996 engine out - what to change?

[G-996]

Thanks to a small coolant leak through the cylinder head gasket on my 996.2 C4, I'm looking at an engine-out job at my local (excellent) Porsche indy specialist to fix this. I've had the car for a couple of years and as far as I know, the engine has never been out before. I think it makes sense to get a few other preventative jobs done at the same time, would appreciate any views on my list of potential jobs:

- Replace cylinder head gasket to cure coolant leak
- Replace Rear Main Seal (currently leaking oil slightly)
- Replace clutch (car has done 69,000 and I think it's the original clutch, so I doubt it will have long left)
- Inspect and probably replace IMS bearing with metal replacement, removing dust shield on new bearing
- Replace brake pipes that go over the top of the gear box/engine and I understand are prone to rust, and require engine removal
- Clean-up and powder coat both (diagonal) sub-frame support struts, which are looking a bit scruffy with some surface rust

Any other preventative jobs I should consider whilst the engine is out?

[Magic919]

DMF.

[G-996]

Magic919 said:

DMF.

Thanks for the fast response.

With the Dual Mass Flywheel, is it case of definitely replace, or inspect and maybe replace? And why? (I've no experience of DMFs)

[Magic919]

At similar mileage our 996 had knackered its one. I noticed some minor judder and the indie that took it apart found it was well gone.

They'll be able to check it by rotating by hand once out.

[G-996]

Magic919 said:

At similar mileage our 996 had knackered its one. I noticed some minor judder and the indie that took it apart found it was well gone.

They'll be able to check it by rotating by hand once out.

Thanks for the info

[Richard Hamilton]

Air oil separator would be worth replacing too. A common failure, and a pig to change with the engine in.

[ooid]

AOS
Oil cooler
Low Temperature Thermostat
Water Pump
Optional - Power Steering pump and pulley. This definitely needs checking, depends on the miles some of them need to be replaced.

[PGNSagaris]

Lightweight flywheel and clutch.

[Rockster]

G-996 said:

Thanks to a small coolant leak through the cylinder head gasket on my 996.2 C4, I'm looking at an engine-out job at my local (excellent) Porsche indy specialist to fix this. I've had the car for a couple of years and as far as I know, the engine has never been out before. I think it makes sense to get a few other preventative jobs done at the same time, would appreciate any views on my list of potential jobs:

- Replace cylinder head gasket to cure coolant leak
- Replace Rear Main Seal (currently leaking oil slightly)
- Replace clutch (car has done 69,000 and I think it's the original clutch, so I doubt it will have long left)
- Inspect and probably replace IMS bearing with metal replacement, removing dust shield on new bearing
- Replace brake pipes that go over the top of the gear box/engine and I understand are prone to rust, and require engine removal
- Clean-up and powder coat both (diagonal) sub-frame support struts, which are looking a bit scruffy with some surface rust

Any other preventative jobs I should consider whilst the engine is out?

A failed head gasket is rare with these engines is what I gather. More often when a head gasket is suspected a cracked head proves to be the culprit.

The best advice I can offer is to address things that are obviously in need of addressing. One can go crazy (and broke) taking of care of things "while there".

The clutch obviously needs to be checked. And the tech can check the dual mass flywheel for any problems but if the clutch action was ok unless the clutch disc shows signs of being at the end of its service life the clutch and DMF are probably ok to use. (Had my 996 Turbo transmission out at 120K miles for an RMS leak. Clutch disc had no measureable wear. The clutch in my 2002 Boxster is original and that car has over 307K miles on it. So clutches (and DMF's) in these cars can last a long time.)

Water pump? Well, it depends upon how old it is. The factory water pump in my Boxster was good for 172K miles. (The Turbo's lasted around 120K miles.)

The water pump doesn't cost that much so unless it was just recently replaced you could just have a new one installed along with a new T-Stat I would *not* use a low temp T-Stat.

What else? Well, you are having the RMS replaced. I have to mention that it is SOP at least with the dealer service departments I'm famiilar with to also replace the IMS end flange and bolts too when doing an RMS. The problem is often one can't tell if the leak is from just the RMS. If the leak is from the IMS end flange and bolts you'll be back in there thinking the RMS is bad when it is not.

Some want to replace the radiator hoses. If they feel ok: Give them a squeeze close to where the connect to the hose fitting. If the bottom of the hose feels soft that's a sign of an aging hose. My experience is and the techs have told me this is the case the radiator hoses are long lived. Both my Boxster and Turbo are on their original hoses. The hoses appear to be more long lived than the radiators, at least in the case of my Turbo. While the Boxster has one original radiator, I had the other radiator replaced when damaged from hitting some road debris, the Turbo had to have all 3 radiators replaced (at 130K miles) from all 3 just plain leaking.) If you replace some hoses you really should replace them all.

Check the coolant tank for any leak sign. Along the bottom seam is a common leak area. Any signs of any leak replace the tank.

If the plugs are near to being due to be replaced doing the plugs is not a bad idea. (When I had my Turbo in for new coils to address some misfires the tech recommended the plugs be replaced even though they were not due for another 10K miles and I agreed. I would pretty much replace the plugs regardless of their mileage unless they were say just 5K to 10K miles old.)

When replacing the plugs if the coils are showing their age these can be replaced. Generally the worse the weather the car is driven in the shorter the coil life.

With the engine out you can have a good look at the rear of the car. Any suspension/drive train/exhaust hardware that has suffered from exposure to the elements can be replaced. Exhaust hardware and heat shields in particular really take beating from exposure to water (and salt if you live/drive where salt is used to help with the snow/ice).

[G-996]

Thanks for all the feedback everyone (Rockster - thanks for all the detail, much appreciated)

Edited by G-996 on Monday 9th January 08:04

[ooid]

You really need to look at Oil Cooler though, if there was a coolant leak, that's almost necessary. Rockster is right, head gasket failures on 996/986 quite rare so some techs out there might easily suggest it's head gasket but it could be oil cooler or cracked cylinder head.

[Pope]

Check the coolant header tank - PITA engine in and regularly split / leak.

[nigelonich]

Just done this in a 996 GT3 mk2.

As above and if youve not spent about £1000+ on parts not including the clutch, DMF and RMS you have not done enough!

I did all the coolant hoses, clips and the water pump housing pipes. I had them removed, knurled and JB Epoxy glued back in. I replaced the header tank and the cap which was not that expensive. I also replaced the engine bay sound deadening mat as mine was scruffy and I had any spots of corrosion repaired.

My front hose clips were kaput too while you are there.....