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Losing coolant slowly


Well-Known Member
March 24, 2009
Reaction score
City, State
Blacksburg, VA
Year, Model & Trim Level
97 XLT 4.0 SOHC 4x4
So about 2 months ago I had to redo the seal on the thermostat because coolant was leaking around it. The other day I was checking my fluids and realized that my coolant bottle was empty and added about a quart of antifreeze. I don't see any obvious leaks in the engine bay. Any suggestions on where to look?


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It could be the lower intake manifold gasket, its a common problem. I had the same problem with slowly losing coolant and noticed a little pooling up behind the thermostat on top of the engine. Not an expensive fix but takes time to remove the parts to get to it. Also if you replaced any of the spring hose clamps with band style hose clamps they can loosen up a bit when the engine warms up.

My engine is throwing codes (bank 1 and 2 running lean). I guess that confirms that it's a bad intake gasket.

So this would be a good time to replace the front tensioner too right?

The lean codes could be a bad upper intake manifold gasket. It would probably be worth your while to replace the upper intake gasket manifold while your at it if you find the leak is coming from the lower gasket. You could buy or make a radiator pressure tester, and see if you can find the leak that way. Here's some instructions on how to make you own http://www.instructables.com/id/Make-an-Auto-Radiator-Pressure-Tester/. If the front tensioner is bad you'd be able to get at it with the radiator hoses out of the way.

Thanks for the replies! With the lower intake already off I should be able to unscrew the hydraulic tensioner without having to take off the radiator hoses correct? Does the thermostat have to come off to take off the upper/lower intake? Thanks

No, you need to drain the coolant and remove the upper hose to get the lower intake manifold out. You seem to have three different problems: leaking coolant, lean codes and a bad tensioner. I'm not sure which one you're trying to fix. But I would make sure that you're pretty certain that the coolant leak is coming from the lower gasket, its a lot work and will take you all day to do.

Oh ok. Thanks for the clarification. Didn't know that I'd have to drain the coolant as well. Yeah, 3 problems and all are fairly important.