Help! I have always had issues with cooling (CHT only, never oil). But it seems like it is worse now than ever. Once I take off and start flying I can manage it, but it is a constant battle. It makes no sense to me that the engine CHT is getting out of hand while idling on the ground. I have the new style radiator cap (1.2 bar) that is now at least 200 hours old. I run DexCool 50/50 mix. I have always had to watch temps on the ground but it is getting out of hand. Once I am flying and I have some air flowing over the engine it is ok. We have had cooler temps lately and nothing is adding up.

Also worth noting, there is no kind of pressure cowling or "ducting" around the heads to direct air over the cyls. I am running a 2 blade propeller.

My first thought is the water pump, but the engine only has 366 hours on it.

Thoughts? Thanks in advance.
  • Re: Engine CHT Climbs While On Ground at Idle

    by » 6 years ago

    After doing some more research, I figured out that the previous owner installed a Thermo-bob. I noticed the in-line "thingy" a while back, but never knew what it was. After looking around here, I found a thread on the Thermo Bob. Could this have failed, and is now causing excessively high temps while on the ground?

  • Re: Engine CHT Climbs While On Ground at Idle

    by » 6 years ago

    Hi Evan,
    What kind of temps are we talking about and where do you live or what was the OAT?
    One way to check is to remove it and fly once. On some plane designs they later find they need to add an air scoop or ducting to help cooling, but I wouldn't go there yet until you check out other simple solutions.

    Some think a CHT of 230F-240F is terrible on a 95F+ day, but that could be normal depending on your cooling and airflow system and how you take off. A flatter climb with a little more speed may cool things off a bit verses a steep hard climb.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

    Thank you said by: Christian Wilfling

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