Question about 1995 Toyota Land Cruiser

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Can a bad catalytic converter ruin a cylinder?

Can a bad catalytic converter ruin a cylinder in my 1995 land cruiser? just replaced them 5 years ago... now #6 cylinder is misfiring; i am told engine needs to be replaced!!

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  • cooper2091 Aug 02, 2010

    that's what I thought about the cat. It was rattling and one mechanic put a clamp on it, said it was no big deal, and that we could get to it in the near future. No smoke, yet, but the check engine light came on while driving up a canyon. took it to another shop. they said they thought they knew what it was immediately, and didn't even check the cat. they said the compression was 80 and should be like 125 (?). then he said something about the cylinder and the rings... yikes!!! i know what you're saying about gouging.. i've had it happen and now i don't trust anyone and don't know where to take my cars :(

  • cooper2091 Aug 02, 2010

    he said they put some oil in there to see if the compression would come up; i believe they said it was 80, and they could only get it to come up to 90, but that lasted for like 10 mins and it started to go down again. also, the others were around 120-125 of the compression. He also mentioned the rings (I'm a dummy, sorry), the cylinder (or is that piston?) rings on #6, are bad; hence the no compression issue. THEN they said that it takes 11 hours to remove the head-- which he said it COULD be the valves or piston rings, or the head gasket-- but they'd have to get in there to see. BUT, to replace the engine is 20 hours, so I may as well replace the engine... WHAT??? that sounds strange to me...
    Error code originally was P0420 when I was told to replace the cats 5 years ago (2 shops told me that, one was the Toyota dealer here in town) and i believe i already had a mis-fire problem at that time, too (I was told to use Lucas upper engine lube). I'm thoroughly confused as to WHY the cats are burning out so quickly...

    I just called and he said the error codes were 300-- random cylinder mis-firing and error code 306-- specifically cyl #6

    thanks again.. sheesh, I wish you worked on toyotas here in utah...

  • cooper2091 Aug 02, 2010

    i meant ...120-125 ON the compression...



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NO, a cat only cleans up pollutants. It has no effect on engine performance unless you have a misfire and the cat works overtime and melts and cloggs the exhaust system. If your blowing grey smoke out the tailpipe then you indeed may have a bad engine. What I would want to know from the mechanic is what is the compression and why he thinks its a lower engine issue rather than a leaking valve on the head which would be alot less expensive to repair. Then again you could get a second opinion from another shop. Mechanic shops are known for gouging customers wallets, Not that i'm implying anything here.

Posted on Jul 31, 2010

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  • Susan Price Aug 02, 2010

    you know, checking compression is pretty easy. all you do is screw a compression tester into the spakplug hole and turn the engine over for about 4 umps with all the spark plus out. Do this to all the cylinders. If one is low squirt a few drops of oil into the cylinder and test again. If the compression does not increase then most likely you need a valve job. Oil will seal rings if the compression is an engine issue. Oil could seal a valve if the leak was real small but usually oil will not seal a vlave leak so compression will remain the same. Get the cylinder number that this mechanic tested as being low and if you choose to have another shop look at it DO NOT tell them aboutthe low compression. Lets see if they come up with the same conclusion. Also look at the spark plugs. If one cylinder was misfiring the sparkplug would look wet or black and sooty compared to the others.

    So what was the code ??. I'l dig deeper once I have more info.

  • Susan Price Aug 02, 2010

    well to begin with a misfire can cause a P0420 cat effeciency code by making it work overtime. A cat does have a life limit based on how clean the car runs so I can't fault anyone from making a bad call back then, but if the car had a misfire back then it should have been dealt with so as not to burn up the new cat. I see you have this listed as a 95. Some 95's are obd2 so I have to assume thats why your getting a 420 and misfire codes. It was mandatory all vehicles became Obd2 in 96.

    But now because you have compression issue the heads do need to be taken off to find the cause. The heads can be sent out and they will bolt the head down on a bench and test it. If any valves are leaking it should show up.

    I know its a bummer but I would hate to replace the whole engine if all you need is a valve job. Being this is a 95 I have to assume you have a good amount of miles on this and not knowing the history of the vehicle its not uncommon for engines to be replaced on alot of vehicle alot sooner than this.

  • Susan Price Aug 02, 2010

    by the way if your not getting a 420 code now then the cat is still ok, you just need to deal with the misfire issue.

  • cooper2091 Aug 03, 2010

    well, they didn't say anything about the 420 code-- but the cats were rattling like crazy and there are clamps on both now... (is that bad they're clamped?) it only has 165K miles :( My 1989 land cruiser (just had to get the fuel sys cleansed, different story, so we won't go there) has only 170K or so, and is rusty as hell.. maybe i should put that engine into the 1995, haha...

    Well, I'll have the heads pulled. I feel a lot better now, though, after our exchange, and your great feedback... yes, I wish the misfire was taken care of earlier, so this repair wouldn't be so costly. it could have been better maintained, but we've just been doing what they've been telling us to. I just had it tuned up (don't know why nothing was mentioned at that time, when they changed the plugs, I'm sure there was some evidence on the plugs-- but like I said, it's at a different shop now). I think it has missed a major tune up or two; my family usually drives stuff till it has a problem (! i know, gotta stop doing that).

    Thank you so much for your input. again, I wish you were here locally! Too bad... I don't understand why it's so hard to find a good and honest mechanic around here; and every time I do find one, it's short lived for one reason or another.

  • Susan Price Aug 03, 2010

    general engine theory is if any cylinder has more than 15% drop in compression you will have a misfire or rough running engine. If this is real your just going to have to bite the bullet and open you wallet to fix it.

  • cooper2091 Aug 12, 2010

    Hi again... hey, I'm gonna get another opinion, but I just wanted to ask you: if it turns out that it needs a valve job, what's the range of cost that appropriate for that? Today, I called one of the local toyota dealers and they asked if the other shop used a boroscope, which they didn't. I've had some problems with this particular dealer, and i doubt i'd have them do the work anyway-- but they said to diagnose, pull codes and plugs and check inside, etc: $165. another place said they'd pull the codes for free, then go from there... what do you think of all this? Please let me know when you can. Thanks again...

  • cooper2091 Aug 20, 2010

    by the way, my friend and husband were looking at the car.. it was a friggin loose spark plug wire. it wasn't snapped in all the way, and it had fallen out. I guess the wires aren't like other wires. thank goodness it was only that. it's only got 126k miles on it. thanks again for all of your help

  • Susan Price Aug 20, 2010

    its always good to hear a problem was never really a problem. I still question why anyone would of said you have low compression, A spark plug wire will not cause low compression unless you drove a longtime with the misfire and damaged your cylinder. Just hope this didnt happen



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