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Discussion Starter #1
Well my 97 cat sounds like it has a bad rod bearing and only 72k miles on the clock.The maintence has always been performed accordingly and records kept.I was driving on the highway(40 miles) yesterday going about 70 or so, running great,i get off at my exit and come to a stop at the end of the ramp and i hear a faint sound.I drive about a 1/4 mile down the road to my folks house and pull in the drive and it sounded like major problems.The car's power didnt change nor did the smoothness, no smoke, no nothing, still fires right up and idles just fine ...Just the sound like a rod bearing was bad.Sound coming from passenger side valve cover area.My father looked at the car and had a mechanic freind of his come over,he pulled the accessory belt off and started the car , the sound was still there..Told me he didnt want to lead me in the wrong direction because he knew that there was certain mechanics that were certified for cateras ect..I have had many cars and bikes and the sound just isnt very reassuring,sounds like bearing to me but i wanted to see if anyone has had similar prob's with their cats, what does it sound like if a valve or pushrod goes out??I have been reading about recalls and im not sure if they were ever done but im in process of finding out, what would the cam idler do if it failed?...This is where im at now just trying to narrow things down a bit and not overlook anything...Any input is appreciated, thanks alot
 

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Catera engines do have their weaknesses, and you have enough miles on her for something to have gone sour.

But having followed the Catera marque for a while, can tell you am unaware of a rash of rod bearing failures. Obviously you could have drawn the short straw and be experiencing such a problem. I would only counsel you NOT to jump to conclusions. Go slow and remain open to other possibilities.

Good luck and I hope you are running well again really soon!
 

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If it is a bearing than it wouldn't run smooth.

Start it up and using a stethoscope (or just use a long screw driver with the handle by your ear and the blade toughing various parts) try to locate the noise.

Try to get the general location(top, bottom, front, back,) and post it here.
 

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Discussion Starter #4
I'll do that tomorrow, my father did the same sort with a breaker bar he had, told me he thought it was coming from the front of the passenger side valve cover..I'll try to pin point it a little better if i can..I was reading in another thread that a guy bought a cat for cheap because the owner thought it had a bad rod bearing but it was actually the cam tensioner gone out?I does seem to be coming from the top of the motor when i put my head in the bay.It does start right up no problem and idles and rev's no different than before except for the LOUD noise, no lights came on in the dash, oil pressure is the same as always,rpm's sit pretty still... I know what it sounds like but there is no other symptoms that would go along with it :confused: Does anyone know exactly what would happen if the cam idler tensioner went out?Would it run?I'm guessing that maybe it would slacken the timing belt and jump time possibly??Bending valves?Would it smoke like crazy if a valve or 2 were bent?or even run for that matter?.......I'll post some more details tomorrow, i appreciate the help..:thumbsup:
 

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My earlier gentle response was respectful, perhaps too respectful, of your own rod bearing diagnosis.

Now let me be less gentle:

If you believe there is any possibility whatsoever of cam timing impairment, due to belt or tensioner or whatever:

DO NOT RUN THE ENGINE!

You could end up with a situation that would make a mere spun rod bearing look like a day at the park.

Instead, get that front cover off and have a look at your timing components, a really thorough and careful look.

Good luck. :thumbsup:
 

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Discussion Starter #6
Thanks for the reply.Is the tensioner something that i will easily notice once i have the covers off?I was reading that it was the bearing that went out on them?I'm just trying to find out if they make that noise when they do go out.I guess its time to go find a shop manual and start taking it apart.
 

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Discussion Starter #7
Ok, i took everything off the front of the motor,and i can see the bearing shredded in the tensioner.:rolleyes: Well now i know my answer.Does anyone know where the cheapest place is to get the part?It doesnt seem like a bad job at all , the only tricky part i can see is keeping the cam cog's in position, the rest looks pretty straight forward.I'll update soon enough , hopefully the parts are readily available..:rant2:
 

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You have done really well to locate the problem. Am happy for you it is not your bottom end. Also, and most important, I hope you have caught this before your cams went out of time. On chance you might be unaware, Cat engines are INTERFERENCE engines. Enough said.

I disagree with your approach which is focus on the bad tensioner primarily. When you have the thing apart is the time to evaluate ALL the cam drive, the timing belt, components. Tensioners, idlers, the belt itself, EVERYTHING merits scrutiny.

This area is a known weakness of Cat engines. Put everything right and you will enjoy many more thousands of miles of driving enjoyment. Screw up and . . . . . . . . well, like I said it's an interference engine.

For example, you need to think really hard about belt replacement. Unless it has been renewed in the last 20,000 miles or so, give belt replacement now careful consideration. This counsel stands unless you enjoy tearing your engine apart as you just have done, or unless you have near-term plans to sell your Catera (which would be a mistake).

Go slow, take your time, and do it right. You will not regret performing this repair properly and in its totality.

Good luck.:)
 

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Discussion Starter #9
I had planned on changing out, the belt, the tensioner, the idlers, the water pump (may as well while im in there), and the accessory belt.I just had the valve cover gaskets done about 1k ago.I'm still looking around in there and inspecting everything, make sure there is nothing else that needs replacing.I plan on keeping this car for a while , i always did like it..I appreciate the help and honest comments. :thumbsup:
 

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Discussion Starter #10
Well,i put the new tensioner ,belt ,idlers ect in and it started right up and sounded good, i let it idle until the heat started building,then i revved it a little and i have a pretty bad lifter or valve noise.So here i am again, sound's like a hung up lifter if you know what i mean..
 

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Hmmmm. A VERY tough outcome after all that work. Sorry to hear it.

This could be a classic example of "double jeopardy", where you had two problems working at the same time, fixed one problem only to be clobbered by the other one. This is at least possible.

Are we talking about a clicking noise here, or is it more severe?

Is any localization of the noise possible, as to cylinder bank for example?

Have you listened to the noise from beneath the engine? Wondering if you can say for sure noise is coming from the upper cylinder, cylinder head, area and not from down below.

Have you been running a good brand of high detergent oil, with regular changes?

Of course the Cat engine is a DOHC engine, so there are no tappets or lifters as you would find on a pushrod engine. Hope it's not a sticky valve or a broken valve spring. The engine is not known for such problems, but anything is possible.

Another thing to try would be rotating the engine manually, with plugs out, just to hear what you might hear that way, without all the combustion/exhaust noise. Do not rotate the engine backwards.

Good luck and I hope you get to the bottom of the problem. You deserve a break at this point.
 

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Discussion Starter #12
Thanks for the reply, i've always been pretty diligent about the oil changes and ive just changed it again yesterday just to be fresh.The sound deffinately sounds like a sticky valve, its not a knocking like what was happening before and it's not quite a ticking niether, more in between.It sounds like it is coming from the valve cover area.I cant hear it at idle, just when i start to come up in the rpm's.The car still idles just fine and no codes came on, all guages sit where they always have.I was thinking that maybe the timing could be off just a hair? I'm going to delve a little further into the motor and check everything out.See if i cant dig up the problem.
 

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If you get the valve covers off be sure to examine the cam lobes for unusual wear patterns, scuffing, that sort of thing. Also there should be an oil film on every lobe.

Check the valve springs as best you can, both visually and with your fingers if possible, feeling for a broken spring. This would click more loudly as RPM's go up.

I still think manual rotation of the engine might prove to be a help, especially with the valve covers off. To do this you must remove the plugs. Perform the operation where conditions are VERY quiet.

If you remove the plugs, keep track of where each came from. Examine each plug carefully for any sign of misfire, poor combustion, excess carbonization, etc., something amiss. This could be the cylinder causing the noise, especially if a valve is hanging and causing that improper combustion.

Good luck.
 

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Discussion Starter #14
Well today i went out to check things out and i turned it over, check engine light came on.I'm going to get it over to my friends shop and run the codes, hopefully it will tell me something like a misfire and i'll have a general idea of where my problem lies.
 

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Discussion Starter #15
Ok i took it to my friends shop but his machine is back at snap on getting reprogrammed, he told me that my car sounds like its off a tooth or 2 on the cam cogs.Said he thinks it would still run if it was only off a tooth or 2?I'm going to dig back into it and check it out,I just dont know if it would make that noise by being off or if there is some more damage i didnt see.It would be nice to set the timing and have it go away but after everything with this car i'm skeptical to say the least.
 

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Your friend is on the scene, up close and personal, able to see and listen to the engine as it runs. This is a great advantage. Thus his counsel is worth ten times anything I can offer.

However

I agree strongly that if the cam timing is off even a tooth it must be put right BEFORE anything else is done and before any other diagnosis is attempted.

Also, though I agree the engine will run even though off a tooth, I would not run the engine if it were my car. Other owners will perhaps have differing views which is fine: this is strictly MHO.

The cam timing needs to be perfect, PERFECT, spot on; then you go from there.

Re Cateras in general, and not your car in particular:

Problems, of all sorts, with the cam drive mechanicals have been legion over the years. Everyone knows this.

By comparison, speaking in terms of frequency of occurrance, problems with stuck valves and/or broken springs are rare.

Any thing can happen to any Catera at any time. Stuff happens. Rare problems surface from time to time. But until proven wrong I always go with the odds:

The odds say there was and is nothing wrong with your engine you have not already fixed - provided the cam timing is made PERFECT.

Good luck!
 
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