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Engine Overheating Insight-FIX

Discussion in 'General Truck Info' started by spaner, Jun 29, 2012.

  1. spaner

    spaner Well-Known Member

    I seem to be getting a lot of these revelations of late. Bare with me, not sure if it's just my truck, my model, or just the make.:confused:

    I am very careful with the cooling system on my truck; even have an in-line filter, to try and get the last little bit of rust out of there. Flushed and repaired rad, I keep the fins clean. New hoses, I service the fan, and I listen for it often (I have an RPM increase set). I keep the overflow can within limits and I've checked the rad-cap-gasket, more than a few times...I can burp the system in about 5 minutes. (after some kind of servicing)...lots of care in general.

    So after putting on my front slider, covers the rad air flow a bit, I had some problems and solved it by cutting some holes into the front. Then last week I drove the same highway, under the same conditions, and it did the exact same thing; overheated, and in the exact same location!:confused:

    Happens just like others have described, just driving along, everything is OK, then glance down at the temp gauge as it passes 3/4, on it's way to the H, pull over and let it cool. Makes no difference, same conditions right away and the only way to fix it is to pull the cap, top it off and burp it. Then it works fine. No more problems. I should have realized what the fault was last month, but it took a second go around to figure it out.

    After driving on the highway at 90kph and 30 deg C, for about 20 minutes, I always pull into the same "last-stop". Shut the engine off, go in buy my cigs and mickey, maybe some minnows, then back on to the road within 5 minutes. Then, within 2 minutes...the overheat.

    What was happening was that, shutting off the engine while still hot, the cap pressure is exceeded, and the overflow can starts to fill up. After about 5 minutes, it has already dumped 2 liters of fluid onto the ground (full can...can overflow). Start it up and drive away, you get the air lock and overheat within 2 minutes, then need to replace the fluid that was lost, and burp it.

    I came through the same way on Wednesday, with the same stop, but this time left the engine running. When I came out 5 minutes later...the fan was still running, but no problems what so ever...or since.

    A long winded way to say, don't ever shut off the engine before the fan cycle is complete.

    If you look at today's newer vehicles, if it's hot when you shut it off, the cooling fan keeps right on going, even though you're walking away with the keys.

    Hope that helps someone out. I didn't need any cooling holes cut into my slider...
    Last edited: Jun 29, 2012
  2. fupabox

    fupabox Well-Known Member

    oh..nice call..that sounds extremely plausible...switching the rad fan to batt + directly would let it remain on as long as the temp sensor is triggered,and off when cooled down
  3. spaner

    spaner Well-Known Member

    Yes sir, it's on the list...

    This little phenomenon is a silent engine killer. There is no indication of loss of fluid as it's happening. No gurgles or popping...you can't hear it, or see it, as it's happening, and NO indication from the gauge that it's about to happen.

    The other little tidbit of information, is that the temp gauge never goes above the "warmed-up" level...45% position, unless there IS a line lock.

    I think of it this way. If you can "see" the gauge moving, you have a line lock. Period.

    Solution, hot-wire the relay, and install "buzzer" on the back of the gauge @ 55% position....CT $3 bucks...
  4. Great advice but I have a request... could you explain in a bit more detail how to wire the gauge up with a buzzer to go off at a certain position?

    Thanx... :)
  5. spaner

    spaner Well-Known Member

    It's not too hard to drive a small component off the gauge's variable grounding line, haven't gotten there yet though.
    I keep a running list of stuff to do on an area..like the gauge cluster...cu'z I get tired of pulling something for every little mod, so the next time I pull it I'll be doing a bunch of stuff and open a new thread for it, under Suzuki probably. Like my fuel indication level problem,
    The last time I had the cluster out, I grounded the gauge and it would not indicate a full tank; it's just tired. Later I realized that I could just swap the drivers of the temp and fuel...that's #1
    I'll also be showing how to adjust the speedo to indicate proper speed with current tire set-up for guys that have monkied with stuff...that's #2
    Then the buzzer...that's #3

    I'm tearing into a bike engine right now, but I'll get there, and let you know...
  6. Will be waiting with eager anticipation...:pop:
  7. spaner

    spaner Well-Known Member

    Just doing some R&D back on this, as my truck is just about parked in the shop for the winter.
    I have a small 12v fan that I want to run against the supercharger and I have the buzzer that I want to go off at high temp. Both from engine temp; not rad.
    I've decided to go another way with this. Going to go with a 3-pin engine mounted fan switch. There is a port just below the existing sensor on my truck.
    Low sensor side for S/C fan, high side for the buzzer. Should be able to do it for around 20 bucks.
    Not finished with the investigation but thought you might be able to run a buzzer this way with a single pronged 5 buck switch.


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