View Full Version : Volvo MD11C Rocker Arm Bolts

10-09-2007, 05:33 PM
"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.

Dick V
10-10-2007, 10:15 AM
"Rob, I have been doing 11's for as long as they have been produced and have never had studs or bolts shearing off at head. Have had them break from over tighting cover. Is valve clearance correct? Is decompression rod touching valve rockers? Something is not right up top."

10-15-2007, 12:42 PM
Thanks Dick.

Valve clearance was checked by the mechanic and checked out.

10-23-2007, 02:04 PM
I have never seen this either. Check again over torque and valve lash. Also check with Stem to Stern in Vancouver or Sidney Propeller in Sidney BC. These guys have been working on these engines for a long time. They stopped making this engine in 1977. It may be time for a repower

03-05-2008, 04:17 PM
If someone has a MD11C water cooled exhaust manifold I would be interested in it. I currently have dry exhaust.

09-09-2008, 01:23 PM
"Rob, I have had a boat with an MD 11 C since 1984 and once (2003) experienced this problem with one rocker arm bolt: the one also bolting the valve cover (the other kept the roker in place with no problem). I only found out because all of a sudden the bolt keeping the alternator in place started shearing and it did so three times. I then removed the valve covers looking for causes of abnormal vibration and found the sheared bolt. I replaced the bolt, checked the tightening of the head bolts, checked the valve clearances and never had a problem ever since. My explanation was that the bolt was overtightened to start with. You must tighten with a torque wrench to the Volvo spec. given in the workshop manual. I can send you a copy if you give me your email."

09-09-2008, 01:29 PM
"Dear Michael, it is very easy (and inexpensive) to make a water cooled collet with two pieces of copper boiler pipe. Make a thick (5mm) copper flange wich couples to the manifold and to this solder a length of 40 mm dia. copper pipe. On the outside solder a 15 mm. dia copper pipe with two 90 standar copper corners soldered to it. One of the corners is soldered to a matching hole in the far end of the 40 mm. pipe, the other is left free for cooling water intake. Try it!"

08-21-2009, 10:59 AM
i have a 9mt sailing yachtw with a 23 hp volvo md11c with freshwater cooling. can anyone tell me what is a reasonable fuel consumption per hr on this engine. Thanks. pedro

08-21-2009, 01:28 PM
I used to get about 1 g/hr at 2000 rpm and now I get about 1/2 g/hr at 1500 rpm

02-12-2010, 05:57 AM
"Hi to everyone,

well, we have a Draco 33 sailboat, built on 1979 with a Volvo Penta MD 11C. Despite all our efforts to fix it, the engine is constantly overwarmed after some minutes of operation at 1200 rpm. Does anyone know any specific reason or faced any similar experience? We have already changed impeller and used an acid salt solvent in the cooling system.
Any advice may help us is very welcomed!"

12-17-2010, 10:38 AM
Hello from sunny Brazil!

I believe every owner of a raw water colled MD11C has already experienced an overheating problem.
In my case, I was living with a hot engine for the last couple of years. I then decided to face the problem by doing as bellow:
- cleaning (with wire) of the reverse gear cooling chamber (there was lots of debris and salt buil-up) by removing water in and outlet elbows, drain and vent plugs for better access;
- removal of the exhaust manifold, cleaning with acid solution;
- removal of the thermostat housing and testing of thermostat.
Since the thermostat has a very important role in this engine, I decided to get it off scene, by removing its coil and allowing the flow of water from cold start condition. Some friends have drilled holes in the thermostat flange, so that in case of failure of thermostat, cooling (in addition to the thermostat by-pass) is provided.
The result is that my engine is always working below the middle of the temperature range, leaving some room to compensate for hull barnacle growth.

07-30-2013, 03:14 PM
Can any one HELP. I need a head for a Volvo md11c. Email [email protected]