imported_TheMan
Petty Officer 1st Class
- Joined
- Oct 19, 2006
- Messages
- 224
Well finally got a chance to run the new engine this weekend. All in all it ran quite well and is a significant upgrade in terms of acceleration and handling (3.0L -> 4.3L mercruiser).
In total, I probably ran the engine this weekend for 3.5 hrs. It is running a bit warm at idle, so I have to check my impeller, lines, and t-stat housing for any blockage..
As for the real issue, when I was calling it quits for the day, I had to idle back down my channel. It is a fairly long haul and the engine was getting pretty dang warm (200+). I had the engine cover pulled to perhaps give it a little more breathing room and noticed steam coming out of the flame arrestor. I disconnected the valve cover ventilation tubes and found the steam coming from the valve covers. I have not had a chance to check for milky oil in the valve covers, but after 1 hr of straight running (I stopped the engine) I had checked the oil on the dipstick and there was no milk. There was also no steam coming from the valve covers that I could see. It then sat for about an hour before I restarted it.
After doing a bit of searching on here, it appears that people believe the manifolds/risers, or their gaskets, are a likely culprit for this scenario. For this to happen, it would mean water leaked from the exhaust manifolds, past the valves, down the cylinder walls into the crankcase, correct? Which I guess is a totally plausible scenario seeing how I did not notice any steam until I was idling home after having it sit for an hour. I was running near wide open for a while before idling into the channel, so the engine oil was probably pretty warm to start with. The hot oil could be evaporating water that leaked in when I shut it down..
What other possibilities (if any) are there for this scenario? Compression numbers are all good, so I don't expect a blown head gasket. If the water jacket were internally cracked, or other cooling passages were bad I would have expected milky oil and lots of it, right? (e.g. water would be getting forced into the crankcase, rather than leaking in?) It was also a bit cold out ~55, so I suppose there could be some condensate, but I think this was a bit excessive...
My short order plan is to run the engine, drain the oil, check the valve covers, remove the manifolds and risers, test them, and inspect and replace as necessary... Since it is about quitting time for winter anyway, I will probably replace the manifolds regardless if i can get the cash together.
Any other thoughts?
Thanks,
SB
In total, I probably ran the engine this weekend for 3.5 hrs. It is running a bit warm at idle, so I have to check my impeller, lines, and t-stat housing for any blockage..
As for the real issue, when I was calling it quits for the day, I had to idle back down my channel. It is a fairly long haul and the engine was getting pretty dang warm (200+). I had the engine cover pulled to perhaps give it a little more breathing room and noticed steam coming out of the flame arrestor. I disconnected the valve cover ventilation tubes and found the steam coming from the valve covers. I have not had a chance to check for milky oil in the valve covers, but after 1 hr of straight running (I stopped the engine) I had checked the oil on the dipstick and there was no milk. There was also no steam coming from the valve covers that I could see. It then sat for about an hour before I restarted it.
After doing a bit of searching on here, it appears that people believe the manifolds/risers, or their gaskets, are a likely culprit for this scenario. For this to happen, it would mean water leaked from the exhaust manifolds, past the valves, down the cylinder walls into the crankcase, correct? Which I guess is a totally plausible scenario seeing how I did not notice any steam until I was idling home after having it sit for an hour. I was running near wide open for a while before idling into the channel, so the engine oil was probably pretty warm to start with. The hot oil could be evaporating water that leaked in when I shut it down..
What other possibilities (if any) are there for this scenario? Compression numbers are all good, so I don't expect a blown head gasket. If the water jacket were internally cracked, or other cooling passages were bad I would have expected milky oil and lots of it, right? (e.g. water would be getting forced into the crankcase, rather than leaking in?) It was also a bit cold out ~55, so I suppose there could be some condensate, but I think this was a bit excessive...
My short order plan is to run the engine, drain the oil, check the valve covers, remove the manifolds and risers, test them, and inspect and replace as necessary... Since it is about quitting time for winter anyway, I will probably replace the manifolds regardless if i can get the cash together.
Any other thoughts?
Thanks,
SB
