jts engines use a lot of oil. 1 liter pr 1000 km's is "normal".

Worn cam lobes are also normal, and it seems to be fuel congestion of oil (direct injection) and low oil pressure in engine top. Most early jts will need new cams, and i changed mine at approx 178' km's. Had the hardning checked in a lab, and it was normal. Also "upped" the oil-pump to deliver higher oil pressure.

This was an industry first engine, so it had some issues.
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Black smoke = rich, which you probably already identified the cause of, a defective thermostat. Excess fuel will also wash oil from the bores and increase oil consumption, as well as hastening wear. And it'll kill the catalyst and lambda sensors. I'd change the thermostat for new OE and see where that gets you.
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Do you up the oil pressure by adjusting or replacing the oil pressure relief valve please?
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This was an industry first engine...
No it wasn't, not by a long way.
Mitsubishi introduced their GDI in 1996
Nissan in 1997
Toyota 1998
Renault in 1999
VW in 2000

and Alfa introduced their JTS direct injection engine in 2002.
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Not much to add other than that MAF and Lambda issues can also lead to rich running as the ecu adjusts mix to compensate for percieved incorrect ratio, did on my JTS anyway..proved when the replacement of MAF and Lambda cleared up the rich running issues, weirdly got no other maf symptoms as such and no codes either, diagnosed after failing emmisions on an MOT, CAT was fairly new having replaced the year before.

I also had a worn lobe on the exhaust camshaft which was replaced,the early manuals state 5w40 as far as I know, this was later revised to 10/60 in order to reduce oil consumption...some are of the opinion that the heavier oil does not adequately lubricate the top end and leads to the premature camshaft wear..if you are not running 10/60 switching will reduce oil consumption somewhat but as stated pluses and minuses to that solution.


all in all the JTS can be a troublesome beast, in just a year of ownership mine cost me 2k on engine related stuff, all unexpected and at the very low mileage of 31k totally unjustified..sound like you have dealt with most of it but don't be surprised if it throws a couple more 'wobblers'' before you get it sorted.

TS is a much better engine overall but must admit I did enjoy the extra torque available from the JTS over the twinnie...that said it doesn't sound nearly as good and the TS is much happier up the rev range than the JTS is.

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Do you up the oil pressure by adjusting or replacing the oil pressure relief valve please?
adjusting
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The huge increase in compression when you did the wet test leads me to think you have very worn piston rings or bores despite what the dry test told you.
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The huge increase in compression when you did the wet test leads me to think you have very worn piston rings or bores despite what the dry test told you.
I agree .. a 100 psi jump is pretty big ..

And yes, you do need a new thermostat.
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Not heard of someone fitting TS cams to a JTS. They aren't the same (actually I think one of them is, but timed different) and if you're interested you could google Alfa JTS development or similar to understand the theory behind the high compression ratio and cylinder scavenging. I would be worried that the more traditional timing of the TS cams in combination with the very high static compression of the JTS could lead to very high dynamic compression and so under load you might get a cylinder meltdown. But then again it might work. As an aside, when you fitted the TS cams which camlocks did you use, TS or JTS?

As for the oil consumption I would use the car a bit and monitor it to see if it settles or gets worse. The worn cam lobes suggest the oil was not changed very often (if at all) through the car's life. So maybe run it for a bit then change the oil and filter again and see where you're at. 100ml per 100km is right on the limit of Alfa's recommendation for 'normal" usage (1 litre per 1000km).
hey SprintVeloce, interesting theories about the timing concepts. The engine to me is running really well and pulls hard and yes, I used the TS cam locks. I visually looked and measured the cam profiles between the TS and the JTS and could not see any difference apart from the worn lobes. I'm no expert but measurements and fitment looks spot on and as proven it is running a lot quitter and efficiently than before. Thanks for the re-assurance of the oil consumption and will replace the thermo and monitor. Happy to hear any feedback. Cheers.
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Last edited by Rockhopper; 14-10-16 at 08:54.
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Quote:
Originally Posted by eivindcl View Post
jts engines use a lot of oil. 1 liter pr 1000 km's is "normal".

Worn cam lobes are also normal, and it seems to be fuel congestion of oil (direct injection) and low oil pressure in engine top. Most early jts will need new cams, and i changed mine at approx 178' km's. Had the hardning checked in a lab, and it was normal. Also "upped" the oil-pump to deliver higher oil pressure.

This was an industry first engine, so it had some issues.

My JTS uses very little oil. Maybe 100ML every couple of thousand miles. 10w60 Castrol Edge.
I must have a gud'n then
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The huge increase in compression when you did the wet test leads me to think you have very worn piston rings or bores despite what the dry test told you.
Just thought I'd add that I did a compression test (dry and cold) last night, post the replacement of the camshaft and I am getting 200 psi across consistently. I can only put it down to better intake in the compression build up when turning the engine over. I think that is good news.
 
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