Penta D6 White smoke and coolant loss

[Andy_V458]

Hi, looking for any experience and pointers to help troubleshoot, as my local Volvo mechanic is at least 2 weeks out to get to the boat.
Sunday, my 2008 Four Winns V458 Starboard Penta D6-435 with 800 hours started with grey sweet smelling exhaust, indicating coolant in the exhaust or cylinders. Running pressures and temps all same as port engine. Coolant loss was approx 20 fl oz. Boat ran absolutely fine, no misfiring or loss of power at 2900 rpm and 25-26 knots. No visible evidence of coolant or water in the oil. I believe the order of minimal issue to max to be:
- possible introduction of coolant to exhaust, via heat exchanger/pipes and maybe a seal or gasket gone there:
- possible introduction of coolant via turbo
- compromised gasket/cracked head.
Any help with how to quickly check and confirm /discount possible issues, so that I can at least line up parts and repair for the mechanic when he can get to me is much appreciated. and any experiences of same / similar, if it was minor/major issue you had welcome.
Thanks

 

[alldodge]

To figure out what is happening is same for gas motor, need to do a compression test. While it might be the exhaust, but I would think more a head gasket. At any rate doing a compression test will verify.

Injectors will need to be pulled

 

[Andy_V458]

To figure out what is happening is same for gas motor, need to do a compression test. While it might be the exhaust, but I would think more a head gasket. At any rate doing a compression test will verify.

Injectors will need to be pulled

Thanks - but wouldn't a head gasket have affected the firing (misfiring), power, and engine temps / oil pressures as well? And not caused a leak into the bilge external to the engine, and caused clear water contamination of the oil with emulsification of the engine oil? none of which were present, which is why I was thinking heat exchanger, and possible visual inspection of that first.

 

[alldodge]

Depends on how bad the leak is.
Not seeing how the HX or Turbo would induce AF in the exhaust. The HX has raw water on one side and AF on the other. If HX leaked then AF would leak into raw water side because pressure would be greater. Turbo has exhaust but only thing to leak into is oil

My first thought before looking up the motor was wondered if it had cylinder liners, but this motor does not

It could very well be the exhaust manifold and could drain it, plug it up and pressurize to 20 or 30 psi

 

[Andy_V458]

Depends on how bad the leak is.
Not seeing how the HX or Turbo would induce AF in the exhaust. The HX has raw water on one side and AF on the other. If HX leaked then AF would leak into raw water side because pressure would be greater. Turbo has exhaust but only thing to leak into is oil

My first thought before looking up the motor was wondered if it had cylinder liners, but this motor does not

It could very well be the exhaust manifold and could drain it, plug it up and pressurize to 20 or 30 psi

Thanks for the response. The heat exchanger seawater then pumps into the exhausts to damp the diesel exhaust, which is option 1 for coolant hitting hot exhaust manifold and ‘maybe’ steaming, but not sure.

I said turbo when I should have said intercooler, which could put coolant into the air and therefore the cylinder I believe?
Then there is the cylinder head and gasket. I think I need to do some visuals, then maybe drain system and remove heat exchanger and have that pressure tested, same with intercooler, and then finally look to remove/replace cylinder head and gasket (providing head is not cracked or warped).
Some I can do myself, but the pressure testing and repairs is rather leave to the pros. Fingers crossed it’s easy/cheap/quick option !

 

[alldodge]

Pressure testing is simple, the issue is just drain all the AF. Could actually drain everything, then attach a automotive radiator pressure cap tester on the HX and pump it up to see if there was a leak