No compression - Rebuild or Replace?

[Flunk]

So,

I have a BG5 Legacy running low/no compression on one cylinder.

I picked up a deregistered BD sedan, with engine in good nick.

The intention was to pillage any spare parts needed to repair the wagon.

Then my wife asked why I dont just swap the engine over completely.

So that is my question, what would you choose?

Also i will e dismantling / selling anything left over from BD.

[funkytown]

What revison is each? A/b/c?

[Flunk]

Ok rookie question, fastest way to tell difference?

I assume it will be something to do with AFM?

Green AFM on BG Wagon ( no compression )

Orange AFM on RS Sedan.

[aim]

Post chassis code(s)

[Flunk]

BG5A59D

BD5C48D

[rslegy]

1 is a and the other is c

[Flunk]

Yeah i figured that after looking at codes.

Are there any major differences though, or is a swap still straight forward?

[Flunk]

Engine is out of Bg.

Half way through pulling engine from bd.

Guess ill figure it out if nobody has any info about this.

[Rosssub]

I\'d be checking/comparing part numbers on the ECU, also ECU loom plugs/pinout connections to make sure the dash/gear box loom etc match up as well.

[Rosssub]

The Zerosports install Pinout diagram shows the difference between Rev A and Rev B-C ECU\'s. You might be in for a headache/loom change?

http://download.robson-brown.co.uk/uklegacy/zerosport/03plugs1.jpg

Edit: Maybe compare part numbers on all sensors/solenoids/TPS etc on the new Rev C engine to make sure they\'re all the same?

EditDedit: If sensor part numbers don\'t match it could mean a different voltage output, so your Rev A ECU won\'t know what\'s going on and you\'ll get constant CEL\'s or it just won\'t run.

[Koom]

If the rev c engine has the same bolt pattern for the inlet manifold, why not swap that over and keep your ecu/sensors?

Compression ratio\'s may need looking at though?

[Flunk]

Done some more investigating, definately different ecu\'s.

As far as i can tell though all the sensors seem to be the same, all the ones i\'ve checked so far anyway.

But none the less, i\'d rather play safe so will either swap loom + ecu, or repair BG\'s engine.

EDIT:

BG5 ENGINE - EJ20HDWAJE

BD5 ENGINE - EJ20RDWEJE

So just doing research about head etc to see if i can swap those.

[Rosssub]

As long as every sensor part number (for voltages) and sensor location (loom length) matches, engine bay loom to engine plugs are the same and compression ratio\'s match. Then the Rev C motor should run no worries on your Rev A ECU.

[Rosssub]

Are they both manual gearboxes?

Edit: And do you know why your original was low on compression?

[Flunk]

Yes both cars manual boxes.

As for compression, no idea. Its only low on 1 cylinder.

Has been this way ever since my brother in law got his bush mechanic cousin to do some work on it, so it is possible that its only something minor, but not sure if I can be bothered trying to fix it, thats why i was hoping to just make a swap.

I swapped my brother in law a vr4 legnum, for both subbies always loved the legacies, owned a few.

[Flunk]

wiring loom and plugs all "look" the same, i will compare them more closely tomorrow.

The other thought i had which i will investigate tomorow is can i use existing loom and swap ecu only? Just a thought.

[Rosssub]

Sweet, hopefully a straight swap. The ECU\'s won\'t swap cause 3plug to 4 plug, unless you did a lot of wiring.

You should be able to determine why you have low compression with a compression leak down test AFAIK. The engine loses compression differently (faster/slower) for different faults i.e Head gasket/cracked head/burnt valve seat/worn piston rings.

[les666]

Wouldn\'t replacing complete engine and sensors and re loom using the rev c be the best option? Cos isn\'t the bg5a 183kw running grey injectors whereas the bg5c is what? 206kw with yellows? Plus easier to convert to single turbo if that way inclined? Maybe something to think about...

[Rosssub]

 les666 said:

Wouldn\'t replacing complete engine and sensors and re loom using the rev c be the best option? Cos isn\'t the bg5a 183kw running grey injectors whereas the bg5c is what? 206kw with yellows? Plus easier to convert to single turbo if that way inclined? Maybe something to think about...

Sold....Change it all over if it\'s worth 23kw.

Edit: So that would mean a compression ratio change A-C as well?

[Koom]

The wiring swap around to match up between a to c is pretty major. Basically every wire has to change position. I\'d never bother going near it again unless it was wiring in a link and making loads more than 23 extra kilowatts.

[les666]

Yeah re pinning would suck but swapping the entire loom from one to the other maybe slightly less sucky?

[Rosssub]

 les666 said:

Yeah re pinning would suck but swapping the entire loom from one to the other maybe slightly less sucky?

As long as the dash pins/loom match as well or it maybe full speedo/dash looms swap too.

[Koom]

 les666 said:

Yeah re pinning would suck but swapping the entire loom from one to the other maybe slightly less sucky?

If you think that re pinning sucks, you\'ll love re looming

Subaru\'s don\'t use a separate engine loom to the ecu. It\'s all intertwined. I converted a bg5a to single and had an entire wrx loom to use. Laid it out next to the car, gave up and re pinned instead as it was the much, much easier option. And it still sucked.

If you\'re going as far to fit a later model ecu, fit one that runs one turbo (and the associated, one turbo).

I don\'t think that the "c" heads will fit the "a" manifold, but I\'d be looking at fitting all sensors from the "a" back into it and just using the original ecu.

[Flunk]

Yeah im thinking engine/loom/ecu swap may end up in too hard bin.

Sell all the RS parts and repair engine for wagon.

[Flunk]

Just to satisfy my own curiosity, I\'ve started looking at removing bc loom, and re-looming the bg.

Its not looking like as much of a nightmare as i was expecting.