a slight knock & idle a bit rough

[djnb40]

I have a question about my SHO. It will be hard to diagnose over the internet, but someone out there may have an idea.

I noticed that at idle, between 550-900 RPM’s my car has a slight knocking noise, about 3 times per second varying by the idle speed.

This sound is much more noticeable when the car is up to normal operating temperature and can barely, if at all be heard when the engine is cold.

I also seem to have a little bit of a “bounce” that goes along with the knocking sound, which makes the idle a bit rough (the engine does bounce back and forth a bit with it).

It has done this for over 1,000 miles that I have now had this car. I have tried to pinpoint the sound but have not succeeded. It sounds as though it is coming from just about the middle of the engine, but could very well be coming from inside one of the valve covers.

Does the V8 normally have a slight knocking sound and idle a hair on the rough side, or should it not? Thank you for any input as I know that this kind of stuff is not easy to diagnose over the internet.

This car has 22,500 miles on it at the moment.

Thank you,
DJ

**Edit** Also, could anyone tell me the specifics of the TSB below, I think it may apply to my car. Sometimes I do get a slight shudder and 3-2 shift is a hard one when accelerating.

99-18-4 SEP 99 A/T - Harsh 3-2 Downshift/Shudder On Acceleration/Turns

<small>[ August 04, 2003, 02:26 AM: Message edited by: djnb40 ]</small>

 

[MilTownSHO]

OK everyone will probably scream cam failure, but its worth getting checked out, failures have happened at low miles. Check out V8 SHO to find a place to have the cams welded nearby. The cams on our 98 were welded at 32k because IMHO its just not worth the risk, currently the car has 36k and no worries anymore. The fact that you say it sounds like its coming from the valve covers is what concerns me...

Get a mechanics stethoscope to isolate the sound and it may give you a better idea of what's going on.

The V8's or at least our 98 does sometime idle weird, most common thing is a coil pack. One time the car refused to idle, it was real rough then the car died. Restarted it, same thing, shut it off, restarted and it was fine. It was weird. Then one other time I started the car and it sounded horrible and was not idleing right at all so I shut it off, restarted and was fine. This has happened a whole two times but it still freaks me out. oh_my

It seems each V8 SHO sounds a little different, when my cams were welded, Eric started his V8 up and each motor sounded a little different. If possible get someone from your area with a V8 SHO to compare yours to.

I dont know what else to tell you, I'd get it checked out though before driving to far or driving at all. Even though you do have low miles, even lower than ours...

One last thing, are you sure your not low on oil? shrug Sorry had to ask, the fact that you say its more noticeable when warmed up and the fact that some people no NOTHING about cars.

<small>[ August 04, 2003, 02:36 AM: Message edited by: MilTownSHO ]</small>

 

[MilTownSHO]

djnb40:


**Edit** Also, could anyone tell me the specifics of the TSB below, I think it may apply to my car. Sometimes I do get a slight shudder and 3-2 shift is a hard one when accelerating.

99-18-4 SEP 99 A/T - Harsh 3-2 Downshift/Shudder On Acceleration/Turns

I could dig them up at work if your really concerned (I work at a Ford dealership) but its supposed to well not shutter but throw you back in your seat a little when you get on it. Have you unplugged the battery lately? shrug It could be the computer reprogramming itself and learning your driving habits. That would be normal.

 

[djnb40]

Thanks for the help!

The oil is up to where it should be, I keep up with all the maintenance in all of my cars very well.

And the 3-2 downshift does really throw me back in the seat at times. Seems a bit harder than it should be. Could you please look that up that TSB for me?

Thank you.

<small>[ August 04, 2003, 03:04 AM: Message edited by: djnb40 ]</small>

 

[99V8SHO]

My idle is only rough during cold starts, then after maybe a minute the idle is back to normal.
Other than that my idle is as smooth as can be. Sometimes I hafta look at the tach to make sure it is still running.

 

[ricky]

I know this may be a dumb question but is this on premium or regular gas?

 

[99V8SHO]

Lately its been strictly premium. I go through phases, though. Sometimes I will use regular, then switch to premium.

Hey, there are no stupid questions here.
Only stupid people. thumb Just kiddin' ya. lol

 

[Mr Anonymous]

TSB 99-18-4 applies to the AX4S tranny, not the AX4N in the SHO. You can view the TSB HERE.

 

[djnb40]

SHOooo:
TSB 99-18-4 applies to the AX4S tranny, not the AX4N in the SHO. You can view the TSB HERE.

Thanks.

I have been running premium lately to see if it would improve this, but it has not. Sbould the main sprocket which you can see through the oil filler hole on the front bank run true on the camshaft, or is it normal to look a bit out-of-round? Below I have a video of the main sprocket and the knocking.

http://www.superford.org/getfile.php?id=78196
Video is about 2 MB.

Any input is appreciated. Thanks!

<small>[ August 04, 2003, 08:05 PM: Message edited by: djnb40 ]</small>

 

[MilTownSHO]

The video runs choppy on my computer so I can't really see the main sproket, but as far as the knock it's not really long enough to really hear it I can hear it for a split second than the video ends. It's hard to diagnose these things over the net, I still suggest trying to find a V8 SHO owner near you to compare.

 

[SHOZ123]

If the sproket is wobbing to ANY extent turn the motor off and do not start it again until the cams are fixed. The motor is soon to be a gonner if you don't.

 

[djnb40]

This morning I went ahead and removed the front valve cover (Still off now) None of the sprockets seem to be lose or have walked on the shaft. Even though it all seems fine, why does my primary sprocket look out-of-round when it is spinning? Could this still be a problem?

Any input is appreciated!

Thanks!

**Edit** By the way, is anyone able to see the video well?***

<small>[ August 05, 2003, 06:02 PM: Message edited by: djnb40 ]</small>

 

[ricky]

I saw the video of the "wobble". went out and looked at my 98SHO in the same spot and it has the same "wobble", perfect idle as long as I have good gas. wife put regular in one day while I was in the waterworks. thats why I asked which gas you were using. my SHO runs very poorly on regular. thought that one tank would last forever. hope you find the source of problem soon,

 

[SHOZ123]

The sprocket will not feel loose until the chain tension is off of it. It is definitely bad.

 

[djnb40]

SHOZ123:
The sprocket will not feel loose until the chain tension is off of it. It is definitely bad.

How do I release the tension to check it?

So...from what I understand all 3 sprockets can actually fail...correct? Both the primary and the other two on the intake and exhaust cams? What is the correct name for those two?

Thanks

<small>[ August 06, 2003, 03:00 AM: Message edited by: djnb40 ]</small>

 

[ricky]

went and double checked the cams in my service manual. you [and all other SHOs] do not have a "wobble" on the sprocket you are looking at. these sprockets have two flat sides for the use of a cam position tool. when spinning it looks wobbly. by the way this sprocket and the other side are pinned thru the face and bolted.

 

[SHOZ123]

ricky:
went and double checked the cams in my service manual. you [and all other SHOs] do not have a "wobble" on the sprocket you are looking at. these sprockets have two flat sides for the use of a cam position tool. when spinning it looks wobbly. by the way this sprocket and the other side are pinned thru the face and bolted.

None of the above applies to the GEN 3.

There is a hex next to, but seperate from the front cam sproket. It too though is a swedged fit.

 

[ricky]

the part that he is observing thru the oil fill is the end of the left hand exhaust camshaft. it has a bump/out or whatever you want to call it with two flat sides for use of a cam position tool. this is what gives the appearance of a wobble. the wobble on the camshafts cannot be seen without removing valve covers.

 

[SHOZ123]

Here is a picture of the front cam.

 

[ricky]

good picture of front cam, back of front sprocket and secondary sprocket. nice welds. the "wobble" effect maker is on the other side of the front sprocket.