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Thread: HO upper intake manifold swap, now spewing antifreeze.

  1. #1
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    Default HO upper intake manifold swap, now spewing antifreeze.

    Well, I took on one of those projects that as usual took longer than planned, but everything appeared to go pretty smoothly (5.0 HO upper intake swap). That is until I fired it up. Turned over, high idle kicked in and ran smoothly, and then when it dropped down, started stumbling and stalled. Started it again and ran really rough. Shut it off to check if everything was still attached and noticed the sound of liquid trickling somewhere. Turns out it was coming out below near the fire wall on the passenger side. Any ideas as to what the heck just happened? Maybe I disloged a hose to the heater core? Would that cause it to stall/run rough? HELP! This is my only car. On the bright side, I have tonight and most of tomorrow to fix it whatever it is. Any input would be appreciated.
    Thanks,
    Dave

  2. #2
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    check all the vacuum lines and make sure they are all in. If its an old hose and you were bending them at all, they can crack sometimes.
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam ,beanman header, Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

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    I havent looked at a V8 SO since i had mine 3 years ago but i know coolant runs in the upper part of the intake manifold by the EGR spacer. Check those hoses out.
    1987 turbo coupe 5speed: Boport stage 3 head/2.5 cam ,beanman header, Precision stage 3 50trim .63 turbo, Tial 38mm wastegate, Jangus gutted/ported intake manifolds, 60mm tb, Jangus open dumptube, Jangus 3" elbow, Perrin boost controller,Esslinger adjustable cam pulley, Esslinger small crank pulley, stinger FMI, RFL BOV, Spec stage 3 clutch, B&M short throw, 140 speedo, Walbo 255lph, BBK fpr, 3G alternator, ARP studs. Be faster...

  4. #4
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    May have been coming from the lower intake at a water port, or the heater core went bad, or the hoses to the heater core (at the core or the pipes).
    '88 Sport--T-5,HURST shifter,TMoss GT-40 intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,70mm t-body,3G,mini starter,Taurus fan,BBK headers,O/R H-Pipe, Dynomax mufflers, deep and deeper Cobra R wheels,Mass Air, Mass Air and 24's,8.8 with 3.55's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft.

  5. #5
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    I only replaced the upper manifold and used a new felpro gasket, cleaned both surfaces of upper and lower manifolds at the gasket. I am planning on pulling the bolts out and lifting the upper back off to see if I can identify the source of the leak. I did not have a torque wrench, so I am wondering if I may have come up shy on one or more of the bolts. I made sure I had the bolts tight, but didn't want to over do it. The Mustang manifold had one of the lines capped on the underside, but my original had hoses attached to both. I went with the stock setup and hooked both up. I'm getting ready to go back outside and start again.

  6. #6
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    This was an upper intake swap from an 87-93 mustang. I pulled the air intake hose off and noticed a puddle of coolant outside the butterfly valve. Wondering if I hooked up the hoses wrong. If not, maybe a bad intake? Purchased on ebay, but looked to be in excellent condition.

  7. #7
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    Check your throttle body coolant lines, mainly the one that runs off the backside of the throttle body to the back of the lower intake. A while back, on my lincoln, I had a coolant leak and couldn't for the life of me figure it out, I traced it down to that hose having a small pinhole in it.

    No idea on the rough idle, just make sure you check all your vac. lines to make sure they are in the right place and the hoses themselves are in good shape.

    When swapping an intake, you can't help but have to disconnect vac. lines and coolant lines and move them around and pull on them and whatnot, this is where old rubber will crack and tear.
    FOXLESS!!

    1994 Lincoln Mark VIII


  8. #8
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    Vacuum lines hooked up right. Runs rough because the cylinders are full of antifreeze. pulled off the throttle body and the gasket was pretty brittle, installed a new one and got it to fire back up after a little cranking. LOTS of white smoke through the exhaust, and still getting a drip behind the engine. Dawned on me that the drip was coming through the larger breather(?) hose that snakes down behind the motor from below the upper manifold. Shut it down and heard kind of a sucking whistle as it stopped, figured plenum gasket may not be seated right. Pulled off the manifold upper and noticed that the new gasket was wet. So, should I have replaced the gasket between the manifold and egr spacer, too? Does coolant flow on the manifold side, too? Mine was stuck fast and didn't budge when I gave it a pull, so I didn't check it. How else would I be getting antifreeze into the maniflod?

  9. #9
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    Yep block off the small coolant lines to the EGR spacer and call it a day, you can just use a length of hose between the heater tube and fitting at the rear of block...... I haven't run water through mine in the 10+ years the 5.0 has been in the TC...

    Not that it will help your condition, but if you're using the original SO throttle body and spacer, the HO intake will net no improvement at all... 65mm opening it the HO upper is pulling through a 50mm T-body and spacer...

    BTW if you've gotten coolant in the oil, be sure to change oil before you drive it, bearings will be toast if you don't...

    - SOLD ----------- SOLD ------------ SOLD --------- PARTED(RIP) --- Yeah It's Got A V8 .
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    1969 Fairlane Cobra 428CJ 4-Speed

    1972 Comet GT 306 C4

  10. #10
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    Ok, project finished....The problem was that the used manifod I installed (was purchased complete with egr and throttle body) was old when I got it, and then sat several years before I felt up to the challenge of installing it. All of that sitting around caused the throttle body-to-egr spacer gasket to dry out, and when I fired it up, it blew out after a few seconds and allowed the coolant that circulated through to enter the throttle body and be sucked into the engine. The coolant dripping from behind the motor was what had run down and out of the underside breather hose. I just didn't run the car long enough after installing the new gasket to burn out all of the antifreeze from the cylinders. It took longer than I anticipated to clear, and I was starting to freak out a little bit. When it was all said and done, I removed and plugged the coolant lines going in and out of the egr spacer to eliminate the possibilty of fluid entering the system. When it still smoked from the exhaust, I figured I just needed a little more patience. Took if for a cruise on the highway so I could open it up and speed up the process. Cleared out in about 2-3 miles. Now that the new HO intake is installed, there is not a big difference, but I get a little more acceleration and performance sound when I step on it. I really think I got at least as much improvement when I took out the intake silencer and installed my K&N panel filter, but it may just be my imagination. Thanks for everybody's input, and I hope this thread will help somebody else some day.

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