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Car Forum / Driving, Maintenance, Tuning / General Car Topics / June 2007Full rebuild, or slap it back together?
Heyas, I'm elbows-deep in the guts of a '92 Geo Tracker engine; at first this was a quickie re-ring and topside gasket set--pull the head, drop the oil pan, pop the pistons, and clean the carbon out. It's got about 107,000 miles on it (hard to say--the odometer only goes up to 99,999). Compression was equally low in all four cylinders--150 instead of 199, drastic improvement with an oil shot (240 on cylinder #1, for example). Burned about a quart of oil every month. Minor head gasket leak--coolant seeping out of the driver's-side rear corner of the gasket joint. I've gotten the head cleaned up, got the pistons brushed off (careful work with a green Roloc bristle wheel and some carb cleaner), and cleaned out the ring grooves. Busted the glaze off the cylinders...then figured out that while the cylinder bores are nice and round, all four are right on the high limit (2.9535"). A ring-gap check comes up .004" at best over the maximum. Okay, so that's a bore up to the next size (0.5mm over), new pistons, new rings. As long as I'm doing that, though, I might as well put in main bearings. Problem is, I need the truck back on the road ASAP (I'm borrowing someone else's car to get back & forth to work)--if I have to wait for the money to catch up so I can get the new parts, it'll be several weeks at least, and I'm guessing several hundred bucks more that I don't really have to spare. What's the best I can expect from putting it back together as-is (new rings, rod bearings, and head gasket set, timing belt)? I can't see that those rings are going to seat or seal well with the bores being that worn, even with everything else being fine. I'd be satisfied with getting a few years of good service out of it--I've had the thing a year, don't race it, and the only complaint I've had with it has been the constant faint smell of burning oil. Thanks in advance.  SignatureJ. If you hone the bores to get a nice crosshatch pattern and use cast iron rings you should be OK for a few years. Moly rings would last longer but are going to have a harder time seating. Jeff DeWitt > Heyas, > [quoted text clipped - 31 lines] > > Thanks in advance. Thanks for the advice; when I saw the specs last night after two hours of cleaning the last pair of pistons (tops & grooves), I just stopped right there, thinking "all this for nothing?!"...then mentally started adding up the cost in additional parts & tools--main bearings, crank seals, bore job, engine stand, engine hoist (rental or purchase). Maybe later. Adds up pretty quickly--I'm already pushing $300 just with the parts, tools and supplies I've already got (getting an employee discount has advantages, y'know ;). > If you hone the bores to get a nice crosshatch pattern and use cast > iron rings you should be OK for a few years. Moly rings would last [quoted text clipped - 13 lines] >> gasket leak--coolant seeping out of the driver's-side rear corner of >> the gasket joint. <snip> SignatureJ.W. Believe me I know. I started accumulating parts to rebuild a Studebaker V8 and after spending $500 or so on parts I found out how much the machine work was going to cost (gulp). Then someone offered me a freshly rebuilt engine for a very good price, and even gave me a warranty with it... about as close as you can get to a Studebaker crate engine these days and I jumped on it. However the parts won't go to waist, I've only got two more of the beasts. Jeff DeWitt > Thanks for the advice; when I saw the specs last night after two hours of > cleaning the last pair of pistons (tops & grooves), I just stopped right [quoted text clipped - 25 lines] > > <snip> > Believe me I know. > > I started accumulating parts to rebuild a Studebaker V8 and after > spending $500 or so on parts I found out how much the machine work was > going to cost (gulp). Oh, yeah. I cringe when I think of some machine shop work that got botched on a classic engine. I was working as a delivery driver; we toted, IIRC, a classic 409 (big block?) to the machine shop for one of our customers. Car and all worth $150,000, according to him. They chewed up one of the cylinders! Yikes. > Then someone offered me a freshly rebuilt engine for a very good > price, and even gave me a warranty with it... about as close as you > can get to a Studebaker crate engine these days and I jumped on it. Nice! > However the parts won't go to waist, I've only got two more of the > beasts. Heh. I've only got the one Tracker. I busted my can for 12 hours on Sunday getting it all back together. I started out removing the brand-new piston rings, running a file over the gap ends (on advice from a rebuilder), got ready to put the brand-new rod bearings in... ...hey, wait. What's this "1.00mm" marking on the old bearing? Uh oh. Measure up the rod journal again. Yup. It's been machined. Crap! Oh well...the old bearings don't look all that bad, and with all the other stuff I've found, this'll probably be the last time this engine will be opened up before a complete rebuild--and I'd rather just find a replacement in better shape. Okay...get the pistons back in...good. Oil pan, head, intake, exhaust, new timing belt...set the valve lash...everything's done! It's been a long 11 hours in 98-degree weather, I've drunk almost 2 gallons of various fluids, sweated 2 gallons...time to fire it up. *sound of starter* No dice. I did get one very impressive backfire at one point. Long story short, I gave up, got back to it tonight, found the distributor 180-out, fixed that, and it fired up on the second full turn. Sounded like hell (mostly clatter in the valve rockers--gotta re-check them), smoked like crazy (less and less as it idled longer), and rough, but still good enough to limp back off the ramps, then down the driveway and back into the yard the right way. It...is alive!!! Thanks again, mon. > Jeff DeWitt > [quoted text clipped - 8 lines] >> tools and supplies I've already got (getting an employee discount has >> advantages, y'know ;). SignatureJ.W. Glad to hear you got it running, I did exactly the same thing with another Stude years ago, that time it was a little Champion 6... actually come to think of it I did that to my Stude truck when replacing the distributor a while back (put electronic ignition on it). Sounds like that machine shop owed a sleeve job at least. Jeff DeWitt >> Believe me I know. >> [quoted text clipped - 66 lines] >>> tools and supplies I've already got (getting an employee discount has >>> advantages, y'know ;). > Glad to hear you got it running So far, it's still not running very well. I was thinking vacuum leak, tightened up the intake (which was about the only thing on the vacuum side of things that got removed--I pulled manifold, hoses and all as one piece), and got the same crappy idle and vibration--it's giving me putt-putt-putt and doesn't like anything but idle (damn near stalls if I put in a little sudden gas). *shrug* Guess I'll pop the rocker cover and timing-belt cover to re-re-re- check that the cam timing's good. If I advance the ignition timing way past the 20-degree mark, the idle smoothes out some--but if it's on the stock 8- degree mark, it's choppy as hell. Hasn't blown up (yet). That's a good sign =D SignatureJ.W. Have you checked the valve adjustment? If the valves aren't closing all the way or are hardly opening it's going to run VERY badly. Yes, you want to check the timing belt again and you might also verify that the spark plug wires are going to the right plugs. One pair of swapped wires can cause this. Jeff DeWitt >> Glad to hear you got it running > [quoted text clipped - 11 lines] > > Hasn't blown up (yet). That's a good sign =D > Have you checked the valve adjustment? If the valves aren't closing > all the way or are hardly opening it's going to run VERY badly. Yes, > you want to check the timing belt again and you might also verify that > the spark plug wires are going to the right plugs. One pair of > swapped wires can cause this. It was the valve lash; when I did the lash settings, it was about the same time I put the distibutor back on. None of the rockers were right--and at least three were 1/2" out! Idle's a lot better, now, but it still shakes like Courtney Love in rehab. It still wants ignition timing 'way back behind 20BTDC--and when I pulled off the biggest vacuum line I could find, the idle smoothed out to near normal (it's pulling 16-17" of vacuum, with a small vibration--retarded ignition timing?) It's running well enough to drive it to work--that's a big plus. I'll monkey around with the ignition settings at lunch--and then it's time for a little run-in-the-rings drive down a 2-lane highway. SignatureJ.W. I don't know much about those engines, it almost sounds like something off the wall is going on like... what kind of drive does the distributor have, is it possible it's got a gear and it's one tooth off? Or maybe the spark plug wires are all off by one? (I've done that, but it's easer to do with a V8). That would really confuse the timing. Glad to hear you are making progress! Jeff DeWitt >> Have you checked the valve adjustment? If the valves aren't closing >> all the way or are hardly opening it's going to run VERY badly. Yes, [quoted text clipped - 15 lines] > monkey around with the ignition settings at lunch--and then it's time for a > little run-in-the-rings drive down a 2-lane highway. Distributor's driven off a spiral gear on the back end of the cam. I tried the "turn the distributor case a bit and move the wires" trick-- nothin' doin', so they're all back where they were. Seems to be getting better and better as it's driven, so I'm just going to leave it alone and let it break in its own way. DAMN, it's good to be back in the saddle. Time for that vodka shot I've been saving for such an occasion. > I don't know much about those engines, it almost sounds like something > off the wall is going on like... what kind of drive does the [quoted text clipped - 26 lines] >> monkey around with the ignition settings at lunch--and then it's time >> for a little run-in-the-rings drive down a 2-lane highway. SignatureJ.W.
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