Tapping noise during warmup from cold start

[TOC]

I noticed that when I start my car after cooling overnight it seems to have a tapping noise until the motor is warm and then it pretty much goes away. Sounds a bit like a solid lifter cam.

I'm thinking piston slap, but my Lightning, which also has forged pistons is quiet on cold start (one would think they'd be similar).

Discussed with the shop foreman at the dealer, and he seemed puzzled as they haven't see this on any other 03 Cobra's.

I'll get them to check it out when I go in for my new drive shaft (yes I have the 80 to 85 MPH vibration too. Ford told shop foreman to install a new driveshaft after they did the EVT diagnostics).

Has anyone else experienced this with their car, or have any information on this condition?

 

[mark f.]

noise on cold start

TOC, I saw your post and your description of the tapping noise sounds similar to what I'm hearing on mine(16,000 miles). Did you learn anything more from your dealer?

 

[Blue03Cobra]

Forged pistons require some time to expand during warmup...a "diesel" sound from a bone-cold start is normal until operating temps are reached.

 

[mark f.]

tapping noise

thanks

 

[tey]

I had the same noise during warm up. Eventually it did not go away after warm up. I had the compression checked on my cylinders and one of them was low. Opened the engine and three pistons were partially melted. I HOPE THIS IS NOT YOUR PROBLEM!

 

[03redfiresnake]

I have about 5,000 miles on my car, but I always noticed it ran a little rough until it was warmed up. I figured it was due to the forged internals. I don't think it is as pronounced now as it was when it was new.

 

[stangin]

Originally posted by tey
I had the same noise during warm up. Eventually it did not go away after warm up. I had the compression checked on my cylinders and one of them was low. Opened the engine and three pistons were partially melted. I HOPE THIS IS NOT YOUR PROBLEM!

Dont tell me this.. I have not been that hard on the Cobra. Sorry to hear that. Can you tell us which cyliders were melted? I hear the tick on and off, usually before it is fully warmed up. It sure sounds like the dreaded tick, but does not always do it and usually before it is fully warmed up.. seems to be the drivers side and mostly goes away after it is warmed up.

 

[NyteByte]

I have the piston slap on startup as do many other people. It's normal.

However, I just developed a new tapping noise right after I did an oil change. It's VERY loud and you can hear it clearly with the hood open. It never goes away, even after warmup.:bored:

 

[03redfiresnake]

Do you here it from the drivers side rear of engine ? Is it noticeable at drive thrus ? You might have the head tick.

 

[stangfan]

I've had this since mile #1. I've been told that it's 'normal'... I'm still not convinced that it's not a 'lighter' version of 'the tick'. I'm curious to hear what other people have to say about this.

 

[03redfiresnake]

stangfan,
I starting to believe your theory. I just had my head replaced, due to the tick- and I don't notice it running rough at start-up anymore........:??:

 

[caveman6666]

Originally posted by NyteByte
I have the piston slap on startup as do many other people. It's normal.

However, I just developed a new tapping noise right after I did an oil change. It's VERY loud and you can hear it clearly with the hood open. It never goes away, even after warmup.:bored:

Change the viscosity?

 

[mike79]

Originally posted by NyteByte
I have the piston slap on startup as do many other people. It's normal.

However, I just developed a new tapping noise right after I did an oil change. It's VERY loud and you can hear it clearly with the hood open. It never goes away, even after warmup.:bored:

Are you sure the oil wasnt contaminated?

 

[Russtang]

Check out this article on piston slap:

http://www.canadiandriver.com/articles/jk/020320.htm

 

[NyteByte]

Originally posted by mike79
Are you sure the oil wasnt contaminated?

It was Amsoil 5W-20 and it looked fine when I poured it in. It shows up on the dipstick (3/4 to the top) and the engine runs fine.

The tapping noise gets louder when I open the hood and I can't really tell where its coming from. Doesn't really sound like it's coming from the left head. Who knows? I'm stumped. :shrug:

 

[caveman6666]

Strange.
Any time the oil is changed, the next time it's started, there's zero oil pressure for a second or two. You can often hear it grind or bang until the oil circulates. On the older stuff, I pull the coil wire and spin it a few times to run the pump.

The change must have exacerbated a problem waiting to happen.

 

[raptorman02]

Mine does it also!! I went to a car show yesterday and there was nothing after sitting for a few hours I started it and it was "tapping real loud" people 20 feet away heard it. After driving for a bit it went completely away, it wasn't even kind off there it was gone so I was GREAT wheeww. Well last night I let it sit again and started it and it came back (mind you its not cooling all the way down just a couple hours. It went away again after getting on the road and driving a bit then it came back and stayed there even after driving it. This morning its back and the worst I have heard. I have had to replace rod bearings because of noises like this so I praying thats not what it is. Also I have had to replace the Timing chain tensioners on a 96 DOHC Cobra that we thought was Rod Bearings but when we got down it turned out it was the tensioners that were loose and causing a slapping of the chain and this same noise. I don't know I only have 10,000 miles so I am taking it in monday and having it checked out!!

 

[raptorman02]

answer for me

Well I just found out that the tapping noise in mine was piston slap. I am going to have to rebuild the bottom end. It looks like the motor got hot and ran lean at some point (very well could be when I had the Fuel rail pressure sensor go out).

 

[mark f.]

Raptorman02, how did they determine the damage from the piston slap? Did they do a compression check? Your engine will be rebuilt not replaced?

 

[raptorman02]

ll

I have it torn down in my shop right now, I went and picked it up from the dealer today. You can move the piston up and down in the bore. its like its egg shaped running across the engine not down the length if that makes sense. I will try to take some pics to show what I am talking about. Essentially what happened is the cylinder overheated and became malleable (sp) when this happened the usual motion of the piston going up and down exerted enough side pressure from the way the rods and crank push it to slightly egg the bores out.

hope that was clear as mud