Catalytic Convertor Test after fuel contamination.

[Philip G]

Hi,  I am recommissioning my 2012 R300 Duratec 2.0L. During COVID I had a problem where one of the injectors got stuck open and fuel entered the cat causing it to overheat to the extent that the trim on the cat heat shield melted and the car cutout. I fixed the injector at the time and the car runs very well.  I have the opportunity to get a used cat but they ain't cheap so looking for a quick test without going full MOT route.   The cat looks ok visually but I have run a temperature test that Google has guided me to,  My understanding is that the out pipe temp should be higher than the in pipe temp as a result of the reaction.  So I have idled the car up to op temp for 15 mins.  Using a laser thermometer, the inlet pipes at the "gather end" are 56c, the front face of the cat, 94c, middle of cat 54c, back face 33c and outlet pipe to silencer is 38c.  Am I reading this correctly that the cat is damaged and replacement is required  or is the test too simple and this is normal ?  Thank you for taking the time to read.

[Jonathan Kay]

Are you sure that you don't have a leak somewhere?

And how about asking a friendly tester to run some emission tests without an MoT inspection? Where are you?

Jonathan

[Jonathan Kay]

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[Philip G]

Pretty sure seal is ok, I will ultimately get the test but interested if anyone has tried this or has a rule of thumb as a start point. 

[TJG]

Can you see the cat when looking down the pipe? It's usually fairly obvious if it has melted or disintegrated, a light at one end helps to see the condition of the honeycomb.

[Philip G]

Yes. I removed it an it all looks ok. It's just the temp piece that has me unsure. 

[revilla]

Are you sure your thermometer is reading correctly? Those temperatures look very low. If I'm reading it right, you've got the inlet pipes into the cat at 56°C. At that you would be able to sit with your hand on it. After 15 minutes idling I think my (K Series) primaries would be at several hundred degrees, and from memory I think they go through 300°C after just a few seconds of running. I certainly wouldn't want to put my hands anywhere near the catalyst inlet.

[Philip G]

The thermometer is pretty accurate when I use it on heating / boiler pipes etc.  If I rev the engine, the front of the cat does rise up through 150c but the exit of the cat is still cooler.  Engine is running fine. It's this differential in cat temp that is interesting me ... theory says back of cat should be hotter than front ?

[Alastair B]

If your exhaust components you are taking readings from an IR thermometer are shiny / reflective you cannot rely on the readings, those readings are as Andrew says are very low.

[revilla]

I've just taken some measurements on mine for reference. OK, different engine, and I've got a decat pipe on at the moment, but measurements at the entry to my decat pipe will be in the same ballpark as measurements at the entry to your cat for sure.

After 10 seconds idling it was already too hot to keep my hand on, so probably over 60°C.

After less than a minute, droplets of water dropped into it boiled off vigorously so over 100°C.

After 15 minutes of idling I was recording 188°C.

After just 2 minutes of raising the revs to 2500rpm I was recording 324°C. That's more like the minimum temperature or a catalyst to operate properly and much more believable.

I don't think your thermometer is reading right at all. Infrared thermometers are very dependent on the colour and shininess (emissivity) of the surface. They also have a limited range over which they are calibrated. I honestly don't think you can draw any meaningful conclusions at all from those readings.

[John Vine]

This is what the input side of my R400D cat looked like after a major over-fuelling event:

The honeycomb was a partially melted mess, and the arrow indicates where it had distorted badly.

By contrast, the exit side looked like this:

Even though this cat managed to pass a one-off emissions test at my local MOT centre, I replaced it anyway.

If both sides of your cat look like the second photo, I'd say you were ok.

JV

 

[Philip G]

Thx for all the feedback. Looks like a contact thermometer will give a better reading. I'll update in due course.