MA1 Thermostat Hose Modification - Page 1 - 911/Carrera GT - PistonHeads UK

On MA1 engines Porsche lists a retaining bar (9A1 106 338 00) for the hose into the thermostat housing. It's only shown on the 981 Boxster PET digrams, but is likely applicable to all similar engines ... especially those exhibiting a slight leak. It cites "Technical information SY 14/16 Attention" can someone share this info with me. Interested in the backgound to this bulletin and what the torque figures are for the three bolts too.

The collar goes over the plastic pipe where it joins to the water pump housing and exerts a more consistent load over the flange/seal to stop leaks that can occur as a result of temperature related movement. If you wanted to replace the pipe; on 981 you need to remove the engine to get the engine mount off to remove the pump housing - hence the workaround. The collar bolts are torqued to 13Nm; in the sequence shown (2-4). 9A1.106.338.00 - Water tube retaining bar 900.385.270.01 - Screws (3 required - M6 x 35) Edited by Pope on Friday 3rd August 21:42

Thanks for the details. I've a very very slight leak on my 997.2 and this had been suggested else where as a solution. Is it possible to fit this without coolant pissing everywhere? i.e. with the coolant system cold and cap removed to release any residual pressure, can the three original bolts be removed and the hose carfully held in place as the plate/bracket is fitted and tightened up.

Officially the coolant isn't drained to fit the collar; installation should stop the leak by compressing the flange seal more uniformly. The pipe design requires that the housing is removed to access the bolts at the other end of the pipe in question - on a 997.2/991 that means exhaust/pump/pipes/housing off but on mid engined cars the engine mount is bolted across it; the engine has to be dropped to remove the mount bolts, to remove the coolant housing - trying the collar fix first is obviously the easiest (and cheapest!!) and it can be reused if the worst happens and you do need to replace the pipe later on. Before you install it, release any pressure from the (cold) system by removing the coolant cap and then refit it to minimise the chance of coolant loss/airlocks

I had a small leak on my 991 from exactly that area. Interesting to see that Porsche have produced a fix for it. I took the whole thermostat assembly apart to get at the sealing washer and replaced that. However, I didn't see any deterioration on the washer so I suspected that that wasn't the issue. The real problem is that the black plastic tube has to be mated to the aluminium housing which has to be flat, clean and very parallel to the pipe (otherwise it will leak - and that is the design flaw, it seems to me). The thing is that after it has leaked there's going to be dried coolant in the interface between the two components which will probably not give a good seal unless it's cleaned up properly. When I got at my thermostat housing there was a fair bit of dried crud between the two components and inside the gasket ring. Also, I cant see how you can put the new bracket on without draining the system, since you have to get the three bolts off at once ... but maybe only a small amount of coolant will come out. Getting the aluminium housing off is a bit of a futz because there are three pipes connected to it and (at least on my 991) you have to do quite a bit of taking stuff off before you can get at the thermostat housing. If you do take the housing off you'll have to drain the coolant and refill it. I did that without a vacuum filler. All I can say is get a vacuum filler! Obviously things may be a bit different on a 981 - but it all looks quite similar in the PET diagrams. Edited by Forrester1 on Saturday 4th August 10:40

Just had this very same retaining bracket fitted to my 2009 997.2 S after I noticed a very small weep from the thermostat housing. Done under warranty by supplying indy dealer and the head tech there said they’ve done a number of them. Porsche clearly admit there’s a problem by producing a ‘fix’ such as this. We’ll see how it holds up. Before:

galaxie500 said: Just had this very same retaining bracket fitted to my 2009 997.2 S after I noticed a very small weep from the thermostat housing. Done under warranty by supplying indy dealer and the head tech there said they’ve done a number of them. Porsche clearly admit there’s a problem by producing a ‘fix’ such as this. We’ll see how it holds up. Before: Is this needed on 997.1's?

I don’t think modification fits the 997.1 /M97 engine.

Slippydiff99 said: Is this needed on 997.1's? 997.1 waterpump and t/stat hose connectors/housings are aluminium alloy, so shouldn't need such factory sanctioned Band-Aids ...

Thank you, that’s one less thing to worry about.

Well folks, despite the ‘water tube retaining bar’ fix the union is leaking again. Its weeping from a number of points along the seam so I can only surmise the housing face wasn’t totally true and free from corrosion. Back I go…. Is the only real fix a new thermostat housing and water tube? And while it’s all apart a water pump too? Thanks.

sort of an Update* My leak has still not been rectified; the independent dealer’s technician I purchased the car from will revisit the issue next week. I’ll post the outcome.

galaxie500 said: *Sort of an Update* My leak has still not been rectified; the independent dealer’s technician I purchased the car from will revisit the issue next week. I’ll post the outcome.

Weep continues…… Indie dealer technician had another look at the water pipe to thermostat union, checked the gasket wasn’t pinched and put it back together. Same issue. Still weeping. I’m going to leave it with them to sort whilst I’m away; I say new pipe and thermostat housing and whilst all that’s off, new water pump, thermostat and any suspect hoses please. This has gone on too long now.

Hi, Just wondered if this issue has been sorted and what was the outcome? I have exactly the same problem on my 997.2. Cheers.

Bajers said: Hi, Just wondered if this issue has been sorted and what was the outcome? I have exactly the same problem on my 997.2. Cheers. I just posted this thread on your post! Edited by FriedMarsBar on Wednesday 13th March 05:50