wood_n_wind
New member
"Apologies for the lengthy pos
"Apologies for the lengthy post but I wanted to include the engine history for context (and for comic relief). Feel free to skip to my questions at the bottom of this post.
So I bought a beautiful 36' LOA Wooden Cutter built in Chester Nova Scotia in 1957. This boat has quite a well documented history and has been featured in a number of publications. The hull, sails, and rigging are in excellent shape, however, the electronics are ancient and she needs lots of elbow grease to restore her brightwork. She would be ready to sail today if it wasn't for the engine.
The condensed engine history is:
Engine is a Volvo MD11C diesel with a freshwater cooling system. It was bought new in 1976 and rebuilt in 1992. Prior to taking ownership we noticed bubbles in the coolant and a problem with overheating after only 10 minutes of use. To us this indicated to us a leaky head gasket. We tried 20 different certified Volvo Penta mechanics but none were available and we waited two months to get a mechanic to come to the boat. It seems like most diesel mechanics have moved to Alberta to work on the oil sands project and the remainder are overwhelmed with the workload. Anyway, during the wait for the mechanic we replaced the impellers, flushed the heat exchanger, changed the fuel and the oil, replaced oil and fuel filters, and did whatever we could to get her ready.
The mechanic finally arrived and after removing the head he confirmed our suspicion of a leaky head gasket. He also found a stripped rocker arm/valve cover hold down stud and a broken rocker arm oil supply tube. Through a series of minor miracles we found the replacement parts but then it took another 6 weeks to get the mechanic back to the boat to reassemble. He reassembled and we fired her up. After running it in forward gear for an hour at the dock we heard a rattling and found that the new rocker arm/valve cover stud ($57....ouch) was sheared off between the rocker arm and the head. We worked many hours to try and remove the bolt with an extractor and finally had to drill it out, re tap the hole, and insert a heli-coil. It is worth noting here that the three other bolts and studs that go through the rocker arm (two per arm for a total of 4) had all previously received heli-coils so stripping/shearing of those bolts was a common problem on this engine. After we installed a heli-coil on the latest bolt to shear off we got the engine working again and ran it in forward gear for 45 minutes with no problem. It ran beautifully!
So, yesterday we went for our inaugural sail and made it 10 miles down the Fraser river and 1 mile out into the sailing grounds when the engine started to rattle and we found that another rocker arm hold down bolt had sheared off. We removed the valve cover, rocker arm, and push rods to decommission one cylinder but with only 1 cylinder and no wind there was no way to get the boat back upriver against the current. We had to get a 3-hour tow back to our slip.
It is also worth noting that despite the age of the engine and our ongoing problem with the rocker arm hold down bolts and studs, this engine has very low hours which was confirmed by the mechanic. If possible we would like to save the engine, but we are coming to the conclusion that we need a new engine.
All of the above leads up to my question, has anybody had this problem with rocker arm bolts shearing off? Are there any suggestions as to what else might be going on in the engine to cause 3/8 inch bolts to shear off? Any suggestions would be appreciated.
Rob"
"Apologies for the lengthy post but I wanted to include the engine history for context (and for comic relief). Feel free to skip to my questions at the bottom of this post.
So I bought a beautiful 36' LOA Wooden Cutter built in Chester Nova Scotia in 1957. This boat has quite a well documented history and has been featured in a number of publications. The hull, sails, and rigging are in excellent shape, however, the electronics are ancient and she needs lots of elbow grease to restore her brightwork. She would be ready to sail today if it wasn't for the engine.
The condensed engine history is:
Engine is a Volvo MD11C diesel with a freshwater cooling system. It was bought new in 1976 and rebuilt in 1992. Prior to taking ownership we noticed bubbles in the coolant and a problem with overheating after only 10 minutes of use. To us this indicated to us a leaky head gasket. We tried 20 different certified Volvo Penta mechanics but none were available and we waited two months to get a mechanic to come to the boat. It seems like most diesel mechanics have moved to Alberta to work on the oil sands project and the remainder are overwhelmed with the workload. Anyway, during the wait for the mechanic we replaced the impellers, flushed the heat exchanger, changed the fuel and the oil, replaced oil and fuel filters, and did whatever we could to get her ready.
The mechanic finally arrived and after removing the head he confirmed our suspicion of a leaky head gasket. He also found a stripped rocker arm/valve cover hold down stud and a broken rocker arm oil supply tube. Through a series of minor miracles we found the replacement parts but then it took another 6 weeks to get the mechanic back to the boat to reassemble. He reassembled and we fired her up. After running it in forward gear for an hour at the dock we heard a rattling and found that the new rocker arm/valve cover stud ($57....ouch) was sheared off between the rocker arm and the head. We worked many hours to try and remove the bolt with an extractor and finally had to drill it out, re tap the hole, and insert a heli-coil. It is worth noting here that the three other bolts and studs that go through the rocker arm (two per arm for a total of 4) had all previously received heli-coils so stripping/shearing of those bolts was a common problem on this engine. After we installed a heli-coil on the latest bolt to shear off we got the engine working again and ran it in forward gear for 45 minutes with no problem. It ran beautifully!
So, yesterday we went for our inaugural sail and made it 10 miles down the Fraser river and 1 mile out into the sailing grounds when the engine started to rattle and we found that another rocker arm hold down bolt had sheared off. We removed the valve cover, rocker arm, and push rods to decommission one cylinder but with only 1 cylinder and no wind there was no way to get the boat back upriver against the current. We had to get a 3-hour tow back to our slip.
It is also worth noting that despite the age of the engine and our ongoing problem with the rocker arm hold down bolts and studs, this engine has very low hours which was confirmed by the mechanic. If possible we would like to save the engine, but we are coming to the conclusion that we need a new engine.
All of the above leads up to my question, has anybody had this problem with rocker arm bolts shearing off? Are there any suggestions as to what else might be going on in the engine to cause 3/8 inch bolts to shear off? Any suggestions would be appreciated.
Rob"