Tensioner Pulley Seized

[stow it]

I had the unfortunate experience of the tensioner pulley on my new engine seizing, which threw the belt and therefore the raw water pump stopped. It doesn't take long for the coolant temp to sky rocket but fortunately I was standing at the helm and saw the temp spike. Yes I had an alarm but I didn't hear it as my pilot house is pretty noisy at full speed. My boat is primarily used for fishing with cruising in its future.

I posted a similar thread on another site and was surprised at the number of people that also experienced the same event. Probably six different people and engine manufacturers. Unfortunately one person fried his engine.

I was surprised that this was such a common problem. My engine only had about 600 hours.

While repairing the engine we learned that the engine computer could be set up to derate, think safe or guardian mode, so that if an overheat temp was reached then we could tell the engine to derate or slow down. On my boat I cruise at 2000 rpm and when we derate the engine slows to 1600 rpm so that you'll definitely know something is wrong even if you don't hear or see the alarm.

That feature worked this year when the impeller failed, and the coolant temp started to rise. We set the derate limit at 199 degrees. As soon as the boat slowed down, I knew I had a problem.

Unfortunately, neither my manufacturer nor the tech that commissioned the engine had either informed me of the derate feature or set it up.

My engine is a Scania, and my boat is located in the NE of US. Why a Scania? It was either that or a Cummins and I thought at the time that the Scania would add to the resale value. It's an engine used in a lot of commercial boats. Plus, when I used to travel overseas, I would see Scania all over the place in buses and trucks.

How many other owners have had failure of the tensioner pulley?

What other engines have computers that have the derate feature?

 

[stow it]

sorry, this should have made it into the engine room forum

 

[mysweetLord]

suggest looking at the condition of the rubber exhaust hose on the exhaust elbow.
that, in case your engine is fitted with water injected exhaust. most engines with raw water pumps are heat exchange cooled and seawater injected exhaust system.
the rubber exhaust hose is sensitive to running with no water

 

[Comodave]

I like the exhaust temp alarm like Borel Manufacturing. It will alarm almost instantly when you loose cooling water flow. Very simple install and I can’t imagine not hearing the alarm when it goes off.

 

[twistedtree]

What model Scania and what boat? I have a DI13, and always interested to find other owners. Sounds like it’s time to put a tensioner in my spares kit, and perhaps an idler pulley too.

 

[utclmjmper]

Many times it's just easier to press out the center bearing and replace it,, rather than replacing the tensioner..>>>Dan

 

[Action]

In the auto world with electronic fuel injection and computers there is a Limp Home Mode. Usually just called the Limp Mode.

Triggered by either high engine coolant temp or low to no oil pressure.
The computer typically stops ignition on half of the cylinders on a rotating basis. And keeps the fuel injection working to add some cooling to the combustion chambers.

Total RPM is limited to about 1000 to 1500 rpm.

It does help in protecting the engine.

 

[Flatswing]

I like the exhaust temp alarm like Borel Manufacturing. It will alarm almost instantly when you loose cooling water flow. Very simple install and I can’t imagine not hearing the alarm when it goes off.

Borel exhaust gas temp alarms are excellent - mine works great on the rare occasion I have a sea water issue. Unfortunately in the case described here with the serpentine belt failure, the coolant pump is no longer driven but the mechanical (not belt driven) sea water pump is pumping happily and cooling the exhaust so no rubber issues downstream of the mixing elbow. The Borel will not alarm in this scenario as I can confirm from experience.

 

[twistedtree]

I think the policy for most marine engines is to disable limp mode. The general thinking seems to be that it's better to alarm and let the operator decide whether conditions demand sacrifice of the engine for safety of crew. Envision crossing a bar in bad weather, or some other hazardous condition where loss of engine power would be disastrous. In such a situation, the best choice is to screw the engine and get to safety.

 

[stow it]

I have the same engine, DI13, in a Flowers 38, which is a downeast design. Have you found any broken screws in the bilge? Last year and this season I found a sheared bolt head in the bilge. Both bolts attached the after cooler to the engine; one was forward the second one aft.
Are you using the derate and shut down features for high temp? We decided not to use the shut down for high high temps since it can be hard to recover from that and reset the computer.
My engine came with Glendenning controls. Do you have those as well? Anyone with Glendenning controls should have a termination resistor from Glendenning in their emergency spares. My cockpit control head shorted due to water intrusion and incapacitated the boat. You cannot fix the control head but you can get home by replacing the control head with the termination resistor. Glendenning also makes a 'condom' for the control heads, which I use all the time. Most water intrusion evidently occurs when rinsing the boat.

 

[stow it]

p.s. the Scania will also derate for other reasons. I had been ignoring a voltage alarm in my first season until the computer went into derate mode. Its a great feature since it protects the engine but it took some investigating to figure out what the problem was.

 

[stow it]

My boat has a substantial wash down pump with a 1-1/2" hose; I have to check the flow rate but it pumps a ton of water. I have been thinking of using it to get me home the next time the impeller fails. I was looking for a way to connect it to the raw water system and found that Groco makes two types of service adaptors that were designed to be used as emergency bilge pumps and engine flushing. (https://www.groco.net/products/raw-water-strainers/accessories/ssc-series-service-adaptor)
One is meant to be installed after the sea cock and the other after the sea strainer. The design is a tee with a quick release plug. Anyone have this onboard or used it?

 

[DennisB1]

I have the Groco tee fitting on both my main engines. I use it two ways: one to back flush the Groco sea strainer (engine not running) and two, fresh water flushing the engine using water from shoreside hose (engine running — idle speed with thru hull closed. Works great for those purposes.

 

[twistedtree]

I have the same engine, DI13, in a Flowers 38, which is a downeast design. Have you found any broken screws in the bilge? Last year and this season I found a sheared bolt head in the bilge. Both bolts attached the after cooler to the engine; one was forward the second one aft.
Are you using the derate and shut down features for high temp? We decided not to use the shut down for high high temps since it can be hard to recover from that and reset the computer.
My engine came with Glendenning controls. Do you have those as well? Anyone with Glendenning controls should have a termination resistor from Glendenning in their emergency spares. My cockpit control head shorted due to water intrusion and incapacitated the boat. You cannot fix the control head but you can get home by replacing the control head with the termination resistor. Glendenning also makes a 'condom' for the control heads, which I use all the time. Most water intrusion evidently occurs when rinsing the boat.

No broken bolts so far, but I'll keep a look out. I guess I really don't know how the derating is set up on mine. I never thought to ask. I know a good tech in my area and will ask him to check with his laptop next time I have him on board. I should know the answer but don't. My gut, however, says not to derate, just alarm. My engine is also only 400hp, continuous duty with max rpm 1800. I typically run 1300-1400 rpm, so arguably I'm derated all the time I know the DI13 is available well into the 700hp range.

 

[twistedtree]

Oh, and my controls are twin disc. A buddy has Glendinning on his DI13, so I'll let him know about the terminator. Does it plug into the cable at the failed control and just bypass/block out that one station, then you use another station to run the boat?