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Lost Compression on one side of 4.0 sohc

Discussion in 'Stock 1995 - 2001 Explorers' started by ninety8, September 20, 2012.

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    1. ninety8

      ninety8 New Member

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      Hello everyone. I'm new here and am having a problem with my 1998 Mercury Mountaineer 4.0 sohc 4x2 with 128,000 miles I bought new. I have always kept it regularly maintained and never had any real problems. It does not use any oil between changes or have any other problems that I know of. All of a sudden about a week ago when it started it had a skip or miss at idle. When you drive on down the road it doesn't run that much different than normal. I took it to the local dealer to have checked they come back after hooking it up to some tester and say I have no compression on one bank. They then tell me I need a new engine since they think the timing chain or something is bad and it would be just as cheap to replace the engine. This is ridiculous. There is no timing chain slap or noise other than what it has pretty much had since new. It also, like I said runs way too good to be running on only 3 cylinders. Oh and I also have a different than normal exhaust sound and it sounds like a very small exhaust leak. This just happened out of the blue, ran perfect then shut it off, then next time it did this. I am disabled and this is our only vehicle. I don't have the money for an engine or major repairs or to let someone just start replacing parts. I think this is a fairly small problem causing the tester to get a false reading. Any help or ideas about this would be greatly appreciated. Thanks everyone in advance for your help
       
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    3. 2000StreetRod

      2000StreetRod Staff Member Moderator Elite Explorer

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      slipped timing chain?

      Low compression of all cylinders on one bank is usually the result of a slipped timing chain. Low compression of two adjacent cylinders is usually due to a blown head gasket or a cracked head. If you don't trust the dealer and can't measure the compression yourself then you'll have to get a second opinion. If the right bank (passenger side) cylinders all have low compression then the engine will have to be pulled to replace the rear cassette. The left cassette can be replaced with the engine in the vehicle. A special tool set simplifies the process and results in less risk of incorrect installation and timing. At least one member with the early S0HC V6 engine experienced cassette guide failure at only 45,000 miles. See my helpful threads to learn more about your engine and its camshaft timing system.
       
    4. 99minneotaexp

      99minneotaexp New Member

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      Unfortunatly Streetrod is correct about the timing chains and these engines. I would be suprised if it hadent been making noise for some time. But the unfortunate design of these engines is prone to tensioner failure. It could be something as simple one of the chain sprockets slipped on a shaft since very few of the parts are keyed.
       
    5. ninety8

      ninety8 New Member

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      Thanks everyone. It isn't I didn't trust them it just seemed so far fetched. I did work there for almost 19 yrs as parts manager so I was not totally ignorant to the sohc' s problems. In fact I had previously worked at another Ford Dealership for almost 8 yrs on the counter. As such I never was a fan of the engine in any of it's forms. My Dad actually bought this and when he passed away in 2006 I started driving it. I guess being disabled for the last 7 yrs. and having no money it just took me by surprise and I was grasping at straws for a less expensive fix. I have been trying to get hold of the recalls and tsb's concerning this problem but have not been successful so far. Does anyone know if there are any open recalls for this? Does anyone know anywhere on the internet I can get tsb's and recall info for free? Yes I know I have heard it all my life if you don't trust them why take it to them. Sorry if I offended anyone technician or other but I thought I needed a coil and was hit with this so I was kinda blindsided. I'm settled down now so on to trying to get her fixed. Thaks again everyone.
       
    6. swshawaii

      swshawaii Explorer Addict

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