Marcoboater
Cadet
- Joined
- Apr 28, 2008
- Messages
- 9
I am a new boater. I purchased my first boat in January and my family of 5 have been enjoying it tremendously since. Unfortunately it has become apparent to me that the previous owner PROBABLY switched out the hour meter prior to putting the boat on the market in an attempt to hide the true number of hours the boat has been used. I did have the boat surveyed but not the motor because at the time I believed there were only 130 hours on them therefore did not think it was necessary. My mistake. I did take the boat to a local marina in order to see if I could obtain the true amount of usage by having the ECU read by a scanner. However this was not possible because my engine is a model year 2000 which is the last year that Mercury equipped them with the "blinky" type of scan info as opposed to the full computer readouts that are available on later models. The engine seems to run fine and I have not had any issues with the exception of an overheating problem that happened when my seawater pump impeller completely disentegrated while a few miles offshore. Thank god the alarm worked otherwise being the "newbie" that I am, I wouldn't have had a clue. I don't think any damage was done but I can't be sure. I replaced the entire pump myself as the housing on the failed one was so corroded as to not be serviceable. Also the manifold and risers were shot which was picked up by the surveyor prior to purchase. These were replaced by previous owner as a condition of sale. The engine is a model year 2000 Mercruiser 7.4 Liter with EFI. It seems to run well. Starts every time. Burns very little if any oil. The level hasn't changed in approx. 30 hours of use. OK that's the history.
My question is about compression test results. Because I am suspect about the true number of hours the boat has been used I decided to do a compression test yesterday. The results were 6 cylinders came in at 160 psi with one at 175 and another at 152. The engine was warm the throttle was WOT and I had the kill switch turned off but did not ground any other electrical connections. Do these numbers sound OK? What might cause the descrepency between the two odd ones? There was a thin brown oily residue on a few of the plug threads especially on the cylinder with the high compression reading. Could this be unburnt fuel entering the cylinder do to WOT with no combustion during test? The cylinder with the low compression reading looked as if was burning extra hot. The plug wire was degraded due to heat and the plug insulator looked like it was cooked close to where it met the block. I havn't pulled the heads to inspect the valves (big job for me). Do you think I might have a problem here?
Any information you might be able to provide me would be greatly appreciated. I'm not an expert on these matters and don't want to cause any further damage if something is wrong. I realize without seeing the boat diagnosis is difficult but once again any and all advice would be welcome.
Should I just shut up and enjoy my boat?
My question is about compression test results. Because I am suspect about the true number of hours the boat has been used I decided to do a compression test yesterday. The results were 6 cylinders came in at 160 psi with one at 175 and another at 152. The engine was warm the throttle was WOT and I had the kill switch turned off but did not ground any other electrical connections. Do these numbers sound OK? What might cause the descrepency between the two odd ones? There was a thin brown oily residue on a few of the plug threads especially on the cylinder with the high compression reading. Could this be unburnt fuel entering the cylinder do to WOT with no combustion during test? The cylinder with the low compression reading looked as if was burning extra hot. The plug wire was degraded due to heat and the plug insulator looked like it was cooked close to where it met the block. I havn't pulled the heads to inspect the valves (big job for me). Do you think I might have a problem here?
Any information you might be able to provide me would be greatly appreciated. I'm not an expert on these matters and don't want to cause any further damage if something is wrong. I realize without seeing the boat diagnosis is difficult but once again any and all advice would be welcome.
Should I just shut up and enjoy my boat?