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lfeather's avatar
lfeather
Explorer
Sep 06, 2014

Onan code 33

Onan Code 33

Just thought I'd pass this on. My Onan HDKAK, SPEC H started shutting down again, and this time I was getting a codes 33, overheat. Turns out is was the overheat sensor. I tried replacing it, was able to remove part of it, but the bottom probe half of the sensor broke off and stayed inside the shroud/flange. Okay, no problem, I'll just change the shroud too. While removing I realized that the whole front of the engine gearbox had to be removed to get the last shroud bolt off. Way to go Kabota! FIREUP on rv.net said he was able to remove the last shroud bolt by removing the engine head. But his shroud broke, so he had no other option, but to remove it. Since my Onan is side mounted, I Decided to take it in and let Onan do it after we got back to FL. During discussion with brother-in-law, he suggested to try an EZ-out. Wala! It came right out! Runs good now, plus no more white smoke and hard starts during cooler weather. Apparently that sensor also tells the ECM the temperature so it knows how long to heat the glow plugs. Mine wasn't heating the glow plugs. Before, As soon as I hit the start button the starter engaged without heating the glow plugs which made it really hard to start in cooler weather with lots of white smoke (unburned diesel). Now when I hit the starter button, there's a delay with an audible clicking sound while the glow plugs heat up, then the starter engages. This hard-start issue started about 100 hours ago, and progressively got worse. So, if you're getting hard starts with white smoke, its a telltale sign that your overheat sensor is going bad and you will eventually have problems keeping it running in warm/hot weather. Happy trails...

Larry, 03 Allure, 30856.

2 Replies

  • My shop works on these gens. More often than not the tip or probe end of the temp sensor breaks off in water housing. You are right, must pull cyl head or timing cover to remove housing. But we came up with easy fix. Remove thermostat cover and thermostat, place a paper towel or rag in the cavity where t-stat was located, then take correct size punch and drive the broken piece on into water housing. The rag will catch it . Take a small round file or drill bit and clean corrosion from hole where new sensor will go, replace sensor, t-stat, refill with 50/50 coolant. anyone with Onan quiet diesel probably should carry a spare sensor especially if you rely on gen a lot.