SnakeEye
05-27-2008, 12:47 AM
First, I might introduce myself. I'm a marine mechanic working in Norway, mostly with big, boring, diesel powered stuff, but I do get the odd hot rig as well. I've been searching for a place to discuss my profession for a while now, and it seems I have finally found it.
Now, the problem: An OptiMax 135 on an Uttern T-55 runs rough after extensive (10-30min) full load operation. It cuts rapidly and aggressively, much like it was hitting a rev limiter at 4.700 - 5.000 rpm. If I back off the throttle for a while, it runs nicely again. I've run it with the laptop on, and all values seemed normal while it was cutting out, except the low temperature, and I was unable to generate any fault codes. I verified fuel / air pressures under load, getting normal results. Then one of the guys from the shop side tested it much more aggressively, bouncing it off the "limiter" for a half-hour plus, generating an "EST 4 short" fault. Thus, I switch out EST 4 plus coil driver 3-4, to no avail. Then I figure to myself that it might be a bad output stage, so switch out the ECU as well. Luckily I have a 150 sitting alongside the 135 so I can switch components.
At this point I give up and call the Brunswick support line. They don't have a clue, and keep making idiot suggestions, such as switching out a bunch of sensors that I'd already verified were working just fine. Now they've decided that the low running temperature (25-30 celcius), which is entirely normal for the small OptiMax six, is the cause of the problem. They don't have a clue why, though (And did I mention that this applies to A LOT of OptiMaxes?!). It'll regulate beautifully to 57 celcius at idle, then drop way down as soon as I put 2k rpm on it. Thus I verified both thermostats OK and fired it cold with the thermostat hoses off. It turns out the thermostat springs are too weak, so they blow off their seats while cold. That seemed like the logical answer, but anyhow...
How do I fix this? I'm lost, my boss is lost, the Brunswick support people are lost, and the customer's getting really unhappy.
~Snake
Now, the problem: An OptiMax 135 on an Uttern T-55 runs rough after extensive (10-30min) full load operation. It cuts rapidly and aggressively, much like it was hitting a rev limiter at 4.700 - 5.000 rpm. If I back off the throttle for a while, it runs nicely again. I've run it with the laptop on, and all values seemed normal while it was cutting out, except the low temperature, and I was unable to generate any fault codes. I verified fuel / air pressures under load, getting normal results. Then one of the guys from the shop side tested it much more aggressively, bouncing it off the "limiter" for a half-hour plus, generating an "EST 4 short" fault. Thus, I switch out EST 4 plus coil driver 3-4, to no avail. Then I figure to myself that it might be a bad output stage, so switch out the ECU as well. Luckily I have a 150 sitting alongside the 135 so I can switch components.
At this point I give up and call the Brunswick support line. They don't have a clue, and keep making idiot suggestions, such as switching out a bunch of sensors that I'd already verified were working just fine. Now they've decided that the low running temperature (25-30 celcius), which is entirely normal for the small OptiMax six, is the cause of the problem. They don't have a clue why, though (And did I mention that this applies to A LOT of OptiMaxes?!). It'll regulate beautifully to 57 celcius at idle, then drop way down as soon as I put 2k rpm on it. Thus I verified both thermostats OK and fired it cold with the thermostat hoses off. It turns out the thermostat springs are too weak, so they blow off their seats while cold. That seemed like the logical answer, but anyhow...
How do I fix this? I'm lost, my boss is lost, the Brunswick support people are lost, and the customer's getting really unhappy.
~Snake