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Replacing a head gasket (Revised)

Discussion in '1994-2004 V6 Mustang Tech' started by Rich, Nov 3, 2003.

  1. Rich

    Rich New Member

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    Mu 94 V6 has low compression in the #4 cylinder but it is not burning oil and there is no oil in the coolant. But overtime I will loose coolant and the car runs hotter and hotter especiall at idle. So I believe that the head gasket has failed between the cylinder and the cooling system.

    I have 2 questions:
    1. How much should it cost to have the head gasket replaced?
    2. Do both head gaskets have to be replaced?

    \/ NEW PART \/
    From the response I received and some conversation I have had, I decided to replace my head gaskets myself. However today a talked with a highly recommended mechanic and he says I could have a coolant leak in my intake manifold. Has anyone heard of this?

    Rich
     
  2. FlooredMustang

    FlooredMustang New Member

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    Ideally, you could replace your head gaskets for 2 to 4 hundred in parts if you could do it yourself. If your going to take it to a shop it will be a minimum of $1000, and as much as $2000 or more! And that doesn't necessarily mean that you will get the best job that can be done. A lot of places will just take your money and slap on new gaskets without resurfacing the heads, or even replacing the head bolts! You will be lucky to get 10k miles on the new gaskets if this happens to you.

    I have a 97 3.8 5 sp coupe that I have been driving with a leaking head gasket for over 8 thousand miles now. Why (and how) in the hell would I do that you say??? Well, I actually wanted to blow the engine because for the price of a shop replacing the head gaskets I can buy a 4.6 engine with computer, wiring harness, all accessories and put it in myself. I like the car, and it's really clean, so why not! I've got other stuff to drive in the meantime. You might want to consider this option.

    But my engine never blew and is still running great. That is probably because I took the thermostat out as soon as I knew the gasket was leaking. The reason for the overheating under these circumstances is that the leak blows the coolant out of the top of the engine faster than the thermostat lets it in. When there's no coolant touching the engine side of the thermostat it closes... A viscious cycle resulting in temp gauge fluctuations, heater not working, and ultimately warped heads. When the heads warp you will definitely have coolant in your oil = End of engine. BTW, an easy way to check for a leaking head gasket if you're losing coolant but don't have antifreeze in the oil is to pull your spark plugs. Coolant going through your combustion chamber will leave a green hue on the plug. It will almost always be the number 3 and/or 4 cylinder.

    Anyway, the most expensive part of the gasket replacement is the labor so doing it yourself is the way to go. You need good tools, a good clean place to work, your Mustang repair manual and some good info from the web. Here is are couple good overviews on head gasket replacement:
    http://www.babcox.com/editorial/us/us80222.htm
    http://www.supercoupeperformance.com/Head Gasket Article.htm

    I like Fel-Pro, here are some of the part numbers:
    Head Set # H88857PT8
    Torque To Yield Bolt Set # ES72156
    Upper Intake # MS94046
    Lower Intake # MS95731
    Exaust Manifold #MS95528
    Sealants: Red #3, Yellow#5, Blue #4, Gray #2, and engine assembly lube.
    You will probably also need an EGR valve gasket and you should get the correct "bleeder valve" type of thermostat. Personally, I would spring for the more expensive ARP head bolts instead of the stock TTY style.

    And yes, you should do both gaskets while it's apart. Only changing the leaker on a 3.8 is just asking for trouble!!! Don't forget to check the heads and block deck for flatness/warpage with a machinist straightedge and feeler gauge. .002 or less is OK for aluminum heads but you should have them resurfaced anyway.
     
  3. FlooredMustang

    FlooredMustang New Member

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    Hi Rich,

    Yeah, it's totally possible that you could have a leak from one of your coolant passages to an intake runner at either one of the gaskets between your lower intake and head(s). Since you have to take off the upper and lower intakes and everything bolted to them to get to your head gaskets anyway, you can check these when you get to that point.

    The thing is that the V6 94's and 95's are especially prone to blowing head gaskets and you're showing low compression in the number 4 cylinder which is particularly suspect. What I would do is have all the parts you need ready to do a head gasket replacement when you start working, and if it turns out that you have an intake leak you could still do a cylinder leak down test (with both valves closed on each cylinder you're testing) to check the condition of the head gaskets. Hell, you could rent the tool to do that before you take the engine apart at all.

    The bottom line though, on this engine is, if you have it far enough apart to pull the bottom intake, you might as well go all the way and do the head gaskets. It's a big job but most anyone with mechanical inclination can do it. Take your time, hell you can even take pictures of what you take apart as you're going, write on a piece of tape where the vacuum hoses and electrical connectors go and stick it to them, flip your local mechanic a tip for info if you get stuck on a big question, build up a good repoire with the machine shop who's going to resurface your heads.

    And of course, post questions to all the knowledgeable people on this board! By the way, I'm new here, and I apoligize for just slipping in out of the blue! My names Rick and I just found this board. There is a wealth of infomation here! My thanks to all the contributors!!!