Spring Time Woes

[Kevins 930]

Just dug out my 930 for a first run out this summer, and after a good 20 or so miles to warm up I realised that I have no turbo boost, the beauty runs rather like a VW Polo 1.1 !!!

 

Was all ok when put to bed last Autumn and has been run every month over winter.

 

any ideas please ?

 

Happy lockdown

 

K

[jevvy]

Ah what a shame - I get you were looking forward to a bit of boost!

What have you checked so far?

Is there absolutely no boost or just very little? Any funny noises? If a boost pipe has come lose you would hear it so if there are no noises then I'd remove a boost pipe near the turbo and check its still spinning freely.

Edited April 11, 2020 by jevvy

[flatsix777]

I’d also check the O rings at either end of the pressure pipe between the turbo and intercooler. The bottom one gets pinched really easily and splits. When this happens the motor runs fine off boost but just doesn’t generate any boost. This would be the first and easiest thing to check.

David 

Edited April 11, 2020 by flatsix777

[Guest Kev]

Thank you folks,

 

Jevvy on the money, absolutely no boost at all, no funny noises either and flatsix777 supplies some useful tips also. flatsix mentions pressure pipe between turbo and intercooler, what sort of diameter are we looking for ?

 

I will have a look in the morning as I have my TR6 on the ramps this afternoon fixing an exhaust manifold leak.

 

No one has touched the car since service 20 months ( 50 miles) ago

 

Thanks very much

 

 

 

 

[flatsix777]

58 minutes ago, Guest Kev said:

. flatsix mentions pressure pipe between turbo and intercooler, what sort of diameter are we looking for ?

There are 2  ‘O ‘ Rings, one large (intercooler) and one a little smaller (turbo).  Matt sells the large one and possibly the small one too.

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.mobile/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/6996

You need to remove the intercooler and then the aluminium pressure pipe, which connects to the turbo, pulls out. It’s a tight squeeze so usually needs some jiggling and, ideally, a few things loosened to give you a few mm of play. 

David 

[Kevins 930]

I have just carried out the rag up the pipe diagnosis, I dont think it has given a clue. Put rag in tube, started engine let it idle revved a little and rag still in place. At tick over speed I removed the rag and placed hand over exit and there is no pressure at all.

 

I did notice however that when I turned engine of there was a clack clack sound that seemed to emanate from the turbo area.

 

Any further thoughts before I strip out a few bits ?

 

I assume to expose the turbo rotor to see if it rotates is a way of understanding if it has seized?

 

Kev

[flatsix777]

I doubt that the turbo has seized unless there is a foreign object floating around (seems unlikely if it’s just sat). To check I think you’ll need to remove the silencer (and rear bumper etc). I think you’ll struggle to pull the large hose off the inlet as there is very little room. 

Im not too sure what the rag test was but are all your seals good on the IC and charge pipe? 

The other possible cause would be the wastegate stuck open, although again unlikely, or an exhaust leak in the engine side of the turbo. 

David 

[jevvy]

Some stuff to read through here:

http://forums.pelicanparts.com/porsche-911-technical-forum/193532-porsche-turbo-problems.html

[Kevins930]

A few moments with the spanners and I find that the lower O ring ( orange around 45mm dia) is broken and a piece missing. I would insert picture here but I have not a clue how to do it.

 

this could be the issue I am hoping

 

Will keep you informed, but where is best place to purchase a replacement item ?

 

Thanks

[flatsix777]

This Is common and is likely the cause. Matt at Type 911 may have one if not OPC. 

I have a serviceable used one which I’ll post if you PM me your address. Will be fine until you next take the IC off. Use a little grease when refitting and loosen the pipe that’s sits right next to the charge pipe; less chance of pinching it.

David 

[Kevins930]

Thank you very much indeed Sir, I will PM my address.

 

Meanwhile am polishing all nuts and bolts ready for re assembly

 

BTW reason for various guises is that this forum keeps telling me my password is wrong, I change it to a new one and then the same again !!

 

Kevin 

[Kevins930]

Fitted replacement lower O ring supplied very kindly by a forum member, but still NO turbo boost at all. The O ring was broken so now I know its intact.

 

Maybe waste gate issues then ??  

 

Any more ideas folks ?

 

Just one thing, when I shut down the engine I hear from the turbo area a "clack-clack" rather like someone knocking pieces of hard wood together......

[flatsix777]

3 hours ago, Kevins930 said:

Just one thing, when I shut down the engine I hear from the turbo area a "clack-clack" rather like someone knocking pieces of hard wood together......

It’s a shame it wasn’t an easy fix. 

The turbo shouldn’t make any noise as you shut down so maybe best to inspect. I think you can just about inspect the intake turbine by sliding back the large black hose on the left. You can probably check if it’s binding. If so the problem will likely be with the exhaust turbine though so you’ll need to remove the silencer. 

David 

[flatsix777]

The wastegate valve would need to jam open to stop boost building. Hopefully you can just see the valve below (bottom between the four studs. The diaphragm works against the spring as boost builds allowing the exhaust gases to open the valve. 

Diaphragm with the alloy cover removed. 

David 

[flatsix777]

The only other thing I can think of that makes a noise is the recirculating valve which closes as the throttle shuts. It’s in this housing. 

Which is here on mine:

A piston & spring sit behind the small alloy cover near the coil. The piston seats against a nylon seal which breaks down. I had to replace mine to get rid of a slapping noise. Won’t stop boost building though. 

Here is the seal:

Are you sure all your intake seals are good (to IC and IC to throttle body). It’s odd it was fine and then happened after standing. That would usually point to something simple. 

David 

[Kevins930]

Gosh thank you so much for detailed appraisal, I have a couple of days being tied up right now but can get to it at weekend.

 

I am also of the view that as this was after a winter lay up it is probably something "simple"

 

More investigations to follow.

 

Best wishes

 

Kev

[Kevins930]

Many months on and due to being so very busy, I turn now to look again at Turbo. Checked the O rings in heat exchanger feed tubes and that all hoses are intact. they are.

 

I am turning now to more investigating.

 

I am sure the waste gate is firmly closed, so no leaks there.

 

So its a look to see if the turbo rotors are seized or damaged I believe next step. 

 

Is it possible to undo jubilee clip on turbo spigot and slide the flex-hose enough to check rotation ? and if so is it a bumper off job ? or even exhaust as well ?

 

If it is a turbo mechanical issue what is the potential for DIY re-build ? I am a competent engineer with well equipped workshop, so are components readily available. I would rather keep original if I can as the car is totally original.

 

Obviously if I have a turbo failure I need to seek a cause given mileage is 38,000 miles from new, maybe oil delivery issue I am thinking ?

 

Thanks

 

K 

 

 

[flatsix777]

Hi Kev,

Sorry to hear it’s still not boosting. Your split lower O ring in the boost pipe was very bad bad and would certainty have killed boost. Are you certain you haven’t pinched the replacement; it’s very easy to do. I loosen everything around the pipe to give me a little wiggle room and then grease the O ring. Tricky even then.

I’ve tried and failed to slip the short hose back off the turbo outlet to access the cold side of the rotor. I’d guess it’s possible with more determination but I’d take the back box off which gives you good access to the hot side of the rotor. You need to first remove the heat shield and bumper. Any physical damage is going to be on the hot side.

I think I’ve read that’s you can get overhaul kits but I imagine there are plenty of low quality parts out there that need avoiding. I had my 3LDZ rebuilt by Turbo Technics (Northampton) some while ago and others on here have more recently used AET (Wakefield) with, I think, good results. 

Cheers

David

 

 

[Nige]

If it comes to a turbo rebuild I'd have it done professionally.  You need to be able to balance them after a rebuild which requires the proper equipment.  I've had a couple rebuilt at Midland Turbo at sensible prices albeit for daily diesels. https://www.midlandturbo.com/  They list all Porsche models.

Edited June 2, 2021 by Nige

[Lesworth]

I had the turbo on my 924 rebuilt by Turbo Dynamics. They were very helpful and even cobbled together all the best parts / casing etc. from two units. I think its a similar unit to that on a 930?

https://www.turbodynamics.co.uk/

[Kevins930]

Thank you, Turbo coming out this week for initial examination, but it does look like just a seized rotor, no explosive mechanical damage. So probably shaft, seals,bearings 

 

My mind will turn to why, other than lack of use, so an oil feed check high on the list.

 

I am located just North of Eastbourne and have found a well recommended re-build firm there, its 20 mins from me Turbo-works.

 

Cant wait to get the beast back on the road and I will try not to let it stand for too long in the future.

 

Oh have seen a short hairline crack in the exhaust also so will have to get the chewing gum out.

 

Cheers

[David Gander]

Kevin, Just a reminder (I’m sure that you’re aware) of the importance of really bleeding the oil supply pipe to the turbo when fitting up and before firing up. I fitted a new K27 turbo to mine and was probably doing over-kill in bleeding! Also wise to fit a new feed pipe if for any reason you have to drop the engine as it’s much easier.

Regards,

David

[Kevins930]

Thank you David.

 

engine still in chassis and turbo now with Turboworks at Eastbourne who are investigating. Checking oil feed number one next job. The turbo was not solid but stiff enough that needed a socket to rotate. Their prelim analysis was that they hold all spares except rotor and will call me tomorrow after stripping down.

 

they gave me a stiff talking to over not using the car which causes oil degradation. 

I found a hair line crack in exhaust system and am getting my welder, I own a fab company, to repair. 

 

Its my own fault really, owned the car for 20+ years and never use it !!

 

 

[Kevins930]

Turbo received back from Turboworks Eastbourne, complete re-build, new rotor, bearings, seals etc. waste gate was OK but re built as why not ? The new rotor has a modified impeller with what looks like twin blades ! They said it was/is now the oem part from BW Germany and it will improve performance.

 

The exhaust manifold had two hairline cracks, the material would not take a weld so new replacement now here.

 

Turboworks inform that the turbo failure was by corrosion and the heat shield had also been damaged. They did also inform that there did not appear to be any oil starvation.

 

all going back together this week so will report after complete. 

[Kevins930]

Further info;

 

The exhaust pipe had a crack in it at two places, specialist tried to weld but the material just wouldn't take a weld. ordered a new pipe and on attempt to refit the pipe was 20mm too short.

 

Lots of head scratching and liaison with supplier also checks on other suppliers and all the pipes are 20mm too short.

 

The current conclusion is that my 930 is one of the VERY late builds where, I had been told previously, that in the period leading up to the end of production a " high performance" variation was built, no more  than 50 in total.

 

I had a specialist look after the car for many years, who has now retired, but he did mention 15 years ago that he thought mine was one of these special variants. Given that the new pipe was short by 20mm this leads into the potential for a larger turbo ?

 

Does anyone have any thoughts ?