No compression in cylinder number five?

Hi,

First, nothing from the catalytic converters will make its way into the combustion chamber, so don't worry about that happening. There is a lot of exhaust pressure from the engine, and it will force things out of the tailpipe.

Next, something isn't making sense. Why would cylinder 5 have no compression when it wasn't where the misfire originated? Also, if there was no compression, you would have had a cylinder 5 misfire code (P0305) and not a random/multiple misfire code (P0300).

Do you know if there was "no" compression or was it low compression? No compression won't be a head gasket or burnt valve. If It has 0 psi, something such as a valve is wide open or there is a hole in the top of the piston. If the compression is low, then we would consider a gasket, burnt valve, or worn piston rings, so let me know exactly what he said to you.

As far as the cylinder head, I attached the parts and labor information below. Note the labor is somewhat high. Multiply that times the shop rate for labor costs.

Finally, the catalytic converters are integral to the exhaust manifolds and are expensive, so make sure they are faulty prior to replacing them. On the other hand, they are known to crack creating an exhaust leak. If that is the case, replace them.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.

Hi Joe,

First of all, thank you for your reply!
I have attached a copy of the engine diagnosis from the repair shop
that I took my truck. And I need to back up a little bit and go into more detail and add what I missed on my previous post.
The following is what took place before I took the truck to the shop:
So, pertaining to the catalytic converters:
When the truck was still running fine, before the misfires, the check engine light came on. So, I plugged in my scanner and all I remember is that it had a cat code, but I don't remember exactly what code it was by number. I read online that some people change out the PCV valves that sometimes when they get a cat code. So, I did that, cleared the code and the truck was running just fine.
And another thing that I needed to add is that posts said that it you have
grey smoke on startup, that changing the PCV valves could possibly help this issue, which mine were faulty, and it helped the smoke issue. (Grey smoke, not white). And the transmission code went away.

So, pertaining to the misfire(s):
While driving one day, the check engine light came on, and I had a pretty good loss of power on the highway. It also flashed until I found a place to turn around and go back home. Drove it 13 miles home, put the reader on.
and the first code was PO303. I don't remember a PO305.So I changed out plugs and coils. The plugs on the driver's side were extremely corroded. Cleared the code, started it up, check engine came on. Multiple engine misfire PO300. That's when I took it to the shop. Drove it 6 miles to the shop. Then after the diagnosis drove it home. So total 25 miles driven with misfire(s). So just FYI I haven't driven it very far with the misfire.

So, they diagnosed the truck with no compression 0PSI for cylinder 5.
(see attached sheet)

So, do you feel that having "no" compression that It could be narrowed down to the head?
What tests do shops do to determine if the cats have damage?

Thank you for sending an estimate for repair. To tell you the truth,
I don't know what I am going to do at this point. On one hand I don't want to put the money in it, but I have spent quite a bit of money on this truck, new transmission, front end suspension parts, new tires, so I am trying to decide whether to continue with a repair or just try to sell it as it is.
Thank you so much for your time....
I want to do the right thing for my truck and get this figured out. Your input makes a huge difference!










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Hi,

If it has 0 psi as mentioned, chances are you either have a stuck valve or something burned through the top of the piston. As far as checking the converters, in this case, I would be checking converter temperatures in and out. If it is properly operating, the output will be 30 to 100F hotter than the input.

Take a look at this link:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

At this point, we have two ways to go. First, the shop could use a borescope to see into the affected cylinder and check for damage. Other than that, the head needs to be removed.

These engines can be difficult to retime (chain) after the head is removed, but I would be happy to help you through it if you want to do it yourself.

Also, chances are the original converter code was either a P0420 or P0421. Does either number ring a bell?

Let me know.

Joe

Joe, thank you for your reply.

Thanks for the info. Just to be clear, the misfire has to be addressed first before running the engine to check the cats, correct?
because further damage to the engine could occur with it running?
And then when the engine issues are corrected, then the cats can be troubleshooted?
Another thing I wanted to ask you is about exhaust mods, assuming that
I can get the engine fixed. I have read where people modify their exhaust
and have the cats totally removed. Is that a wise thing to do? I wanted to know if this would be an option if my cats are found to be bad. And this is something that shops don't do because of the emission laws?
Also, is it possible that my head issues could be in the driver's side head only? So maybe I could get by with one head being fixed, if it is the head, or do you think it would be a good idea to get both done? I'm saying this because no misfires were found on the other side. And the old spark plugs were really corroded on the driver's side only and seemed pretty normal on the passenger side. I don't want to try to tackle this by myself. This is something that I want a reliable mechanic to look into who knows what they are doing. Would you be able to point me in the right direction on where I could take the truck?
I live in a rural area, and there isn't much to choose from where I live. I'm about 50 miles out of San Antonio, TX. And wherever I take it I will have it towed because I don't want to damage the engine further.
Thanks again for your help!

Oh, and a couple of other things I forgot to add.
I remember that the cat codes that I had were either PO420 or PO421.
That does ring a bell!
And what do you think about an engine swap being a possibility?
There are lots of sites on the internet that have used engines Ebay, and other sites. pretty costly on new motors, but I was looking at Remanns.com. I got a quote for a used engine for $2,295.00 for an engine with 65,000, 5 year or 50,000-mile warranty parts and labor. what is your take on that? Is this something that could be considered?

65 k miles

Hi,

If those were the codes, it indicates the converter was functioning below the threshold. In other words, they weren't doing their jobs. Also, the misfire would need to be fixed before testing temperatures. Raw fuel in them will change the output.

As far as removing or cleaning out the converters, first, it is a federal law that prohibits that from being done, so chances are most shops won't do it. Also, if you do that, the oxygen sensors will not work as designed and it will turn on the check engine light and can create drivability issues.

If one cylinder head is rebuilt, it is likely that the engine compression will increase and could cause a rough idle. Both really should be inspected, and repairs made at the same time.

A used engine is not a bad idea. If you can get a good one, I suspect it would be less expensive to replace it simply due to the labor involved with repairs.

BTW: God Bless Texas. I hope things are okay where you are located. The news here in Pittsburgh indicates some really big issues.

I hope this helps. Let me know if you have questions.

Take care,

Joe

Hi Joe,

Thanks for your reply, and thanks for your kind words on Texas, it is a mess on the border!
Thank you for the info. Do you happen to know of a website that has a list of certified shops that would be good candidates for my repair? I am having a little trouble finding the information on finding trustworthy shops as opposed to just calling someone or a repair shop I don't know anything about. I for sure don't want to get ripped off by someone that says they can do the work and do a shotty job because they don't know what they are doing. Or maybe you know or know someone that can guide me to a good shop in my area, if that's possible.
Thanks again for your time!

Hi,

Unfortunately, I don't have any contacts. The site owner's son lived there for a while, so I will ask him if he has any suggestions.

Also, you and all of the citizens there have my support. I wish I was a smart enough person to find a resolution, but I'm not. I also haven't forgotten we are one nation under God. We must stay together and help each other.

Take care and I will send him this link. If he has any suggestions, he will be contacting you. On the other hand, I'm here if I can do anything to help.

Joe

See pic below. I messaged the owner for you. Let's keep our fingers crossed. LOL

Thanks, Joe! I appreciate you asking that question. I am looking also at reviews on the internet and on google reviews and have found a few places that are an option. When I find out what I'm going to do whether I fix the truck or just end up selling as is, I will let you know!
Maybe your friend knows a place I can contact.
Thanks again!

Hi,

I'm hoping he does know someone. However, Texas is a big state. He hasn't gotten back to me yet. I will let you know what he says.

Take care,

Joe

Thanks!

Hi,

No go on the shop recommendations. I'm sorry about that. Have you had any luck locating anyone?

Joe

Hi Joe,

I am waiting for a response from a shop a sent a message to on Saturday
Other than that, I am still looking. Thanks for letting me know. I will eventually figure out something.