Part # 910-850 910-855
-1-
Modified 03/18
Coolant Reroute Kit
Installation Instructions
For 1994-1997 Miata 1.8L
PART # 910-850 and 910-855
Tools required:
• Timing Light
• Jack, jack stands, wheel chocks
• Phillips Head and Flathead Screwdrivers
•
¼
" Ratchet
•
3/8
" Ratchet
• 10mm Socket
• 12mm Socket
• 19mm Deep Socket
•
11/16
" Deep Socket
•
7/16
" Socket
• 5mm Allen Wrench
• 10mm Wrench
• 12mm Wrench
• 22mm or
7/8
" Wrench
• Thread Sealant
• Razor blade or similar gasket scraper
• Radiator Hose Cutter
• Telescoping mirror (recommended)
• Spill-Free Funnel such as Lisle 24680 (recommended)
• Torque Wrench
¼
" (recommended)
• Cooling System pressure tester (recommended)
Kit number 910-855 does not include an EGR
tube, EGR block off plate or block off nut. 910-855
is intended for an individual who has already done
away with the EGR system.
If your car presently has a working EGR system,
we recommend returning this kit and purchasing
Coolant Reroute Kit part# 910-850 which includes
a compatible EGR tube.
Removing the EGR tube and blocking off the ports
will turn the “Check Engine Light” on.
Notes:
The stock coolant routing on the Mazda 1.8L
engine leaves much to be desired. Since the 1.8L
was originally developed for light-duty transverse-
mounted front wheel drive applications, little thought
was given to the rear-wheel drive Miata. Coolant
flows from the water pump at the front, through
passages in the engine to the rear of the cylinder
head. Some coolant can exit at the rear of the engine
but only through the small heater hose leading to the
heater core, a major flow restriction. The majority of
the coolant has to reverse direction and travel back
through the block again to exit at the thermostat at
the front of the engine; transferring unwanted heat
back into the block on the way. As a result of this
inefficient design, the rear cylinders run hotter than
the front. This can lead to a hotter running engine and
premature failures of the rear cylinders. The design is
especially problematic when a Miata is driven hard on
the track or modified for increased power output.
This kit will relocate the thermostat from the front of
the engine to the rear, thereby allowing coolant to
flow more efficiently one direction through the block.
The full-size radiator hose outlet at the rear of the
engine ensures maximum coolant flow is directed out
of the engine to the radiator. This helps to keep all
cylinders at a more uniform lower temperature.
