Vacuum leak CTSC

[Gerard van Santen]

Because my idle problem seemed to be SC related I started this new thread.

This is the thread I started with:

idling problem

This morning, with the help of Cees-Jan, I lifted my SC including the manifold to see if the blue hose under the manifold was the cause of my idling problem.

Mark Basch was right. The blue hose under my SC was broken. A vacuum leak as a result.

Here are some pictures of the trouble maker:

 

[Gerard van Santen]

I ordered a new hose from Comptec. But because I haven't had a positive reaction on the order yet, Cees-Jan and I fabricated a home made tube. I couldn't use just a hose from the cooling system, because it has to be oil resistend. When I get the original one from Comptech I think I will replace the home made one. But perhaps it is not necessary.

Everybody thanks for the input and help :smile:

This is the result and it works. Idling problem solved:

 

[Gerard van Santen]

Bad luck never comes alone

On my way back home a high squeezing noise came out of the engine bay. At home I heared the noise came somewhere from my idler plate. I disassembled the idler plate and found out, that two of the idlers had a weak bearing. So now I have to find new bearings and someone who can repair the idlers.

 

[NSXTech]

Gerhard, I laughed SO hard at your repair pic. I did the EXACT same thing first time I saw that problem. I had flown 1000 miles to a customer who wanted me fix his SC problem. When I discovered the hose leaking, and had no way to get one in my remaining time, I went to Home despot and fabricated a pvc replacement using scavenged bits of the original to fashion two clamping bands. I did take a pic for posperity but can't find it this morn.
Great minds think alike :biggrin:

I keep those pulleys in stock, three of each, because of their high failure rate. It is MOST common for them to fail immediately after a repair such as yours, because they were on the ragged edge to begin with and when you reinstalled and tightened the belt, it could not take the load change.

You have good luck! You had a baffling engine control problem, you found it quickly, and fixed it easily! :biggrin:

Cheers,
MB

 

[Gerard van Santen]

Mark, Thank you very much. I take your comment as a compliment.

Do you think the pseudo hose will hold?

 

[Gerard van Santen]

In my last report I mentioned I had bad idler bearings. I did my second best trick of today.
I removed the rubber sealings of the bearings and cleaned the bearings with washing fuel. Then I filled the bearings with bearing grease and closed the bearings with the rubber sealings.

I installed the idler plate and in the proces changed the old SC belt with a new one. Then I took my baby for a ride and YES... Everything turned out to be OK...

I hope the bearings will hold :smile:

 

[DutchBlackNsx]

Isn't PVC proune to become very britle in a short period of time, due to heat ( a lot!), and virbrations (also a lot) ?

For that reason, replace the part with a proper tube when you receive it.

 

[Gerard van Santen]

Isn't PVC proune to become very britle in a short period of time, due to heat ( a lot!), and virbrations (also a lot) ?

For that reason, replace the part with a proper tube when you receive it.

PVC can hold at least the heat of cooking water 100 degrees Celsius and more. Not to mention the housewifes who dump their cooking oil (sometimes more then 100 degrees Celsius) into the sink. The tube is in open air under the manifold and will never get this heat. The engine is watercooled. So I assume, that the aluminum on the manifold side won't get hotter than the water in the cooling system.

For vibrations reasons we used parts of the original tube to make the connections to the manifold. But yes, as soon as I get the OEM one from Comptech I will replace the home made one.

 

[DutchBlackNsx]

Good point Gerard.

 

[Gerard van Santen]

I did take a pic for posperity but can't find it this morn.

If you find the pic. Please show it to us.

 

[Cees-Jan]

After some Googling :http://www.vink.be/Default.asp?ID=1903

They officially allow use of PVC between -10 C and +70 C. This means that it it will break down eventually, I couldnt find the exact numbers of the brand pipe we used.

It is wise to change the bearings and keep the old ones for backup.

 

[Gerard van Santen]

After some Googling :http://www.vink.be/Default.asp?ID=1903

They officially allow use of PVC between -10 C and +70 C. This means that it it will break down eventually, I couldnt find the exact numbers of the brand pipe we used.
QUOTE]
This is what I found on this site:PVC

 

[DutchBlackNsx]

This is what I found on this site...

Thats only for the 'high temperature' variant.

 

[NSXTech]

From the Samco site (OEM for the CT provided hose)

Standard Colour: Blue
Colour Options: Red / Green / Yellow / Purple / Black / Orange
Standard Hose Max Temperature: ~ 170ºC (338ºF)
Size Tolerance: ± 0.5mm

That said, or copied as the case may be, I think you will be okay for a while but I would take Cees-Jans advise and replace it when you can. The new hose will be wire reinforced- Shad told me a few years ago that they believed the flexing from constant vac/press changes caused the failure. To me, looking at the brown or black surrounding the crack, it seems heat is a factor.
We left the PVC hose we made in place for a quite a while 'if' I recall, but it was sch 125 and was a bit heavier duty perhaps.

Also as Cees-Jans suggests, your bearings will not last. The new grease is simply packing the ruined ball bearings a little tighter and filling the surface irregularities. I doubt they would last even 500 km before being noisey again.

Heres the link on the hose, for you techies.
http://www.samcosport.com/elbows.asp

Cheers,
MB

 

[Gerard van Santen]

Mark, thanks for the info.

Do you know the max temps under the manifold? Will it ever come over 90 degrees Celsius? I have done a test in the oven. For more than 2 hours at 90 Celsius everything was OK. At 100 Celsius the structure became a little weaker. Out of the oven the structure normalised.

I renewed the bearings this morning. The noise didn't dissapear. It was even louder than before. Than I changed the new belt for the old one and the noise was gone

 

[j14nsx]

Gerard,

I don't know why you are having difficulty getting a replacement. Samco, and SFS (another silicone hose company) are both in the UK. If you have problems getting hoses, ask me, and I get them from suppliers here.

Kevin

 

[drew]

Can you folks shed some light on the "unintended acceleration" that happens if the hose fails completely?

I'm unclear on how that works...

**

How do you tell if the blue hose has the wire reinforcement?

Thanks

Drew

 

[NSXTech]

The old belt is a Gatorback, the new one is not. I doubt the change in sound is from the belt, but rather my best educated guess would be that you somehow assembled something a little differant (better? correctly?) the last time, than you did the previous time(s). Hard to say. Belt tension? Alignment? If the two 1/4 allens that hold the tensioner assy were not tight perhaps.
New belt, new bearings, no noise- no worries!

Have never measured the temps you ask about, however we can walk it backwards. If the water temp is a max 'average' of 200f, then the metal around it will be never be more. Subtract from that the immediate cooling effect of an air barrier and you are down to at least 160f, or 72c. Even if my best guess is wrong, and its an air temp of 180f that is still only 82c and I can assure you the surface temp of all the alloys in the immediate vicinity of the intake manifold are far lower than 180f. This is a design goal for all engine designers, in an effort to control EFE, or early fuel evaporation.

HTH,
MB

 

[Gerard van Santen]

Have never measured the temps you ask about, however we can walk it backwards. If the water temp is a max 'average' of 200f, then the metal around it will be never be more. Subtract from that the immediate cooling effect of an air barrier and you are down to at least 160f, or 72c. Even if my best guess is wrong, and its an air temp of 180f that is still only 82c and I can assure you the surface temp of all the alloys in the immediate vicinity of the intake manifold are far lower than 180f. This is a design goal for all engine designers, in an effort to control EFE, or early fuel evaporation.

HTH,
MB

As I said before I did a test at 90c/194f. If you are correct, than the PVC hose should be sufficient.

 

[Cees-Jan]

The new hose will be wire reinforced- Shad told me a few years ago that they believed the flexing from constant vac/press changes caused the failure. To me, looking at the brown or black surrounding the crack, it seems heat is a factor.

Heres the link on the hose, for you techies.
http://www.samcosport.com/elbows.asp

Cheers,
MB

This hose is always (!) under vacuum or at max. atmosperic pressure, never under boost: If the valve is open, the air will flow through the hose, back into the suction side of the compressor, when the valve closes, the hose is on the suction side of the compressor, so under vacuum.....

As clearly can be seen in the pictture the hose has become black because it has absorped oil fumes, where the "slang klem" whas mounted the hose remaned blue. Conclusion: This whas a standard heaterhose.

 

[Gerard van Santen]

From the Samco site (OEM for the CT provided hose)

Standard Colour: Blue
Colour Options: Red / Green / Yellow / Purple / Black / Orange
Standard Hose Max Temperature: ~ 170ºC (338ºF)
Size Tolerance: ± 0.5mm

That said, or copied as the case may be, I think you will be okay for a while but I would take Cees-Jans advise and replace it when you can. The new hose will be wire reinforced- Shad told me a few years ago that they believed the flexing from constant vac/press changes caused the failure. To me, looking at the brown or black surrounding the crack, it seems heat is a factor.
We left the PVC hose we made in place for a quite a while 'if' I recall, but it was sch 125 and was a bit heavier duty perhaps.

Cheers,
MB

My guess is, that the blue hose used by Comptech isn't oil and fuel resistend. The new ones probably are. I have let somebody look at the old hose and he told my, that this hose is the standard blue hose SFS and SAMCO sells and that it is not reinforced for resistence of oil and fuel.

The black/brown color is not heat related. The hose can keep up to a temp 170c/338f. But is related to oil or fuel.

If this is true, a lot of CTSC owners have the wrong hose! And Comptech should replace them without costs.

 

[NSXTech]

Can you folks shed some light on the "unintended acceleration" that happens if the hose fails completely?

I'm unclear on how that works...

**

How do you tell if the blue hose has the wire reinforcement?

Thanks

Drew

The blue hose pipes bypassed air from the bypass valve (when it is closed) to the MANIFOLD side of the throttle plate. Having a large hole in this hose is therefore the same thing as having the throttle open, as far as air flow is concerned. You also get the matching fuel due to lower vac which equals a greater 'load' signal to the ecu.

HTH,
MB

 

[DutchBlackNsx]

I have done a test in the oven. For more than 2 hours at 90 Celsius everything was OK. At 100 Celsius the structure became a little weaker. Out of the oven the structure normalised.

Very likely, the secret is in a little ingredient in the pvc called 'weekmaker', free translated 'weakmaker'. This ingredient will keep the pvc flexible, but everytime the pvc is exposed to heat/vibrations or UV (!!!) it will loose some of it, until there's nothing left in the pvc, and it will become brittle.



Damn.... i knew that school would be usefull one day!

 

[Gerard van Santen]

Gerard,

I don't know why you are having difficulty getting a replacement. Samco, and SFS (another silicone hose company) are both in the UK. If you have problems getting hoses, ask me, and I get them from suppliers here.

Kevin

Hi Kevin, thanks for the offer. These hoses can be obtained from any tuningshop and I have a SFS hose in back order now. I also asked Comptech to send me one. I haven't heard from them yet.

It is no problem to get a standard blue hose but an oil/fuel resistend is the problem. Last saturday when I opened the manifold, I had to improvise. I couldn't get a right hose at that time.

Gerard

 

[Gerard van Santen]

Very likely, the secret is in a little ingredient in the pvc called 'weekmaker', free translated 'weakmaker'. This ingredient will keep the pvc flexible, but everytime the pvc is exposed to heat/vibrations or UV (!!!) it will loose some of it, until there's nothing left in the pvc, and it will become brittle.

Damn.... i knew that school would be usefull one day!

Hi Mich, the PVC tube I used only gets weak when the temps rises higher than 90 degrees Celsius. So if Mark is right it will not weaken and won't brittle.

But I have scheduled for friday to replace the PVC tube for an oil/fuel resistend blue hose. At least if I get one in time.