GTA Turbo timing chain

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GTA Turbo timing chain

Postby bobkay » Tue May 28, 2019 12:19 pm

Hi. Finally got back to the engine I was having trouble getting oil pressure - now OK. But the b******* won't start, despite new HT leads, dizzy etc, and what look like good signals from all the sensors (including crank position - perfect waveform on oscilloscope), good sparks and injector signals when cranking, and injectors squirting fuel when 12 v is applied.
I'm wondering if the cam timing is off, because the Engine Repair manual has me confused. The diagrams of chain positions shows the "camshaft end" with two blobs of paint one tooth apart. My chains have a round blob and a line, five teeth apart. Not knowing any better, I just centred the timing mark between them. The Valve Timing Check looks OK.
Any thoughts from you experts out there on the correct alignment?
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Re: GTA Turbo timing chain

Postby stephendell » Wed May 29, 2019 2:29 am

I seem to remember the instructioms for setting the timing chain in the engine manual are wrong but I may be mistaken.
Trafic, Twingo GT, Vel Satis Turbo x 2, Clio V6 Proto Ph2, Vel Satis 3.5, Avantime, Alpine A610, GTA Atmo x 3, GTA Turbo x 3, R5 Gordini Turbo Mid Engine, Alpine A310 4cyl, Alpine A110, Yellow Smart
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Re: GTA Turbo timing chain

Postby BobFromNorway » Wed May 29, 2019 9:01 am

I had the same trouble as you, I did find a really good guide somewhere, but can't remember where, I'll have a look again when I get home, see if I bookmarked it.
I think it actually was one of the Delorean pages.
I might even have pictures of mine during re-assembly

Biggest thing I learned was that after initial set up the marks won't line up again for many revolutions
1987 Alpine GTA V6 Turbo
2000 Chevrolet Camaro Z28 SS
1997 Mitsubishi Legnum VR-4 V6 Twin Turbo
1993 Alfa Romeo 155 V6
1987 Honda VFR 750F
2001 Audi A6 2.5 Allroad daily driver
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Re: GTA Turbo timing chain

Postby bobkay » Wed May 29, 2019 9:34 am

Thanks. Glad to see it's not just me.
Look forward to the details
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Re: GTA Turbo timing chain

Postby BobFromNorway » Wed May 29, 2019 10:06 am

There you go, this is what I used when I did my turbo.

http://www.tmproductions.com/repairs-an ... lve-timing
1987 Alpine GTA V6 Turbo
2000 Chevrolet Camaro Z28 SS
1997 Mitsubishi Legnum VR-4 V6 Twin Turbo
1993 Alfa Romeo 155 V6
1987 Honda VFR 750F
2001 Audi A6 2.5 Allroad daily driver
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Re: GTA Turbo timing chain

Postby bobkay » Wed May 29, 2019 3:19 pm

Thanks Bob. It looks like my two marks are like your two coloured links, so centering the camshaft sprocket mark between them looks OK. The GTA Turbo engine is the Z7U, with offset crankpins, so the alignment for the left-hand bank (4,5,6 cyls) is slightly different from yours, if I can believe the manual. The timing mark should align with the bottom of the bank A chain guide, not the lower oil pump bolt.
I'll have to give it another check and try to measure the valve opening and closing points.

BTW, in my list of good sensors etc., I forgot to mention that the fuel pressure is 3.0 bars measured at the injection manifold, so that's good too. One interesting thing I found was that the connector for the Throttle Position switches reverses the wires, like the Crank Position sensor. The connector only fits one way, and it tests as expected at the ECU end. Weird!
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Re: GTA Turbo timing chain

Postby bobkay » Sat Jun 08, 2019 7:11 pm

Geronimo! It runs! The valve timing was way out, but now seems better. It still failed to start, but I finally found that the idle regulator valve was only operating one way - to shut. Since the throttle plate is normally shut at idle, there's no air getting in. So I forced the valve open and left it disconnected, and voila! What magical beasts these PRV engines are.
All this was just to prove that everything is in place to make the motor work. Now to strip it all down and recondition it.
Where is the best place for things like liners, piston rings, main/big end shells, valves and guides etc? Simon.de, Meca....., or does anyone have local bits?
Thanks for the help.
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Re: GTA Turbo timing chain

Postby Custard » Sat Jun 08, 2019 9:15 pm

I would no be in such a rush, unless you want to modify the engine you could be opening a can of worms. Do a compression test if they are all good I would not strip the engine, you could take the sump off and clean and check everything they’re a pretty strong engines.
Piston and liners could get very expensive and when you disturb and remove the liners you may find that the liner seats are bad then you are in trouble and money. Clean and flush the water ways and check and change bits if necessary. It’s up to you :angel


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