Maxie
Well-known member
- Joined
- 11 Mar 2007
- Messages
- 8,436
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:
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 8)
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:
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 8)