98 Ford Windstar GL Diagnostic Results - Need guidance

I wanted to get your opinion on how I should proceed after getting a diagnostic done. I originally wanted to get a tune up but wanted to get a diagnostic first since the check engine light was showing on my dash.

Here are the results:
Coolant leak at radiator
Coolant and oil leak at rear end
Air leak at upper intake
Code 420 Catalyst system low efficiency

How should I proceed in getting these issues resolved? I don't have a ton of $$ to work with so I wanted to kind of prioritize things and take them step-by-step. Keeping in mind cost.

It was also suggested I get an engine shop.


98 Ford Windstar GL 3.8 - 88850 miles

You will need to resolve the coolant leaks, particularly as far as the engine goes.
It is very possible that coolant is also leaking INTO the engine.
Just reading your message does not make it possible for me to read the diagnostic results, just possibly ask some questions.

The leak that you mention on "rear end", is that the side of the engine?
Bank #1 is the back side of the engine.
P0420 is for the catalytic converter for Bank #1.
Coolant is not good for catalytic converters.

A common leak that can get coolant into the cylinders (and on back to the catalytic converter) is the lower intake manifold gasket.
A failure of the lower intake manifold gasket(s) is often misdiagnosed as a head gasket leak.
The Head gaskets were pretty good by 1998, there was a problem with the 1995.
Coolant can also be getting into the crankcase, which will destroy the bearings in the engine.

I have pictures posted of what is involved in the lower intake manifold gasket job.
I recommend replacements from FORD as they will have the latest improvements.
The lower intake manifold gaskets MUST be dry fitted, with not added sealers.
The end seals get a small blop of SENSOR SAFE sealant at each end as indicated in my pictures.

The upper intake manifold gaskets are re-usable.
Make sure all seating surfaces are clean before putting things back in place.

Also, if you do the job, or have the job done, the EGR ports should also be checked and cleaned at this time also, as you are right there, and they are very easy to do at this point.

Not sure if the lower intake manifold gaskets tend to leak badly enough to cause the vaccum leak.....I guess it is possible.

Very likely sources of vaccum leak on a pre-1999 windstar would be from one of the many vaccum lines that connect to the back of the upper intake manifold, and from the PCV line that connects to the upper intake manifold next to the throttle body, and goes back to the rear valve cover, with several lines connected to it along the way.
Check the 90 degree elbow for the PCV line on the top of the upper intake manifold.

Also, check to make sure that the crankcase breather line, that goes from the front valve cover, to the back side of the flex hose (that goes from the throttle body to the MAF / Air filter unit) is connected at both ends.....easy for it to be bumped out of the flex line and be overlooked.

Coolant leak at radiator, can be a hose, or hose connection, leaking radiator cap or overflow bottle line........or more expensive, the radiator.

Another coolant leak that is common is the front cover, aka timing cover.
This is on the passenger side of the vehicle.
The water pump and oil pump are mounted onto the front cover.
The gasket is cheap, the labor is major.

I actually got the lower intake manifold gasket done last year. I pray that isn't the issue again. What is the best method in getting the coolant leak stopped? As always thanks for your detailed post. Would using Bar's stop leak help in this case?

You could try Bar's stop leak, it worked for me on the front cover gasket leak....but I caught it at the very early seepage stage.
It only slowed the lower intake manifold gasket leak for me.
So, depends on the size of the actual leakage points.

If it were my vehicle, I would give it a shot.....in fact, I advocate keeping some in all the time anyhow.
They sell powder and tablets, but they are harder to find....and my own opinion is that I would use the bottled version of Bar's before I tried another brand.

The other leak points that I would give a serious looking at are the heater hoses, and that small elbow on the bypass tube......on the passenger side.
They bypass tube is the one that goes through the intake manifold.
This originates with a metal tube on the water pump that goes toward the firewall.
Then the rubber elbow hose connects to that, and turns back 360 degrees toward the front of the vehicle, and connects to the bypass tube that comes forward some more......then turns 90 degrees and enters the lower intake manifold.

Some have mentioned the metal tubes rusting, but I have not experienced this on my '96.

Also check the heater hose connection to the lower intake manifold on the driver's side....next to the upper radiator hose connection.

Thanks. I will get it checked out asap. For the P0420 code, which is a misfire, should I get the plugs and wires changed to resolve that?

The P0420 is saying that the catalytic converter for bank #1 is not functioning at the minimum level that is expected.
You could try looking to see if the oxygen sensor in the rear most catalytic converter has come out.....
My '96 had that one mounted into the rear part of the catalytic converter.
When I was changing the "Y" pipe, which is both converters, the mounting ring for that oxygen sensor broke right out of the converter body.
The metal is very thin at that point, and I would not be optomistic about a weld job there.
In my case, it was not an issue as I was changing the unit anyhow.

It is possible that the converter got enough coolant when your lower intake manifold gasket was leaking coolant.

One thing you could try is switching the downstream oxygen sensors from side to side....but be VERY careful about that one mounted into the converter body.
Mine came out with very little turning only force, after soaking the threads with P-Blaster.