Jonathan5
New Member
Hope we find an answer, because are searching for a long time. Maybe someone can help here. Hopefully you are not going through the same experience but this is our story in 2 stages:
Stage 01 (coolant problem)
We experienced engine trouble at sea, where the engine lost power, as if you were driving into a net. We immediately shut off the engine, and upon opening the engine compartment, a cloud of steam greeted us, and we saw coolant in the bilge. According to the dashboard, the temperature did not exceed 90°. The boat was then towed to the harbor, and there we began to search for the cause of the problem.
The following tests were performed in our search for the coolant issue:
- Tested the coolant cap, which was in perfect condition.
- Pressurized the cooling system, and there was no leak; the pressure remained stable.
- Disassembled and checked the water pump, which looked like new.
- Tested the thermostat, and it opened at the correct temperature.
- Conducted a CO2 test above the expansion tank, which came back positive, indicating exhaust gases in the coolant.
- Performed a compression test, which was fine.
- Removed and sent the cylinder head to a specialist, who pressure-tested and resurfaced it, confirming its integrity.
- While the turbo was off, we had it overhauled, and it was in good condition; new seals and bearings were installed.
- Cleaned the coolant cooler.
- Installed a new head gasket and reassembled all the components.
Stage 02 (power loss)
However, we now have a new problem. We cannot get the engine to rev above 2600 rpm. In our quest to find the cause, we performed the following checks:
- Pressurized the exhaust manifold, both on the exhaust and coolant sides, but found nothing.
- Had the injectors retested, and they open at the correct pressure.
- Disconnected the 4 injector lines at the injector and collected diesel during startup; all provided an equal amount of diesel.
- Verified the clearance, camshaft length, valve diameter, intake and exhaust port size, and valve length on the new cylinder head with pre-mounted valves and camshaft. These measurements matched those of the old cylinder head and the specifications in the workshop manual.
- Checked the timing of the timing belt.
- Cleaned and pressure-tested the intercooler.
- Set the wastegate turbo to 1.16 bar, and it opens at the correct pressure.
- Adding extra diesel while sailing made no difference, only more smoke.
- Pressurized the bypass of the small filter located between the intake and the injection pump with an external pump set at 1.3 bar while sailing. We observed that the injection pump is fully compressed by turbo pressure, and the turbo pressure is at the correct level.
- Adjusted the injection pump timing, resulting in more smoke but no increase in RPM.
To be sure there was no blockage in the fuel system, after installing the tested injection pump, we connected both the supply and return lines directly to a jerrycan placed on the injection pump. This resulted in an additional 50 rpm due to the elimination of filter backpressure.
Finally, we inspected the hull and, in particular, the propeller with a camera. There was minimal fouling, and nothing was found in the propeller.
The propeller shaft is easily turned by hand.
During the test run, we observed that the engine revs up to 2600 rpm. Beyond that point, there is still 1/4 of the throttle lever left, but pushing it further does not increase the RPM, and the engine sound remains the same, with a little extra smoke. The engine starts very well, and up to 2600 rpm, it sounds and responds as if nothing is wrong.
Where are the last 1000rpm?
