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Coolant in spark plug holes?


Old 10-05-2007, 01:45 AM
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Location: Tijeras, NM (Albuquerque)
Posts: 81
Coolant in spark plug holes?

Hi everyone, I finally signed up and registered. This site has saved me numerous times when working on my wife's 97 Expedition with 4.6. Great site with lots of real helpful information. I used the help here to fix my EGR passage in the intake elbow that was plugged up. Also replaced the coil paks which had a bad one. I used the forum to help with replacement of the heater hoses, although I could not get off those damn hose connectors, I ended up cutting them off with a real small cutoff wheel, then used regular old worm drive hose clamps. I had coolant leaking into the #3 spark plug well and causing a misfire, that is where the forum here helped me determine I needed to replace the hoses as my fittings were leaking. No heater lines leaking now, they are dry. Changed the plugs out around 105K, that was a PITA job. It has about 125K on it right now.

So now to my problem. I can smell coolant from under the hood, but no leaks on the ground. I look all over the engine and can not see any obvious leak, but there has to be as I am getting coolant in the #3, #4, #7 and #8 spark plug holes. I look and can not figure out how it is getting in there, no coolant lines in that area for #7 or #8 or obvious path from somewhere. I have been taking the plug wire out, blow compressed air in the hole to "dry" it out. Also blow out the plug wire boot. Spray a little WD-40 to help seal it and also make easier to remove in future. This is a fairly recent occurrence, over the last couple months. The engine starts missing, sets the CEL, and the reader indicates P0303, P0304, P0307 or P0308. Misfire in that number cylinder. My blowing air fix has seemed to help thus far, but I am concerned about how I am getting coolant in the spark plug holes? Any help is appreciated.

Oh yeah, even though I go by 38Chevy454, I have used that name on several forums, I am really a hot rodder that tolerates my wife's newer Expedition I have some old Chevy's and Fords as well, here is my daily driver 49 Ford COE, one pic at Bonneville Salt Flats this year during Speedweek , and one closer up:

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Old 10-05-2007, 01:56 AM
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Join Date: Oct 2007
Location: Tijeras, NM (Albuquerque)
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Forgot to add, overall this Expedition has been a pretty good vehicle. The mileage is not bad for a big vehicle, pretty reliable as far as no major breakdowns. Knock on wood no spark plug blow-out(s). The driver's P/W motor broke and replaced that several years ago. Keep the PM up and current: engine oil changes every 3000, trans every 25K with synthetic, did the rearend and transfer case at 100K. It's a 4x4 version, also forgot to add that.......

Probably the biggest repair was the A/C compressor failed, and of course when i was out of town for a new job while my wife was still back at the old house getting it sold. Could not do that repair myself being out of town. Most of the work on the truck I try to do myself.

Thanks gain for any help with my mysterious coolant problem. I tried searching the forum and could not find anything that was not due to the heater hoses. I am pretty sure this is not form the heater hoses, this time. Terry
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Old 10-05-2007, 10:29 AM
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Location: Abilene
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WOW and welcome

That is one cool looking truck, have you tried making a LSR

I'm guessing but maybe you have a intake gasket leaking ??

Last edited by RacingJake; 10-05-2007 at 10:32 AM.
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Old 10-05-2007, 10:36 AM
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Jake's got the right idea. Usually coolant in the plug wells on a 4.6 is from leaking intake gaskets. If you have a cooling system pressure tester, you can catch them with the engine cold. Pump it up to 17 or 18 pounds or so and listen for any hissing. They seal up when the engine warms up, since the heat makes the gaskets swell.
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Old 10-05-2007, 10:48 AM
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Welcome! That is one fine looking truck! What engine are you running in it?
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Old 10-05-2007, 03:52 PM
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Join Date: Oct 2007
Location: Tijeras, NM (Albuquerque)
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Thanks for the words on my COE. I mounted the cab on a 74 GM dually reg cab chassis. I still need to build the flatbed for the back, out of diamond plate steel. The chassis was given to me by a friend, can't beat the price! I used a 350 SBC and turbo 400 trans. Nothing too fancy, not trying to build a car hauler or trailer towing truck, just a fun run around driver.

Back to my coolant in the spark plug holes, so the likely culprit is a leaking intake gasket you say Jake? I was wondering if there is any better gasket for this, or recommendations? Fel-Pro, Motorcraft or other? Thanks again for the help! IS it a common problem for the gaskets to start leaking a bit when the miles get up to the range, 125K, I am at? I assume the intake gasket replacement is a pretty easy straightforward job, just a R&R type job? Except for the wonderful access to the bolts in the back of the intake under the cowl.

Also Jake, I do happen to beplanning/building a land speed racer, I have a rough 55 Studebaker coupe that I am going to build up. Too rough to bring back for a resto, perfect for making a racer. My goal is 200+ mph. Right now I just got the car and cleaning it up and deciding exactly what chassis, rollcage, safety, drivetrain, etc.

Last edited by 38Chevy454; 10-05-2007 at 04:00 PM.
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Old 10-05-2007, 04:31 PM
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One of these days I'd like to get my hands on a 53 or 54 Studebaker Starlite coupe - I think that is one of the sharpest looking cars ever built. If I'm going to drive it, I want a V8 with a stick.
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Old 10-07-2007, 12:11 PM
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I'd go with motorcraft, other's might be Ok but these Mod motor's seem to be alittle touchy when you step out of the oem box
I'd double check the torque value after a heat cycle too

Everytime I see the salt it make's want to watch the World's Fastest Indian again. I'm more of a motorcycle nut but I'd love to take my dragbike out there just to see what it could do
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