Motor knock? Camshaft?

J

Jeasen

New Member
Joined
May 25, 2001
My TTA develops a knock when the motor gets to operating temperature. When cold no knock but it does not run as smooth as I think it should. It runs rough when cold and is worse when hot. I had some very knowledgeable Buick V6 guys listen to the motor when cold and then to the knock as it warmed up. The best diagnosis I received was it was due to a flat cam. If you shut the motor off and let it cool for a short period of time and restart it the knock is gone but it does not take long and it is back. The oil pressure is good at idle, over 60 when cold and above 25 when hot. I am going to tear into the motor and am planning to install a roller cam. I purchased a Comp Cams #69-400-8 cam, grind #269hr 218/212 from a member of the TurboBuick board.

I called Comp Cams and the tech guy thought that this would be a good cam for my car. I feel that it might be too big but I have no experience with roller cams in these motors. I thought it would be a good idea to ask some of the people that know these cars.

Is this cam too big for a TTA motor with bluetop injectors, a TA49 Turbo and a 3000 stall convertor?

Also has anyone ever experienced a knock like I described?
 
Time to pull the engine :frown:

You've got low oil pressure, and a knock. To check for a wiped cam lobe, pull the valve covers, and watch the rocker arms- you'll be able to tell pretty quickly if you have a cam problem. Cut open your oil filter and tell us what you find......

IMO that cam's a bit big, but it should work fine- consider that people had had much success with much smaller grinds (206/206, 204/214, 214/214), and that even the stock cam has been deep into the 11s.
 
Yup- got me- I was thinking (a dangerous thing to do when not awake!) and equated 25 psi with WOT, and put the two together.

Negate my last re low oil pressure......
 
Knock?

Anyone have any idea what this might be? Would a flat cam cause a knock? My son is putting a looser converter in his Turbo Buick and made the comment that my TTA sure runs rough when he backed it out of the garage to use the lift compared to his Buick.

I already did the valve cover removal thing and everything looked fine. I also did a compression check and everything seemed to be OK. I guess I will not know what is wrong until I tear apart the motor. What about a bad thrust bearing on the crankshaft. Will this cause a knock?

Maybe I am getting old, but I only want to do this once. Should I just go ahead and install the 218/212 cam. My Turbo Buick had way too much low end torque and I had to shut it off many times to avoid hitting the wall in second gear. So, a little less low end torque would not upset me.

I just want to have a car that runs somewhere near its potential.
 
Is #3E pushrod spinning?

If your chassis is set up right, the car should be able to take the HP/TQ and launch straight and hard....
 
If you are having a knock problem.. fix that first.. then worry about changing the cam

If the cam got damaged.. or lifter. there will be metal in the oil. New cam and metal in the oil=bad things.

You can pull the valvecovers of the motor.. and using a small machinist ruler measure the opening of each one of the rockers. If the cam has gone bad, one will not open as much as the rest.

You can check your thrust by disconnecting the serpentine belt and using a small prybar, pry the flexplate back and forth and see how much play you have. Should be like .1 movement.

I have seen knocking from broken timing chain tensioners.
 
Almost forgot.. thats a 9 second cam. Way tooo much

Julio
 
Camshaft?

Razor said:
Almost forgot.. thats a 9 second cam. Way tooo much

Julio
Click to expand...

That is what I was thinking also. Once I find what is knocking and get that fixed I want the car to run good and I do not want to go through this again. Or at least for a while until I decide what I will do next to this car ;) .

Razor, on the crankshaft end play, did you mean .010" (10 thousands of an inch)?

I want to thank everyone for their replies.

James Armbrust
 
Knock?

Just wanted to let everyone know that I just got back from having a little freeway fun with some sort of Acura. At 120+ he did not want to play anymore or could not. Car runs good and pulls hard at the 120+ mark. I am sure that I could have hit the 140 mark with no problem but got into some traffic and had to slow down:cool: !

What I forgot to tell about my knock is that it is only present when the car is up to temperature and is at an idle. It is a very deep and hollow sounding knock and it seems to be coming from the center top part of the motor:confused: . I tried to find it with a stetoscope but it seems to be as loud no matter where you put the sounding device. As soon as the RPMs is brought up above an idle it goes away. Also the knock is not something new. It has been there since I bought the car some 5000 miles ago. It has not gotten any worse or any better. Any one have an idea what this might be?

I would sure like to know what to look for when I start my tear down. I do not want to go further than I need to. I would really like to leave the heads on the motor. Does this still sound like a camshaft problem? How about crankshaft end play?

Why does the car pull so hard but run so ruff:confused: ? All comments and opinions are appreciated:) .
 
Jeasen; said:
Just wanted to let everyone know that I just got back from having a little freeway fun with some sort of Acura. At 120+ he did not want to play anymore or could not. Car runs good and pulls hard at the 120+ mark.

What I forgot to tell about my knock is that it is only present when the car is up to temperature and is at an idle. It is a very deep and hollow sounding knock and it seems to be coming from the center top part of the motor:confused: . I tried to find it with a stetoscope but it seems to be as loud no matter where you put the sounding device. As soon as the RPMs is brought up above an idle it goes away. Also the knock is not something new.


Well, from my experience, if you have a real mechanical knock it will be severe enough that, you'll want to shut the motor down. I have heard knock from a main bearing that was suttle but loud enough to reveal a real problem. If it's a cam lobe you don't need to do anything fancy, just pull yer valve covers and start trying to move yer rockers up and down by hand, you'll find the wiped lobe real fast. Also, just watch yer belt tensioner and see if the knock follows the movement of the pulley, these babies do produce a knock noise. The problem here is yer perception of knock. Running rough when warmed up could be as simple as a bad o2 sensor.
Click to expand...
 
Knock?

Well here is the new parts I have added with no change in the knock. Not any worse or any better.

New parts added are plugs, plug wires, injectors, coil pack, fuel pump hot wire kit and new Walbro pump, new O2 sensor, I have removed the valve covers and watched the rocker arms, I have checked the belt tensioner, and I can not remember what else.

I never had anything simple go wrong with my car. For example if a wheel fell off then you could say if I would put the wheel back on then I could go. But I never have anything that simple. "Always some Never Heard Of That Before BS".

Any and all suggestions and opinions are welcome.

James
 
Hi,
I believe you are going to find that this is a generic problem with our cars, and that it doesn't get better or worse, just the same kanock. Right side on my car. I always thought it was a valve train issue. I am not willing to pull down the motor to fix it, infact I don't think it needs fixing. I run the crap out of this car, and it always comes back for more. I have seen 120 plus, without a hiccup. By the way, the car feels great at high speed, it just hunkers down and wants more. What a proud machine we are so lucky to own!
 
Knock?

So you are saying this is just a part of owning one of these cars? I can accept that as mine knocks like h_ll when hot. I can run the $hit out of it and it still keeps going. However, I am ashamied of the knock and I do not want to contiue to explain it to the guys at the curise when I pull in. I just want it to go away. What is the problem here?????:confused:
 
I mean my motor has a "knock" that goes away after idle but you can only hear it in the car. How loud is this? If you can hear it pulling in, I would imagine it would be loud..

Jason
 
Knock?

It is pretty loud. I notice people answering their doors when I drive down the street. (Just kidding)

It is a deep hollow sounding knock that seems to be coming from the top of the motor just under the intake dog house. It is pretty noticeable when the car is at operating temperature and at idle. The first time I heard it I thought it was a rod getting ready to introduce itself to me on a face to face basis. I immediately shut the motor off. Then after it cooled down I decided to start it again and no knock??? So I proceeded to drive it from California to the Eastern part of Kansas. And have been driving it like that for a couple of years now.Like I said, when the RPMs are brought up just above idle it goes away. You can only hear it when the motor is below 1200 RPMs.

The more I think about it I think it is the crank shaft or the cam shaft moving back and forth in the motor and hitting what ever they hit when it moves at idle. When the RPMs are brought up the cam or the crank do not have enough time to move back and forth to cause the knock.

However my theroy does not explain why the motor runs rough. And the rough gets worse as the motor warms up.

I am just trying to figure out if I should pull the motor or try to solve this while the motor is still in the car?
 
Maybe a lifter that bleeds down until at rpm? Just a thought....there's not much under the doghouse to localize- the lifters, pushrods, and the cam....
 
loose torque convertor bolts ???? my t type was knocking until the bolts fell out . put some new ones in and it went away.just a idea. when the cam got wiped on my tta the vaccum side on the boost gage was surging up and down and had two wiped lobes but no knockin.
 
Knock

The torque converter bolts and the belt tensioner was some of the first things I checked. No problem there.

Thanks for the suggestion though.
 
take off the belt and see if the balancer moves :rolleyes: my original TTA wore a 1/4" groove on the keyway :eek:
 
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