dwb
Proven Member
- 848
- 602
- Sep 9, 2021
-
Broomfield,
Colorado
I'm looking for some opinions and maybe some first hand experience on performing a DIY head/bottom end assembly vs taking it to a shop. I don't want to put a lot of money into it, hence DIY, but I also don't want to have to tear it down multiple times to get it right. Time isn't much of a factor but I would like to be done before next fall.
A little background first:
It's a stock 91 TSi AWD 6 bolt with 270k miles on the bottom end. I believe it's a virgin factory build. It burned a fair amount of oil and is definitely ready for a refresh. I swapped the head with a fresher used one several years ago, but kept my old head with about 230k miles on it in storage, also virgin as far as I know. The old head has no bent valves and came off a running car, but needs valve seals and probably upgraded lash adjusters at very least.
Fast forward to a few weeks ago, the timing belt broke and I'm sure it took the valves with it. I haven't tore it apart yet to assess the damage, but I do know I want to rebuild it. So I have a tired old 6 bolt block/crank, and 2 heads - one likely with bent valves and the other needing refreshed. Should be a good candidates for rebuild.
Goals:
Daily driver. Maybe an Evo3 16G turbo with mild supporting mods in the future. Nothing extravagant and probably won't ever see the track. It's been stock for the last 23 years I've owned it, so I don't see a lot changing there.
My ability, for considering a DIY:
I've never rebuilt a motor or even tore one apart (yet). I really would like to do it myself as the only thing I've ever needed a shop for is tires and alignment. I've done everything else myself, including rebuilding the manual trans, head swap, timing belt, BS elimination, power steering rack/pump rebuild, transfer case rebuild, wheel bearings, brakes, axles, clutch, and anything else that's needed to be fixed on my DSM. Everything has held up well and I'm proud I've kept it running as long as I did. I'd be even more proud to say I rebuild the motor myself!
Obviously I'd need a machine shop to take care of all the surfaces. As far as assembly, this is where I'm looking for some advice. I feel like the spare head is do-able DIY (after machining) but the bottom end is a little more daunting. While I don't think anything in the bottom end is damaged, it's definitely worn. If possible I'd like to reuse the pistons and rods to keep the cost down, but I'm still researching the benefit vs cost of going aftermarket or even 2g pistons. Crank should be fine and probably only needs polishing and new bearings. However, everything in there is a total unknown until I tear it down.
If you were in my shoes, and keeping cost in mind, what direction would you go? Pay a shop to build a short block or just have it machined and do all the assembly yourself?
A little background first:
It's a stock 91 TSi AWD 6 bolt with 270k miles on the bottom end. I believe it's a virgin factory build. It burned a fair amount of oil and is definitely ready for a refresh. I swapped the head with a fresher used one several years ago, but kept my old head with about 230k miles on it in storage, also virgin as far as I know. The old head has no bent valves and came off a running car, but needs valve seals and probably upgraded lash adjusters at very least.
Fast forward to a few weeks ago, the timing belt broke and I'm sure it took the valves with it. I haven't tore it apart yet to assess the damage, but I do know I want to rebuild it. So I have a tired old 6 bolt block/crank, and 2 heads - one likely with bent valves and the other needing refreshed. Should be a good candidates for rebuild.
Goals:
Daily driver. Maybe an Evo3 16G turbo with mild supporting mods in the future. Nothing extravagant and probably won't ever see the track. It's been stock for the last 23 years I've owned it, so I don't see a lot changing there.
My ability, for considering a DIY:
I've never rebuilt a motor or even tore one apart (yet). I really would like to do it myself as the only thing I've ever needed a shop for is tires and alignment. I've done everything else myself, including rebuilding the manual trans, head swap, timing belt, BS elimination, power steering rack/pump rebuild, transfer case rebuild, wheel bearings, brakes, axles, clutch, and anything else that's needed to be fixed on my DSM. Everything has held up well and I'm proud I've kept it running as long as I did. I'd be even more proud to say I rebuild the motor myself!
Obviously I'd need a machine shop to take care of all the surfaces. As far as assembly, this is where I'm looking for some advice. I feel like the spare head is do-able DIY (after machining) but the bottom end is a little more daunting. While I don't think anything in the bottom end is damaged, it's definitely worn. If possible I'd like to reuse the pistons and rods to keep the cost down, but I'm still researching the benefit vs cost of going aftermarket or even 2g pistons. Crank should be fine and probably only needs polishing and new bearings. However, everything in there is a total unknown until I tear it down.
If you were in my shoes, and keeping cost in mind, what direction would you go? Pay a shop to build a short block or just have it machined and do all the assembly yourself?
