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Thread: engine overheated in 04 Discovery

  1. #1
    Join Date
    Jan 2012
    South East Michigan

    Default engine overheated in 04 Discovery

    Over the summer I had a coolant leak which has been fixed but the engine did overheat a few times.( My wife uses the vehicle as an everyday driver and loves driving it, but neglects to check any oils or coolant.) We started having coolant loss even after fixing the leak and the engine would periodically overheat, but not all the time. Its probably worth mentioning that shortly after we bought the Landy it started misfiring. I changed the plugs and leads, but she still misfires slightly during warm-up. We've gotten to the pont to where its not drivable. Its obvious the head gaskets leak. I can see that exhaust gasses are leaking into the coolant system.

    I'm preparing to do a gasket job and was wondering if there is anybody out there who can help me on what to expect. Are the heads more than likely cracked due to overheating?
    Should I just go ahead and buy replacement heads from Roverland Parts.Would I be better off going this route or should I have my heads checked first. Are there any good all in one kits out there that anybody knows. I know that to do the job right you need to replace all the head bolts. Then there's the question of did the bolts get stretched in turn messing up the threads.

    Can anybody help get this job done, the right way,the first time?

  2. #2
    Join Date
    Oct 2011
    Mountains of Western Pennsy.


    Overheating one time is enough to drop a cylinder liner and/or warp a cylinder head. On the 4.0 check for head warping and seeping around liners on the cylinder deck of the block. On the 4.6 additionally check for cracks around the upper cylinder head bolt holes on the block. I don't bother with the torque to yield cylinder head bolts, I use ARP studs instead (there are folks who say this is not needed, but I don't like doing jobs twice), the Buick 215 studs are cheaper than the Land Rover studs (you just get some extra studs for the lower deck holes that new type Rovers don't have). I also use spray-on head gasket sealer (again folks say it's not needed, or desirable). Use a thread sealer on the head bolts (blue Loctite is good). I did this on a 4.6 a couple years ago (with cracked bolt threads) and my 3500S many years ago and all is still good. On the 4.6 CRC sealer ended up being used due to leaks caused by the bad bolt threads in the block. If the heads are warped (and I bet they are) a good automotive machine shop can fix them up. If a cylinder liner has fallen out of place, that's a whole new can of worms...

    '99 Disco II
    '95 R.R.C. Lwb (Gone...)
    '76 Series III Hybrid 109
    '70 Rover 3500S

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