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Exhaust leak cat cat converter


As many of you know I’m having problems and experimenting with my 2004 Ford Taurus rather than junking it just as a learning experience and maybe with some luck I might fix it and get some more miles out of it.

I found my problem…A valve spring was broken and the valve was also damaged. I had a used cylinder head from a 2002 Ford Taurus and I put it on with a new head gasket. I realize I could have repaired the old one but it looked too complicated and the other cylinder head was fine.

The car is running fine now. It’s not sputtering anymore.

However the exhaust manifold where it meets the catalytic converter is leaking. I can see the exhaust smoke coming from the connectino where the two bolts were.

My first thought was it was on crooked or the bolts weren’t tight enough. I redid that and it is still leaking.

Question - Should there be any distance in between here? I have like a 3/8" gap evenly around the space where the exhaust manifold meets the cat converter.

Also…I did the head gasket exactly as instructed but I see a ton of white smoke coming out of my exhaust. I’m hoping this is somehow from the connection issue on the cat converter and not something I did wrong with the head gasket.I followed a instructional video and did everything exactly as shown.

Help please.

uh, OHC or OHV 3.0? front head or rear head?

It is the 3.0 OHV engine. It is the front exhaust manifold closest to the radiator.

The white smoke usually means water/coolant in the combustion chambers - leaking head gasket or a crack in the cylinder head or the block (from more to less likely.)

Are you sure you used the correct head gasket, set in place correctly, and torqued the head bolts in the correct order and steps? Some engines need new head bolts, on others it’s OK to reuse the old ones. Maybe rechecking the torque of the bolts is worth a try.


Yes I ordered the correct head gasket and I also followed the torque specs exactly.

It was 37 ft lbs
loosen bolts 1 turn
22 ft lbs
90 degree
90 degree turn

They were TTY bolts so I bolt new ones. I just think my issue is at that connection on the cat converter and the exhaust manifold.

Take off the oil fill cap and look inside. If it looks like a chocolate milkshake, you have coolant mixing with the oil.

I will check that. I have heard of that method before.

But would that connection not being correct cause the white smoke?

There is a 3/8 inch gap around the space and it is definitely leaking there I can see the white smoke coming from it.

i sold my taurus so i cant go look at it. i cant think a gap is good. you see a gap and smoke is coming from it? im not a betting man but that dont sound good

That’s what I’m thinking. But would that cause the exhaust to produce white smoke? Yes I can see the smoke and the gap is there.

Not sure if that is supposed to be there or not. Unfortunately I took them both off and didn’t pay attention if that gap was there or not.

The exhaust is produced in the combustion chambers, not in the exhaust system.

Nope, you have a coolant leak not related to the convertor issue.

Okay. So perhaps the cylinder head was cracked on the old Taurus or maybe somehow the gasket didn’t go on properly but I did everything step by step.

Still not understanding the leak at the exhaust manifold and the cat converter though. Any Taurus owners have any feedback on that?

You have two problems:

  1. Smoke exiting the exhaust system where the catalytic converter connects to the exhaust header. It doesn’t matter what color the smoke is, that gap is dangerous to your health.

  2. White smoke is a different issue. Did you get the surplus head shaved before you installed it? You should have checked for flatness or had a machine shop check it for you. I wouldn’t be surprised if the head is warped enough that there is a leak between the coolant channels and the cylinders.


Would the exhaust manifold have changed from the 2002 Taurus model to the 2004 Taurus where the flange would fit properly to the cat converter?

I guess I’ll redo the head gasket. I ordered an extra just in case. Maybe I’ll just take the 2004 cylinder head to the machine shop and they can repair the valve spring and everything will be original rather than swapping the parts from the 2002 to the 2004. They can check the flatness for me too.

Any other advice on the head gasket? I followed everything exactly. It must have been a problem with that used 2002 cylinder head.

I think you’re on the right track now.

rockauto says heads are the same from 2000-2007 and only diff is flex fuel part number. you have same exhaust manifold but pipes dont fit right. hmm

I would take both heads to the machine shop and ask their opinion on how best to proceed. If one is cracked, it still has parts that might be useable on the other.

On the outside chance the block is cracked, ask them how to diagnose that.

When you put in the head bolts, be sure they are not too long and that there is no debris in the holes in the block. Good luck and please keep us informed.

Okay just starting to look back into this. I took a picture because it’s impossible to see whats going on down here on the cat converter where the exhaust manifold is supposed to mount on here.

I checked with Auto Zone , Advance Auto and many searches online and they all said the cylinder heads were exactly the same for the 2004 and 2002 model. I put the cylinder head from the 02 onto my 04 taurus.

The head bolts all lined up and everything looked the same but I don’t think they are 100% alike. Here in this image you can see the exhaust flange is not lining up. Perhaps it is at just a slight different angle than the original part keeping it from going on which is the obvious cause of my exhaust leak.

Now since I did the head gasket exactly as instructed and it is leaking. I believe the that might also be related to the two cylinder heads not being exactly alike. Maybe there was a slight variation there too causing the head gasket to fail.

So my next plan is to deconstruct this thing once again and I’ll just have the 04 Cylinder head checked for flatness and have the valve spring and valves replaced so I can use the original cylinder head.

I don’t possible see where I could have went wrong. There is no way to have put the cylinder head on incorrectly since all the head bolts lined up and went on. That should have aligned the exhaust manifold and the cat converter so they would have joined without there being a gap.

***Without there being a gap and without it also sitting crooked which you can see in the photo.

It looks like the nut is loose. Did you replace the flange gasket?