MFH-5398
Block Only Fresh Water Cooling
Kit Instructions
IMPORTANT
Before you unpack the kit and start installation, make sur e you have the right kit for
your engine by studying these inst allation instru ctions. These installation instructions
have been written to cover most sterndrive and inboard installations on Chevy small block
engine conversions made by the major marine engine manufacturers before 1999. The
system is front mounted at the level of the thermostat housing and the engine must have
the alternator and/or the power steering pump mounted low or to the extreme port side of
the engine. The heat exchanger is 22 inches long.
These instructions cover a normal installation situation. Sometimes problems can occur
due to engine variations and boat-builder or owner modifications. If you run into such
problems you can call Monitor Products for advice during normal business hours.
If you determine this is the wrong kit for your type of engine:
o Call the distributor you purchased the kit from for their return policy.
o If you purchased the kit from Monitor Products Inc., call 1-800-334-4591 for
a return authorization. No returns will be accepted without this authorization.
The kit must be in new condition and repacked in its original packaging to
qualify for credit or replacement.
The installer must make sure that the overall installation is safe and in accordance with
Coast Guard and industry standards.
Installation tools & supplies
Flat head screw driver
Phillips head screw driver
11/16” deep socket or box wrench
9/16” socket or box wrench
7/16” socket or box wrench
3/16” hex key
7/32” hex key
Hose Cutter or Knife
Gasket scraper
RTV silicone gasket sealer
Antifreeze solution (See flush and fill
instructions
)
MFH5398_REV00.doc Page 2 of 7 Last printed 10/23/2006
Items included in kit:
Item Qty. Part Number
1 1 M5398-9700 Heat Exchanger 20 1 4500-3004 Grounded T’stat Hous. Gasket
2 1 5001-1327 Expansion Tank 21 1 5000-3012 Thermostat
3 1 5000-1763 Cap, Expansion Tank 22 2 5200-1143 Hose Clamp #24
4 1 5000-1343 1/8” NPT x 5/16” Hose Adapter 23 4 5200-1144 Hose Clamp #16
5 1 5102-2125 5/16” ID x 48” PVC Hose 24 2 5200-1401 Hose Clamp #12
6 2 5200-1344 Mini Clamp #02 25 1 5000-3021 Lower Bracket
7 1 3000-1351 3/8” NPT x 5/8” Hose Adapter 26 1 5002-2611 Upper Bracket
8 4 4300-2802 5/16” Washer 27 4 5102-2124 Isolators
9 4 4300-2801 #12 x 3/4” Flat Head Screw 28 1 5107-2128 5/8” ID x 12” Hose
10 2 4300-2790 5/16-18 Nylon Locking Nut 29 1 5118-2126 1” ID x 21” Hose
11 2 4300-3015 3/8-16 x 2-1/2” Stud 30 1 5100-1290 1-1/2” ID x 14” x 6-1/2” Hose
12 4 5000-2637 Spacer, 1” OD X 1” Long 31 5 5000-1154 Tie Wraps
13 4 4300-2791 3/8-16 Nylon Locking Nut 32 2 4400-1377 3/4” NPT Plug
14 2 4300-3016 3/8-16 x 3” Flat Head Cap Screw 33 2 5100-1722 Manifold Cap 1-5/16” ID
15 1 3103-1291 1” x 1-1/4” 90° Hose Coupling 34 1 5104-2129 1-3/4” ID x 4” Hose
16 1 5000-3014 Raw Water Splitting Tee 35 1 0321-2100 1-3/4” Hose Coupling
17 2 5200-1610 Hose Clamp #72 36 2 5200-1475 Hose Clamp #28
18 1 4005-2003 Thermostat Spacer 37 1 4400-1314 3/8” NPT Plug
19 1 4500-1381 Thermostat Housing Gasket 38 1 5105-2126 1” ID x 12” Hose
Description
Item Qty. Part Number
Description
MFH5398_REV00.doc Page 3 of 7 Last printed 10/23/2006
Installation Steps
Fig. 1
Fig. 2
1. Drain water from block by removing
plugs from both lower sides of
engine.
2. Remove hoses from the existing
thermostat housing. Save all hose
clamps. See Fig. 1.
3. Disconnect wires from temperature
sender(s) and remove the
sender(s) from thermostat housing.
4. Remove and discard existing
thermostat housing, thermostat,
gasket and bolts. Scrape surface
clean especially grooves where
new thermostat will be located.
Avoid getting scrapings into
thermostat opening. See Fig. #1
5. Flush engine. If new, flush engine
briefly with fresh water through
thermostat opening. Use a garden
hose with a rag around it. If used,
more thorough flushing may be
needed. See Flushing instructions in
Fresh Water Cooling General
Maintenance Manual.
6. Install two 3/8-16 studs (Item #11)
into intake manifold.
7. Install spacer (Item #18), thermostat
(Item #21), and lower bracket (Item
#25), with two gaskets (Item #19 and
Item #20) as shown in Fig. #2.
Tighten 3/8-16 nuts (Item #13)
securely.
8. Thread straight hose adapter (Item
#7) into center threaded hole in
spacer.
9. Thread temperature sender into
spacer. If overheat alarm is used,
thread into the other threaded hole
of spacer. If not, install 3/8” plug
(Item #37). Reconnect wire to temp
senders. We strongly recommend
that you install an audible “buzzer”
type alarm. These overheat alarms
are usually combined with low oil
pressure alarm and are very
reasonable in price.
MFH5398_REV00.doc Page 4 of 7 Last printed 10/23/2006
Fig. 3
Fig. 4
10. Install upper bracket (Item #26),
with the 3/8-16 flat head screws
(Item #14) and 3/8-16 nylon locking
nuts (Item #13), using the
appropriate number of spacers
(Item #12) needed for your
application. Be sure that when heat
exchanger is installed it will not
interfere with any belts, fuel lines,
or hatches and covers. See Fig. #
3.
11. Install isolators (Item #27) onto
bracket rails.
12. Install heat exchanger (Item #1) on
rails of upper bracket and secure
with two large hose clamps (Item
#17). See Fig. # 4.
13. Install the 90° hose coupling, (Item
#15) into raw water supply hose
located vertically along the front of
the engine under the heat
exchanger bracket using existing
clamp. Supply hose may need to be
trimmed. Measure and cut 1” ID
hose (Item #29) to length. Trim
hose as required to fully engage
90° hose coupling. Secure using
two hose clamps (Item #23).
14. Trim 1 3/4” molded hose running
from circulating pump to engage 1
3/4” fitting on heat exchanger.
Secure using existing clamps. See
Fig. # 4. (If need, use 1 3/4” hose
coupling (Item #35), 1 3/4” hose
(Item #34), and hose clamps (Item
#36) to make this connection.)
MFH5398_REV00.doc Page 5 of 7 Last printed 10/23/2006
Fig. 5
15. Connect tee assembly (Item
#16) to heat exchanger at top
rear left side of heat
exchanger with 1” ID hose
(Item #38) using clamps
(Item #23). Place Tee
assembly on top of heat
exchanger bracket and
between 1 1/2” fitting and
heat exchanger. Attach
hoses leading to bottom or
front of exhaust manifolds to
each side of tee assembly.
Use existing hose clamps.
See Fig. #5.
16. Connect heat exchanger to
lower bracket with 1 ½” ID
molded hose (Item #30) using
clamps (Item #22). See Fig.
#5.
17. Attach 5/8” ID hose (Item #28) using clamps (Item #24) to hose adapter on spacer and 5/8” hose
fitting on heat exchanger. See Fig. #4. If heater system hook-up is used this 5/8” hose is extended
to heating devices and back. Trim as necessary. If desired, an optional flushing tee, available at
most automotive supply stores, can be installed in this 5/8” hose.
Fig. 6
18. Thread plastic elbow (Item
#4) into bottom of (Item #2)
using sealer. Expansion tank
cap (Item #3) should already
be in place. See Fig. #5.
19. Mount overflow bottle on
studs on front of heat
exchanger using 5/16-18
nylon locking nuts (Item
#10). If space in front of
engine does not allow
installation on heat
exchanger, install on vertical
surface next to engine using
washers (Item #8) and screws (Item #9). Keep as close to engine as is practical, with top of tank at
the same level as the top of heat exchanger.
20. Connect 5/16” clear PVC hose (Item #5) to the fitting on filler neck and elbow on bottom overflow
bottle with mini clamps (Item #6).
21. Some model Mercury Marine engines only:
Remove hoses from exhaust elbows and discard. The
kit includes two rubber caps (Item #33) as well as two ¾” NPT pipe plugs (Item #32). Depending on
the type of connection use one or the other to plug the connection of each exhaust elbow.
22. Use tie wraps (Item #31) to make sure that hoses or other parts are not in contact with critical engine
components, such as V-belt and fuel lines.
23. Reinstall engine block drain plugs.
MFH5398_REV00.doc Page 6 of 7 Last printed 10/23/2006
24. Double check total installation and make sure all fasteners, fittings, and hose clamps are tightened
properly. See Filling and Start-Up Instructions in Fresh Water Cooling General Maintenance
Manual.
We strongly recommend that you install an audible “buzzer” type alarm. These overheat alarms are usually
combined with low oil pressure alarm and are very reasonable in price.
Part Number Description
5000-1763 Cap, Expansion Tank
4000-1857 Pressure Cap, 16# SS
5000-3012 Thermostat
4500-1381 Gasket, Thermostat Housing
4500-1622 Gasket, Rubber Thermostat
4500-3004 Grounded T’stat Hous. Gasket
4500-1082 O-Ring, Buna-N
4500-2005 Gasket, 4” (end cover)
4400-1044 Zinc Anode, 3/8”NPT, 1-1/4” Long
Replacement Parts
MFH5398_REV00.doc Page 7 of 7 Last printed 10/23/2006
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