A couple years ago I bought a '96 Grand Prix that was in good condition other than obvious overheating issues. I suspected head gaskets from the get go since the PO had rigged the cooling fans to run all the time, which told me they kept driving it without fixing it. It sat it my garage till this spring when I had time to work on it. I pulled the heads off and confirmed a bad head gasket on the front bank, and did what I thought was a thorough inspection of cylinder bores before I ordered reman heads and related parts to fix it.
When I went to put the new parts on, I noticed an area of one of the bores that was in pretty rough shape, not sure how I missed it on the initial inspection. It's on the front side (that's hard to see) of the middle cylinder of the front bank. I guess enough coolant was getting in that cylinder that it allowed metal to metal contact, some scraping was going on as there was rough metal and it created a noticeable dish in that area. The picture of the damage is pretty poor, but it was fairly significant.
At that point I contemplated pulling the block and rebuilding it, but I decided to try to use it and if that failed, I was going to replace the whole engine with a 3.5L. I did what nobody would ever suggest-- using fine grit sandpaper to smooth roughness out and restore that side of the bore to a smooth surface. It succeeded except for a small spot of porosity that would have required sanding too deep. I crossed my fingers, buttoned it up and gave it a whirl.
Everything seemed normal, engine ran good but I was still suspicious and proceeded carefully, doing 3 oil changes back to back to get any debris that got in the oil out of there. Well now it's been 3500 miles since then, I've basically been daily driving it to work most days (35 miles each way.) My goal was just to get it in running condition so I could assess the condition of everything else on the car, and continue to restore it. Oddly enough compression is 180-185 PSI in all cylinders, including the suspect one. After 3.5k, oil level has dropped just a tick under full on the dipstick. Kind of baffles me how good it runs, having seen the condition of some of those cylinders. I figured it would be a smoker and/or low compression / lots of blowby. But it seems none of those things. I did a UOA at about 400 miles and it didn't show anything unusual except some very small amount of residual coolant (39ppm potassium, 23ppm sodium) which Blackstone flagged. Averaging 27mpg mostly highway, no SES light or codes set. I plan on changing the oil any day now and will send another sample in for a UOA. I'm not particularly attached to this engine, so wouldn't shed too many tears if it blew up one day, but would like to see it run a good while longer to recoup the few hundred bucks I put into it.
Anyone have any similar experiences?
When I went to put the new parts on, I noticed an area of one of the bores that was in pretty rough shape, not sure how I missed it on the initial inspection. It's on the front side (that's hard to see) of the middle cylinder of the front bank. I guess enough coolant was getting in that cylinder that it allowed metal to metal contact, some scraping was going on as there was rough metal and it created a noticeable dish in that area. The picture of the damage is pretty poor, but it was fairly significant.
At that point I contemplated pulling the block and rebuilding it, but I decided to try to use it and if that failed, I was going to replace the whole engine with a 3.5L. I did what nobody would ever suggest-- using fine grit sandpaper to smooth roughness out and restore that side of the bore to a smooth surface. It succeeded except for a small spot of porosity that would have required sanding too deep. I crossed my fingers, buttoned it up and gave it a whirl.
Everything seemed normal, engine ran good but I was still suspicious and proceeded carefully, doing 3 oil changes back to back to get any debris that got in the oil out of there. Well now it's been 3500 miles since then, I've basically been daily driving it to work most days (35 miles each way.) My goal was just to get it in running condition so I could assess the condition of everything else on the car, and continue to restore it. Oddly enough compression is 180-185 PSI in all cylinders, including the suspect one. After 3.5k, oil level has dropped just a tick under full on the dipstick. Kind of baffles me how good it runs, having seen the condition of some of those cylinders. I figured it would be a smoker and/or low compression / lots of blowby. But it seems none of those things. I did a UOA at about 400 miles and it didn't show anything unusual except some very small amount of residual coolant (39ppm potassium, 23ppm sodium) which Blackstone flagged. Averaging 27mpg mostly highway, no SES light or codes set. I plan on changing the oil any day now and will send another sample in for a UOA. I'm not particularly attached to this engine, so wouldn't shed too many tears if it blew up one day, but would like to see it run a good while longer to recoup the few hundred bucks I put into it.
Anyone have any similar experiences?