924 Exhaust Manifold removal
- Thread starter tref
- Start date
924nutter
PCGB Member
Yes tref it looks a pig and even I have never tried. Nothings impossible, and no douobt when the cars were current a quick up on the ramp and a bit of red heat on the studs, but now? On LHD cars probaly easier access i.e no steering column, and what's to say that even with all the nuts removed, the manifold will clear said column. If you attempt it then almost certainly you will need 12 and 13mm flexible sockets, i.e. a socket with a U/J on the end. Using a U/J attachment will not be the same. You will need 3/8 drive to get throught the two into one brach to access some of the manifold to down-pipe nuts. Don't be afraid of shearing these as the manifold is coming off but leave then till last. In practise it is likely that some of the studs will unscrew from the head, and it would be no bad thing to replace all the studs and helicoil any that pull out on tightening. When you take into account the better access, and the fact that the head will lift off with both manifolds in place you might consider the extra time to take the head off. Extra workwise it is remove the belt cover the water pump pulley to get the alternator belt off, then turn engine to timing marks then remove cambelt and 10 head bolts, but these have to be replaced on the 924; funnily not the Turbo. By the way if you want to nick the mainfold for the turbo don't. The turbo manifold is different, in a number of ways
vincematthews
Member
I need to do this on mine as one of the gaskets is blowing. Not keen on removing the head (unless I have to) because of the extra hassle.
I was thinking of balancing the engine on a trolley, undoing each engine mount and pulling the whole lot to one side on the jack which should give another 2-4" of clearance to get in there. Only flaw in this plan is that, having done it before, the exhaust side mount is a right pig to get to.
Let us know how you get on if you get there before me.
I was thinking of balancing the engine on a trolley, undoing each engine mount and pulling the whole lot to one side on the jack which should give another 2-4" of clearance to get in there. Only flaw in this plan is that, having done it before, the exhaust side mount is a right pig to get to.
Let us know how you get on if you get there before me.
Thanks guys,
The good news is it isn't my car, just being done on my driveway so I can throw in "useful" suggestions, and undo the odd "easy" nut and bolt to make me look good!
So far the starter, steering shaft, and a few bits of tin have been taken off, and on my advice he has gone off to buy good spanners!
Annoyingly they appear to have been 12mm nuts... A trick I have regularly used on 13mm ones is to use a 1/2" spanner or socket - the 0.3mm tighter fit seems to make all the difference to rounding 'em off (why do exhaust nuts shrink so?). 7/16" is too small, though I must admit to not having gone through my BSF/BSW set as none are 3/8" drive - not that a socket would be any good on the underside of the manifold.
I reckon that if the manifold will come off, now the steering shaft is out of the way there should be enough room without the need to drop the engine mounts/slew the engine.... Now I know these scribblings will be of use to some-one, I'll let you know.
Tref.
The good news is it isn't my car, just being done on my driveway so I can throw in "useful" suggestions, and undo the odd "easy" nut and bolt to make me look good!
So far the starter, steering shaft, and a few bits of tin have been taken off, and on my advice he has gone off to buy good spanners!
Annoyingly they appear to have been 12mm nuts... A trick I have regularly used on 13mm ones is to use a 1/2" spanner or socket - the 0.3mm tighter fit seems to make all the difference to rounding 'em off (why do exhaust nuts shrink so?). 7/16" is too small, though I must admit to not having gone through my BSF/BSW set as none are 3/8" drive - not that a socket would be any good on the underside of the manifold.
I reckon that if the manifold will come off, now the steering shaft is out of the way there should be enough room without the need to drop the engine mounts/slew the engine.... Now I know these scribblings will be of use to some-one, I'll let you know.
Tref.
vincematthews
Member
Cheers Tref that would be good . . . also what the minimum removal of stuff you can get away with
Rain stopped play today, but a 3/8 drive, 6-pointed socket suvccesfully undid the last of the nuts on the top of the manifold. Just leaves three on the underside now. Unfortunately I'm back off to work tonight so I may not see what really works on those. One other thing worth mentioning, I have been told of "Rost off" I think it is called - a Wurth product. this is the first time I have "felt it" in action, and I must say, I think it made a difference compared to the usual WD40 or Duck oil on this last nut; and I have seen a lot of seized and knackered nuts and bolts!
Exhaust manifold is possible to remove with the head still on, be be prepared for a world of hurt and not for the faint hearted !
Lots of different tools are needed due to hard access and removal of rusted nuts.
There is a lot of stuff needed to be removed to get the manifold clear.
Drop downpipe
remove starter
remove starter heat sheild
remove engine mount heat sheild
drop steering rack and remove UJ joint
plenty of fiddling around, new nuts/studs a good number of days,
and aches and pains !
It's my car and thanks Tref for your help with my money pit !
No problem Dave, and believe me, compared to the cab (and many other Porsches I have seen), that is no money pit!
One other thing worth mentioning for those that might be tackling an exhaust manifold off job...
A couple of the bolts on the underside of the manifold were beyond normal spanners and sockets - they were to far coroded. the solution was the old hammer and cold chisel to knock 'em round and undone (without damaging the studs). If you are familiar with the technique, you'll know what I am on about, if you're not, get some-one to demonstrate it before tackling these particular nuts!
I couldn't get my favourite cold chisel in for this job, so ended up grinding a point on a long builders chisel, so I could hold and hit in relatively clear air under the car.Combined with the Wurth product mentioned above, it removed the last couple of nuts nicely.
Tref.
One other thing worth mentioning for those that might be tackling an exhaust manifold off job...
A couple of the bolts on the underside of the manifold were beyond normal spanners and sockets - they were to far coroded. the solution was the old hammer and cold chisel to knock 'em round and undone (without damaging the studs). If you are familiar with the technique, you'll know what I am on about, if you're not, get some-one to demonstrate it before tackling these particular nuts!
I couldn't get my favourite cold chisel in for this job, so ended up grinding a point on a long builders chisel, so I could hold and hit in relatively clear air under the car.Combined with the Wurth product mentioned above, it removed the last couple of nuts nicely.
Tref.
vincematthews
Member
Well I've finally taken the plunge and the manifold is off no problems . . . this is the sequence I used:-
1. Get both front wheels about 9" off the floor.
2. Remove undertray
3. Undo centre joint and remove tail pipe/silencers.
4. Undo manifold joint and remove twin pipes and front silencer combined (saves wrestling with the other joint while under the car).
5. Remove heatshields
6. Disconnect battery and remove starter motor.
7. Drop steering rack and remove steering shaft.
8. Disconnect plug leads and tie out the way.
9. Remove top manifold heat shield
10. Remove manifold.
11. As Haynes says refitting is the reverse of removal . . .
Comments:
I was thinking of removing the alternator to get the manifold out but this only works if all the studs in the head are out because you still can't get the manifold off with the steering shaft in place thanks to Porsche's wonderful 'design'!!
While on the subject of Porsche 'design' I noticed that in some places the manifold casting is substandard. The casting process has left material missing near the machined areas of the manifold ports. This means that you don't have the full area of the flange to help with sealing - hence leaks. I happened to have a spare manifold and this was similar though better. Looks like their quality control is not as good as it should have been. Its what happens when a niche car maker gets seduced by the mass market . . .
Looks like the boys at AFN Guildford did a good job of rebuilding the engine 55k ago as none of the the manifold retaining nuts were excessively tight - although one stud had been sheared off subsequently presumably by someone trying to stop the leak.
All in all not nearly as difficult as I had anticipated. Now I've just got to get the gaskets etc and put it all back.
Tref / Big Dave did you use any extra sealing on the gasket faces?
Anyone else had problems trying to get the joint just aft of the front silencer to seal. There's a measured 0.5mm difference in ID & OD on the units I've got.
1. Get both front wheels about 9" off the floor.
2. Remove undertray
3. Undo centre joint and remove tail pipe/silencers.
4. Undo manifold joint and remove twin pipes and front silencer combined (saves wrestling with the other joint while under the car).
5. Remove heatshields
6. Disconnect battery and remove starter motor.
7. Drop steering rack and remove steering shaft.
8. Disconnect plug leads and tie out the way.
9. Remove top manifold heat shield
10. Remove manifold.
11. As Haynes says refitting is the reverse of removal . . .
Comments:
I was thinking of removing the alternator to get the manifold out but this only works if all the studs in the head are out because you still can't get the manifold off with the steering shaft in place thanks to Porsche's wonderful 'design'!!
While on the subject of Porsche 'design' I noticed that in some places the manifold casting is substandard. The casting process has left material missing near the machined areas of the manifold ports. This means that you don't have the full area of the flange to help with sealing - hence leaks. I happened to have a spare manifold and this was similar though better. Looks like their quality control is not as good as it should have been. Its what happens when a niche car maker gets seduced by the mass market . . .
Looks like the boys at AFN Guildford did a good job of rebuilding the engine 55k ago as none of the the manifold retaining nuts were excessively tight - although one stud had been sheared off subsequently presumably by someone trying to stop the leak.
All in all not nearly as difficult as I had anticipated. Now I've just got to get the gaskets etc and put it all back.
Tref / Big Dave did you use any extra sealing on the gasket faces?
Anyone else had problems trying to get the joint just aft of the front silencer to seal. There's a measured 0.5mm difference in ID & OD on the units I've got.
Sorry, a little late, but to answer the question, no, we didn't use any additional sealing material. There may be something suitable, but I have it in my head that exhaust sealant is corrosive, and aluminium cylinder heads are relatively reactive, so I fear the head being eaten away by the exhaust sealant! Probably totaly misfounded, and an electrolitic reaction between aluminium and cast iron is worse, but until I hear of an ideal media, and a descripotion of the long-term behaviour in both theoretical and practical terms from a source I trust, I'll continue using nothing!
Regards,
Tref.
Regards,
Tref.
Hi Tref,
The long proven way with cylinder head gaskets has always been a wiping of ordinary grease. This allows the head to ease down properly, it is non-corrosive and if there is any minor distortion, the grease will burn, carbon up and seal. I have been rebuilding cars for fifty years, so I should know. Bert Gear agreed with me. John Lord.
The long proven way with cylinder head gaskets has always been a wiping of ordinary grease. This allows the head to ease down properly, it is non-corrosive and if there is any minor distortion, the grease will burn, carbon up and seal. I have been rebuilding cars for fifty years, so I should know. Bert Gear agreed with me. John Lord.
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