New York Office
123 Steel Avenue New York, NY 10001 United States
Chicago Office
456 Iron Street Chicago, IL 60607 United States
Los Angeles Office
789 Metal Lane Los Angeles, CA 90015 United States
Say Hello
All Cart
- October 27, 2025
- 0 Comments
We were approached by a company based in Greece reporting the failure of a crankshaft of auxiliary engine on one of their vessels operating in the Gulf.
It was reported that the accident resulted in the failure of the bearing of crankpin no. 1, 3, and 6.
DETAILS OF YANMAR 6N18AL-DV ARE AS FOLLOWING:-
| S. NO | Crankshaft Details | |
| 1 | Engine Make | YANMAR |
| 2 | Engine Model | 6N18AL-DV |
| 3 | Crankpin Diameter Standard | 145 mm |
| 4 | Crankpin Bearing Width | 65 mm |
| 5 | Name of Vessel | MV GULF Traders |
Our team of two technicians boarded the vessel in short notice and requested the chief engineer to open the connecting rod of all six crankpins.
THE CRANKPINS AFTER CLEANING WERE SUBJECT TO DIMENSIONAL INSPECTION AND FOLLOWING DIMENSIONS WERE OBSERVED:-
STANDARD DIMENSION: 145.00 mm
STANDARD /SPECIFIED NO
SIZE OF CR PINS
| A | Aa | C | Cc | B | Bb | Min | Max | Remarks | |
| CR-1 | 144.66 | 144.83 | 144.77 | 144.82 | 144.69 | 144.82 | 144.66 | 144.83 | Ovality – 0.17 MM |
| CR-2 | 144.64 | 144.77 | 144.79 | 144.81 | 144.65 | 144.73 | 144.64 | 144.81 | Ovality – 0.17 MM |
| CR-3 | 144.69 | 144.76 | 144.76 | 144.83 | 144.64 | 144.81 | 144.64 | 144.83 | Ovality – 0.19 MM |
| CR-4 | 144.61 | 144.74 | 144.74 | 144.79 | 144.68 | 144.75 | 144.61 | 144.79 | Ovality – 0.18 MM |
| CR-5 | 144.66 | 144.81 | 144.77 | 144.84 | 144.71 | 144.73 | 144.66 | 144.84 | Ovality – 0.18 MM |
| CR-6 | 144.67 | 144.85 | 144.78 | 144.80 | 144.72 | 144.77 | 144.67 | 144.85 | Ovality – 0.18 MM |
- On going through the above dimensions, it was noticed that all 6 crank pins had ovality between 0.17 mm to 0.18 mm and were considerably down in comparison to the standard diameter of 145.00 mm.
- The hardness of crank pins was checked with a portable hardness tester and was observed within limits.
- The MPI was conducted by our level 2 qualified technician.
- Multiple hairline cracks were observed on crank pin no.4 having a length ranging from 6 mm to 25 mm.
REPAIRS UNDERTAKEN BY RA POWER SOLUTIONS:-
- Considering the ovality , multiple cracks on crank pin nos 4 and rough surface observed of YANMAR 6N18AL-DV.
- All the six crankpins except crankpin no. 4 were undersized to 0.80 mm. The crank pin no. 4 has to be undersized by 1.20 mm due to the presence of cracks.
THE FINAL DIMENSIONS MAINTAINED AFTER GRINDING OF CRANK PINS IS MENTIONED BELOW:-
STANDARD DIMENSION: 145.00 mm
STANDARD /SPECIFIED NO
SIZE OF CR PINS
| A | Aa | C | Cc | B | Bb | Min | Max | Remarks | |
| CR-1 | 144.19 | 144.20 | 144.18 | 144.18 | 144.19 | 144.20 | 144.18 | 144.20 | Ovality – 0.02 MM |
| CR-2 | 144.20 | 144.19 | 144.19 | 144.18 | 144.20 | 144.19 | 144.18 | 144.20 | Ovality – 0.02 MM |
| CR-3 | 144.20 | 144.18 | 144.19 | 144.19 | 144.20 | 144.18 | 144.18 | 144.20 | Ovality – 0.02 MM |
| CR-4 | 143.80 | 143.80 | 143.79 | 143.78 | 143.80 | 143.79 | 143.78 | 143.80 | Ovality – 0.02 MM |
| CR-5 | 144.20 | 144.20 | 144.19 | 144.18 | 144.20 | 144.19 | 144.18 | 144.20 | Ovality – 0.02 MM |
| CR-6 | 144.20 | 144.19 | 144.18 | 144.18 | 144.20 | 144.20 | 144.18 | 144.20 | Ovality – 0.02 MM |
SUPPLY OF UNDERSIZE BEARINGS OF YANMAR 6N18AL-DV BY RA POWER SOLUTIONS:-
- The 0.80 mm and 1.20 mm under-size bearings were supplied by RA Power Solutions in a very short time and engine was put back into operation.
- We maintain a large stock of spare parts of YANMAR 6N18AL-DV or arrange through our principals on short notice.
THE MAIN FEATURES OF REPAIR OF CRANKSHAFT OF YANMAR 6N18AL-DV:-
The crankpin having a diameter of 145 mm and a bearing length of only 65 mm was successfully repaired by us because of the fact, we have a dedicated crankshaft grinding machine which can undertake the grinding of crank pin having a small diameters and bearing widths.
Most of the companies based in Europe and other countries do not have the equipment which can on-site grind the crank pin and main journal diameter having a small diameter and bearing width. They advise clients to open the crankshaft from engine and send it to the workshop for repairs.
We extend our services all over the world at a very low price.
MAK , B&W , Sulzer , Bergen , Detroit Diesel ,Stork Werkspoor , Pielstick , Deutz , Yanmar , MTU , Cummins , Nohab Polar , Caterpillar , Mitsubishi , Yanmar , MAK and many more.
We have been regularly executing the repairs in Armenia, Azerbaijan, Bahrain, Bangladesh, Bhutan, Brunei, Cambodia, China, Cyprus, Georgia, Indonesia, Iran, Iraq, Israel, Japan, Jordan, Kazakhstan, Kuwait, Kyrgyzstan, etc.
For more information on crankshaft repair, Crankshaft Journal Machining of Yanmar 6N18AL-DV, and Yanmar engine repair, contact us at rajshahani@rapowersolutions.com or info@rapowersolutions.com or call us at +91 9582647131 or +91 9810012383.
FAQs:
A: A crankshaft journal is the part of the crankshaft either a main journal or a crankpin (rod journal) that rotates inside engine bearings
A: Journals need machining when they show wear, surface roughness, ovality, cracks, or other damage that exceeds OEM tolerances and could lead to bearing failure or reduced engine performance.
A: Undersizing means grinding the crankpin/journal slightly below its original diameter to remove damaged material, then fitting a matching undersize bearing.
A: Yes, if technicians have the right portable grinding and machining equipment, they can perform on-site crankshaft journal machining. This avoids complete dismantling and saves time and logistics.
A: Proper journal machining restores smooth rotation, correct oil clearance, reduces vibration and noise, prevents bearing seizure, extends engine life, and avoids costly major engine rebuilds.