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Rebuild or Motor Swap?

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  • Rebuild or Motor Swap?

    Hey everybody, wanted to ask your expertise if I may. Ive got an 89 Festiva. Its been somewhat of a frankenstien machine. Has a homebrew A/C delete, the wiring is rough to say the best (works, but splices everywhere) but it ran fine for the first 2 weeks I had it, and it lost compression. Prior owner did a head job on it, head gasket and up, and it was shotty work at best. I got it tore down to find the root cause of the freshly rebuilt top end losing compression. Long and short, the 2 middle pistons are burnt up, and one is damaged. Looks like it happened when they ran it hot, maybe it dropped a valve, etc... the head looks brand new, freshly cleaned up and new valves put in, but the pistons are junk. Not sure why someone would put it back together like that, except to set up a return visit to do more work . Anyway, im at a crossroads. The motor has 150k miles on it. Fresh head, but all the hydraulic rockers are shot. Have a full set of adjustable manyal ones to swap in though, so thats not a huge issue. But wanted to get some advice, since this motor has a good new head, should I go ahead with putting pistons and rings and bearings in it and do a good rebuild, or should I invest in a different engine to swap in? $$ is the big object here, trying to decide whats better in the long run, but cheaper at the same time... I have all tools and knowledge to rebuild motor, or swap, so it goes either way.

  • #2
    There was a time (and probably still is so) that there were quite a few essentially 'free to good home' B3s available through swappers that had bolted in B6s. Try an ad on the forum. Costs nothing!

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    • #3
      Burnt pistons followed by low compression is usually caused by to lean a mixture.On a carbed car I'd first suspect an intake leak 1st a plugged or too small main jet 2nd. Injected car intake leak or injectors not working properly.If the ring lands are broken on the pistons that is normally too much ignition timing. If the engine ran good without lower end noise before and the cylinder walls aren't scarred up,on the cheap I 'd drop the pan pull the offending pistons and check those rod bearings if they aren't beat out and the crank journals feel good I'd do two pistons all rings and rod bearings in the car.I would use good used pistons from a donor motor before I bought junk aftermarket pistons.Pull the center main bearing cap and look at main brg condition,if it looks like crap put in a set of mains while you are there.They can be changed in the car too without dropping the crank.Do them one at a time drop one cap change the bottom shell roll the top one out if you go that way I'll teach you how to get the top ones out.Check real good for intake leaks and fuel delivery issues no matter which way you go,melted pistons are usually a lean out problem.
      Last edited by ricko1966; 10-18-2015, 05:19 AM.
      30 + Vehicle projects right now.7 Festiva/Mazda 10 GM IDK how many others,hope that helps explain all the stupid questions/shortcuts/interchanges etc. trying to liquidate so I concentrate on the good ones. Goal finish 1 amonth using as much stuff as I already have accumulated.

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      • #4
        Thanks for the tips guys. I was thinking of goin to the salvage yard to pull pistons, my problem would be A) finding an appropriate donor and B) hoping the center 2 pistons were good and doin the work associated with getting them. That being said, I was a little apprehensive about using "used" pistons, but if the general concensus is that a used set would fair just as well as a new aftermarket set, I will gladly take the advice of the wise-man and go that route. Would save me a couple bucks at the least. As far as the running lean situation, the festy had a LOT of top end noise, the thing sounded like a dang deisel it was so loud. I checked out the rockers, which are hydraulic on this one, non-adjustable type, and they are all wore through on the top of the rockers, and only one of them are any good. About 6 months ago, I happened across a festy with manual adjustable rockers in the junkyard, the only one ive seen at that yard period (but then again, i hadnt always been looking) and snatched the rollers, rockers, and spacers off of it. Had intended on swapping in the adjustable set for my wore out hydraulic set. If that is not a good idea, please let me know. Id much rather pop the valve cover off to adjust the rockers every now and then rather than replacing garunteed to fail hydraulics lol. That being said though, could that have possible had some effect on piston failure, if the valves werent operating as well as they should have been, with wore out rockers?

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        • #5
          If the ring lands and skirts are good on the donor pistons all is good.I'm not saying all aftermarket pistons are junk but some are.When you pop your pistons out of the block you will know more broken rings and or lands is caused by detonation,too much advance,engine overheated,and I know no one wants to hear this but properly working egr reduces detonation. I've never seen a piston melted that wasn't caused by a lean condition usually an intake leak. For what it is worth VW sorts their pistons at the factory before assembly so pistons from a factory engine will have pistons that match by weight.I do not know if Mazda/ford does the same or not but it wouldn't hurt to weigh the donators and check them against yours. It's been a long time since I balanced an engine I think VWs were within 5 grams on a set I got them within a 1/2 gram anyways if they are close all good if not lighten them all to match the lightest
          30 + Vehicle projects right now.7 Festiva/Mazda 10 GM IDK how many others,hope that helps explain all the stupid questions/shortcuts/interchanges etc. trying to liquidate so I concentrate on the good ones. Goal finish 1 amonth using as much stuff as I already have accumulated.

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          • #6
            So having done some research in parts, gaskets, and all that Im looking in the ballpark of $250 to rebuild this stock festiva motor. I reckon I could do about the same swapping in a motor for that amount. I've read over the forum and I've had a hard time finding good info for a near bolt in motor swap to get a more powerful motor in there. Ive read about the B6 swaps, B8 swaps, all sorts of things, and all the information is a little daunting. Wondering if someone can give me some direction. Im not looking for something relatively easy to accomplish that wont break the bank. Spending $250 on a motor that already lacks in power just seems like a silly idea if I can spend $250 on a motor swap to a better motor with more power to get up the hills and get up and go in traffic. Can anyone point me in the right direction here?

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            • #7
              *Im looking for something easy to swap* Ignore the not that slipped in there by mistake! Hoping for something I can manage to do where the car is with what tools I have at my disposal, no crazy rewiring or difficult tuning.

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