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Thread: Climbing temps

  1. #1
    FEP Super Member erratic50's Avatar
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    Default Climbing temps

    I’m thinking about a problem we are having with my son’s 86GT

    When we got it it cranked like there was plenty of compression (and there is) but It idled unevenly and pretty much just wouldn’t get out of its own way. I disassembled the throttle body and Engr spacer area and cleaned the holy crap out of everything. Idle much better, hello 5.0L with VR1 ECU at 8 degrees BTDC. I left it there because the kid was still learning to drive a stick and a car with crappy brakes.

    (Redid all the brakes - booster, master cyl, etc, as stock but added carbon pads in front. New shocks, new struts, new tires).

    When we bought it the motor never came up on the temp gauge at all and got poor fuel economy. Likely the source of the carbon. Found the Ford Racing plug wires were crap and causing a misfire on #4. Cap and rotor weren’t great, etc. replaced them.

    I later determined the low temp was caused by a thermostat that was rigged to always stay wide open while tearing into it but summers here are brutal and it was staying cool so I left it a while. during that time the fan clutch failed and temps started climbing in traffic of course. We fixed that and it went back to running below range all the time. Put in a failsafe thermostat and it worked right about a week then failed safe for some reason.

    Winter came around and no heat so time for a new thermostat. This time a normal one. Things worked perfectly with the 195. Right on the R of normal all the time.

    The water pump failed so that became a cold project. I back flushed the block through the heater hoses when it was apart. Usual twisted off bolt cursing, etc.... but got it back together and up with no more leaks.

    Was fine for about a year. The heater core started leaking so that was replaced and a flow restrictor was added to the high pressure side.

    Things stayed fine. We dialed up the timing to 13.5 degrees and things remained fine. Swapped over to a VM1 ECU from my 1986GT and again temps stayed fine.... started running like a raped ape — about the way my 86 always did when it was SD much to my surprise. This one is minus the Ford Racing late 80’s cam and ported intake and exhaust. It pulls like mine always did but runs out of steam by 5300 where mine was good until 5600. Anyway — cheap upgrade and way more fun to drive. Probably around 15% more torque at the wheels it feels like. Good ol driveway tuneup!

    Good for about a year.

    Then this summer came around. We’ve been battling keeping it in operating range all summer. A few Ignition modules have burned up due to heat also.

    Sharp contrast from my 1986 — I never had these problems!!

    The radiator in the car is a modern plastic end AL fin unit and it really doesn’t fit very well. It’s never been serviced with a blow-back machine and it’s flow is not looking awesome. Where I’m at is replace the radiator with an OE style but 3 core.

    im thinking about overdriving the water pump with a cobra pulley also.

    the stupid part is it runs fine and comes up on temp slowly until about the time the EGR would come into play.

    Im wondering if there are documented cases of anything EGR related sticking causing heat problems. I had a valve stick wide open on a 350 Buick and it wouldn’t idle for **** and ran hot as hell in town but fine on the road.

    Whats the easiest way to bypass or block off EGR for testing?
    Last edited by erratic50; 07-15-2018 at 02:24 PM.

  2. #2
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    Have you tried replacing the fan clutch? It’s one of those over looked things.

    I did one recently on my 67 Tbird. Not sure if there is a good way to test them at temp. I would love to hear if there is a way. I guess one could devise a way to put a tach on it for rpm measurement. Maybe use a timing light.
    Last edited by KevinK; 07-16-2018 at 01:12 PM.
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  3. #3
    FEP Super Member erratic50's Avatar
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    Fan clutch was replaced.

    #9 wire or metal straps from blade to clutch hub will lock the clutch temporarily.

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    FEP Power Member Ourobos's Avatar
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    Pull EGR, put block of plate in place - fairly staright forward.

    I'd lean towards a real radiator and GOOD motorcraft 180 thermostat. It's brutal here in Hawaii also, both of mine run dead on with good radiators, fans and motorcraft consumables.
    1986 CHP SSP Coupe

  5. #5
    FEP Super Member erratic50's Avatar
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    Went to a radiator “with heavy duty cooling” available from Rock Auto. Rather than multiple cooling tubes forming multiple cores it uses a special shaped tubes that are an oval that’s flat on the sides

    fin density is nice and high too. Should work well

    its no FB169, but it should cool less than 300 HP easily on the hottest days.

  6. #6
    FEP Senior Member Matt J's Avatar
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    It sounds like owning an old car to me!

    It sounds like you've been doing the right stuff, things just wear out. I know you're having issues with the thing that your old one didn't, but I'm guessing your old one wasn't 30 years old when you were driving it. It's a miracle a lot of these components lasted as long as they did, when you think about it, but for sure the replacement parts aren't as well made as the originals. I'd definitely keep the thermostat to whatever the stock rating is, because the computer controls things based on temp as well as other measurements, so if the car is running cool it's not always a good thing. My 84 CFI system needed to be hot to run right, just the way they were built. Replacement radiators give guys fits on this site, some work better than others...but if you have a good radiator, the standard water pump setup should work well. I needed to replace my fan clutch too, it made a big difference. Is the shroud still on the radiator? I know you mentioned you've replaced it, the shroud makes a huge difference to pulling the air through the radiator more efficiently too.

    I don't have any experience with using a tester on the 86, but the computer tests were hugely helpful for me diagnosing problems with my ECR and the sensors attached to making it work right. If the thing is mostly stock, consider using the diagnostic test function of the onboard computer, it will help at least point you to the right area.

  7. #7
    FEP Senior Member Matt J's Avatar
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    It sounds like owning an old car to me!

    It sounds like you've been doing the right stuff, things just wear out. I know you're having issues with the thing that your old one didn't, but I'm guessing your old one wasn't 30 years old when you were driving it. It's a miracle a lot of these components lasted as long as they did, when you think about it, but for sure the replacement parts aren't as well made as the originals. I'd definitely keep the thermostat to whatever the stock rating is, because the computer controls things based on temp as well as other measurements, so if the car is running cool it's not always a good thing. My 84 CFI system needed to be hot to run right, just the way they were built. It's funny, too hot is bad, too cool is bad... Replacement radiators give guys fits on this site, some work better than others...but if you have a good radiator, the standard water pump setup should work well. I needed to replace my fan clutch too, it made a big difference. Is the shroud still on the radiator? I know you mentioned you've replaced it, the shroud makes a huge difference to pulling the air through the radiator more efficiently too.

    I don't have any experience with using a tester on the 86, but the computer tests were hugely helpful for me diagnosing problems with my EGR and the sensors attached to making it work right. If the thing is mostly stock, consider using the diagnostic test function of the onboard computer, it will help at least point you to the right area.

  8. #8
    FEP Super Member erratic50's Avatar
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    Yea, I still have my 86GT hatchback. I’ve owned it about 26 years and have accumulated nearly 1/2 million miles. It still makes it out of storage for an occasional cruise and is still licensed and insured and gets driven often.

    the 86GT conv is what we picked when some idiot rear-ended my son and totaled his first car, a 2004 Sebring conv LXI.

    components do wear out for sure, we all know it. Just aggravated me that the convertible has 1/4 the miles and is being the antichrist of the stable when it decides to be.

    fan shrouds and fans, etc, are all in place. Totally agree on the thermostat temp decision. I went to 160 then to 180 on my 86 years ago. It got terrible fuel economy!

    both 86’s have highway gears and T5Z’s.

    The hatchback has gotten as good as 33 mpg highway at 70 with a T5 a long time ago. 28.5 well north of that sustained for thousands of miles in a cannonball run style trip years ago.

    Most recently it got 29 on a 300 mile round trip on the interstate rolling ~82 most of the time. I’m certain if I would have sped up mileage would have improved as honestly I was not much above idle with the 0.63:1 at those speeds. 2.73 gears gotta go goodbye,

    The 86Conv has very recently gotten 27.5 on interstate rolling fairly “hot” for several hundred miles.

    Amazes me — the best that Sebring conv could muster at as little as 80 was 22....

    My Saleen build will be interesting on mpg. Flowtech cam, Edelbrock heads and intake, 331 stroker at just over 10:1. 0.59:1 overdrive and 3.55’s — yields the same FD as T5 with 3.08’s!

    Radiator swap tonight. We shall see.
    Last edited by erratic50; 07-16-2018 at 04:49 PM.

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    FEP Member James2488's Avatar
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    I would check the again, I had someone one time complain about engine temp in a explorer and they had the vacuum line set to pull egr all the time. I personally would ditch the egr in general.

    I was ecstatic with the 23.5 once in my 85.
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    Another quick idea, check the lower radiator hose for the spring. The last one I checked, the spring was rotting away.
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  11. #11
    FEP Super Member erratic50's Avatar
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    Good point.... and also come to think of it a disconnected EGR will never open! Hmms.

    Engines without EGR get ****ty mileage in comparison though because EGR effectively reduces CID as it relates to air with oxygen. That means less fuel is required....

  12. #12
    FEP Super Member erratic50's Avatar
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    That’s a DAMN good point! Who knows what that hose is doing when the water pump is sucking for all it’s worth!

    New gates hoses sourced locally! I’ve personally had great luck with them over the years. Only Napa hose I ever put on my 86 split like a banana up top when my passenger motor mount broke. Unacceptable!
    Last edited by erratic50; 07-16-2018 at 06:36 PM.

  13. #13
    FEP Super Member erratic50's Avatar
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    Swapped the radiator. Installed new gates radiator hoses too. They say they don’t need the spring but I transferred it from the old hose anyway as it still looked good.

    we topped it off and drove it and it was hanging out between the A and L of Normal but not going past that.

    We had the Slant pressure relief cap on it from my 1986GT that I ran for over 300K miles. It acted right as there was pressure but there was air. I flipped the relief and we brought the engine up on RPM and topped it off and capped it then drive some more.

    heat cycled it and this time there was minimal pressure when it was warm

    We topped it off again and drove it

    again minimal pressure

    tried another cap — the car’s original one actually — which I didn’t really believe was any better

    i got ticked and bled the air out by loosening the temp sender and leaving it until coolant came out

    as a trouble shooting step plugged the vacuum line to the EGR

    it ran OK and made it across town and back in traffic with the AC on but still was between the A and L all the time.

    I checked the hose and again still no major pressure and now I knew for certain there was no air

    went and bought another Slant cap with pressure relief and put it on. Never bled it or anything and drove it home.... R of Normal.


    So the radiator was for sure faulty. The cap broke while messing with it before the new radiator got a real chance to prove itself. The second cap was already known to be not great..... new cap is good

    it speaks volumes for the radiator that it made it across town and back with no radiator pressure on a hot day with the AC cranked

    Time will tell but seems to run lots cooler now. Middle of normal. About right for a 195 degree theremostat. As air works it’s way out via heat cycles it should improve

    Fingers crossed, sure hope it’s fixed!

  14. #14
    FEP Super Member erratic50's Avatar
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    Piece of crap Autozone 195 thermostat started sticking closed or partially closed on us shortly after temps stabilized.

    Went to a Motorcraft 192 with a thermostat neck that has a temp bung in it for a future electric fan project. Found that Gates gaskets are the bomb-- they are self-stick and hold the thermostat in place in the neck. Their bolt holes are oblong and hold the bolts too.

    runs on the R of normal all the time now. Any bets that with a proper Motorcraft temp sender it will be back on the O where these cars always run factory?

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