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Diesel rookie, feeling a little overwhelmed

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Rod K, May 14, 2019.

  1. Rod K

    Rod K Registered User

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    Hi friends, I'd been wanting an OBS diesel for years now and a few weeks ago I bid on a '94 F250 7.3 IDI on eBay and ended up winning the thing. Had the truck shipped here and I've had it for a few days now and am totally in love. I've flipped a few cars in my day but this is the first vehicle I've owned that I plan on keeping until someone pries it out of my cold, dead, hands.

    All that being said, it's a 25 year old truck so it has a few issues here and there and I'm terrified I'm going to try and fix something, get it wrong, and end up destroying my beautiful baby along the way. I put new door locks in it and changed all the engine fluids and filters, but that's as far as I've gotten. Right now my main concern is that my temp gauge isn't working and the ENGINE TEMP light is permanently on to the right of the steering column. I figure its just a bad sensor since the truck seems to be running fine and showing no signs of overheating, but it still makes me nervous every time I drive it because I hate having no idea whats going on under the hood.

    I read on some other forums that there are 2 separate temp sensors in the engine, one that goes to the gauge and one that serves as an overtemp alarm. If the gauge reads 0 but the overtemp light is on does that mean both of them are probably bad? Are they both the same sensor? Does anyone know the part number?

    Apologies if this has been answered elsewhere, I searched around for a while but I'm not too versed in the layout of the forum yet. Thanks in advance for any help.

    - Rod

    75EEE5AF-1625-413A-AF82-8EB1D6C2C33E.JPG
     
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  2. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Welcome. Don't worry about feeling overwhelmed. We'll be glad to talk you through your issues. I'll start off by saying that electrical problems aren't my forte, but I'll try my best. The first thing that I'd do would be to check the wires on top of the senders themselves. It's possible that they don't have a good contact or aren't plugged on. The one for the temp gauge is right in front of the driver's side head on the block. The one for the (overtemp) light is basically right behind that one on the front, lower part of the head above the exhaust manifold. Those are the only two senders in that area. Thinking back now, I don't think that a bad contact would make the light come on. Try unplugging that one. If the light goes out, it's probably bad. The bad contact could affect the temp gauge though. I wouldn't say that the temp sender isn't bad, but I've seen several of them that weren't making good enough contact.
     
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  3. DaveBen

    DaveBen Supporting Member Supporting Member

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    That is one FINE truck you have!! :Thumbs Up:Thumbs Up:Thumbs Up
     
  4. 1992 idi 73

    1992 idi 73 Registered User

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    Same thoughts as IDIBRONCO after 25 years your electrical contacts won't be all that tight. Wiggling wires and cleaning connectors will solve a lot of your electrical problems. That is a awesome truck you have too.:thumbsup:
     
  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Welcome to the forum Rod! You found a place where we all love these IDIs as much as you love yours, you are correct that there are two coolant sensors, although only one is a sensor, and the other is an overtemp switch. The sensor you are looking for is behind the vacuum pump as pictured here: 6C8F105C-118B-4F53-A5A5-AFA21044FBC5.jpeg


    Although, since you say it is pegged to the right I would first unplug the overtemp switch just above the front of the exhaust manifold on the head because if it is stuck shut it automatically pegs the gauge to show the driver it is overheating. Unplug it and if the gauge returns back to a normal area you know that is your issue. Realistically, the factory gauge is completly useless as far as any real temp readings. Youre best off replacing the overtemp switch with an aftermarket mechanical temp gauge so you can have a more exact reading of your coolant temp. Good luck!
     
  6. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    while youre there, may I suggest deleting those 2 sensors for a set of real gauges.
    also a pyro and fuel pressure gauges are great to have in these old things.
    I have actually deleted all the stock gauges for aftermarket stuff.
    you can pretty much do anything you want with these old beasts.
    if youre running an auto I also advise a trans temp gauge.
    heres what I did

    if you do decide to pop into the cooling system, I would also advise changing your thermostat and temp switch behind the t-stat housing.
    then you wont have to get in there again for a while.

    some of us also put coolant filters in to keep the coolant clean

    24883422_2092270394123391_7258097271056752274_o.jpg
     
  7. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    IDIoit forgot to mention that you need to use a Motorcraft thermostat. All of the other one will give you trouble.
     
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  8. YJMike92

    YJMike92 Full Access Member

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    Very nice looking truck.
     
  9. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    100%!!!
    ONLY MOTORCRAFT T-STATS AND GLOWPLUGS
    ok im done yelling
     
  10. Rod K

    Rod K Registered User

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    Holy crap, I am floored by the response and all the help! Thanks everyone for all the support and help, especially WesPaul for the diagram. I’m going to dig around in there this weekend and take a look! What gauges would be the easiest to mount on my A pillar?
     
  11. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    They sell gauge pods that mount to your A pillar. You can get double or triple gauge set ups. They use a 2' or 2 1/8" gauge. You could put whatever gauges you want to there. I had to modify (cut up) one to work in my 1985, but I have boost, pyro, and a vacuum gauge in mine. The vacuum gauge is not for engine vacuum, these don't actually produce much intake vacuum. It's hooked into the vacuum lines to keep an eye on the vacuum pump. After installing it, I'll NEVER own another IDI without one.
     
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  12. Runningaford

    Runningaford Registered User

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    Another couple easy mods are running a grounded wire through a switch for the option of manual glow plugs(it can be nice), and also a headlight relay to save your dash from any possible overload issues; the switches burn up due to being overloaded.
     
  13. jim x 3

    jim x 3 1988 F-350 DRW

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    Rod K,

    Welcome, and nice looking truck you've acquired.

    So first your overwhelmed with the vehicle; and now your overwhelmed with advice.

    This is a great forum and most of the advice here is relevant and accurate - a lot of these guys really know what they are talking about. Bear in mind they are IDI-heads - they know and love their trucks and like to diddle with them.

    My advice is to fix what's immediately broken and get your feet under you before you consider modifications. Some are highly advisable where others are nice to have. Some, IMHO, are of questionable value. (I use my truck for business so it has to be reliable, but I don't generally make modifications).

    So take your time and have fun.

    Regards,
     
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  14. Exhumis

    Exhumis Registered User

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    How about only motorcraft EVERYTHING? Went through 2 autozone and advance vss till I bought a motorcraft one that fixed the problem
     
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  15. Mulochico

    Mulochico Supporting Member Supporting Member

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    At least until the next time. :D
     
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