ReactionEffect

Well I have a S4 13BT that has about 3000-5000 miles on its rebuild. It came out of one of my parts car which was never tuned right by its previous owner, needless to say it has quite a bit of carbon build up. I varified this with borescope, the housings look great, no signs of a broken seal, just a lot carbon build up. To make matters worse this motor has sit for almost 3 years, two years with out any oil or MMO in combustion chambers. Needless to say the motor has almost no compression. ( Rear has around 0)





I would rather not pull this motor, but I am thinking about pulling it, tearing it down, and cleaning everything up and replacing anything out of spec.



BTW I oil down the chambers about month ago with MMO and added more yesterday with no luck.



Other idea was to try to find something else that might break the seals loose. Any suggestion?

ColinRX7

Hold on.. You can spin the motor over?



I'm not sure if you mean it's stuck as in won't turn over, or turns over but the seal springs are stuck in the down position..



If the springs are stuck, what works for me is to (first off make sure your exhaust is all off and you can see inside the port), turn the motor over until you see an apex seal, then spray it with penetrating lube and push the seal as much as you can, over and over.



You will see slight rust coloured formation break free from between the rotor groove and seal (which is what is holding the spring down to begin with) and drip down the seal with the lubricant as it starts to work back and fourth more.. Then turn it over a bit more and do the opposite housing.. until you have all 6 seals worked.



But as for the age, I don't know what kind of tension is left on those springs sitting that long. I've never done this with a motor that has sat more than 1 year.

mazdaspeed7

I know its not what you want to hear, but I highly recommend you tear down the motor. Heres why. You said the housings are in excellent condition, verified by a boroscope. Given the mileage, you will be able to reuse ALL hard seals, including apex seals and all the springs. From that period of sitting, its likely the soft seals are showing some age, as well as the carbont hats causing you all sorts of problems. There is no really effective way to clean out carbon whil eth emotor is together, but you can spend a couple of hundred dollars to pull apart the engine, clean everything up, replace the soft seals, and get everything back together as a good as new engine. On the flip side, you could try everything out there and maybe free up the seals, but still have an engine with 3-5k miles worth of carbon from a bad tune, and possibly compromised soft seals from what you used to try to free the hard seals.

rfreeman27

agreed with 7.

ColinRX7

I was salvaging non-rebuilds, just old junkers trying to get some last breaths of life.. If I knew the hard parts were new I would probably do a teardown as well.

ReactionEffect

I know... I should have torn the motor down last year. The parts had the most getto turbo swap I have ever seen done to it. I don't know how it ever ran.



It had a S5 turbo ECU, Low Imp injectors from S4, knock sensor was no where to be found, no O2 sensor, and S5 N/A MAF.



Scary thing was... it had S5 N/A flywheel.

RONIN FC

So its an N/A with a TII engine swap? The N/A fly is too small for the TII tranny.



When you used the borescope, did the rotors look to have a machined finish? Maybe S5 rotors.

ReactionEffect

The car had a NA tranny. It has S4 rotors.

ColinRX7

The counterweight would have been wrong, maybe the engine sustained damage?

mazdaspeed7

Mismatched counterweights makes for abnormal bearing wear, but its not real serious unless the engine has a lot of miles on it. I ran an engine for 20k miles with the wrong flywheel(long story), and the bearings werent far out of factory spec, and that was just 2 spots on each bearing.



But given the cars uncertain history, Id highly recommend you tearing it down and freshening it up.