Blown Piston after crankshaft and piston replacement

[Fundikali]

I have a 2003 WRX STI that has done 50,000 Kms. Two weeks ago, I was cruising on the highway when my car lost power and started producing a ticking sound from the engine. I took it to the local Subaru garage and was told that I had rod knock. There was no damage to the engine block. The garage replaced the affected rod and put in a new piston assembly for the affected cylinder. They also put in a new crankshaft, bearings, piston rings, rocker cover gaskets, crank seal. They even put in a new water pump for good measure. They never clearly explained to me what caused the rod knock since as I was driving there was no warning light (Oil, Coolant Temp, CEL).

I got the car out after a week and drove moderately for one week. Yesterday morning I decided to go out for a drive and was doing about 140kph up a slight incline on 6th gear, at about 5000rpm when the car lost power and started emitting thick whitish smoke. Again the coolant temp was normal and there was no warning light. I immediately stopped and had it towed back to the same garage. This time, I had a blown piston (not the new one) which has damaged the engine block. Again the mechanic is not really clear on the problem and says that it may have been caused by low oil pressure. My STI is completely stock. I do not have an oil pressure gauge, only the turbo boost gauge.

What caused the rod knock and later on, the blown piston after the repair? Could the garage have made an error that led to the blown piston (they're not accepting liability)? What needs to be done to solve the problem permanently? I do not have the money for a new engine. I'm in Nairobi, Kenya and the options on garages are really limited.I would appreciate the advice.

[carwisperer]

Originally Posted by Fundikali

I have a 2003 WRX STI that has done 50,000 Kms. Two weeks ago, I was cruising on the highway when my car lost power and started producing a ticking sound from the engine. I took it to the local Subaru garage and was told that I had rod knock. There was no damage to the engine block. The garage replaced the affected rod and put in a new piston assembly for the affected cylinder. They also put in a new crankshaft, bearings, piston rings, rocker cover gaskets, crank seal. They even put in a new water pump for good measure. They never clearly explained to me what caused the rod knock since as I was driving there was no warning light (Oil, Coolant Temp, CEL).

I got the car out after a week and drove moderately for one week. Yesterday morning I decided to go out for a drive and was doing about 140kph up a slight incline on 6th gear, at about 5000rpm when the car lost power and started emitting thick whitish smoke. Again the coolant temp was normal and there was no warning light. I immediately stopped and had it towed back to the same garage. This time, I had a blown piston (not the new one) which has damaged the engine block. Again the mechanic is not really clear on the problem and says that it may have been caused by low oil pressure. My STI is completely stock. I do not have an oil pressure gauge, only the turbo boost gauge.

What caused the rod knock and later on, the blown piston after the repair? Could the garage have made an error that led to the blown piston (they're not accepting liability)? What needs to be done to solve the problem permanently? I do not have the money for a new engine. I'm in Nairobi, Kenya and the options on garages are really limited.I would appreciate the advice.

ive only read this quickly but you say the first job the rod and bearing went on one piston ye??where all the rod bearings for the other 3 pistons changed too??they should have been!as if you have one set of bearings gone you dont just change the one set you do them all (as in rod to crank bearings)!if one lot where damaged then the rest aint gona be up to much really,plus when ive brought them i get the full set for 4 rods in one pack!never had just bearings for one rod..

[Fundikali]

Yes. The bearings for all four rods were replaced. Sorry, i should've mentioned that.

[Tidgy]

Rod nock, mmm, not sure what he means, im guessing bottom end nock.

sounds like what ever the origional fault was they didn't fix. bottom ends can let go for any number of reasons, but that soon after a build? def something wrong and sounds like there trying to fob you off.

is there any legal action you can take? or get legal advice,

did they supply the repair with a warrenty? if so i'd be claiming on that.

[shambles]

Have to agree with tidgy. You must get some sort of warranty. I noticed that you are from Kenya. Are you getting the correct grade of fuel for you're car there?

[Fundikali]

Yes, I am writing from Kenya and no, there are no clearly defined systems for warranty from garages but it is something I am pursuing. Shambles, I'm not sure about the correct grade of fuel that needs to be used on the STI but we do not have much choice here, I use unleaded premium, just like everybody else, including those with STIs and other performance cars.

[carwisperer]

Originally Posted by Fundikali

Yes. The bearings for all four rods were replaced. Sorry, i should've mentioned that.

the only other bit that cringed me a bit...is that you say it happen'd at about 5000rpm!thats only a week later after new rings etc where you not advised to keep you rpm to under 3000 for the first 500miles+??this is important as your running in new piston,rings,bearings etc mate..and you need a good oil for this period too!then changed after the running in period still preferably a good oil again..,components could have failed due to this mate..

[Fundikali]

Originally Posted by carwisperer

the only other bit that cringed me a bit...is that you say it happen'd at about 5000rpm!thats only a week later after new rings etc where you not advised to keep you rpm to under 3000 for the first 500miles+??this is important as your running in new piston,rings,bearings etc mate..and you need a good oil for this period too!then changed after the running in period still preferably a good oil again..,components could have failed due to this mate..

No, they did not tell me and neither did I know that I was to keep it under 3000. In fact as I went to pick it up from the garage we went for a road test with the mechanic and I was gunning it. He never mentioned anything. Thanks for that information carwisperer.

[carwisperer]

Originally Posted by Fundikali

No, they did not tell me and neither did I know that I was to keep it under 3000. In fact as I went to pick it up from the garage we went for a road test with the mechanic and I was gunning it. He never mentioned anything. Thanks for that information carwisperer.

Hmmm thats not good mate... what a duff mechanic!!cant believe he let you gun it on the road test even!!id have been crying if any of my customers did that!! well i wouldnt let them simple!!and every mechanic should know this!its simple basic stuff but can mean the life or death of your engine..,hope it helps ya on this one,good luck fella

[carwisperer]

also mate if not all the piston rings were renewed then why not??if you do one piston you do them all on a car like that if your a professional theres no reason not to!the engine is in bits there doing the bottom end bearings,the pistons are free to pull out!you just would do them it makes sense to!

[Fundikali]

Originally Posted by carwisperer

Hmmm thats not good mate... what a duff mechanic!!cant believe he let you gun it on the road test even!!id have been crying if any of my customers did that!! well i wouldnt let them simple!!and every mechanic should know this!its simple basic stuff but can mean the life or death of your engine..,hope it helps ya on this one,good luck fella

That's sad considering that the garage where I took my car is renowned for their "expertise" in Subaru. Thanks carwisperer, you've been helpful mate.

[Fundikali]

Originally Posted by carwisperer

also mate if not all the piston rings were renewed then why not??if you do one piston you do them all on a car like that if your a professional theres no reason not to!the engine is in bits there doing the bottom end bearings,the pistons are free to pull out!you just would do them it makes sense to!

Oh? I figured that it was only one so I don't need to change the other three. Here one piston assembly costs about USD 200. Should I then change all four or just the blown one and the other two that I did not change?

[carwisperer]

Originally Posted by Fundikali

That's sad considering that the garage where I took my car is renowned for their "expertise" in Subaru. Thanks carwisperer, you've been helpful mate.

It is sad and a big let down...,does sound like he may have just been bit lazy on this one and cut some corners..,no worries mate good luck!

[Fundikali]

Originally Posted by carwisperer

also mate if not all the piston rings were renewed then why not??if you do one piston you do them all on a car like that if your a professional theres no reason not to!the engine is in bits there doing the bottom end bearings,the pistons are free to pull out!you just would do them it makes sense to!

Oh? So should I replace all four pistons or should I leave the one I had replaced recently and buy 3. One piston assembly here goes for just under 200 USD, quite a tidy sum.

[carwisperer]

Originally Posted by Fundikali

Oh? So should I replace all four pistons or should I leave the one I had replaced recently and buy 3. One piston assembly here goes for just under 200 USD, quite a tidy sum.

check all the pistons mate but if they are fine then you just want to be changing the piston rings that are fitted to the pistons not the actual pistons unless they are damaged or some thing not right with them