1.2 TSI Loss of Compression

[Minimoke]

Hi

 

2010 Fabia with 1.2 TSI engine. Cam chain replaced by main dealer under warranty 2+ years ago. 28,000 miles to date. Owned since new.

 

Now got loss of compression on cylinder 3 - might be the dreaded gummed up exhaust valve issue. So head off and clean required at a minimum.

 

Anybody had this sort of problem fixed by a independent, and if so at what cost?

 

Car is only worth circa £3K as a trade in so unsure whether to reapir or not anyway. 

 

Regards Minimoke

[rum4mo]

Holy smoke, this is not what should be happening, though at 28K over 7 years, is most/all of its use just short journeys so it has not being getting nice and hot?

 

Maybe it is another isolated problem??

[Minimoke]

My local indy tells me that compression on three cylinders is circa 195 but is only 135 on the fourth (number 3). So suspect either a bent valve or carbon build up. 

 

If bent valve then I'm puzzled.  VCDS confirms car not breached rev limiter, and the cam chain was changed 10,000 miles ago by the main dealer.  It was replaced by what is still the latest version of the chain and sprockets. So unlikely to be that the valve has touched the piston because of the well known chain issue. 

 

And carbon build up typically causes misfires rather than compression problems. Wish VAG supported their main dealers with walnut blasting on DI engines as BMW and MINI do, but as usual VAG try and pretend its no great problem on their engines. I'm dubious about the real value of an  "italian tune up" - that will not help a DI engine clear the valves of carbon as the injector ports are on the "wrong" side of the inlet tract. So fuel never touches the valves and thrashing the engine or using different fuel makes absolutely no difference to the carbon build up  - its mainly a design problem and is one of the reasons for moving to dual injectors (both before and after the valves) on later generation engines.  

     

May ask for a borecsope examination before going much further.

 

But am still interested in hearing of anybody who has lifted one of these cylinder heads and how much the work cost.

Edited 18 October, 2017 by Minimoke

[bigjohn]

8 hours ago, Minimoke said:

2010 Fabia with 1.2 TSI engine. Cam chain replaced by main dealer under warranty 2+ years ago. 28,000 miles to date. Owned since new.

Now got loss of compression on cylinder 3 - might be the dreaded gummed up exhaust valve issue.

 

When you had the cam chain was replaced had any damage been done to the engine. If a damaged valve wasn't picked up at the time it would have been "burning" away since eventually reducing compression.

 

Make sure the compression test is repeated after a slug of oil through the plug hole - if compression returns to normal for a while - it could be a piston/rings/bore issue

 

Would an  Inspection camera fit through the spark plug hole to have a look. (These were on offer in Aldi recently - I use mine for allsorts including finding/clicking the tiny lever to mod my headlights for European driving and checking for leaks under floorboards)

 

Likewise an inspection camera could be inserted into the inlet manifold to have a looksee for carbon or burning behind the valves(seemto remember om my 1.4 EA111 there is a sensor on top that could be undone to possibly achieve this.

 

If the valves are carboned up - rather than removing the head to clear the carbon (walnut blasting etc) it may be possible to remove the inlet manifold to achieve this leaving the cam chain etc untouched

 

My 1.4 EA111 (similar cam chain engine the to 1.2 but with 16 valves) has done 50k+ miles and drives as well as the day I picked it up (mpg average is pretty consistant as well)

 

[bigjohn]

6 hours ago, Minimoke said:

its mainly a design problem and is one of the reasons for moving to dual injectors (both before and after the valves) on later generation engines.  

     

 

Port and Direct injection only avalable on later EA888 1.8&2.0 tsi engine. The main reason for this is particulate reduction as direct inject injection had high particulate production whereas port injection has very low particulate production(less efficient though) - the good side effect of this is valve wash during any port injection cycles.

 

later tsi direct injection engines have had improvements (time will tell) re carbon buildup with different variable valve timing mappings, improved crankcase ventilation and EGR performed using variable valve timing (no seperate valve!) . As the old 1.2tsi only has 8 valves/ 1 cam shaft then some of this isn't possible

Edited 18 October, 2017 by bigjohn

[istannbullu34]

So sad to hear that minimoke, i believe you have low mileage for carbon buildup but not impossible.

 

Hoping to hear some good news!