TFatC's 99T - The madness continues!

[TFatC]

First, sorry, no pics as my cheapskate brother does not have a digital camera. Can't say too much as he paid for and collected the car last night

First reports are very encouraging. It came with a HUGE history file and every MOT certificate. The car had 1200 spent on it not very long ago. The interior is immaculate, new headlining a couple of years ago, a few rust scabs but nothing too serious. Half a tank of petrol

The car is on 4 Ronal alloys with good tyres, and came with 4 Incas with better tyres . My brother drove it home last night, did not break down and hit 90 for a while.

Only problems encountered so far, the tacho is intermittent (suspect a dodgy connection) and here is where I ask for help. The turbo obviously needs setting up as it boosts into the red before the waste gate opens, in effect switching off the turbo! My last 99T 12 years ago did this after I had the head done, but rust killed it before I had a chance to investigate.

So, what is causing this, and how do I put it right? All advice gratefully received.

Must be a good car, my brother has no taste in cars (he is an accountant! ) and drives an Audi S4, admittedly with ABT bits and 320 bhp, and he LIKED my Saab!

[tom]

the rev clock is propably a dodgy connection at the induction coil.

we want some pics!!

[Ken]

I think I remember a friend telling me that the wastegate on those works on some type of diaphram thingy which often weathers & splits

[AndyH]

And here is that friend Ken!

Yes it could be one of a couple of things. The wastegate is essentially a valve which opens when a certain exhaust manifold pressure has been reached. This is actuated by a flimsy rubber diapragm which due to the hot exhaust gasses eventually perishes. It is almost certain that this diapragm will need replacing. This means that the wastegate does not open and the engine shuts down to prevent a catastrophe!

Also if the diapragm has been gone for a while the valve can also stick. This can be released with a few gentle taps of a hammer, but be careful, I broke mine a few years ago, and they are not easy to find....saab were quoting over £200 for one a few years back, but they are nolonger available I don't think.

Try an independent specialist for the diapragm, saab will charge you about £50...and when you see it you will realise how much of a rip off that really is!

This problem can in the future be prevented by actuacting the diapragm with the inlet manifold gasses rather than the exhaust...this prolongs the life of the diapragm sunstantially, and prevents the tail off of boost at high revs.

Hope that helps!

[nutcase]

Sounds like a great Car How long until you get your mitts on it?
Pictures! :P
I expect my wastegate will have similar, if not worse problems having stood for so long.

[TFatC]

Collecting the car around the 24th April, and will post pics when I get back. Must be OK, my brother claimed it still looked "quite smart" this morning!

AndyH - Welcome to the madhouse. In fact WELCOME with capital letters as it sounds like you know a bit about these turbo things, and there are a few of us here who have just obtained one needing various amounts of work. Hope you enjoy typing....

Personally, I know almost nothing about modern cars (anything post 1970 is modern in my book!) so hope you will forgive my ignorance.

Is it much of a job to change this diaphragm?
Is it much harder to convert to inlet manifold activation?
Does a waste gate do the same job as a dump valve?
Would it be possible or even beneficial to install a dump valve instead? I would like to tune this one a bit (alright a lot) and intend fitting an intercooler very soon. Of course, the hooligan sound of a dump valve going off on "an old mans car" also appeals.

Thanks for your help so far

Nick

[nutcase]

Oh nick, shhh! You'll get me tempted into mods like that - but I think I should get mine going first!

I *think* wastegates and dump valves are totally different things. Wastegates limit the amount of boost produced, and dump valves drop some stored gas into the exhaust when the revs drop for gear change, so the power is ready and waiting as soon as the throttle is pressed again.

Could someone confirm/elaborate? I'm not to hot on turbo's myself

Richard

[AndyH]

Yes wastegates and dump valves are very different! Wastgates stop the pressure from getting too high...hence the boost needle should go up to the end of the orange and then the wastegate starts to open to stop it going into the red causing pinking and eventual terminal problems!

A dump valve opens when you take your foot off the accelerator and releases the pressure which builds up in the inlet manifold, until you put the boot in again. This pressure stalls the turbo meaning you have to wait until the boost builds up again from scratch. So basically it should mean a bit less lag.

Changing the wastegate actuation to the inlet manifold is apparently really easy, but i'll dig out the exact instructions...sounds like a 30 min job.

The wastegate diapragm should be easy, but is often a swine! Its all located in the lump of metal which sticks out of the pipework between the turbo and exh manifold. You undo the four securing bolts on the wastegate cover and then you have to slacken a large shallow nut which is essentially the boost control nut, the tighter this is the more boost you get. Problem is that if the valve is free it simply spins round and you can get no grip on this crucial nut, and you often have to strip the whole thing down to get access. Too complicated to type about tonight! Let me know how you get on!...but get this nut off and you are there.

BTW for tuning water injection is the way forward, you will probably not manage to find room for an intercooler. Both do essentially the same job of cooling the inlet air.

A typical kit is betweem £200 () http://www..se available from Julian at elkparts http://www.elkparts.com or £400 for an Aquamist system http://www.aquamist.co.uk I would love to try any one of these, apparently they are amazing...at least 185bhp!!

[TFatC]

Thanks Andy, at least I now understand the differences. Had not thought of water cooling, will look into it!