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  1. #1
    12 PSI Boost
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    SVO's: 1986 1D

    Cooling issue potentially?

    1986 SVO, 1992 LX bumper and hood. Has a front mount intercooler that was an eBay special home brew, dual core radiator, and a manual switch fan. Finally finished the brake work it needed today and took it out for ~8 miles of driving in circles in my neighborhood (uninsured) at 25mph. Car hit the A on the temp gauge (just over 3/4 gauge) while cruising, Iím not sure if I should consider that excessive or just sketchy gauge since it didnít do that before the FMIC or LX nose. I intend to space out the back of the hood so it sits above the cowel and allows air flow back past the firewall and out of the bay. Water pump and hoses are all new, as is the coolant (70/30 water/coolant). I made sure I had the heater on back when I was bleeding out the cooling system, and itís still full of coolant. Any other things I should be looking at?

  2. #2
    OVER-BOOST!! Chuck's Avatar
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    SVO's: 1986 2A
    Blocked water passage in the lower intake manifold.
    <-Find the car; women: 0.001 secs, men: 2.4 mins.

  3. #3
    12 PSI Boost
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    SVO's: 1986 1D
    Quote Originally Posted by Chuck View Post
    Blocked water passage in the lower intake manifold.
    Is there an easy way to deal with that? I thought I cleaned all the crap out with some CLR and 5 gallons of distilled water over 3 days before I put the new cooling components in

  4. #4
    OVER-BOOST!! GAboySVO's Avatar
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    SVO's: 2 - 9Ls
    I checked the actual temp when my stock gauge shows at "A" and it was ~200*. The stock gauge is sketchy at best. Use a real gauge to verify what the temps are doing.

    I know that guys who use the 87 and up 5.0s for track events always cut an opening in the bumper cover between the bumper and hood.
    Last edited by GAboySVO; 07-17-2020 at 11:15 AM.
    Mike S

    '86 SVO 9L Leather
    '86 SVO 9L Road Warrior
    '96 300ZXTT

  5. #5
    Pimpin Pumpkin Carver Laredo's Avatar
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    SVO's: 86 2R
    Quote Originally Posted by GAboySVO View Post
    I checked the actual temp when my stock gauge shows at "A" and it was ~200*. The stock gauge is sketchy at best. Use a real gauge to verify what the temps are doing.
    ^^ This. And...

    Are your fans coming on?

    And...That FMIC is going to hinder airflow to your radiator. In stock format, the cooling capacity is marginal at best. Any minor restriction in airflow path can push you over the top.
    Best investment I ever made on my SVO was a 3 core aluminum radiator. Even on the hottest, 90+deg days, thrashing at extended full boost on the race track - perfect consistent 190deg coolant temps.
    And that's with the less-than-ideal original electric fan.

    Make the investment, and never look back.
    "If there's no plan, what can go wrong...?"

  6. #6
    OVER-BOOST!! Chuck's Avatar
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    SVO's: 1986 2A
    Quote Originally Posted by ClayBelt View Post
    Is there an easy way to deal with that? I thought I cleaned all the crap out with some CLR and 5 gallons of distilled water over 3 days before I put the new cooling components in
    My passage was completely blocked but I only discovered this when I tried to remove the temperature sensor for the fan control. It broke off, necessitating the removal of the manifold. This is when I discovered that the lower passage was completely blocked, like concrete. I took it to a shop where they blasted it clean. Now everything is working again. CLR would NOT have done a thing on the blockage. If you can remove the temperature sensor and have water come out then the passage is likely NOT blocked.

    Chuck
    <-Find the car; women: 0.001 secs, men: 2.4 mins.

  7. #7
    12 PSI Boost
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    SVO's: 1986 1D
    Well, I’ll try to address all the items mentioned in replies:

    1) I have a manually wired fan, as the fan wasn’t kicking on despite being good and me replacing all the components. I flip it on anytime I am below 15mph.

    2) Radiator I have now is an all aluminum unit that’s about twice as thick as the factory radiator, I put it in back when I first got the car because the radiator it had may as well have been full of oatmeal. I also replaced the water pump and rad hoses when I did that, post CLR and one flush of distilled water, prior to second round of distilled water and coolant.

    3) The passage is not blocked, although it did have some nasty stuff in it. I put the sensor for a parts store mechanical gauge in that hole instead after I checked it out with ye olde probe (screwdriver). I spaced the hood up 1/4” as well, so it now sits just above with the cowel instead of underneath it. About to go drive and see what temperatures I get, as well as bleed out the cooling system.

  8. #8
    12 PSI Boost
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    SVO's: 1986 1D
    So I drove it in circles in the neighborhood for like 8 miles, and temps (as per parts store mechanical gauge) are 190-200ish until I hit boost. When I enter boost temps shoot up about 20 degrees. Thinking to eliminate some error (because mechanical gauge) a turbo blanket would be my next course of action, and maybe finding/fabricating a good fan shroud.

  9. #9
    OVER-BOOST!! gbeaird's Avatar
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    SVO's: '86 2R
    Quote Originally Posted by ClayBelt View Post
    Well, I’ll try to address all the items mentioned in replies:

    <SNIP>
    3) The passage is not blocked, although it did have some nasty stuff in it. I put the sensor for a parts store mechanical gauge in that hole instead after I checked it out with ye olde probe (screwdriver). I spaced the hood up 1/4” as well, so it now sits just above with the cowel instead of underneath it. About to go drive and see what temperatures I get, as well as bleed out the cooling system.
    Tape some tufts of yarn to the leading edge of the cowling to make sure the air is moving in the direction you are expecting it to. You could just be pressurizing the engine compartment doing that.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  10. #10
    12 PSI Boost
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    SVO's: 1986 1D
    Quote Originally Posted by gbeaird View Post
    Tape some tufts of yarn to the leading edge of the cowling to make sure the air is moving in the direction you are expecting it to. You could just be pressurizing the engine compartment doing that.
    I would, except the LX hood sits lower than the SVO one did. They sit about even now with the spacing

  11. #11
    12 PSI Boost
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    SVO's: 1986 1D
    Picked up a Focus fan at the junkyard today, seemed to be about the same size as the oh so famous contour fan. Should have it in in the next few days to see if it helps. Thinking that and maybe a turbo blanket would be the golden tickets to drop my temps a little. Maybe a new 180 thermostat as well

  12. #12
    12 PSI Boost
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    SVO's: 1986 1D
    The Focus fan helps when stationary, saw temps drop from 205 to 190 and dropping over 20 seconds. Car has a 160 or 170 thermostat (leaning towards 160), so a 180/185/190 is definitely in the cards. IAC appears to be nonfunctional again after I cleaned it out last week, so I’m back to idling at 2000rpm which probably doesn’t help. All good things though so far.

  13. #13
    Pimpin Pumpkin Carver Laredo's Avatar
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    SVO's: 86 2R
    Quote Originally Posted by ClayBelt View Post
    ...Car has a 160 or 170 thermostat (leaning towards 160)...
    That's not good, the engine was designed to run at 190. That's also the proper temp to "boil off" water from your crankcase (which runs about 20 deg warmer than coolant temps).

    Quote Originally Posted by ClayBelt View Post
    ...so a 180/185/190 is definitely in the cards...
    Definitely a good plan!
    "If there's no plan, what can go wrong...?"

  14. #14
    Pimpin Pumpkin Carver Laredo's Avatar
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    SVO's: 86 2R
    Quote Originally Posted by ClayBelt View Post
    ...temps (as per parts store mechanical gauge) are 190-200ish until I hit boost. When I enter boost temps shoot up about 20 degrees. ...
    Have you checked for over-advance timing?
    How old is the fuel? Octane drops as fuel ages.
    "If there's no plan, what can go wrong...?"

  15. #15
    12 PSI Boost
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    SVO's: 1986 1D
    93 octane from March, haven’t checked the timing as my timing light I think got left in Indiana. I hadn’t thought to check that one though

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