Losing antifreeze
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Joined: Feb 2004
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From: Iowa
Losing antifreeze
The last few times that I have change the oil in my 99 4.0 I have had to add not quite a half gallon of antifreeze. The oil looks clean cannot find any leaks or smell antifreeze inside or out. Any ideas? Thanks
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Joined: Jan 2003
Posts: 9,748
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From: Connecticut
Originally Posted by Ken00
The 4.0s are known for leaking a little at the intake manifold. Rockledge should have more info on this topic.
After my inital surprise, I looked into the issue a little bit and bounced it off a few knowledgeable people. Turns out that the 4.0L can have some problems with lower intake bolts loosening up and/or the lower intake gasket breaking down. (This can also cause air leaks and lean conditions). After considering all possible causes, I honed on this one, as it made the most sense.
So I re-torqued the lower intake bolts (5 of the 6 needed some torquing, a couple of them were way off) and then performed a cooling system pressure test (and radiator cap test) which showed no leak down. Sometime after that I performed a compression test, and all the cylinders were within specs.
So I think I'm good to go. But I will be having another oil analysis done later this spring, and if my oil still has traces of coolant in it, then I'm going to tear into my 4.0L a little and replace some gaskets.
Freshman User
Joined: Mar 2004
Posts: 45
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From: Tughill (snow country)
Just had to take my 98 in for a intake gasket (Antifreese leak). It used some coolant for the past 6 months. I pressure tested and no leak down. Luckly I was driving when it went, it really leaked out the left rear corner of the intake. So if your using coolant really check it out.
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