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worn cam, clatter

Posted: Thu Dec 02, 2010 6:58 pm
by ghnl
I have a clattery noise in our GTV6. I could best describe it as sounding like the baseball card we used to put in the spokes of our bicycle when we were kids (back when the dinosaurs still roamed the earth...). It is present at any engine speed or throttle postion/load & varies in speed directly to the RPM's. I cannot find any exhaust leaks. As a matter of fact, I am only now hearing it after quieting down the exhaust. When I bought the car it had no center muffler and a gutted catalytic converter. I have put in a new catalytic converter & resonator so the exhaust is now merely loud and not LOUD. (thus the noise may have been present earlier and just difficult to hear before)

Anyway, I am fairly certain it is from the camshaft/lifter area of the #6 exhaust valve. The camshafts are correctly timed (verified #1 at TDC/compression & both cam shaft marks align with the marks on the caps). I've checked the clearances. The exhausts are all at 0.009". The intakes are all approximately 0.016" (a bit tight but all equally so thus I am assuming/hoping the PO set them that way)

With the cam covers off & spark plugs out I had my trusted assistant turn the key to 'start' and I can clearly hear a clacking from the #6 exhaust lifter/lobe area (using a piece of heater hose as a stethescope to narrow it down).

So, I took another, closer look at the left side camshaft. I guess I didn't want to see it before but the evidence is clear to me now. The #6 cam lobes are worn. There isn't enough room to measure base circle & lobe height in situ but looking closely I can see that both the intake & exhaust lobes for #6 are not as 'pointy' as the other cylinder's. The photo makes the intake lobe appear pitted. It may be but I did not see or feel that until I downloaded the photos.

Any ideas as to why this happened? (I do not know what type of oil was used prior to my purchase.) One other thing I noticed is that the exhaust tappet has a series of shiney marks running parallel to the length of the tappet. Is the bore grooved? I suspect this indicates the tappet is not rotating...

Who sells good quality camshafts?

Re: worn cam, clatter

Posted: Fri Dec 03, 2010 11:35 am
by xrad
worn through the hardened surface. Why? dirt, poor manufacture, poor oiling,, who knows. Just dont keep running it. bet the lifter is shot as well.

do a compression test on all cylinders. Check your spark plugs for fouling (especially #6) and do an injector test (have them cleaned) This way in case #6 was running too hot, at least you can address the basics.

pop in a new set of lifters AND 164 cams and reshim and have fun

Re: worn cam, clatter

Posted: Fri Dec 03, 2010 11:59 am
by ghnl
Compression & leak down tests are excellent. Spark plugs look fine.

Compression 165psi (highest cylinder 170, most 165), Leak down 3% (best = 2%, worst 4%) Fuel injectors have been serviced at OK Injectors in October (all were described as fair/good before service, none were way off in flow testing - after service the flow rates were closely matched)

So, what is a good source for new/good camshafts?

Re: worn cam, clatter

Posted: Sat Dec 04, 2010 4:22 am
by fedezyl
RJR...why now, since you are getting new cams... :D

Re: worn cam, clatter

Posted: Sat Dec 04, 2010 5:41 pm
by xrad
exhaust lifter has a wear mark on the side.....maybe loose in the lifter bore?

I would have to think a bad cast or hardening on the cam as the two lobes are right next to each other...odd...

Do an oil change too...

and of course check the cam bore for wear also..

Wait, I just thought of something... I had an unusual wear pattern on a cam once because there was a warped head. Hate to say it, but you may want to check the head for flatness and check the cam bore as well

Re: worn cam, clatter

Posted: Sat Dec 04, 2010 6:33 pm
by ghnl
xrad wrote:exhaust lifter has a wear mark on the side.....maybe loose in the lifter bore?
Do you mean the shiney areas visible running parellel to the lifter's travel? (see photo below) I wondered if the lifter wasn't rotating and the marks are due to gooves in the lifter bore?

Also, I noticed that there was some oil in the areas around the camshaft but it wasn't 'full' like the right side head. Does that say anything?
Wait, I just thought of something... I had an unusual wear pattern on a cam once because there was a warped head. Hate to say it, but you may want to check the head for flatness and check the cam bore as well
Don't be giving me more things to lose sleep over...

Re: worn cam, clatter

Posted: Sun Dec 05, 2010 6:58 am
by xrad
Yep, those marks...see what the cam shaft and bearing caps look like when you pull the cam....Clogged oil port?

Re: worn cam, clatter

Posted: Mon Dec 06, 2010 2:44 pm
by kens
I once had the exact same problem on my 2.0 V6 turbo 164. My wife even mentioned that it sounded like playing cards on bicycle spokes.

The #5 lifter was slightly concave. I replaced just the lifter, noise went away. No more related problems.

Re: worn cam, clatter

Posted: Mon Dec 06, 2010 4:15 pm
by xrad
yep, that would work for one lifter. but both lobes worn..unusual..

Re: worn cam, clatter

Posted: Mon Dec 06, 2010 4:26 pm
by ghnl
Yes, both lobes are worn. If I had taken a photo with more of a 'side view' of the lobe the change in shape would be more obvious. The other cam lobes appear good.

How would I check for adequate oil supply to the cam? I assume it comes up via the oil passages that have the O-ring & roll pin between the block & head.

Re: worn cam, clatter

Posted: Tue Dec 07, 2010 1:29 pm
by xrad
I would think that you have to pull the head and really clean everything out to be sure.

Re: worn cam, clatter

Posted: Wed Dec 08, 2010 2:54 am
by Typhoon90
You know what I see on the sides of that lifter? Corrosion pitting. If that has happened, I be that lifter has stuck at some stage, that'll wipe out a cam lobe.

Regards, Andrew.

Re: worn cam, clatter

Posted: Sun Dec 12, 2010 2:10 pm
by ghnl
I removed the left side camshaft for a closer look. It is obvious more lobes are worn (perhaps all of them?). The bearings look good. I am still concerned about whether the cam is getting an adequate oil supply. If I can attribute this to the PO using the 'wrong' type of oil (inadequate zinc) then I'll feel better about replacing the cams/lifters and driving it.
lobes #4.jpg
lobes #4.jpg (27.42 KiB) Viewed 4390 times
lobes #5.jpg
lobes #5.jpg (27.23 KiB) Viewed 4389 times
lobes #6.jpg
lobes #6.jpg (27.01 KiB) Viewed 4392 times
Would it be feasible to crank the engine with the left cam shaft removed & spark plugs out and watch for oil being delivered to the (empty) cam bearings? The timing belt is still in place (I have documented evidence the timing belt was replaced ~ 7,000 miles ago and I was not planning to replace it unless that would be foolish with new cams). Will the cam pulley remain in place with the camshaft removed?

Re: worn cam, clatter

Posted: Sun Dec 12, 2010 4:32 pm
by xrad
I there is a cam position where you can turn the engine and not touch a valve, if you crank by hand...maybe then you can find the safety spot BEFORE electric cranking

WOW those are some worn lobes!! looks like a blown racing engine! lifter bores need to be checked closely

did a shim slide off and wedge in the valve spring or something?

could be no oil to this area

What does the other cam look like?

Bad oil pump?

Re: worn cam, clatter

Posted: Sun Dec 12, 2010 6:26 pm
by ghnl
xrad wrote:there is a cam position where you can turn the engine and not touch a valve, if you crank by hand...maybe then you can find the safety spot BEFORE electric cranking
Yes, but I was hoping to leave both the right cam in place and the timing belt. Thus if I were to crank the engine the timing belt will turn the right camshaft (and the left pulley sans camshaft). My thought being (if this is even do-able) is that leaving the right camshaft in place will provide 'normal' oil pressure to that side and let me see if oil is getting delivered to the left side. If I remove both camshafts & the timing belt* then crank the engine I wouldn't have to worry about valves hitting pistons but the lack of the right cam shaft leaves those cam bearings 'open' and might not prove anything.

* I was hoping to leave the timing belt in place because I wasn't planning to replace (remove) it.

So, is that even possible - to remove the one camshaft, leave the pulley & timing belt in place, crank the engine and not have either fly off?

What does the other cam look like?
I have to take the right cam cover off (again...), remove that cam and get a good look. My memory is that it is not as worn as the bad left lobes.
Bad oil pump?
Oil pressure via dash gauge (new sender) is good. With a warm engine about 20 psi at idle, 65-70 psi running (~ 2,000 rpm & above).