RS2- Just had a dyno run...power down (any thoughts?)

[pixsaudisex2]

May sound a bit stupid as well but if its all standard never touched id so change the dump valve..

[weta.worker]

This is why its better if you can work on the car yourself unless you can find old skool mechanic! Like Prj

yeah, thats what these guys are supposed to be (old school mechanics)

i've pointed them in the direction of the boost leak page so they just need to do some home work.

[weta.worker]

hi guys,

forwarded the boost link page ( http://www.s2forum.com/forum/showthr...e+leak+testing ) and they came back with this

"In one of the pages they talk about testing and holding pressure after 30 secs, which is what it does, so if they are not happy with that, what timeframe do they want, or how long do they want it to hold 30psi?"

[prj]

It's not about how long it holds the pressure, it's the question of how they are testing it.
The reason I think that they are not doing it correctly is the stock MAF->Turbo hose is going to most likely explode at 30 psi.

So, how are they testing it?

[weta.worker]

It's not about how long it holds the pressure, it's the question of how they are testing it.
The reason I think that they are not doing it correctly is the stock MAF->Turbo hose is going to most likely explode at 30 psi.

So, how are they testing it?

Hmmmm, they are running it at 30 psi because someone else on this forum said they needed to do the test at 2 bar...

Judging by your post this is incorrect?

Here is more info.

"Hi John, how much time do you want me to spend on this? We have 30 psi running into the system, it will leak out past the engine rings, valve seats, breather system etc (remember your engine has done 200,000kms). The fact you cannot hear it or see it leaking (we filled it with smoke from a smoke tester first) to me means there is no serious leak. It would have to be fairly serious to drop off 4psi when your turbo is running flat out.

We removed low pressure intake hose to turbo, blocked off turbo port, blocked off vacuum lines etc to recirc valve and N75 and blocked off breather vent from tappet cover. Air was feed into the recirc connection into the turbo outlet hose via a Schrader valve. So pressure was through whole intake system through to combustion chambers, valves rings etc, and into breather system, and it still held pressure about 6/7 psi after 30 secs. That seems pretty good in my book.

How much of a leak do they think there should be (or have seen previously) that would drop 4psi on full boost?

We have not been unable to find a leak previously on anything using our smoke tester, which only runs up to 10psi max, so this is all new/possibly over the top for finding a leak to me.
"

AND


I forwarded them the boost leak page (http://www.s2forum.com/forum/showthr...e+leak+testing) pointing out the diagram on mid way down the page that shows a leak test with the engine out of the loop



And the comment and chart that mentions you ("Many people, most notably prj (dmitri) have suggested that the simplest method of boost leak testing that captures all the possibilities in one go is to place the pressure bung in "A1" in the diagram and disconnect the hose from the cam cover to "A3" and plug "A3", leaving the rest alone. This falls some where between test Option 1 and Option 3."





They came back with this

"Hi John, it’s the only chart that is relevant, all the other info is just data copied form manuals and parts diagrams, nothing on how they test it, what timeframes for leak down are acceptable for which test etc, which ports are blocked and how. Pretty positive none of the boost hoses are leaking, it would be very obvious at 30psi.

In one of the pages they talk about testing and holding pressure after 30 secs, which is what it does, so if they are not happy with that, what timeframe do they want, or how long do they want it to hold 30psi?"

I know this is probably a huge pain for you but is there anyway you can detail what they should be doing so I can pass to them?

They seem to have too much half information at the moment and maybe its just time for a set of instructions....

Sorry! But this would help me and them out immensely to they can either confirm there is a leak or move on.

They've had the car for over 2 and a half weeks now (went in for new rear shocks and I also asked them to check out the power down \ boost leak) . They aren't working on it full time (thank god) but I'd love for them just to get a clear set of instructions so they can get on with it and I get the car back.

These guys are well respected mechanics in Wellington so I'm surprised that they don't know how to do this but they did say they work on hundreds of different cars and any info is welcome.

I just think they've been given a bit too much spam (by me) and it would be awesome if someone who knew what they were talking about (you) could pleeeeeease help us out.

Thanks so much

John

[prj]

If it drops from 30 psi to only 6 psi after 30 seconds, there is a leak somewhere, but probably not too major.

What they did not test is the recirc valve. Also, the recirc valve has a certain way around it must be fitted, fitting the other way around can cause problems.
Also, the N75 was not tested this way. Test from the maf->turbo hose instead of the MAF with ALL plumbing in place bar the PCV.
Do NOT put 30 psi in there, 14 psi tops.

Check baro pressure and IAT sensor readings with diagnostics as well.

[AndyP]

I notice in your post that they've blocked off the vacuum line when testing. You definatley need to test these, if they are the original lines, I'd replace them all anyway. I find it easier to test these in isolation, like this

http://www.s2forum.com/forum/showpost.php?p=471734&postcount=41

As PRJ said, don't go mad with the pressure, I only ever use 1bar, if you have a leak you'll hear it or see it with soapy water.

[AndyP]

Also, go visit your neighbour, he's just found his missing 4psi!!

http://www.s2forum.com/forum/showpost.php?p=774354&postcount=12

[weta.worker]

thanks! Nik just emailed me so I've passed on that info to the mechanics as well.

[weta.worker]

More from this end

"Hi John, that all helps. Third response backwards, I had already found the recirc valve (DV valve?) was fitted the wrong way, vac line was pointing up, not out to the guard, so had swapped that over and hoped it would fix it, but still only getting 16+ psi. Second response, I tested all the vac lines, just blocked the end where it goes into the recirc valve as I had removed that to fit the pressure tester, so hopefully they are covered o.k.
Thirdly have sort of tried that way of testing through the MAF hose, but it was just ballooning outward with over 15psi (not built for pressure as before the turbo). Could hear the recirc valve unseat at 15 or so psi, but would also possibly have boost pressure on vac line to increase its resistance(plus it was fitted wrong way round at that stage!) Will try again tomorrow morning two tests before moving on. 1, will block off from throttle body so just test intercooler pipes etc, will run up to 30psi as have already done that much on them, should be much less leak down as no valves rings etc in the mix. 2 Will do as suggested by the first response, does he block off the fore/aft connection (running along engine block) or the up down connection, I suspect the fore aft?

Regards"

And

"Can hear the recirc valve chatter on lift off from boost, someone noted in that thread they thought that meant it was split? Doesn’t seem to be split to me, but they are not that expensive..."

[weta.worker]

And from me "Thanks so much ****!

Sounds like you're at least putting things back to how they should be (things were plugged in wrong)



Will ask about where they suggest blocking off things.

Also not sure if you saw what he said about psi? "Do NOT put 30 psi in there, 14 psi tops."

Not sure if this applies to this test or all tests?

Thanks again!

John"

[prj]

1. No need to pressure test over 15 psi.
2. No need to EVER remove the hose from the TB. If they have been doing that each and every time, that's exactly where they go wrong. 99% of all the boost leaks are things connected to the IM.

Look, taking the assembled car, the only things that have to be done are:
1. Untighten clip on MAF end of MAF->turbo hose.
2. Slide off the MAF->turbo hose from the MAF.
3. Fit pressure tester instead of the MAF into the opening.
4. Disconnect the PCV from MAF->Turbo hose.
5. Block the PCV on the MAF->Turbo hose end, leaving the other end (the metal pipe) open to atmosphere.

Now put 14psi in. Does it hold?
That's literally all you have to do. Not undoing ANY other hoses. Not undoing ANY vacuum lines, DV etc. EVERYTHING must be in place.
If they have each time been disconnecting the throttle body hose, then in fact they have not pressure tested the car at all. I have no idea why so many people keep disconnecting the TB hose.
You will also never hear anything about the recirc valve as it has the same pressure on both ends.

This thread is getting utterly ridiculous for what is a 5 minute job.

[weta.worker]

1. No need to pressure test over 15 psi.
2. No need to EVER remove the hose from the TB. If they have been doing that each and every time, that's exactly where they go wrong. 99% of all the boost leaks are things connected to the IM.

Look, taking the assembled car, the only things that have to be done are:
1. Untighten clip on MAF end of MAF->turbo hose.
2. Slide off the MAF->turbo hose from the MAF.
3. Fit pressure tester instead of the MAF into the opening.
4. Disconnect the PCV from MAF->Turbo hose.
5. Block the PCV on the MAF->Turbo hose end, leaving the other end (the metal pipe) open to atmosphere.

Now put 14psi in. Does it hold?
That's literally all you have to do. Not undoing ANY other hoses. Not undoing ANY vacuum lines, DV etc. EVERYTHING must be in place.
If they have each time been disconnecting the throttle body hose, then in fact they have not pressure tested the car at all. I have no idea why so many people keep disconnecting the TB hose.
You will also never hear anything about the recirc valve as it has the same pressure on both ends.

This thread is getting utterly ridiculous for what is a 5 minute job.

hiya, thanks so much for the detailed reply. Have passed this on. hopefully there will be some good news soon.


thanks again!

john

[Golfboy666GTI]

John, Ive been told (prj what are your thoughts) that boost should be tested with 3rd gear (or higher) runs.

[weta.worker]

from them

"Carried out the two tests I mentioned last night, first the boost pipe test, again no leak to speak of, it took 36 secs to drop from 15psi down to 10 psi, and I could hear most of that bubbling through the oil feed/return to the turbo, not to mention the plastic caps sealing off the turbo nose and throttle body connections. It was still holding pressure a minute later. Soap spray and smoke testing could not reveal any leaks.
The second test is a bit more difficult as the intake (MAF) hose doesn't seal very well on the nose of the turbo, but doesn't hold any pressure so can't be a source of a boost leak when running, but stops the rest of the test being very accurate. Removed the intake hose and blocked off turbo nose, but connected in rest of system (bar breather connections), did find it bubbling out of IAC motor (like in one of the pictures on the forum), so will price that up too, but can't see 4psi leaking from there.
Cheers"