Reel Precision
Seaman
- Joined
- Feb 4, 2004
- Messages
- 51
Re: Merc 150 V-6 idle problems
It is very hard to diagnose on 6 cyl. But it sounds to me like the crank seals are leaking between cylinders. This will cause it to run lean on those two cylinders and idle like athree legged dog. As far as the reeds I dont think that is your problem. If the crank seals are leaking you will loose crank case pressure. Esssentialy you are just pushing crank case pressure between the cylinders instead of positive pressure pushing the fuel out of the crank case into the cylinder. On this model with three carbs it is hard to diagnose. On a motor with a carb per cylinder it is much easier to find this problem. Also if you see any sputer out of the reeds this can also be caused by crank case leak. Think about it. If the reeds are partialy wore and need slightly more pressure to seal them completly plus you have next to 0 crank case pressure because it all went to the adjoining cylinder then there is not enough crank case pressure to close the reed completly. This would normally not be the case. One easy way to see if the fuel is spitting back through reeds at all is to place a timing light on that cylinder and shine it right in the carb throte. It will cause a strobe light effect and catch that fuel right in mid air coming out. Bad thing is this would mean a complete teardown to diagnose. Hope ya solve it without that happening. Good luck
It is very hard to diagnose on 6 cyl. But it sounds to me like the crank seals are leaking between cylinders. This will cause it to run lean on those two cylinders and idle like athree legged dog. As far as the reeds I dont think that is your problem. If the crank seals are leaking you will loose crank case pressure. Esssentialy you are just pushing crank case pressure between the cylinders instead of positive pressure pushing the fuel out of the crank case into the cylinder. On this model with three carbs it is hard to diagnose. On a motor with a carb per cylinder it is much easier to find this problem. Also if you see any sputer out of the reeds this can also be caused by crank case leak. Think about it. If the reeds are partialy wore and need slightly more pressure to seal them completly plus you have next to 0 crank case pressure because it all went to the adjoining cylinder then there is not enough crank case pressure to close the reed completly. This would normally not be the case. One easy way to see if the fuel is spitting back through reeds at all is to place a timing light on that cylinder and shine it right in the carb throte. It will cause a strobe light effect and catch that fuel right in mid air coming out. Bad thing is this would mean a complete teardown to diagnose. Hope ya solve it without that happening. Good luck
