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Old 19th December 2010, 18:01   #1
Jules
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ZT 260 SE Twilight and 10 other 75 ZT's :O

Join Date: Jan 2007
Location: Conwy NORTH WALES
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Default Install a RENAULT 5 88 THERMOSTAT into a CDT/i top hose.

Install time under 30 mins
This is an experimental project spurred on by member Wuzerk.

Installed in one of our ZT's as a temporary measure as I was temp out of stock of the OEM original stats.

First off we decided to leave the clip on plastic union in situ (as ours was well and truly stuck on. Probably due to static friction of the internal O ring)
Undue force would break the plastic Y piece attached to engine block so leave spring clip in place!

Using a Dremil tool (or equiv)



Remove top engine cover qty 3 x 8mm bolts.
Carefully almost cut through the stainless band here.



Here's how to avoid loosing any coolant:
Loosen Qty 1 x 8mm bolt at the header tank.
Lower the tank as far as it will go.




It is possible to drain approx 2 litres out of tank.









With a little silicone grease the stat will slip in with ease but still be firm enough to hold itself in place.
Insert as shown with wax bulb towards engine.
Push in a further 10mm so stat doesn't fowl the plastic union




Refit the hose using good quality 21mm - 44mm stainless clamp.
Refill with fresh OAT or with coolant saved previously




Test results

Some extensive varied driving conditions
Some where performed on the Nurburg Ring.

While the results are encouraging some of the temp readings are NOT ideal.

Results: (FBH disabled)

Outside temp = 0 deg C
Level ground
2 miles of town driving achieved OBD temp = 52 deg
Then 1.5 miles at 50 MPH on A55 (speed limit at this junction) .......OBD temp up to 72.

2 more miles at 2000 RPM 5th reached 83 deg
Full throttle short burst in 4 th gear to 3000 RPM .....90 deg

Full throttle short burst in 5th gear to 4000 RPM...... 99 deg!
Slowed to 50 MPH on over run temp very quickly dropped to 88C

Onto a B road now with some very steep inclines.
2nd gear 3000 RPM 87 C - 89 C coping well.

Steep down hill on the overrun for 1 mile..... dropped to 76 C (understandable)

Back onto level open road in 5th gear at various speeds 86-91 C


More test driving still to be done but so far the temps are not as stable as the OEM Stat would be.
I suspect the Renault Stat opening port is just slightly on the small side with heavy engine load.
May have to wait and see next year for HOT ambient conditions under heavy engine loads.

Of course if Temp rises above 100 C when in top gear, the cooling fan is going to be active (wasteful so not ideal)

Could be a good Winter Stat for careful drivers !
Of course this mod is totally reversible as no cutting of hoses required, so we can always find a different Stat, but doubtful if we'll find one physically big enough with enough flow to fit within the 38mm internal hose diam


Disclaimer:
You are responsible for any work or modifications carried out on your car and you undertake any such work at your own risk. The 75 and ZT Owners Club nor the original author of this How-To can be held liable for anything that may happen as a result of you following this How-To.
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Newbies do now!!
1. Plenum drains..all 3 or 4 year dependent
2. Cooling fan..All speeds functioning
3. Bonnet cable divider block

Last edited by Jules; 17th January 2016 at 09:59..
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