05 Ford 500 Intake hole - melted

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Geauxtiger

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I recently replaced the ignition coils in this vehicle per this discussion:
2005 Ford 500 Engine Isssues
After coil replacement, the engine ran great for ~10 days.
Then, nite before last, the owner was on the way home after running some errands and suddenly the engine starting stumbling and running poorly. It progressively got worse and the engine completely died about 1/4 mi from home.
Upon inspection this afternoon, I found a hole in the intake, just downstream of the throttle body (see pic).
The hole is approximately diagonally opposite of the EGR valve.
The hole shows evidence of melted plastic.
The plastic around the hole seems to have been thinned considerably.
Did the EGR valve fail open, allowing a steady stream of hot exhaust to burn/melt the manifold ? ( a re-check seems to indicate that I did not miss anything when I last reassembled the manifold)
I wonder if any bits of plastic were sucked further into the intake, waiting to cause damage to the engine?
Thoughts on what could have caused this?
FYI...I was able to stuff a paper towel into the hole to get the engine to run (barely) to get it the last 1/4 mi home today.
I don't want to jump into this job again without having some idea of the failure root cause.
thanks!

gbX7MlE





burnt intake2.jpg
 
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Upon some investigation using Google, it appears there is reasonable possibility that the cat's are failing, allowing stuff to get into and the EGR valve inner working, causing a stuck open condition.
Since the vehicle was run for some unknown miles with failing ignition coils, I wonder if a rich condition could have expedited cat failure? Can I even diagnose cat converter health at home? I mean ...other than finding debris in the EGR valve after removal and autopsy?
 
Can you cut the cats out legally where you are in Louisiana? How long do you plan to keep driving this car?
 
The usual way to diagnose the cat is to disconnect the flange at the intake side and look inside. Driving with a constant misfire will definitely melt them down.

For testing you could make sure the EGR valve is not stuck open, replace the intake, temporarily disable the EGR so it can't melt again, then test drive to see if the performance is normal.

It's not legal anywhere in the US to hollow out a cat. The chances of being caught vary based on where you live.
 
Gentlemen, thanks for the input. I am leaning strongly toward ruined cats. I do not have access to a lift and am not committed enough (LOL) to try to get to the cats just using my jackstands. My beer belly is too big! Already told the young lady owner of the car that a new intake, new EGR, and new cats are, at best prices I could find, in the $750 range. Told her I can't do the cats, so probably best to get local shop (they are good) to do the entire job. At least 6 hrs labor?
She only paid $800 for car. When I replaced coils last week, the engine ran very well and trans felt healthy. She had paid (and got ripped) over $300 the previous week to have some supposed mechanics replace the plugs. No way in Hades that they should not have replaced the coils at the same time (they had coil issue codes), thus is the reason I got involved and did their work all over and replaced those coils.
I think running on marginal coils for who-knows-how-long did-in the already tired cats.
She now has to struggle to figure out whether to just sell the car for scrap or invest another $1300+ into it.
Personally, I think the engine and trans are solid and are capable of giving another couple of years of service.
kinda don't know what advice to give her about repair vs sell for scrap.
thanks!
 
I would think a melted cat would cause some drivability issues especially at higher rpm's like bucking and flashing CEL. I have also seen GM 3800 gen II with burned EGR burning the plenum but the ones I came across were due to GM not using a steel sleeve and the EGR chimney was too close to the plastic plenum. The aftermarket plenum uses a reduced diameter chimney and a steel sleeve and that seems to cure the issue.

After so many miles it is also possible the manifold finally just burned through, I remember some early EGR Ford engines with a carb used an aluminum plate for the EGR under the carb that had a habit of burning through and that was made of aluminum so EGR temps can certainly generate enough heat it all depends on the routing.

Before scrapping this car I would definitely check the cats out, just remove the pipe and look in there with a flashlight, if you can see right through the honeycomb the cats are not the problem. It wont tell you what the efficiency is but that's another story and will throw a P420/430 code.

49.gif
 
some cats do not have a flange, but they do make a band type clamp now. So you can cut thru the pipe and look, then seal over the cut with the clamp.

Rod
 
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Thanks for all the advice! I will recommend that the lady at least have the cats checked out before making a decision on how to proceed.
 
Originally Posted by Trav
I would think a melted cat would cause some drivability issues especially at higher rpm's like bucking and flashing CEL. I have also seen GM 3800 gen II with burned EGR burning the plenum but the ones I came across were due to GM not using a steel sleeve and the EGR chimney was too close to the plastic plenum. The aftermarket plenum uses a reduced diameter chimney and a steel sleeve and that seems to cure the issue.

After so many miles it is also possible the manifold finally just burned through, I remember some early EGR Ford engines with a carb used an aluminum plate for the EGR under the carb that had a habit of burning through and that was made of aluminum so EGR temps can certainly generate enough heat it all depends on the routing.

Before scrapping this car I would definitely check the cats out, just remove the pipe and look in there with a flashlight, if you can see right through the honeycomb the cats are not the problem. It wont tell you what the efficiency is but that's another story and will throw a P420/430 code.

49.gif




Let me expand on my Series II 3800 comment......I've seen a few burn/melt a hole through the TOP of the upper plenum & every one had a clogged Catalyst.
 
Originally Posted by clinebarger
Originally Posted by Trav
I would think a melted cat would cause some drivability issues especially at higher rpm's like bucking and flashing CEL. I have also seen GM 3800 gen II with burned EGR burning the plenum but the ones I came across were due to GM not using a steel sleeve and the EGR chimney was too close to the plastic plenum. The aftermarket plenum uses a reduced diameter chimney and a steel sleeve and that seems to cure the issue.

After so many miles it is also possible the manifold finally just burned through, I remember some early EGR Ford engines with a carb used an aluminum plate for the EGR under the carb that had a habit of burning through and that was made of aluminum so EGR temps can certainly generate enough heat it all depends on the routing.

Before scrapping this car I would definitely check the cats out, just remove the pipe and look in there with a flashlight, if you can see right through the honeycomb the cats are not the problem. It wont tell you what the efficiency is but that's another story and will throw a P420/430 code.

49.gif




Let me expand on my Series II 3800 comment......I've seen a few burn/melt a hole through the TOP of the upper plenum & every one had a clogged Catalyst.



Hole burned thru upper plenum: that is exactly what I have. thanks!
 
Easiest was to check for blocked cats is to remove an O2 sensor and screw in an exhaust pressure tester. General rule of thumb is 1 psi at idle and 3 at 2000 rpm. More than 1/4psi above is a fail.
 
True but not everyone has one in their home garage. I have one but it cost over a hundred, not sure how the cheap ones on ebay work or if they even rent this tool.
 
Results are multitudes more certain. A bad cat isn't guaranteed to look like anything. That trip to breaking down the exhaust system (which might be a battle) is a big one to take for potentially no gain at all.

Screwing in the tester is going to give a 100% positive answer as to whether or not there is a restriction.
 
You will see a blocked/melted cat that is blocked enough to cause excess back pressure, as I said it wont provide any info on its efficiency. You are right a pressure tester is the better way if you have one. On blocked converter the waveform of the rear o2 will also be abnormal.
 
Possible, true, and true.

My concern here is that a person without repeated experience with these sorts of things might end up a little lost in the woods. I've seen too many exhausts that were a mission to remove. What if all looks good in there? You're left with a person having done R&R of the exhaust, and back at square one. This could be one on those exhausts where the manifold is built with the cat in it. On a transverse V6, I can think of various forms of Soviet corporal punishment I'd rather engage in.

The stakes here are another IM purchase and R&R if OP is wrong. Given the gravity of the consequences, I would not hesitate to invest in a final and certain answer.
 
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