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Control line busted
Posted: Wed Oct 22, 2025 11:37 am
by Belgian951
It seems I found another issue on my 86 944 turbo. The control line (951 110 061 03) has a big fat tube that goes to the J Boot. It has a few holes in it it seems.
From what I can find, Porsche doesn't sell this line but you can buy the whole assembly for the lovely price of about 800 eur.
Questions:
- is there a way to just buy that single hose?
- what does the hose do and what does the control line do?
- are the holes a problem for running the car?
- can I patch the holes with duct tape?
Pictures of issue and PET:
- Screenshot_20251022_203222_Chrome.jpg (424.81 KiB) Viewed 471 times
- 20251022_144430.jpg (3.47 MiB) Viewed 471 times
- 20251022_144423.jpg (3.67 MiB) Viewed 471 times
- 20251022_144417.jpg (3.81 MiB) Viewed 471 times
- 20251022_144920.jpg (3.63 MiB) Viewed 471 times
Re: Control line busted
Posted: Wed Oct 22, 2025 1:07 pm
by gb951
Yes, that hose is important. It provided the boost pressure to the cycling valve (M in the diagram) which controls the wastegate and, thus, controls the boost. I highlighted the path of the hose from the J tube to the cycling valve in red.
No, it is not separately available, at least from Porsche.
It is possible that you could remove the hose (a clamp on one end, and a press in fit to the J tube on the other) and remove the crimped part with a dremel tool and take it to a hydraulic hose shop to have the press in end redone. If you are not too concerned about originality, the hose could be replaced with an appropriate length of hose (I'm guessing 17 mm diameter or so) and hose clamps on both ends.
Re: Control line busted
Posted: Wed Oct 22, 2025 1:37 pm
by Tom
gb951 wrote: Wed Oct 22, 2025 1:07 pm
Yes, that hose is important. It provided the boost pressure to the cycling valve (M in the diagram) which controls the wastegate and, thus, controls the boost. I highlighted the path of the hose from the J tube to the cycling valve in red.
No, it is not separately available, at least from Porsche.
It is possible that you could remove the hose (a clamp on one end, and a press in fit to the J tube on the other) and remove the crimped part with a dremel tool and take it to a hydraulic hose shop to have the press in end redone. If you are not too concerned about originality, the hose could be replaced with an appropriate length of hose (I'm guessing 17 mm diameter or so) and hose clamps on both ends.
944 TURBO CHARGE CONTROL HOSE DIAGRAM.pdf
Agreed. In its infinite wisdom, Porsche made the whole metal pipe and hose contraption one 'part.' As George says, it's fairly straight-forward to cut the old hose crimp off and attach a new hose to the fitting with a regular hose clamp. You can also get a double-sided barb fitting and use that. At the risk of offending the Porsche gods, you might use a 'hose mender' made for connecting gardening hoses -- they come in about the right sizes. If you have any way to make a good bead on a pipe, you can also just make up a little 2 or 3 inch long beaded pipe to use as a connector.
Re: Control line busted
Posted: Wed Oct 22, 2025 1:44 pm
by four0four
That's not a wastegate line - this is at the inlet to the turbocharger (so, nominally a slight vacuum). The line in question is responsible for making the AOS work and is routed to the top "hat" that so often leaks. It may be worth inspecting the rubber on the far side of that metal assembly also, since replacing this alone won't do much if that is also leaking.
Otherwise correct about the cutting of the crimp and replacing. I think it was originally crimped where the clamp is now (oetiker on mine), so someone already fussed with it.
It might reduce the effectiveness of the AOS, and on cars that retain the AFM it could cause rough running issues (unmetered air entering...which the AOS sort of does by design, so it's all down to how much flow the crack causes on top of the normal AOS mass air).
Re: Control line busted
Posted: Wed Oct 22, 2025 1:51 pm
by gb951
four0four wrote: Wed Oct 22, 2025 1:44 pm
That's not a wastegate line - this is at the inlet to the turbocharger (so, nominally a slight vacuum). The line in question is responsible for making the AOS work and is routed to the top "hat" that so often leaks. It may be worth inspecting the rubber on the far side of that metal assembly also, since replacing this alone won't do much if that is also leaking.
Otherwise correct about the cutting of the crimp and replacing. I
think it was originally crimped where the clamp is now (oetiker on mine), so someone already fussed with it.
It might reduce the effectiveness of the AOS, and on cars that retain the AFM it could cause rough running issues (unmetered air entering...which the AOS sort of does by design, so it's all down to how much flow the crack causes on top of the normal AOS mass air).
Yes, you are right... I was looking at the wrong hose. The hose I was describing is actually the smaller hose about an inch forward of the subject hose. My bad...
Re: Control line busted
Posted: Wed Oct 22, 2025 2:27 pm
by Belgian951
Thanks everyone for the insight. So this will again delay the car running. Big bummer really.
I found this kit:
https://944online.com/vacuum-manifold-h ... 944-turbo/
I rather have a kit instead of sourcing the material locally since I have no idea of where, how, ... and I prob trust 944online more than some local shop to be honest.
Re: Control line busted
Posted: Fri Oct 24, 2025 7:23 pm
by Evan
Belgian951 wrote: Wed Oct 22, 2025 11:37 am
It seems I found another issue on my 86 944 turbo. The control line (951 110 061 03) has a big fat tube that goes to the J Boot. It has a few holes in it it seems.
From what I can find, Porsche doesn't sell this line but you can buy the whole assembly for the lovely price of about 800 eur.
Questions:
- is there a way to just buy that single hose?
- what does the hose do and what does the control line do?
- are the holes a problem for running the car?
- can I patch the holes with duct tape?
Pictures of issue and PET:
Screenshot_20251022_203222_Chrome.jpg
20251022_144430.jpg
20251022_144423.jpg
20251022_144417.jpg20251022_144920.jpg
No, you can't buy just that hose. It's part of the whole assembly.
That hose controls the turbo's wastegate. Holes in it are a big problem. They cause a boost leak, so the turbo will over-boost and you'll lose power.
Do not use duct tape. The heat and pressure will make it fail. Use high-temperature silicone tape or proper heat-resistant hose as a temporary fix, but you need to replace the assembly.
