I just bought a 1986 mr2, body and paint are good, but the main bearings are thrashed. I'm looking at several options for fixing it up. from a crate motor (if i can find one) to just redoing the bottom end. I'm new to toyotas and am looking for good information and parts sources, as well as advice on what to do with it. It runs ok right now, but there is some knocking in the bottom end, so i'm not driving it. My mechanic said the main bearings are done and guessed around $1200 to fix that. If it's not a lot more i'd rather get a new crate engine. any advice on where to look for parts/engines at good prices is welcome. It has the 1.6L 4a-ge engine. what other engine options are there, and would they be worth it?
hrm.... im not a mr2 specialist, but if your guna spend like 1200 on just fixing the motor, you might as well as go to a JDM engine shop, and just swap in the 4age Silver Top 20v motor, its a way better and stronger version of the 4age that you have, and it has 20v with individual throttle bodies, ive seen a complete motor, ecu, uncut harness and transmission for about $700 and you might be spending like another $200 on the harness to be modified for the mr2 and the transmission might cost you like another $200 or so for it to be modified for mid-rear setup from a front-front setup. but thats a option, or you can just rebuild the 4age motor, its still a nice high revving machine, but thats just my opinion if you were going to spent that kinda money on it, and you can still sell your messed up 4age engine for about $100 to people on the forums that cant afford expensive swaps, but just want to build a 4age for their non-4age car.
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You can rebuild that motor for less than $800 guaranteed. I have rebuilt five 4AGE motors and they all cost between $500 and $800 to fully rebuilt (if you are going stock).
Just get a full rebuild kit, way cheaper. The kits cost $350-400 block and head machine work shouldnt be more then $200-350.
And even if you dont want to do a full rebuild (I recommend you do for longer engine life). As long as the journals weren't damaged, you could probably just have the crank machined and get just the bearings. A bearing set would cost about $50-75. Machine work $100. And it should literally take 3-8 hours of labor depending on how good the mechanic is.
Thank you for all your input. I'm thinking that, for now, i'll get it running as inexpensively as i can, and, if I love it as much as i think i will, i'll end up going with a 20v age or even a 3s engine later. Other than the living room, i don't have any space to rebuild it currently, or i'd be tempted to try to rebuild it myself. thanks guys, wish me luck
It's entirely possible that it's rod bearings, i talked with another mechanic who said its usually rods that go first, have to tear it apart to find out i guess. got some pricing going on with a couple mechanics to see what i'm actually gonna spend. I'd like to go full rebuild, anyone have any recommendations on performance cams? I wouldnt mind a bit of xtra HP.
you can also run into other problems like the crankshaft being scored beyond repair from the bearings being shot. So just something else to be aware of and account for.
I don't have a recommendation for Cams, but upgrading cams with higher lift/duration, requires upgrading of the valve train via stiffer springs and stronger retainers, at the least. You will also need adjustable cam gears to degree them .
You can't, or should I say shouldn't just throw cams in there. You risk valve float.
good to know, i figured i might need a new crank, but i'm hoping i don't. If i decide to go with a cam upgrade, i'll definitely follow your advice MR2Jedi. I really appreciate all the good advice I'll also try to get a pic or two posted of my mr2, in case anyone is interested.
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