cold start, engine tapping/slapping, possible cause
07-23-2017, 06:51 AM
#1
Pro
Thread Starter
cold start, engine tapping/slapping, possible cause
OK, So if you search, chain slap, cold start, ticking, or a combination of these, you will read about an engine tapping/slapping some of us get when we start a cold engine.
It lasts only seconds, maybe 5 or 10, and usually fades in, then fades out. I would best describe it as a dull muted slapping sound. Anyway, its well documented here in several threads.
Most believe it to be chain slap due to worn chain tensioners and/or chain tensioner guides. And as the oil has all dripped from these components as the cars sits, it further attributes to it.
So today I finally went to fix something I had noticed some months ago. There is an aluminum coolant pipe that runs in the front to back direction pretty much underneath the coolant tank reservoir. Probably 2 or 3 inch diameter. You can't miss it. Peering in from the engine compartment you can see it without removing anything. It runs forward until it disappears around a bend. It connects to a rubber coolant hose as it runs underneath the tank to the back of the car and turn towards the center of the engine, then the rubber hose goes downward. So that's the pipe I'm speaking of.
Using a flash light, you can look at the aluminum section that runs towards the front of the car under the coolant reservoir. There should be a plastic brace that encircles this pipe about a foot forward of the tank. If you do not see it, it has broken off.
Mine is broken off.
It would be really difficult to replace it without removing the tank which is why I haven't fixed mine. The brace really prevents the pipe from moving side to side not so much up and down. I know this as I have grabbed it and wiggled it. Grab yours and try moving it from side to side, if movement, brace is broken.
It has always bothered me that it was free to slide back and forth several inches without this brace. I don't know what it attaches to as it goes forward to the front since it disappears out of sight. But worst case I figured it may be slowly working its way out from where it attaches, and that can't be good.
So today I used a velcro strap to temporarily secure this pipe until I remove the tank for some reason and replace the brace.
Well, so what is all this leading to you ask? My car has always had the ticking/slapping at cold start. Been doing this for the year and a half I've owned it. It bugs the sh.t out of me and have done much research.
Well to my surprise, having done nothing else to the car while I was in there fitting this velcro strap to secure the pipe, the ticking/slapping has stopped. As in, stopped the first cold start since securing this pipe and every cold start for the last week or 2.
You can imagine my delight that it might have been something as simple as a pipe tapping as the engine started up cold.
My working theories are as follows:
1) that perhaps this pipe is empty when the car is cold and the coolant has flowed out and it vibrates more when the car is first started since it is lighter due to having no coolant in it. Now this assumes there is no coolant in it at cold start. I am assuming it doesn't, but I could be wrong. I'm sure someone can confirm or deny this. If I'm right then when the car is warm and the pipe is full, it doesn't vibrate, therefore no ticking/slapping upon warm or hot start up.
2) that it is depressurized at cold start up and the rubber hoses that attach on each end of this aluminum section are loose and allows the aluminum section to vibrate. As the rubber hoses it attaches to on each end pressurize and become firmer and more rigid, it doesn't allow the pipe to vibrate. If it takes anywhere from 5 to 10 seconds for this coolant system to pressure, this would explain why it stops quite quickly. If I'm right then it takes some time for the system to depressurize and therefore no ticking/slapping upon warm or hot start up
3) it has absolutely nothing to do with me securing this pipe and just happened to correct itself on the first cold start and every cold start since. Stranger things have happened.
So, I've taken the time to put this out there for those of you who have this cold start noise. It could be your issue. If your brace is missing, have someone hold the pipe as you start it cold. If ticking/slapping gone, your welcome. Then find a way to secure it permanently.
I am very delighted that my car no longer ticks/slaps at cold start ups. It stressed me out every time I started it cold.
I am going to leave it as is for 10 or so more cold starts, then I will remove the velcro strap and see if the ticking/slapping reappears on cold starts. I'll report back once I do this.
If this is clear as mud to anyone having this issue, I can take pictures or you can PM me with questions.
It lasts only seconds, maybe 5 or 10, and usually fades in, then fades out. I would best describe it as a dull muted slapping sound. Anyway, its well documented here in several threads.
Most believe it to be chain slap due to worn chain tensioners and/or chain tensioner guides. And as the oil has all dripped from these components as the cars sits, it further attributes to it.
So today I finally went to fix something I had noticed some months ago. There is an aluminum coolant pipe that runs in the front to back direction pretty much underneath the coolant tank reservoir. Probably 2 or 3 inch diameter. You can't miss it. Peering in from the engine compartment you can see it without removing anything. It runs forward until it disappears around a bend. It connects to a rubber coolant hose as it runs underneath the tank to the back of the car and turn towards the center of the engine, then the rubber hose goes downward. So that's the pipe I'm speaking of.
Using a flash light, you can look at the aluminum section that runs towards the front of the car under the coolant reservoir. There should be a plastic brace that encircles this pipe about a foot forward of the tank. If you do not see it, it has broken off.
Mine is broken off.
It would be really difficult to replace it without removing the tank which is why I haven't fixed mine. The brace really prevents the pipe from moving side to side not so much up and down. I know this as I have grabbed it and wiggled it. Grab yours and try moving it from side to side, if movement, brace is broken.
It has always bothered me that it was free to slide back and forth several inches without this brace. I don't know what it attaches to as it goes forward to the front since it disappears out of sight. But worst case I figured it may be slowly working its way out from where it attaches, and that can't be good.
So today I used a velcro strap to temporarily secure this pipe until I remove the tank for some reason and replace the brace.
Well, so what is all this leading to you ask? My car has always had the ticking/slapping at cold start. Been doing this for the year and a half I've owned it. It bugs the sh.t out of me and have done much research.
Well to my surprise, having done nothing else to the car while I was in there fitting this velcro strap to secure the pipe, the ticking/slapping has stopped. As in, stopped the first cold start since securing this pipe and every cold start for the last week or 2.
You can imagine my delight that it might have been something as simple as a pipe tapping as the engine started up cold.
My working theories are as follows:
1) that perhaps this pipe is empty when the car is cold and the coolant has flowed out and it vibrates more when the car is first started since it is lighter due to having no coolant in it. Now this assumes there is no coolant in it at cold start. I am assuming it doesn't, but I could be wrong. I'm sure someone can confirm or deny this. If I'm right then when the car is warm and the pipe is full, it doesn't vibrate, therefore no ticking/slapping upon warm or hot start up.
2) that it is depressurized at cold start up and the rubber hoses that attach on each end of this aluminum section are loose and allows the aluminum section to vibrate. As the rubber hoses it attaches to on each end pressurize and become firmer and more rigid, it doesn't allow the pipe to vibrate. If it takes anywhere from 5 to 10 seconds for this coolant system to pressure, this would explain why it stops quite quickly. If I'm right then it takes some time for the system to depressurize and therefore no ticking/slapping upon warm or hot start up
3) it has absolutely nothing to do with me securing this pipe and just happened to correct itself on the first cold start and every cold start since. Stranger things have happened.
So, I've taken the time to put this out there for those of you who have this cold start noise. It could be your issue. If your brace is missing, have someone hold the pipe as you start it cold. If ticking/slapping gone, your welcome. Then find a way to secure it permanently.
I am very delighted that my car no longer ticks/slaps at cold start ups. It stressed me out every time I started it cold.
I am going to leave it as is for 10 or so more cold starts, then I will remove the velcro strap and see if the ticking/slapping reappears on cold starts. I'll report back once I do this.
If this is clear as mud to anyone having this issue, I can take pictures or you can PM me with questions.
Last edited by rolex11; 07-23-2017 at 07:13 AM.
07-23-2017, 08:00 AM
#3
Pro
Thread Starter
By the way, we have spoken on the phone several times. I had those coil packs available, which you decided against me shipping you. We chatted several time thereafter.
07-25-2017, 08:11 AM
#4
Rennlist Member
That's pretty interesting, will have to check it out on my car.
Here's a picture of the coolant pipe that you are referring to when I replaced the tank. Are you referring to the clamp seen in this picture or one forward of this? This clamp is pretty much below the tank, where you say it's approximately 1 foot forward of the tank.
Here's a picture of the coolant pipe that you are referring to when I replaced the tank. Are you referring to the clamp seen in this picture or one forward of this? This clamp is pretty much below the tank, where you say it's approximately 1 foot forward of the tank.
07-25-2017, 11:15 AM
#5
Pro
Thread Starter
Great picture. That's the pipe and you can see the black plastic brace that holds the pipe.
Without that brace that pipe is free to rattle around. When it is filled with coolant it is heavy and can really slosh around.
My ticking/slapping at cold start has disappeared since I secured mine.
Without that brace that pipe is free to rattle around. When it is filled with coolant it is heavy and can really slosh around.
My ticking/slapping at cold start has disappeared since I secured mine.
Trending Topics
08-02-2017, 09:23 AM
#10
Rennlist Member
So last night I parked the car in my main garage so I could try this in the morning. Just got back from testing this theory.
You know what happened? The cold start knock went away!!
It does not look like my pipe clamp is broken, you can feel the metal part of the pipe and the clamp just below the coolant expansion tank (it's pretty much directly below it) if you put your hand to the outboard side of the air intake plastic piece that feeds the airbox and get it down below the tank.
I felt around before starting the engine, nothing seemed loose. I double checked that the belt wouldn't get me before starting the engine, started it, it had the knock for a few seconds until I could get my hand down to the pipe again and then I exerted force on it in the outboard direction and the noise went away.
I took my hand out after about 10 seconds and the knock never returned at idle, ran it for about 3-4 minutes and then shut it off. Normally it would keep knocking for 1-2 minutes (but now I just drive away and it doesn't happen after it warms up just a few seconds).
Somebody else has to do this.....I will repeat again tomorrow morning.
If it's just this pipe knocking until the forces on it are reduced due to coolant flowing or something (could be some slight water hammer, dunno).....that would make me sleep better at night!
You know what happened? The cold start knock went away!!
It does not look like my pipe clamp is broken, you can feel the metal part of the pipe and the clamp just below the coolant expansion tank (it's pretty much directly below it) if you put your hand to the outboard side of the air intake plastic piece that feeds the airbox and get it down below the tank.
I felt around before starting the engine, nothing seemed loose. I double checked that the belt wouldn't get me before starting the engine, started it, it had the knock for a few seconds until I could get my hand down to the pipe again and then I exerted force on it in the outboard direction and the noise went away.
I took my hand out after about 10 seconds and the knock never returned at idle, ran it for about 3-4 minutes and then shut it off. Normally it would keep knocking for 1-2 minutes (but now I just drive away and it doesn't happen after it warms up just a few seconds).
Somebody else has to do this.....I will repeat again tomorrow morning.
If it's just this pipe knocking until the forces on it are reduced due to coolant flowing or something (could be some slight water hammer, dunno).....that would make me sleep better at night!
08-02-2017, 11:53 AM
#14
Rennlist Member
I checked mine and did not try this because my clamp looked fine, but I will definitely be trying this today! This is insanely great news for some of us. It is too bad, there was a guy a few months ago who I believe sold his car after this sound occurred on morning starts. Could have just been a simple fix all along!