4.6 coolant leaking.

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so my fiances friends mom has a 99 marquis. has 230,000 miles and has had a coolant leak for apparently a long time like a year or more. she took it to A mechanic. just a random place. the told her the driver side head gasket was shot. but here is the thing it doesn't smoke oil is fine and the only wet spot i can find is on the coolant outlet. she said once in awhile it will leave a puddle of coolant when its parked overnight other than that nothing else. she ads about half a gallon of antifreeze every week. we did a pressure test. it did drop very slightly but not very much it was pretty steady. so my knowledge tells me the head gasket is probably not bad. what do you guys think.
 
The oil filter appears to have oil stains on it and not coolant. It is possible the dampness is actually an oil leak or are the photos just not revealing all?
 
hard to tell its all cruddy around the outlet it looked more lik water though there wasnt any fresh oil around the seal
 
The oil that is on the filter--is it from oil that is running down from the coolant neck area? Perhaps, the corner of the valve cover?

You may want to pick up a can of brake cleaner and hose down the area to remove the gunk to glean a better view of the leak...
 
i didnt see any oil leaks or anything except right on the outlet. could the oil be from when the oil was changed maybe they got some on the filter? in the picture you can see a greenish tint on the outlet
 
well i couldn't get under the car didn't have a jack or anything. but on top i couldn't see anything except the outlet being moist. i noticed a little wetness near the head behind the manifold but i figured it was just because the outlet and coolant blowing off of it. if the head was bad wouldn't it fail a pressure test for sure?
 
These cars had a known issue with intake manifolds cracking and causing coolant leaks. It was recalled on cop cars, but not "civilian" models. Something to look into.
 
I may be remembering incorrectly, but this may be one of the years that would have the failing crossover tube on the intake, which would lead to an external leak. Depending on the severity of the leak, it may just be evaporating.
 
Look at the coolant crossover at the front of the intake. Plastic or aluminum?

As pointed out above, there is a gasket between the oil filter adapter and block that can leak. Actually very easy to replace.

The bypass hose under the intake can leak. In that case the valley fills up and can drip at the rear of the block.
 
I would not say for sure about the head gasket. But judging by the photo and the we are talking about a Ford modular a common enough failure is the oil filter housing gasket I am willing to say this is the problem. It should cost something like 15-20 bucks from the dealership. But follow others advice to try to find out the problem for sure.
 
Originally Posted By: 01rangerxl
These cars had a known issue with intake manifolds cracking and causing coolant leaks. It was recalled on cop cars, but not "civilian" models. Something to look into.


It was on all models. They extended warranty coverage on the intake manifold to 7 years from in service date.

That leak looks like it is the oil filter adapter to block gasket. I sell a TON of those and that leak is very common. It it were the intake leaking there would be coolant on the top end.
 
That lovely pipe under the intake is always a good suspect for a coolant leak when you don't see any drips. It's a lot easier to see the puddling if you pull the alternator out.

That said, Mechanic A is telling you that one specific head gasket is leaking and not the other. It would follow that he's actually seen something to get that idea in his head, perhaps a shiny clean piston top or coolant blowing out a spark plug hole while cranking....

Does it hurt to ask the guy how he knows the head gasket is leaking? Once he tells you then you'll know where to look if you want to confirm.
 
Originally Posted By: chevyboy14
How do you replace the adapter seal. I imagine its straight forward.


Take off the lower hose and filter and all the bolts are right there.

Head gaskets are not common on mod motors that are stock.
 
Originally Posted By: chevyboy14
If the head was leaking wouldnt it be obvious. Coolant in oil or in exhausr or a failed pressure test


It would probably give you some sort of warning other than just coolant loss. I would put money on one of the known coolant leaks for this engine long before a head gasket.
 
Originally Posted By: chevyboy14
If the head was leaking wouldnt it be obvious. Coolant in oil or in exhausr or a failed pressure test


As bdcardinal points out, it's unusual to have a head gasket leak on one of these. That said, head gasket leaks aren't always that obvious, no. Sometimes you get a nice big blown out piece of gasket and a cloud of smoke. Sometimes you get tiny bubbles in the coolant reservoir when you're accelerating.
 
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