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Maxie
Yas Marina


Joined: 11 Mar 2007
Posts: 8386
Location: London


PostPosted: Sat May 18, 2013 10:11 pm    Post subject: Fitting a low-temp thermostat to a 997 Reply with quote

First of all, massive thanks to GT4 worship

Having read enough about bore-scoring and hot-running M97 engines, I decided to take the preventative measure of ordering a low-temp thermostat from eBay (I got mine for £53 incl. p&p). What you get is this:



And what's inside is this:




Quote:
Reading and referencing from GT4's extremely useful guide here:

http://www.911uk.com/viewtopic.php?t=65932



I decided what better way than to invite the author of the above thread and ask him to help me fit it. Except, he didn't - he fitted it himself! However, I did come in useful by holding his tools, shining a test lamp for added illumination and supplying him the odd Coke now and again……

So, first of all, we needed to jack the car up. Using some old wooden sleepers that I had left over from a gardening job last year, we chocked the fronts, put the car in gear, jacked the car up, braked the rear wheels. Then we placed the wooden blocks under the rear tyres and supported the car again using axle stands:





Once the car had been jacked up, next job is to extract all the coolant fluid from the system into a clean bucket (as this will be poured back into the engine at the end of the job):









As we were about to loosen (ok, it strictly wasn't we, it was he….!) the bolts securing the existing thermostat, we discovered that the bolt head pattern was not the 10mm hex bolt as the 996.

These are the bolt-heads securing the thermostat on a 997:





Paul suspected they were an "inverse" Torx, but didn't know the exact name to google (Torx and socket just pulled up the Torx key version).

Paul called OPC Hatfield, who were kind enough to quote them as female Torx or E-Torx (and their best guess of E8 or E10 as the size).

Now we had a name, google confirmed and Halfords sold them!

The name is an E10 Female Torx socket and looks like this:



As we still weren't sure of the exact size, Paul had the brainwave of taking an impression of the bolt-head pattern in a blob of Blu-tac. We then made the impromptu trip down to Halfords to buy those tools. (These bolt head patterns had changed during the transition from 996 to 997 from 10mm hex to this new E10 Torx).

At the Halford's check-out, the young & pretty blonde girl working the till was suitably impressed by the Blu-tac idea:



What then transpired was that I could not have possibly attempted this procedure myself owing to the specialist tools one needs to do this job. If you look under the engine of any 996 or 997, you cannot fail to notice the myriad of curving, conjoining spaghetti junction of pipes and other rubber hoses (and in the case of the 997) extra support arms. This was a problem as some of the bolts that needed undoing were located behind said pipes. The only way to do it is if you have a socket set that can work at a multitude of angles. Luckily Paul had those tools and the know-how.

("UJ" or Universal Joints are the answer! - see GT4's 996 thread above)



After spraying with WD-40, these bolts eventually came off however, a large rubber hose-piping stubbornly still held onto the intake of the thermostat. Secured by a pipe clip, a pair of plyers was used and the rubber adherence from the heat released by working a small flathead screwdriver in-between the rubber pipe and housing surfaces and spraying WD-40.

just before WD-40 (?):




The piping eventually came off after much forceful effort. The thermostat finally fell into our hands. It looks like this:







And notice the temperature stamp (83C of this one vs 71C of the new one):



Also notice the 996 part no.:



Compare it with the 997 part no. right......?



Once this had been taken off, excess coolant also fell through which was caught in another bucket (this excess will not be used as it is dirty with bits floating around in it).

The adjoining part to the thermostat housing was cleaned down using wet/dry paper:



Once cleaned, it should look like this:





Using some Loctite 5922, the new gasket was sealed onto the new thermostat:





Luckily fitting the new thermostat back onto the engine again wasn't as much hassle as taking off but you will still need those specialist UJ and E10 Torx. Once back in, it looks like this:



With the large rubber hosing back over the new thermostat again:



Now the car needed its coolant, so this was duly funnelled back in. Be aware of air-gaps (air locks) now circulating in the system. In fact, we forced some of the air gaps out simply by turning the engine over and depressing the accelerator (in GT4's thread, a minute or so of revs rising to 4k rpm should clear the initial air-locks). We could see the level of the coolant dropping and so we immediately re-topped with coolant & distilled water once more.

The initial refill seems to fill to about 2L below actually full (but you can't fill any more until a twisty drive has "shaken" the air locks fully out).

Proof of the pudding always comes in the actual performance and that's what we did next. GT4 in his 993 led the way whilst I followed in my own car occasionally stopping to top up with coolant. I did this twice within the hour and the coolant level seems to have stayed the same.

For a full settling of the refill, a cycle or two from cold to hot and back may also be required.

I will keep an eye for this over the next few days.

So, has the thermostat worked? The water temp gauge still reads the same old 80C as it ever did. However the big difference is the oil gauge reading.

Gauge now reads 80C at normal operating temp as opposed to 90C previously at speeds up to 4k rpm. When operating in the 4k-5k rpm rev band, my temp rose to 92C vs 100C from previously.

Early signs suggest that the thermostat is doing its job as intended.

An early evening dinner + drinks at The Red Lion in Welwyn Garden City went down well!

~ Maxie Cool
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Zantaz
Suzuka


Joined: 14 Apr 2012
Posts: 1161



PostPosted: Sat May 18, 2013 10:26 pm    Post subject: Reply with quote

Great write up. Based on your pictures it's certainly a job I wouldn't consider doing myself Smile

It's a good preventative measure. One of the first things I'll be doing when my OPC warranty runs out is having one fitted. Thumb

Cheers Maxie.

PS any other mods planned? Thumb
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Poker2009
Österreich


Joined: 09 Sep 2009
Posts: 936
Location: London


PostPosted: Sat May 18, 2013 10:55 pm    Post subject: Reply with quote

Really useful write-up - planning to install one next week!

Looked at it today and realised we needed the female torx. Most of the write-ups on the internet are for the 996, so this is great.
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Sat May 18, 2013 11:09 pm    Post subject: The long way round! Reply with quote

Thanks Maxie.

The job is in theory very simple:

1.) jack car
2.) drain (partial) coolant
3a) undo hose clip and remove rubber hose
3b) undo 7 bolts (3 for coolant hardline supports, 4 for housing)
4.) remove old gasket and clean up block surface with wet and dry etc
5.) apply sealant to new housing and gasket
6.) reverse fitting
7.) re-fit drain plug
8.) re-fill (first fill)
9.) flip header tank bypass valve up
10) run engine to "burp" (first burp)
11) drop back to ground
12) run engine to "burp" (second burp)
13) tidy tools away
14) drive and refill until levels stable (drop bypass valve)
15) check again once cold and the next few drives

The delays in changing Maxie's thermostat were mostly:

1?) jacking protocol (on my car, I cheated and jacked on the jacking points both sides, and placed a third jack under sump momentarily - with wood weight spreader - and whipped the jacks out a side at a time to immediately replace with axle stands back under. Once on axle stands, the centre sump jack stayed *just* under the sump in case the car moved) - as this method is neither best practice, nor was this my car, we did it the long way!

3a/b) on my 996 the hose just popped off (once Jubilee clip was loosened), making housing bolt access much easier. On Maxie's it was almost welded on! Again, not wanting to risk damaging someone else's car, we did it the long/difficult way: remove the housing first to get purchase/access on the stuck rubber tubing (of course both 3a and 3b were stymied when my 10mm hex sockets didn't fit the E-Torx 997 heads - the fact I had brought enough 1/4" drive sockets and UJs for England didn't help when the E10 was a 3/8ths drive! - and 3/8ths wise, I only had 1 UJ and some slightly too long extensions for comfort!)

Different exhaust manifold design to 996 (X51) and additional muffler support rigging (from muffler to block) on the 997 didn't help getting to the slightly obscured top two housing bolts.

8.) there will always be random airlocks: whether it is the modified block (M96 3.4 vs M97 3.8 ) or the fact that I fitted my thermostat deliberately on a hill for extra angle, or just (bad) luck, but the 997 refill was more like trying to feed a recalcitrant baby!

All mechanical works hindered (Grin) by both the owner and amateur photographer peeping over my shoulder with too many questions!

13) to 14) was overly extended due to me taking all my tools home, having a shower, putting my dirty work clothes in the wash and returning to Maxie's for a cross-country drive-out (in clean clothes) in my 993.


Would do it all again Maxie Thumb (now I have the E10!)

PS - Cheers for dinner too. Laughing
 
  
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markiii
Imola


Joined: 07 Mar 2011
Posts: 757



PostPosted: Sat May 18, 2013 11:14 pm    Post subject: Reply with quote

Any noticeable difference in heater efficiency?
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Zantaz
Suzuka


Joined: 14 Apr 2012
Posts: 1161



PostPosted: Sat May 18, 2013 11:31 pm    Post subject: Reply with quote

Nice work GT4 Thumb

When you outline the work like that it does appear straightforward but still outside my skill levels when it comes to cars. It's no doubt a confidence thing. I'll stick to washing and polishing Smile

PS I do like your write up here as well:

http://www.911uk.com/viewtopic.php?t=65932
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Sat May 18, 2013 11:40 pm    Post subject: Reply with quote

Thanks Zantaz, Maxie did quote that (996) FAQs thread in the first paragraph or two.
 
  
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Zantaz
Suzuka


Joined: 14 Apr 2012
Posts: 1161



PostPosted: Sat May 18, 2013 11:45 pm    Post subject: Reply with quote

GT4 wrote:
Thanks Zantaz, Maxie did quote that (996) FAQs thread in the first paragraph or two.


Yep...that's where I saw it from on the second read.
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Anthonyw
Trainee


Joined: 22 Sep 2011
Posts: 69
Location: Lincolnshire


PostPosted: Sun May 19, 2013 10:50 am    Post subject: Reply with quote

Nice work guys. I followed GT4's excellent guide a couple of months ago when I did my low temp stat on my 997 C2S. Also came up against the same issues as Maxie so good that you have both taken the time to publish this thread.

Luckily I had the female torx sockets as they are the same on the wife's old smart roadster Smile

Anthony.
 
  
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
Posts: 30174
Location: Hertfordshire and Hampshire


PostPosted: Sun May 19, 2013 11:48 am    Post subject: Reply with quote

Only downside to fiddling with older cars: sometimes I don't have the newest "security" tools.

I will cross-link the 996 thread to this and move thread to 997 FAQs once it has had some visibility in 997 Forum for week or so.

Not sure where Maxie bought his from, but Bennets Motor Factors sell the housing, gasket and thermostat for £49.

This is a massive saving to what the restrictive sources were when I did the mod (looking at circa £150 for the set, or £70/80 just for thermostat insert)

And replacing the whole housing is one or two less stages in the mod (else you have to remove old thermostat insert, clean up the housing and refit the new thermostat insert).

http://www.bennetts.com/porsche-engine-timing-tools/porsche-low-temperature-thermostat-71-degree-with-gasket-and-housing-2216377-414401-830828.php
 
  
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pzero
General
General


Joined: 18 Jul 2010
Posts: 5519
Location: London


PostPosted: Sun May 19, 2013 4:05 pm    Post subject: Reply with quote

Outstanding collection of boxed Porsches you have there Maxie.
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Jam911
Albert Park


Joined: 31 Oct 2010
Posts: 1528



PostPosted: Sun May 19, 2013 6:53 pm    Post subject: Reply with quote

I like the pic taken at Halfords ...lol
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GT4
Nordschleife
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Joined: 08 Nov 2008
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Location: Hertfordshire and Hampshire


PostPosted: Sun May 19, 2013 8:09 pm    Post subject: Reply with quote

Didn't see any milk at Halfords Question
 
  
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Maxie
Yas Marina


Joined: 11 Mar 2007
Posts: 8386
Location: London


PostPosted: Sun May 19, 2013 10:51 pm    Post subject: Reply with quote

Zantaz wrote:
PS any other mods planned?


Not for the time being but I am interested to hear of anyone who has retro-fitted the third central radiator to their car and what effect it has had on cooling. This maybe something to do in future.

GT4 wrote:
Would do it all again Maxie (now I have the E10!)

PS - Cheers for dinner too.


Welcome Paul, planning a further session with you to bore out the drilled discs sometime soon.

Zantaz - not strictly a mod but more a maintenance measure as drilled discs often get filled with brake pad residue and other such crud which harden over time.

GT4 wrote:
All mechanical works hindered ( Grin ) by both the owner and amateur photographer peeping over my shoulder with too many questions!


Indeed! It was a much needed edification on my part.

markiii wrote:
Any noticeable difference in heater efficiency?


Not sure what you mean by this....?

GT4 wrote:
Not sure where Maxie bought his from, but Bennets Motor Factors sell the housing, gasket and thermostat for £49.


Yes, I also bought from their eBay shop:

http://myworld.ebay.co.uk/bennetts1954/

pzero wrote:
Outstanding collection of boxed Porsches you have there Maxie.


Cheers Malcolm - can't seem to stop buying them. Just picked up a 991 GT3 model the other day too; sits next to my white 997 GTS model with black centre-locks Wink

~ Maxie Cool
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markiii
Imola


Joined: 07 Mar 2011
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PostPosted: Sun May 19, 2013 11:11 pm    Post subject: Reply with quote

Last car I fitted a lower temp thermostat to, the heater never got as hot afterwards

Just wondering if you've noticed anything similar?
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Maxie
Yas Marina


Joined: 11 Mar 2007
Posts: 8386
Location: London


PostPosted: Sun May 19, 2013 11:30 pm    Post subject: Reply with quote

markiii wrote:
Last car I fitted a lower temp thermostat to, the heater never got as hot afterwards

Just wondering if you've noticed anything similar?


Ahh - ok, got you. Haven't noticed anything out of the ordinary yet but will keep an eye and report back.

Just an update to everyone else reading this thread. My oil gauge seems to have stabilised somewhat after taking the car out for another run today.

Running temp up to 4k rpm is now reading 85C (before fitting it was reading 90C or just over). Between 4-5k rpm, it is reading 91C (previously this was 100C).

I have added another half-litre of coolant in this morning.

~ Maxie
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GT4
Nordschleife
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PostPosted: Sun May 19, 2013 11:36 pm    Post subject: Reply with quote

markiii wrote:
Last car I fitted a lower temp thermostat to, the heater never got as hot afterwards

Just wondering if you've noticed anything similar?


The most likely reason for that is an airlock.

80° C coolant will be just as capable of supporting 24° C etc on the climate control as 90° C coolant.

In fact the CC will do whatever is necessary (in terms of bleeding and mixing of air flow and heater matrix coolant flow or indeed air-con refrigeration via the evaporator and vent direction to maintain the same temperature throughout the cabin as per on the dash digital control unit)


As for thermostat vs third rad:

Whisper it quietly, but once you thermally load the engine enough (eg outside temp, racing, lack of rad air flow - eg traffic jam, towing up-hill etc) to exceed about 93/94° actual, the thermostat is fully open and there is nothing more it can do to cool the engine.

That is why you need to fit the third centre rad.

As I explained to Maxie, the two mods are required to cover both regimes during use:

Low temp thermostat adds block longevity up to and including normal operating temps (and use) by optimising the use of the current rad surface area, the third centre rad mod adds more rad surface area to cope with high use loads - ie actually improves the heat extraction and raises the safe maximum thermal limits.

If you regularly see 100° C coolant temp (note: 100°C actual can look just like 90° on the dash temp gauge if you aren't aware of how it works), you need a third centre rad, and even if you don't, it will do no harm to add.

The low temp thermostat WILL NOT and CAN NOT hold down max temperatures in itself - it just changes how you use the rads you have fitted and hence how the mid range (normal operating range) coolant flows.

 
  
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GT4
Nordschleife
Nordschleife


Joined: 08 Nov 2008
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PostPosted: Mon May 20, 2013 12:07 am    Post subject: X51 centre rad Reply with quote

Maxie wrote:
Zantaz wrote:
PS any other mods planned?


Not for the time being but I am interested to hear of anyone who has retro-fitted the third central radiator to their car and what effect it has had on cooling. This maybe something to do in future.


A few have done this (and there's a nice "kit" from Design911 with all you need)

AFAIK Gibbo205 did the mod most recently, but just do a forum search on "centre" and "rad*" with the 997 Forum option.

The X51 rad mod is quite a straightforward mod: remove PU, some rubber plumbing, and fit a few new brackets to hold the new rad.

The only pain can be prising off "welded" on rubber pipes, but they are at least easily accessible.

Jack up front of car so not much coolant escapes (although keeping the header tank cap on pretty much stops anything pouring out anyway).
 
  
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Zantaz
Suzuka


Joined: 14 Apr 2012
Posts: 1161



PostPosted: Mon May 20, 2013 7:28 am    Post subject: Reply with quote

Am I right in thinking the Tiptronic has a 3rd radiator? I can see one in the middle on mine.....
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GT4
Nordschleife
Nordschleife


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PostPosted: Mon May 20, 2013 8:25 am    Post subject: Reply with quote

Yes

Carrera with Tip or PDK get the centre rad (unless 996 C4S, which has the larger Turbo rads, so does without)

(And yes, that means the C4S gets better POTENTIAL top-end cooling out of the box, but still suffers higher operating temp due to same 83° thermostat.)

Back to the auto centre rad, this doesn't really help overall cooling, as the centre rad is added to remove the extra gearbox heat (the gearbox gets its own oil:coolant heat exchanger on the side of the gearbox)

No LTT means it still runs too hot operating temp, which is the most pernicious aspect of the standard setup.
 
  
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