Motor ST loopt ontzettend rot

Bedankt, hoop ik ook. Moet &$!#% wel met de trein naar werk morgen .

Ik ben wel dit moois tegengekomen: MARKTPLAATS

Dit is de mijne:

en dit is Marktplaats:


Als dit dezelfde zijn en ze zijn nieuw, dan scheelt het meer dan honderd euro met de dealer. Die wou er, meen ik, 128 euro voor hebben. Normaal zouden ze zo'n 50 à 50 60 euro moeten kosten. Op mijn bobine staat dat ze gemaakt zijn door Bosch, en deze zijn 51 euro: KLIK

Ik kijk morgen ook wat ze bij Volvo kosten, want dit verschil is gewoon asociaal groot.

 

Dat bedoel ik... Ik meen toch echt dat ik iets van 128 euro hoorde van de dealer.

 

Da's dan een hele dikke tax! Lijkt wel benzine

Ik heb net antwoord van de marktplaats verkoper. De bobines zijn niet gebruikt en, volgens hem gaat het om het Bosch nummer rechtsonder. Deze zijn hetzelfde, dus ze zouden geschikt zijn voor mijn auto...

Ik vraag me wel af waarom Volvo verschillende nummers hanteert voor hetzelfde artikel (8677837 / 30713417). Misschien een verbeterde/nieuwere versie? De nummers rechts zijn ook anders, misschien batchnummers?

 

Maar... zijn ze ook intern hetzelfde? De verkoper is 100% zeker dat ze goed zijn voor mijn auto. Ik denk dat ik het ga doen, 2x voor deze prijs... 1 als reserve .

 

Een paar tientjes verschil, ok, maar wat hier gebeurt is gewoon schandalig veel.

Vandaag de bobines ontvangen en één geplaatst om de kapotte te vervangen. De andere is reserve. Motor loopt weer als een zonnetje. Heb de foutcodes gewist en een ritje gemaakt... en na bijna een week droog gestaan te hebben, word je weer met de neus op de feiten gedrukt: wat een superfijne auto is dit om te rijden zeg! Ik zit nu nog na te genieten, en weet zeker dat ik voorlopig even niet op mijn buik kan slapen .

 

Dat heb ik ook gelezen, ja. Dat het bij mij een cracked liner zou kunnen zijn, is nooit bij me opgekomen. Vanwege het verlies aan vermogen en het gebrom, dacht ik in eerste instantie dat het de turbo of downpipe/uitlaat zou kunnen zijn. Kwam al snel tot de conclusie dat het aan de ontsteking lag, en de foutcode bevestigde dit.

 

Dankjewel Ronald, ben er ook wel blij mee

 

Wat de cracked liners betreft, heb ik hieronder een gepinde post geplaatst van focusstoc.com. Allemaal knip- en plakwerk en de credits hiervan gaan naar Matt_C.

Gaat het hier om een paniekreactie of een knap staaltje marketing inspelend op het gevoel van de autoliefhebber? Ik zou het niet weten... Feit is wel dat het blok in een later stadium op deze plekken is aangepast en er toch meerdere mensen op focusstoc.com dit probleem hebben gehad. Lees het als het je interesseert, en trek je eigen conclusie .

Extra info:
http://www.volvoclub.ru/UPLOAD/File/850dviglo.pdf

http://volvospeed.com/vs_forum/topic/159452-liner-shimming/

______________________________________________

Introduction:

There seems to be a lot of posts asking about cracked liners at the moment with much of the information scattered about the forum, I have written this to try and consolidate the information into one place for future reference. I had firsthand experience with this as my first ST had cracked liners when I bought it from a main dealer, the dealer took it back after failing to fix the problem and found me another ST.

Much of this is recycled from other users.

The problem:

The engine block fitted to the Focus ST is manufactured from an aluminium alloy with cast iron liners as the block material is too soft to form the cylinder bores. The liners are only a few millimetres thick and cast into the block as part of the casting process, for all intensive purposes they cannot be removed from the block. The cylinder bores are spaced very close together with a slot cut between them to allow coolant to flow between the bores, the consequence of this layout is that a weak point is formed where the block material supporting the liner is at its thinnest and this is susceptible to cracking. These cracks allow combustion gases to pass into the coolant and coolant to pass into the combustion chamber depending on the pressure differential between the two.

A cracked liner



Symptoms:

1. Water loss from coolant reservoir with no visible signs of a leak
2. Miss fire on start up, this can be more pronounced after the car is restarted from hot after an hour or two
3. A spark plug that has been removed from a cylinder with a cracked liner will appear cleaner than the other plugs
4. Excessive steam from the exhaust, this will be accompanied by the first three symptoms
5. Pressure in the coolant reservoir when the engine is stone cold
6. Excessive coolant pressure
7. Exhaust gases present in the coolant when a cylinder head testing kit is used to test for exhaust gases in the coolant.

Causes of the cracks:

There have been two possible causes of the liners cracking discussed on the forum:

1. At the thinnest point the block could possibly flex under the pressure from each combustion event and this flexing could eventually lead to the cracks forming.

2. The volume of coolant in the passage between the liners may not be sufficient to conduct the heat away at high power outputs, especially if the engine has been modified. As the temperature of the coolant rises above boiling point in the slot it could vaporise and will no longer provide any effective cooling at the weakest point of the block.

The cast iron that the liner in manufactured from will expand more than the alloy that the block is cast from for a given temperature. Under the normal operating range of the engine, -20c to 120c this is not a problem. However, if there is no longer any liquid coolant present the temperature will quickly rise beyond this range due to the lack of cooling and the very narrow section of the block. In my opinion the liner overheats due to lack of cooling and expands to the point where it cracks the block and the liner then goes on to crack as it is no longer properly supported by the block.

Standard v Modified:

The consensus of opinion seems to suggest that standard un-modified cars also suffer from cracked liners as do modified cars. I am not sure how relevant this really is as these cars often change hands and a cars history can be all but impossible to properly trace, what looks like a pristine un-modified car may have spent the first year of its life running a map and several other modifications. In my opinion modifications will probably accelerate the cracking process, keeping it standard will not guarantee reliability.

Face lift v Pre face lift:

At some point the block was modified in an attempt to prevent the problems with cracked liners. The exact date that this change took place seems to be a bit of a mystery, some people have suggested that it took place as part of the face lift and others some time shortly afterwards. One thing that is clear is that this modification was applied to the RS block and ST blocks manufactured after this date also have the newer design, it would be logical that the redesign was part of the work for the higher output RS engine.

The earlier block has cooling channels that are very narrow and cut much deeper into the block while the newer design has wider channels that were not cut as deeply. In my opinion the designers were trying to increase the volume of coolant at the top of the block where the cracks form to try to prevent boiling whilst also increasing the strength of the bock.

Early slots : 0.50mm wide by 14.50mm deep
Late slots: 0.94mm by 5.00mm deep

Later block, note the depth (Picture courtesy of Puma build)


Early block, deeper slot (Picture courtesy of Puma build)


The information on cracked liners with the newer blocks seems to be sketchy, some people have stated that none have cracked while others suggest that they are little better. At least one well respected tuner has stated they have not seen any crack and I am yet to read of a firsthand account of problems.

Plasma liners:

The RS block was cast with a process where a plasma coating process was applied to the outside of the liners to help them bond with the block. Some people have suggested that this is also used on the later block, there doesn’t seem to be any confirmation either way though.

Lottery:

There seems to be little pattern to failures outside of the redesign of the cooling channel. How much of this is can be attributed to age and mileage is debatable, over the next few years the redesigned blocks may also start to also fail. It would appear that there is a variation in the quality of the casting and the blocks that have an inherent weakness are more likely to crack.

Block Mod:

One tuner has been offering this service for a while now and there are rumours that others are about to join in. While this hasn’t been directly confirmed it seems to be accepted that the process involves filling the cooling slots with shims of metal. While there is no longer any coolant flowing in the channels the shims conduct the heat away from the weakest area into the mass of the block to prevent localised overheating and to also provide additional support in the weak area.

Repairs

1. It appears that a block mod may “fix” cracked liners if the problem is caught early enough.
2. New engine / block
3. Machine the block to accept Darton liners

Cracks form closest to the turbo...

A few years ago I was a member of a Vauxhall Calibra forum and modified my engine with an intercooler, re-map, porting and cams. There are two important similarities between the two engines, firstly they run the same relatively high compression ratio and secondly they both use a small turbo that is cast into the exhaust manifold as close to the engine as possible. In both cases the engine was designed with low to mid range torque in mind with minimal turbo lag, neither engine was intended as a homologation special to go racing with. The weak point on the ST is the block and the weak point on Calibra was the pistons that could melt.

The similarity between to the two is that when the pistons / liners fail they always seem to be on the cylinders closest to the turbo charger. On the Calibra the problem was traced to the back pressure from the turbo, while the turbo could supply increased boost pressure to the engine this resulted in an increase in back pressure in the exhaust manifold and this back pressure could quickly rise above the boost pressure that the turbo was producing. Almost all engines have an overlap in the valve timing where the exhaust valves are left open while the inlet valve opens, the flow of exhaust gases out of the engine helps to draw in a fresh intake charge. This is more effective at higher engine speeds, hence the introduction of variable valve timing where overlap is increased as engine speed increases.

Overlap can be disastrous on an engine where the exhaust back pressure is greater than the pressure in the inlet manifold. This leads to reversion where the gases flow in the wrong direction, the cylinder overheats as it does not receive the full inlet charge that helps to keep it cool, the inlet charge is contaminated with exhaust gases and fuel can be blown back against the injector leaning the mixture. I would be interested to know if any tuners have found greater reliability from reduced overlap or a bigger turbo. It is interesting that a larger turbo was fitted to the RS while tuners have extracted the same 300 bhp from the ST engine & turbo.