z1nonlyone
Seaman
- Joined
- Apr 20, 2010
- Messages
- 58
Maybe some of you recognize my user name from earlier posts about buying a boat and finding water in our engine. For the record, its a 1997 Chaparral 1930, with a 5.7EFI and gen 2 alpha drive with 200 hours on the engine. We had some bogging problems and the engine would not tach over 4Gs. The next day I started it and heard a knocking sound. Long story short, today we pulled the engine and disasembled. We were not happy what we found. We thought we had a Connecting rod knock. We looked in the spark plug holes and found one cylinder with verticle lines. With a wire, we were able to feel the scratches! My first question is coincedently (or not) this same cylinder's spark plug was missing the center electrode! It looked like it broke off completely! It must have been sparking as the idle was great and it ran smooth even though the gap was over 1/8"!!! It was in this same cylinder that the verticle scratches were. Soooo,,, we took off the heads and could see stains and corosion spots in all the cylinders. In the bad cylinder, we could see spots on the top of the piston that were rubed off and galled to the cylinder walls! NOt good!
Then we noticed something else. The pistons had a +.030 stamp on them!!!! We were told this boat only had 200 hours on it! Well, maybe the boat did, but it seems to me that the engine had, at least, been bored 30 over, and I wonder if it was the original. I tried to attach some pics but they probably didn't come out too good. So, we pulled all the pistons and rod caps. Then we bore gauged the cylinders. All the cylinders were in dimensional specs but were out of round from .0007-.001. The bad cylinder was .002 out of round. The weird thing was that the bad/galled piston was
.03 undersize even in the areas that were not scratched/galled!! Although the piston had a +.030 stamp, it measured to be stock size and was .03 under the size of the cylinder. On the back of the cylinder heads, was a temperature stamp/sticker that said "void if removed". We are thinking that it is there for the purpose of determining if the engine had been overheated. Do stock engines have this?? It also said Pioneer, or something. Is there a reman called Pioneer? Well, we know now that the "knocking" was probably piston slap as the bearing journals looked ok, EXCEPT that they were rough. Kind of like abrasive was inbedded in the babbit. Although the engine ran ok after we discovered water in the oil, we are thinking that the rust inside the engine circulated and imbedded and caused wear. We can not figure out why one piston is .03 undersize, unless some remanufacturer put a stock size piston in a .030 oversize cylinder!! However the piston said +.03 on the face, but we micked it and it was not .03 oversize!!! All the pistons measured .01 out of round when measured at 90 degrees to the piston pin and then measureing again rotated as far as posible. Are they supposed to measure .01 out of round??? When measured 90 degrees to the wrist pin, they had the proper clearance, barely.
1. Has anyone heard of "Pioneer"
2. HOw much out of round should a piston be?
3. Any connection between the spark plug and the bad cylinder?
4. Any gut feelings if we should "rebuild" the engine or just buy a reman? The crank seemed to be ok, but we have not removed it yet. The cam seemed to look ok although we have not removed it. The whole engine has rust spots scattered thoughout.
5. Any recomendations as to a good source for reman engines? We are thinking at this point that we infact had a reman engine and some "hack" put a stock size piston in a .030 oversize bore even though the piston said it was a+.03 piston. (bad quality control)
Then we noticed something else. The pistons had a +.030 stamp on them!!!! We were told this boat only had 200 hours on it! Well, maybe the boat did, but it seems to me that the engine had, at least, been bored 30 over, and I wonder if it was the original. I tried to attach some pics but they probably didn't come out too good. So, we pulled all the pistons and rod caps. Then we bore gauged the cylinders. All the cylinders were in dimensional specs but were out of round from .0007-.001. The bad cylinder was .002 out of round. The weird thing was that the bad/galled piston was
.03 undersize even in the areas that were not scratched/galled!! Although the piston had a +.030 stamp, it measured to be stock size and was .03 under the size of the cylinder. On the back of the cylinder heads, was a temperature stamp/sticker that said "void if removed". We are thinking that it is there for the purpose of determining if the engine had been overheated. Do stock engines have this?? It also said Pioneer, or something. Is there a reman called Pioneer? Well, we know now that the "knocking" was probably piston slap as the bearing journals looked ok, EXCEPT that they were rough. Kind of like abrasive was inbedded in the babbit. Although the engine ran ok after we discovered water in the oil, we are thinking that the rust inside the engine circulated and imbedded and caused wear. We can not figure out why one piston is .03 undersize, unless some remanufacturer put a stock size piston in a .030 oversize cylinder!! However the piston said +.03 on the face, but we micked it and it was not .03 oversize!!! All the pistons measured .01 out of round when measured at 90 degrees to the piston pin and then measureing again rotated as far as posible. Are they supposed to measure .01 out of round??? When measured 90 degrees to the wrist pin, they had the proper clearance, barely.
1. Has anyone heard of "Pioneer"
2. HOw much out of round should a piston be?
3. Any connection between the spark plug and the bad cylinder?
4. Any gut feelings if we should "rebuild" the engine or just buy a reman? The crank seemed to be ok, but we have not removed it yet. The cam seemed to look ok although we have not removed it. The whole engine has rust spots scattered thoughout.
5. Any recomendations as to a good source for reman engines? We are thinking at this point that we infact had a reman engine and some "hack" put a stock size piston in a .030 oversize bore even though the piston said it was a+.03 piston. (bad quality control)
