Blackhawknoe
New Member
- Mar 13, 2022
- 6
- Boat Info
- 2008 47DB
- Engines
- QSC 600
This post is to the person under contract now to buy a rare 47 DB for sale in the Northeast after the original contracted buyer walked away from the deal last week. You must be the person the broker was talking about when he told me no less than 10 times “I’ve got 15 people lined up behind you who will buy this boat for full price in cash”. Nice to meet you. It’s a beautiful boat and I wish you the best. Here’s some humble advice I paid a ton of money to learn. Shame to let it go to waste, so I hope it can help you.
An engine blow-by test is an important measure of the health of a Diesel engine. A failed test is an indication of everything from an extra gallon of oil in the crankcase to a faulty turbocharger, worn valve guides, or cylinder damage via seawater intrusion from a poorly maintained aftercooler or intake vent leak.
An engine that produces blow-by pressures 79% above Cummins’ maximum specification needs to be diagnosed and a root cause identified for a sale to continue. “But it runs great!” and “Your engine surveyor doesn’t know what he’s doing!” doesn’t cut it.
Engine blow-by pressure is measured in inches of water column or inWC. Centimeters of water column is a cool unit of measure too but the meter manufacturer verified the meter was reading in inches after seeing the video. So the second test, performed to prove the engine surveyor wrong was low by a factor of 2.54x and displayed the same failing result once interpreted properly. Strike two.
An old school water manometer removes the new-fangled digital meters from the equation entirely. The third video test performed to prove the engine surveyor wrong showed blow-by to be 20% below the spec for a brand new engine without ever turning a wrench! An Easter miracle for sure. Strike 2.5.
A Cummins tool with a calibrated orifice size of .302 inches is specified to be used for the blow-by test. A larger opening would produce false lower readings. In the fourth and final in-person test performed to prove the engine surveyor wrong it was laughs all around when I pulled a Vernier caliper out of my pocket and measured the tool to be used at .520 inches! Honest mistake, could happen to anyone, right? So we swapped in the proper tool and…unbelievably…the failing results matched the engine surveyor’s exactly. And I’m certain the loose oil cap on the engine was pure oversight. Strike three.
The owner sealed my exit when I was informed I’d have to pay for any subsequent engine work required. That was in addition to the $5-7K of other engine, generator, cutlass bearing, propeller, systems and enclosure work identified in the condition survey I’d already agreed to absorb.
So my friend tread cautiously and choose your advocates well. At least I got them to fix the overheating problem in both engines and repair the fire/smoke damage from the failed electrics in the engine room for you before you came into the mix. Also be advised the air intake seawater separation/drain system is rotted and partially missing on the boat resulting in structural damage from rainwater intrusion and tens of gallons of seawater observed entering the engine room every minute while underway in 3’ to 4’ chop.
Guess it’s still a seller’s market for a little longer. Then maybe this crap will start to subside.
An engine blow-by test is an important measure of the health of a Diesel engine. A failed test is an indication of everything from an extra gallon of oil in the crankcase to a faulty turbocharger, worn valve guides, or cylinder damage via seawater intrusion from a poorly maintained aftercooler or intake vent leak.
An engine that produces blow-by pressures 79% above Cummins’ maximum specification needs to be diagnosed and a root cause identified for a sale to continue. “But it runs great!” and “Your engine surveyor doesn’t know what he’s doing!” doesn’t cut it.
Engine blow-by pressure is measured in inches of water column or inWC. Centimeters of water column is a cool unit of measure too but the meter manufacturer verified the meter was reading in inches after seeing the video. So the second test, performed to prove the engine surveyor wrong was low by a factor of 2.54x and displayed the same failing result once interpreted properly. Strike two.
An old school water manometer removes the new-fangled digital meters from the equation entirely. The third video test performed to prove the engine surveyor wrong showed blow-by to be 20% below the spec for a brand new engine without ever turning a wrench! An Easter miracle for sure. Strike 2.5.
A Cummins tool with a calibrated orifice size of .302 inches is specified to be used for the blow-by test. A larger opening would produce false lower readings. In the fourth and final in-person test performed to prove the engine surveyor wrong it was laughs all around when I pulled a Vernier caliper out of my pocket and measured the tool to be used at .520 inches! Honest mistake, could happen to anyone, right? So we swapped in the proper tool and…unbelievably…the failing results matched the engine surveyor’s exactly. And I’m certain the loose oil cap on the engine was pure oversight. Strike three.
The owner sealed my exit when I was informed I’d have to pay for any subsequent engine work required. That was in addition to the $5-7K of other engine, generator, cutlass bearing, propeller, systems and enclosure work identified in the condition survey I’d already agreed to absorb.
So my friend tread cautiously and choose your advocates well. At least I got them to fix the overheating problem in both engines and repair the fire/smoke damage from the failed electrics in the engine room for you before you came into the mix. Also be advised the air intake seawater separation/drain system is rotted and partially missing on the boat resulting in structural damage from rainwater intrusion and tens of gallons of seawater observed entering the engine room every minute while underway in 3’ to 4’ chop.
Guess it’s still a seller’s market for a little longer. Then maybe this crap will start to subside.
