Under Hood Insulator

Discussion in 'Fox 5.0 Mustang Tech' started by NFLjunkeez, May 18, 2013.

  1. I just ordered a custom fiberglass hood for my 1991 convertable at http://www.latemodelrestoration.com/item/CER-101/1987-93-Mustang-Ram-Air-Fiberglass-Hood-15-Rise

    My question is... will I need to put on a "Under Hood Insulator" like the one that's on the original metal hood? Or will the fiberglass hood withstand the extream heat that's put out from the custom headers?

    I'm having an overheating issue so I replaced the mechanical fan with an electrical dual fran from a contour. (Obviously I've also upgraded my altenator to a 3g as well) My fans are powered though some relays... yada yada yada.

    My 40amp relay (mounted close to the hood on the passanger fender side) burnt out (Melted connector) at the power wire to the fans. I think this is a combination of the headers putting out so much heat and not having a proper ventalation system, hence the ordering of the new hood.

    EVERY wire is running hot to the touch, including the possitive battery cable at the battery connection. The aforementioned relay can't be held for more than a couple of seconds without getting burnt.

    The overheating is somehow causing battery drain. In other words, when the car gets to hot (3/4 to max range on temp gauge) and I shut it down to prevent damage I can't start it again without a jump. Is this an isolated problem or is it all connected to the heat under the hood?

    Sorry for the lengthy post but I wanted to ensure you guys had all the info. Thanks
  2. When you did the 3g did you up the power wire coming off of the alternator or did you reuse the black and orange wires?
  3. you don't need the insulation , I have a cervini with no insulation

    Sent from my iPhone using my fingers
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  4. [;) L8trquote="MikeH686, post: 8728725, member: 179793"]When you did the 3g did you up the power wire coming off of the alternator or did you reuse the black and orange wires?[/quote]

    I used the same 3g wire that came off a 3g alternator in a junk yard. it's yellow and green. it goes about 4' to a 150 amp inline fuse. from there it's the black and orange line for about a foot until it connects to the starter solenoid.
  5. 1 you don't need or use an underhood liner for a fiberglass hood
    2. the power wire for a 3g needs to be at least 4 gauge all the way to the starter solenoid- both sides of the mega fuse. Do not reuse the factory power wire as it is a fire hazard and does exactly what you are describing. It cannot handle the amperage of a stock alternator and certainly not a 3g.
    3. you need to also add another 4 gauge ground from the block to the chassis or the ground post behind the battery

    The relays are melting because you probably don't have a sufficient ground and/or faulty connections. Did you use at least 10g wires for the fan wiring to and from the relays/ground/power with at least a 40 amp megafuse in the power wire. Did you solder all of the connections or crimp them? Crimping will loosen over time and often make bad connections.

    If you used relays, the fans are coming on full amperage when they kick in. I prefer a variable speed controller like the FAL 33054 or the DCC model. If you want to use relays, I recommend the Volvo one as it handles 2 speed and a temp son/off sensor which screws into the thermostat housing.

    Unless the wires are right on the headers, I've never heard of headers melting the wires or relays. I've run e fans on several cars, from mild t0 10 second cars and never had that issue. The most likely problem is the wiring of the alternator and.or the fan is not adequate.
    NFLjunkeez likes this.
  6. I agree, custom headers wouldn't really be putting out more heat than any other kind of headers. Depending on the amount of space between the primaries they could run minimally cooler due to better airflow around them, but that's a stretch. Most likely a wiring issue as opposed to a "heat" issue.
  7. I have a Cervini hood with open ports, I noticed temp when down after I installed it. Heat rises and with the open ports the heat has somewhere to go as opposed to the Factory sealed in hood. No insulator required
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  8. If your car is getting to hot maybe you should fix that issue first, and if its getting hot while at cruising speeds over like 60ish then you have a problem somwhere in your cooling system like 1 of the following.

    1.Your temp sender isnt working rite
    2.your raidiator is clogged up internally/externaly or its just junk by now if its the old stock one
    3.your coolants might be getting low
    4.your motor might have a clogged cooling line or passage internaly (not to likely)
    5.your just driving to slow and your fans arent working properly
    6.you live on the sun or it might be an eletrical issue like stated above with the alt wiring but i wouldnt think so if you have the correct gauge wire already.
  9. Also have you considered just upgrading to a nice aftermarket raidiator? They come in chrome and stock looking form and most will decrease your temp like 20degrees i think maybe more I cant remember but you could pick up a new one off feebay for like $150 give or take some
  10. Thanks for the info. I changed over the battery cables from 8ga to 4 ga and now they dont get hot. as far as the fan wiring goes I used the same wiring harness that came with the fans, which were also being run off a 3g alternator. So I assumed that the wiring was already meant for the 3g alternator. I never changed it and it looks to be 12 to 14 gage. Since I upgraded my alternator and battery cables to 4ga I have been blowing my 30amp inline power fuse that goes to the relays. So based on what you said my next job is to upgrade the fan wiring to and from the fans and relays to 10ga and replace the inline 30amp fuse to a 40amp mega fuse. Hopefully that will end my overheating and fuse blowing issues.

    Thanks for the in depth step by step info as it helped out a lot!
  11. I upgraded my radiator to a 3 core a few months ago. That was my 1st attempt to attacking the overheating issue. Then I had the engine block routed to remove any cloggings and that didn't help. So I continue to plug away. Trouble shooting is always fun!
  12. 1) It's a new sender, but always a possibility
    2)It's a new radiator
    3)Keep putting in new coolant due to frequent overheating
    4)Was recently routed thinking that was the last option
    5)To slow? LOL, My wife wishes!
    6)I live in Vegas so the heat outside is a variable
  13. That's my logic but wanted to ask those who have done it. Thanks for your reply
  14. My car runs very hot. The temp gage doesn't show it but a lot of heat comes out, especially from the passenger side. A mechanic (not high performance) friend of mine said that the owner before me installed some wicked headers and they put out a lot of heat. The owner before me was a ford mechanic and he raced the car but never made the improvements to handle his upgrades.

    Speaking of which... what size distributor cables should I be running. I just had a tune up done and they installed 8mm.
  15. If you really feel like your headers are putting out more than "normal" heat then you should wrap them. Do you know what temp your thermostat is? Maybe you're running lean if you're getting too hot as well, pull your plugs and read them. I believe 8mm or 8.5mm is good for wires.

    Good luck
  16. To me, this sounds like its more than just a "cooling issue", especially if every wire is extremely hot to the touch. I had over heating problems, stock hood, and my wires were never hot. My guess, you have an issue with your cooling system, and a wiring issue. Check your grounds, and make sure the power wire to your solenoid, from your 3G, is brand new. I didn't use a fuse for mine, I ran 1 foot of (2) 12G fuselink wires, with an o-ring crimped on, which attached to my starter solenoid. This was for liability and for a cleanlier look under the hood.

    I now have no cooling issues. I flushed my system, bought a Pro-form electric fan, new 180* thermostat and my car stays extremely cool now.

    I also have never heard of headers, especially aftermarket, causing the extreme heat issues your having. Your exhaust should have enough flow to exit most of the heat out of the engine bay, unless your running cats and they are clogged, or there are other issues causing this to happen. As its been said above, if you strongly believe its the headers, wrap them up.
  17. I believe the engine temp and hot wires are two separate issues and should be treated as such. The HOT wires are from being undersized for the amount of current being drawn and undersized wires cause flow resistance and as a result get really hot. This is one way electrical fires are created. The OP already bumped up the size and already see's the benefits.

    So now it's time to move on to why the engine is getting hot. Is your fan kicking on at the right temperature? Have you inspected the water pump?

    Headers also can get super heated if you run too lean or have the timing too far advanced. I'd get a timing light and check your timing. My friends sand rail had a brand new motor in it and the headers would glow after a short 15 min run around the camp site in Glamis. Turns out his timing was too far advanced even while running high octane (91) pump gas. No timing light? Read the plugs, they'll tell you everything you need to know about air/fuel ratio.

    Good luck.
  18. Something else that I forgot to mention is... the fenders are also getting getting very hot and can't be touched for very long. This is when I have the car running in the garage. So, can a clogged cat cause this. I have 4 cats. If so, how do I test for a clogged cat?
  19. If this happens while letting the car idle in the garage, what I would do, is disconnect the exhaust after the headers. Let it idle just like you would before and see if you see a heat difference. I would highly recommend NOT driving it this way though. Just my way of diagnosing if its a clogged cat.
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  20. Fans are kicking on ok and the Water pump is new. Timing light was put on it today and the timing is within parameters. I just had "Firestone" do a complete tune-up so I'm now running with new plugs, wires, and rotor. As far as the "Running lean" comment... I think it does. When you pop the hood you can smell the fuel. How do I adjust?

    Another thing I've noticed is I have NO air flow into my radiator due to no grill opening on this car. I have ordered a 93' cobra grill insert http://www.latemodelrestoration.com/item/LRS-8200F/1987-93-Mustang-93-Cobra-Grille-Insert-Kit so I'm hoping that (along with new hood listed above) will help with my overheating.