Thermostat modification drill hole size
Posted: Tue Feb 24, 2015 8:20 pm
Regarding taking a drillbit and allowing the thermostat to bleed coolant to effectively reduce its cycles, I have found that a 1/16" a good size.
How do I know? Ive been doing this for years and last summer, my 89gt got gummed up in deteriorating block seal [been running 50k miles with a 2" vertical crack in the front drv side cylinder WALL]. The block seal stuff also clogs the radiator cap, preventing flow from reservoir during cold-down... look for small fiber stuff if you use this stuff too. just rinses out with kitchen sink water...
anyway, I drilled my 89gt thermostat with a 1/8" bit since previous experience of 1/16" had been great. More better desired right? well, the 1/8" is WAY TOO BIG. 45min at idle before the fan kicks on is way too long. I drive 30min before passing the 1/4 mark on the coolant gauge when it normally rests at the half mark.
For those of you interested in this mod, drill 1/16" if the thermostat doesn't come with the bleed hole in the first place.
This is for a 2.8 V6 with manual trans [no auto cooling lines with manual] in my 89gt.
Andy
89gt <---subject car
lemon 3800 <---2.0 I4 radiator still in effect with trans fluid! no thermo mod, no problems
How do I know? Ive been doing this for years and last summer, my 89gt got gummed up in deteriorating block seal [been running 50k miles with a 2" vertical crack in the front drv side cylinder WALL]. The block seal stuff also clogs the radiator cap, preventing flow from reservoir during cold-down... look for small fiber stuff if you use this stuff too. just rinses out with kitchen sink water...
anyway, I drilled my 89gt thermostat with a 1/8" bit since previous experience of 1/16" had been great. More better desired right? well, the 1/8" is WAY TOO BIG. 45min at idle before the fan kicks on is way too long. I drive 30min before passing the 1/4 mark on the coolant gauge when it normally rests at the half mark.
For those of you interested in this mod, drill 1/16" if the thermostat doesn't come with the bleed hole in the first place.
This is for a 2.8 V6 with manual trans [no auto cooling lines with manual] in my 89gt.
Andy
89gt <---subject car
lemon 3800 <---2.0 I4 radiator still in effect with trans fluid! no thermo mod, no problems