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Thread: Mystery coolant leak

  1. #1
    What a Luxury car should be. mercurygm88's Avatar
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    Default Mystery coolant leak

    I've had a minor coolant leak on the '02 LSE for going on a month now. In the past month I've slowly lost the contents of the coolant reservoir, between 2-3 quarts. I haven't been able to find any wet spots in the engine bay. After a week or so I get a small puddle on the garage floor, can't seem to find anything dripping. So tonight I took it out on about a ten mile ride with some full throttle pulls, came home and I have some wet spots. It appears the coolant is spraying rearwards on an angle towards the drivers side. The top of the alternator stabilizing bracket is wet as well as the top of the intake tube and drivers side wiper cowl, I lost maybe 1/4" of coolant on that drive. While the thermostat housing isn't wet I'm thinking it may be spraying out the back side of it under heavier load. I've put three thermostats in this car in a little over a year and I'll admit I've been reusing the gasket. One of those thermostats was changed a month ago when this issue started.

    Tomorrow I'm going to grab a new gasket and see if that does any good. I will say that I've torqued the thermostat housing bolts to 20ft lbs per what I've found online on each occasion. I'm really not sure where else it could be coming from. I don't believe it's that dreaded line under the intake because I don't think it could spray way over to the drivers wiper cowl, also I don't see any liquid down in the valley of the block when shining a light in there. I do have the intake with the aluminum crossover, so I'm hoping it's not leaking there, again I don't think that would spray as high and left as what I'm getting.

    If anyone has any other suggestions let me know, per records I have from the previous owner all hoses were changed in the summer of 2018 at 90,000 ish miles. I don't know if that includes the one under the intake but it doesn't look 19 years old. I don't know what the deal was with this car but I have records showing extensive engine and suspension work was performed by a Ford dealer in Akron Oh between 40,000-75,000 miles. Work that shouldn't have been done at the mileage listed, I don't feel like listing everything but at 75,000 miles this thing practically got new gaskets from the oil pan up. Other than thermostats and an alternator it's been trouble free for the almost year and a half I've had it. I'm thinking it was owned by an elderly person that had money and this dealer knew they could make money lying about nonexistent issue. Say what you will but I've seen it happen, we have a local Chevy dealer who's head mechanic is known around town as "Head gasket Dan." I don't care what problem you have he'll tell you you need head gaskets and he'll do the job for only $2500. People fall for it all the time.
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  2. #2
    2 decades of DDing Box Panthers, now in a Whale VicCrownVic's Avatar
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    I had a coolant leak on my '89 that ended up being a pinhole in one of the small hoses above the water pump.
    When I had the car running with the hood open there was no leak to be found. When I goosed the throttle the leak finally made itself known.
    To track your leak down, open your hood and with the engine running pull the throttle cable or lever to rev the engine. Your leak might make itself known when you do this.

    On my '89 it would spray coolant up and the radiator cooling fan would blow that coolant all the way to firewall/wiper cowl area.
    Vic

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  3. #3
    What a Luxury car should be. mercurygm88's Avatar
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    Quote Originally Posted by VicCrownVic View Post
    I had a coolant leak on my '89 that ended up being a pinhole in one of the small hoses above the water pump.
    When I had the car running with the hood open there was no leak to be found. When I goosed the throttle the leak finally made itself known.
    To track your leak down, open your hood and with the engine running pull the throttle cable or lever to rev the engine. Your leak might make itself known when you do this.

    On my '89 it would spray coolant up and the radiator cooling fan would blow that coolant all the way to firewall/wiper cowl area.
    I plan to give that a try but it was past midnight when I was messing with it and that didn't seem like the best time to make a bunch of noise. When I had the '88 I had a slow leak in that little tiny right angle hose coming off the water pump. Then I believe on the day I was going to get a new one it just decided to blow off halfway between home and the parts store.
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  4. #4
    Stow It! GM_Guy's Avatar
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    Wrap or stuff some paper towel around some suspect areas. easy visual when you remove it (ie: wrapped around heater core to hose connections, stuffed under the intake, over the coolant pipe. And if something is spraying, it'll somewhat contain it rather than spraying down everything.

  5. #5
    Road Warrior Kodachrome Wolf's Avatar
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    When the puddle forms, where under the car is it forming?

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  6. #6
    What a Luxury car should be. mercurygm88's Avatar
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    Well as luck would have it after 3 tries throughout the day I can't get it to leak anywhere.
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  7. #7
    What a Luxury car should be. mercurygm88's Avatar
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    Quote Originally Posted by Kodachrome Wolf View Post
    When the puddle forms, where under the car is it forming?
    Directly under the front of the engine, even though the leak is obviously up top somewhere judging by last nights coolant spray pattern. Try as I might I couldn't get it to leak anywhere today.
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  8. #8
    Member tbear853's Avatar
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    If driving or just fast idling hot, the pressure cap will limit coolant pressure. I once found a leak by simply rinsing all evidence of a leak off an engine, letting it dry, then letting it idle at a high idle until good a warm, and watching suspect areas closely, avoiding belts and fan.
    No ... I'm not arguing with you ... I'm just explaining why I'm right ...

    Now go ... and whatever you do ... have a safe trip!

  9. #9
    What a Luxury car should be. mercurygm88's Avatar
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    I donít know if the coolant reservoir caps on the later cars without an actual radiator cap work the same way.

    Mine appears to just be a one piece plastic cap with no way to release pressure.

  10. #10
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    Rent a cooling system test kit. Should be able to find it that way. Pretty sure MityVac has one that will work with that style cap. And you won't have to deal with a hot engine/coolant to do it.
    These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.

  11. #11
    What a Luxury car should be. mercurygm88's Avatar
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    Neither of the auto parts stores in this shit hole town have a cooling system test kit that will fit this car. Autozone doesn't have one at all, someone rented it and stole it and they never replaced it. O'Reilly's doesn't even have one for rent at our store. I have not been able to get it to leak a drop the last 4 days and I've driven a good 4-500 miles in that time. I guess I'll update if it ever comes back, I still suspect an iffy thermostat gasket.
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  12. #12
    What a Luxury car should be. mercurygm88's Avatar
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    Well I fixed it. Turns out it was my crappy deformed thermostat gasket thatís been reused multiple times.

  13. #13
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  14. #14
    fomoco panthers !
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    Why would anyone reuse a thermostat gasket ? Says allot about a mechanic. Makes me wonder how cheap the thermostat is.

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    Member ZackN920's Avatar
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    ^

    Re-read his first post. He was reusing that gasket. Kept getting bum thermostats.

  16. #16
    fomoco panthers !
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    My apologies to mercurygm88 .

  17. #17
    What a Luxury car should be. mercurygm88's Avatar
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    Quote Originally Posted by Mainemantom View Post
    Why would anyone reuse a thermostat gasket ? Says allot about a mechanic. Makes me wonder how cheap the thermostat is.
    Because it is just a rubber o-ring on the 4.6 there is no gasket around the bolt holes between the water neck and intake like on a 5.0, and everyone including Ford says it is reusable. Also the only parts store in the area that carried that o-ring charged $10.99 of it! Yes $10.99 for a rubber o-ring! The thermostat was $8.00.
    Last edited by mercurygm88; 06-20-2021 at 07:27 AM.
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  18. #18
    What a Luxury car should be. mercurygm88's Avatar
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    Quote Originally Posted by ZackN920 View Post
    ^

    Re-read his first post. He was reusing that gasket. Kept getting bum thermostats.
    I was getting bad thermostats I have all three of them laying in the garage as examples, not one lasted over three months. They are all stuck wide open.
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  19. #19
    What a Luxury car should be. mercurygm88's Avatar
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    And I was mistaken. 200 miles since I replaced the gasket and the leak is back. This is very frustrating since itís an intermittent leak and I canít make it leak on demand, itís also an incredibly slow leak. I was starting to think it might be the front drivers corner of the intake manifold. But thereís no way that could spray coolant in the areas that are getting wet. Iíve tried revving the engine by hand and looking for the leak but when I do I canít cause it to leak. Nobody around here has a test kit with an adapter that will fit my coolant reservoir. Iím completely stumped.
    2002 Mercury Grand Marquis LSE - Daily Driver
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  20. #20
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    Ebay says it is not compatible but stant says #12026 is correct and the sellers description says it will fit.

    https://www.ebay.com/itm/11481600370...wAAOSwKvdgpQmy
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