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Thread: Coolant running hotter than normal?

  1. #1
    Join Date
    Jul 2018
    Location
    Florida
    Posts
    17

    Coolant running hotter than normal?

    Hello again!

    After my adventure with getting the supercharger working I'm now having some temperature issues with the car. This is going to be a long one so bear with me...

    When I first got my 1989 TSC back in June/July of this year I noticed the temperature gauge would fluctuate over the "TEM" part of "TEMP." I asked a buddy of mine about it and he said his Nissan 300ZX does the same thing. Called it a "linear gauge." I didn't think anything of it trusting his judgement and my brother's Focus would sit in the middle area too (his didn't fluctuate though). I had it for a week or so before driving it from southern PA to Lorton VA to auto-train it to Florida, and the temp gauge did its usual thing of fluctuating back and forth during the 3 hour trip.

    While I had it up in PA and down in FL I have been periodically swabbing junk out of the radiator cap and noticed some black gunk along the walls of my expansion tank. I took it to a garage for a slew of related and unrelated problems that needed addressed. Part of the trip was to solve a leak which they claimed to be the thermostat, and they flushed the system twice while they were there. They ALSO said my radiator fan wasn't working due to a faulted fan control module, so they hardwired the fan to always run in the meantime.

    I got it back and my temp gauge never passed the 1/4th mark with the fan always pulling... until today.

    I got my supercharger working in my car today and took it out for a test run. It pulled nice and hard, but before I could even make it 3 miles down the road I noticed I was sitting on the T in TEMP so I eased up and took it easy coasting at 45-50 mph in 4th. The needle rose to the E. I thought "Oh great. The puller fan's fuse popped, didn't it?" Nope. Pulled over and the fan was still pulling strong. Shut the engine off for 4 minutes then fired it back up and brought it back home. Behold, the fluctuating has started again even though the fan is constantly pulling.

    I already have a list of issues relating to the cooling system. First off I'm STILL loosing coolant from somewhere (It's stops seeping if it hasn't run for a week. Looks like it's originating from the lower end of the motor. Water pump gasket maybe?), the expansion tank has black junk caked on the walls, and I do have a replacement fan module nicked from the junkyard, but I have to turn it back over to the garage for them to undo their hardwire kit. Really... the coolant issue could be caused by any one of these creating a slew of issues further down the line I'd imagine.

    Chronological TL;DR version:
    -Car temp gauge fluctuating over the word TEMP when I got it in June/July. Noted system was circulating garbage
    -Took car to garage in late July for several things. One was stopping a coolant leak. Garage diagnosed a bad fan module and hard-wired the fan to always run. Put in a new thermostat. Performed 2 coolant system flushes
    -Car still leaking coolant from lower end of engine. Stops after sitting for a week. Temps stay low at the 1/4th mark
    -Fixed supercharger today. Temp gauge fluctuating again. Noted garbage flowing through system again. Still leaks from lower end. Hardwire fan still runs, but is fighting a loosing battle.

    So here's my questions:
    -Where is the needle supposed to sit?
    -How is the temp gauge supposed to act?
    -What all should I check/do myself before taking it back to the garage?
    -Does the car have an OBD port that can give a second reading of the coolant temp?
    -Is there anything I can put in the coolant to break down the junk that's grown on the surfaces over time?
    -Anybody know how to test a fan module with a multimeter? (It's the black box that mounts in front of the air filter box)

    Thanks. This is a multiple problems problem for me. Any help would be appreciated.

    Side note: My washer fluid tank has a leak somewhere too, but that drains out from full within a few days. I suspect the tank is cracked. Do I really need to take the supercharger pipe off to get to the connectors on the tank to remove it?

  2. #2
    Join Date
    Jul 2005
    Posts
    427
    Good morning


    Coolant leaks/high temperature issue can be tough to isolate for a fix. Jack the car and place on stands. Here are items I inspect for.


    1. Coolant recovery tank "bubbles" when engine is running. If found refer to item 8.

    2. Top radiator hose. Check for "budge" at radiator inlet connection side. Check for excessive hard /soft and or cracking conditions.

    3. Cracked radiator cap seal cracked and or worn.

    4. Lower radiator hose. Check for "bulge" at radiator outlet side. Check for excessive hard/ soft and or cracking conditions. The factory original hose has a spring at the bottom that collects sediments over the years.

    5. Original factory coolant hose swage sleeves for leaks. Examples are water pump to oil cooler hoses, throttle body (if equipped) heater hose, engine temp sensor mount fitting.

    6. Blocked/dirty A/C condenser and or excessively bent rows of cooling fins. Check condenser sides for damaged and or missing weather seals strips.

    7. Missing bumper air dam.

    8. Check for exhaust gasses in the coolant system using engine block test.

    9. Check water pump "weep hole" for evidence of leaking.

    10. Check radiator recovery tank and hose for leaks.

    11. Remove radiator and take to shop for pressure test and rodding cleaning.



    You can check computer temperature with a scanner. Must have EEC IV attachment adapter. The EEC connector is located on the engine bay back side of passenger body shock strut tower.

  3. #3
    Join Date
    Jan 2010
    Location
    Bossier City, LA
    Posts
    2,243
    There's also a TSB on the sending units for the gauge failing; some failing reading low, some failing reading high, depending on the production date.

    I'd go ahead and replace the sending unit while you're working on it.

    RwP

  4. #4
    Join Date
    Dec 2007
    Location
    Salem OR
    Posts
    6,785
    Quote Originally Posted by FurryWrecker911 View Post

    Chronological TL;DR version:
    -Car temp gauge fluctuating over the word TEMP when I got it in June/July. Noted system was circulating garbage
    -Took car to garage in late July for several things. One was stopping a coolant leak. Garage diagnosed a bad fan module and hard-wired the fan to always run. Put in a new thermostat. Performed 2 coolant system flushes
    -Car still leaking coolant from lower end of engine. Stops after sitting for a week. Temps stay low at the 1/4th mark
    -Fixed supercharger today. Temp gauge fluctuating again. Noted garbage flowing through system again. Still leaks from lower end. Hardwire fan still runs, but is fighting a loosing battle.

    So here's my questions:
    -Where is the needle supposed to sit?
    -How is the temp gauge supposed to act?
    -What all should I check/do myself before taking it back to the garage?
    -Does the car have an OBD port that can give a second reading of the coolant temp?
    -Is there anything I can put in the coolant to break down the junk that's grown on the surfaces over time?
    -Anybody know how to test a fan module with a multimeter? (It's the black box that mounts in front of the air filter box)
    • About the gauge - I've found the first thing to check is the push-on connector at the sender. The sender is on the thermostat housing.

    You want to remove the wire/connector and inspect it and the post on the sender for corrosion. Make sure both are shiny and clean. Then determine that the connector is snug on the post...might need to gently squeeze it to close it up a bit so it grabs the post tightly when pushed on. This check alone is important regardless of how the cooling system is performing, so pls. do it first. About a TSB (technical service bulletin) …see below”

    • About the reading on the gauge - I normally talk about where it sits relative to the letters NORM - N is cold and M is hot, of course. My ‘90 sits at N once it warms up and rides on the thermostat, then climbs towards O/R (pointing straight up) as the coolant temp rises based on driving/sitting, then back to N when the fan comes on.

    • About the thermostat - which one did they install? What temp?

    • About reading temps via OBD in your car, not without expensive diagnostic equipment, I think. Our EEC-IV lacks the ability to casually connect and read temps, fuel, etc...it's more about coughing up codes hinting at various issues, another topic for another day, perhaps. I use a combination of seat ‘o the pants, IR temp gun and IR photography. Those, and I tap into the ECT sender wiring, reading volts that I convert to engine coolant temp. Some owners add a better gauge.

    * About the gunk in the coolant - It’s good that you have new in it now, and I’ll assume it is a 50/50 mix, bu it might not be that simple and need various repairs, vs. just a flush or two or three, but I’d keep my expectations low depending on needed repairs. I’d take a hard look at the entire system, starting with the radiator. I’d not make any decisions until I knew the source of the leak.

    That leak could be keeping the system from balancing temp when hot if the system isn’t holding pressure, as an example. You could spy the gauge all day and not make the right conclusions just because the system isn’t capable of working correctly. Gunk in the cap might be preventing the system from recovering coolant from the expansion tank (does the upper hose collapse when things cool down?) - a new cap is a good thing, but that gunk can foul it up in as little as one heat cycle, sooo…lots of basics to get right before fine tuning the small things. AutoZone has a new cooling system testing kit...suitcase, actually. You can pressure test the system and cap to try to locate leaks.

    • About testing the IRCM (fan module) - see this thread:
    http://www.sccoa.com/forums/showthre...ight=IRCM+test

    Good you grabbed a spare IRCM, just be sure to confirm the part number.

    TSB for temp gauge 1989 SC:

    TEMP GAUGE INOP - R&R COOLANT TEMP SENDER ASM (3.8L)
    TSBID: 29387 Mfg Num: 90-23-10


    I have that TSB as a PDF…minimum 10 posts on your side and we can PM if you like - I’ll message/email you and hand it off then then. Note they are available for download here: http://www.bbbind.com - requires a bit of hoop jumping, but a wealth of info awaits.

    About the washer tank..I had a leak from the one-way valve/filter that sits inline, right after the tank, on the body, adjacent to the exhaust manifold. Looks for some thin heat shielding on the body, inboard the fender panel. Might want to climb underneath and confirm. Replaced that part and good to go. If it's the tank itself, you might get lucky and just work on it from above without pulling other parts.

    BTW, luv'n the TL;DR version

    Ken
    Last edited by KMT; 10-29-2018 at 11:56 AM.

  5. #5
    Join Date
    Jul 2018
    Location
    Florida
    Posts
    17
    Thanks for the replies guys! I'm getting the car prepped for a shop visit next week, so I'll try to burn through as many of these as I can this weekend. For starters, after doing some more research it seems that where my needle has been resting is normal since it stays in the middle, and I guess it was abnormal that it was running so cool beforehand. Weird.

    • What thermostat did the garage put on there? I have no idea. I'll have to take a close look and see if I can find any part numbers this weekend.
    • All the hoses seemed fine. Had a coworker who tracks his car verify it as well in the parking lot on Monday on a whim. He was really eager to see the car. lol.
    • The radiator was bought from a parts warehouse, but sometimes new products can fail. I'll take a look at the lower end of it over the weekend. Same thing with the weepholes. Really the upper end of the car seems dry as a desert. It's the lower end I have yet to inspect.
    • I've actually been looking for a new air dam since I got the car. about 3/4ths of it is still there, but it looks so bad with the corners busted off from hitting snow banks in a past life.
    • I'll check the temp sensor over the weekend. I got some electrical cleaner and dialectic grease from restoring the taillight sockets around here somewhere.
    • IRCM was pulled right out of another 89 SC (with a cute "Touring Edition" decal added to the deck lid) so I'm 100% sure it's compatible with mine. I skimmed through the thread, and it looks like I'm gonna have to get diagnostic equipment either way if I want to test the electrics it seems.
    • IR temp gun definitely seems like a good investment though. I'll pick one up at harbor freight tomorrow or Friday.


    I'd be happy to have that TSB. Never read one before so this ought to be an experience. I'm just 2 posts short of 10 so I'll just have to make some replies up here.

  6. #6
    Join Date
    Jul 2018
    Location
    Florida
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    Post 09. Almost there.

  7. #7
    Join Date
    Dec 2007
    Location
    Salem OR
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    6,785
    Quote Originally Posted by FurryWrecker911 View Post
    IRCM was pulled right out of another 89 SC so I'm 100% sure it's compatible with mine.
    Face value parts are a fool's errand... For all you know, someone installed a mismatched IRCM from a different Ford, it didn't work out and they gave up on repairs altogether and junked the whole vehicle. Good you found a same year SC donor and grabbed it, just want you to be sure Also, you can get the number off the spare and search here to confirm.

    The part number is on the outside. At least match the first 5 digits - the suffix could be a revised version that is otherwise correct. It's easy to check.

    Be careful w/the dielectric. Not advised to go nuts on low tension connections. Just make sure the metal connectors are clean/shiny, and then use the dielectric on the connector's internal gasket.

    About the air dam...you want it in place, along with the thick black skirt that goes under the rear of the radiator, back to the crossmember. Both work to generate air flow that creates a negative pressure zone under the engine, which promotes air flow into the radiator and down across the block, exiting under the car to the sides and back.

    You have enough posts to PM now, so as soon as that feature is enabled, we can hook up.

    Ken
    Last edited by KMT; 10-31-2018 at 11:16 PM.

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