2. Drivetrain
3. Carburetor venting
4. Distributor venting
5. Windshield wiper venting
6. Fuel tank venting
7. Master cylinder venting
1. Engine crankcase venting
Ventilation of internal combustion engines is necessary to prevent harmful condensation, to relieve internal pressures set up by the action of rapidly moving hot parts, and to rid the crankcase section of volatile vapors. When the CJV-35/U was built, engines usually were vented directly to the atmosphere through suitable openings or vents. The CJV-35/U engine was a standard 4 cylinder jeep engine with the added components to make it waterproof, or watertight, which also makes it airtight. Therefore, the method used to ventilate the engine is different than most engines of the time period. It has the same system utilized by most modern automobiles, the PCV (positive crankcase ventilation) system. A PCV system is a closed system within the normal engine intake air and exhaust systems. During normal operation with the engine running, the vacuum created in the engine intake manifold draws fresh air into the ventilating system through the upper crankcase vent control valve on the air intake crossover pipe assembly. The flow of air enters the oil filler pipe. The air then passes downward into the crankcase. The contaminated crankcase air leaves the cylinder block at the side valve cover through the series of parts that include the lower crankcase vent control valve and the metering valve (PCV valve). The air is then drawn into the engine intake manifold and continues on into the cylinders, where it is burned, and then exhausted into the engine exhaust system. During normal operation the two vent control valves are open and play no part in the ventilating system. The metering valve (PCV valve) however, operates to automatically control the amount of vacuum developed within the engine crankcase regardless of the engine speed. Prior to entering deep water, the vehicle operator closes the two vent control valves by pulling out the fording control cable on the dash. Closing the vent valves renders the entire engine ventilating system inoperative. This does not include the vent systems of the carburetor, wipers, master cylinder, fuel tank and the distributor, which are vented independently. When the vent control valves are closed, with the engine running, the unrelieved pressure within the engine builds up to approximately 2-psi. Internal engine pressure will rarely go higher than 2-psi. At higher pressure, leakage occurs through the crankshaft front and rear oil seals. This internal pressure offsets the external pressure of the water surrounding the engine and effectively prevents the entry of water into the engine past imperfectly sealed joints or through the front or rear oil seals.
2. Drivetrain venting
The gear boxes would normally be vented to the
atmosphere to eliminate internal pressure or vacuum from forming as
they heat and cool with use. On the CJV-35/U the transmission and
transfer case are
internally connected by passageways and vent to the air filter. The
transfer case has a tube that extends to the air filter by way of the
right dash tee fitting on the passenger side of the firewall. The axle housings do not have a connection to the
underwater venting system. This seems odd
since they are similar to the other gearboxes. Axle breathers are
located on both differential covers. A few
illustrations, from the service manuals, show
vent tubes from
the rear axle and transfer case going inside
the right frame rail. These vent tubes do not actually exist on the
V-35 nor are there any parts listed for them.
3. Carburetor venting
The upper section of the carburetor must be
open to atmospheric pressure to maintain a balanced condition in the
carburetor. Therefore, the carburetor is vented by means of the vent
tube that connects the top of the carburetor to the air intake pipe.
4. Distributor
The distributor needs to have a supply of fresh
air to eliminate moisture due to condensation and to remove oxides,
which develop in all equipment where an electric spark is formed. The
front edge of the distributor cap is connected to the air crossover
pipe by a metal tube. This tube supplies clean air to the distributor.
The lowest point of the distributor is connected by a metal tube to a
special elbow fitting in the vacuum wiper supply Tee. The special elbow
has a .043" restriction to limit the amount of vacuum in the
distributor to a predetermined value. It should be noted that
since the wiper supply line is directly connected to the intake
manifold it creates a vacuum leak to the carburetor. The .043
restriction controls the vacuum leak and keeps the engine idle quality
acceptable. Later in M-38 production, the restriction was made smaller,
to .040”.
5. Windshield wiper venting
The vacuum supply to operate the windshield wiper comes from the intake manifold. To insure a constant vacuum regardless of engine speed the vacuum booster section of the fuel pump is connected in series between the intake manifold and the wiper supply tee fitting. Since the vehicle can be submerged, the wiper needs to have a fresh air source to avoid ingestion of water. This fresh air comes through the tube on the right side of the windshield frame which is connected to the air filter housing.
6. Fuel tank vent
The fuel tank is vented by a tube that runs from the top of the fuel tank to the left dash tee fitting on the driver's side of the firewall. Another tube crosses the firewall to the right dash tee; from there, a tube continues to the air cleaner. Although other tubes in the ventilation system are steel the fuel tank vent tube, from the tank to the left dash tee, is special thick walled copper tubing.
7. Master cylinder vent
The brake master cylinder is vented through a
tube that extends up between the foot pedals to the left dash tee,
mounted on the driver's side of the firewall. Since the
fuel tank vent is also connected to the left dash tee it is possible
that gasoline could contaminate the brake system. With a full tank
of fuel expansion could force gasoline up the vent tube to
the left dash tee where it would drain into the master cylinder. This
potential problem was eliminated in the next generation of underwater
ventilation systems. The M-38 fuel tank vent ran directly to the air
filter housing.
Parts
Using the Parts Catalog and an existing vehicle I
attempted to locate every part associated with the ventilation system.
Click on the images for a larger view with descriptions and part
numbers. A database of all ventilation system components is found below
the images.
Distributor, engine ventilation, right side
of engine
Vacuum tubes, engine ventilator, left side of engine
Carburetor
vent, engine ventilator, left side of engine
Dash tees and tubes, firewall right side (passenger), air filter removed
Air filter connections, rear view
WO part # | Description | Quan | Group | Fitting type | System | Notes |
---|---|---|---|---|---|---|
A-6919 | BODY, ventilator | 1 | 0107-N | 1 | on side cover | |
A-6885 | ELBOW, 5/16” inverted flared tube (WH-100-43405) | 1 | 0107-N | 1 | Ventilation tube to control valve | |
384549 | ELBOW, 5/16” inverted flared tube (GM-137422) | 1 | 0107-N | 1 | Ventilator to vent tube | |
52805 | ELBOW, 1/4-90*, inverted flared tube (GM-144112) | 1 | 0107-N | 1/4 street el | 1 | Control valve to vent valve |
GM 144592 | NIPPLE, 1/4 x 1-3/8“ (Steel) (Interchangeable with GM-115144) | 1 | 0107-N | 1/4 pipe | 1 | Control valve to vent valve |
GM 115144 | NIPPLE, 1/4 x 1-3/8“ (Brass) (Interchangeable with GM-144592) | 1 | 0107-N | 1 | Control valve to vent valve | |
A-17842 | PIN, swivel, ventilator valve | 1 | 0107-N | 1 | part of 648083? | |
53890 | *SCREW, rd. hd., No. 6-32 x 3/16 | 1 | 0107-N | 1 | ||
53843 | *WASHER, plain, 1/4 | 1 | 0107-N | 1 | ||
53891 | *PIN, cotter, 1/16 x 7/16 | 1 | 0107-N | 1 | ||
648126 | TUBE, crankcase ventilation, assembly | 1 | 0107-N | 1 | ||
A-17841 | VALVE, control, crankcase ventilation | 1 | 0107-N | 1 | part of 648083? | |
648083 | VALVE, control, crankcase ventilation, assembly | 1 | 0107-N | 1 | ||
A-6895 | VALVE, ventilator, assembly (AC-1543018) | 1 | 0107-N | 1 | pcv valve | |
647551 | FLANGE, pipe | 1 | 0300 | 1/8 pipe | 6 | fuel tank vent fitting, top of tank |
53892 | ELBOW, inverted flared tube, 5/16 | 1 | 0301 | 3 | carb to vent tube fitting | |
384569 | ELBOW, 3/16, inverted flared tube | 1 | 0301-C | 90* 1/4 tube x 1/8 pipe | 5 | air filter to wiper vent tube |
643892 | HOSE, air cleaner tube to oil filler tube | 1 | 0301-C | 1 | ok | |
800780 | HOSE, flexible, 2-1/8x5-1/2 | 1 | 0301-C | intake |
air filter to crossover | |
801051 | HOSE, flexible, 2-5/16x5-1/2 | 1 | 0301-C | intake |
crossover to carb | |
649373 | TUBE, assembly | 1 | 0301-C | 1/4 steel | 5 | air filter to wiper vent hose |
117504 | TUBE, vent, timer to intake manifold, assy | 1 | 0301-C | 4 | ok | |
800566 | TUBE, w/bracket and valve, assy | 1 | 0301-C | intake |
air crossover pipe with control valve | |
A-17161 | BRACKET, air intake pipe (Up to Serial No. . .) | 1 | 0301-D | intake | requires 2 spacers 800860, using up early inventory? | |
54059 | *BOLT, hex. hd., 5/16x24 x 1” (Up to Serial No..) | 2 | 0301-D | intake | ||
52626 | *NUT, hex.,5/16-24 | 2 | 0301-D | intake | ||
GM 446363 | *WASHER, plain, 5/I6” (Up to Serial No..) | 2 | 0301-D | intake | ||
52558 | *WASHER, lock, 5/16 | 2 | 0301-D | intake | ||
A-17844 | BRACKET, clamp, valve control conduit | 1 | 0301-D | 1 | To crankcase ventilation valve, mounted on PCV valve |
|
A-17845 | BRACKET, support, dual control | 1 | 0301-D | 1 | To hood hinge bolt | |
800893 | BRACKET, air intake pipe (After Serial No..) | 1 | 0301-D | intake | no spacers required | |
53068 | *BOLT, hex. hd., 5/16x24 x3/4” (After Serial No..) | 2 | 0301-D | intake | Air intake bracket to RF fender | |
52626 | *NUT, hex.,5/16-24 | 2 | 0301-D | intake | Air intake bracket to RF fender | |
53735 | *WASHER, plain, 5/I6” (After Serial No..) | 2 | 0301-D | intake | Air intake bracket to RF fender | |
52558 | *WASHER, lock, 5/16 | 2 | 0301-D | intake | Air intake bracket to RF fender | |
11386 | CLAMP, (Bowden Wire) dual valve control | 2 | 0301-D | 1 | on each cable bracket | |
53889 | *SCREW, rd. hd., No. 10-24 x 1-1/4 | 1 | 0301-D | 1 | Dual control Bowden Wire to support bracket and clamp | |
52237 | *SCREW, rd. hd., No. 10-24 x1/2 | 1 | 0301-D | 1 | Dual control Bowden Wire to support bracket and clamp | |
53888 | *NUT, sq., No. 10-24 | 4 | 0301-D | 1 | Dual control Bowden Wire to support bracket and clamp | |
800890 | CLAMP, flexible pipe to support tube | 4 | 0301-D | intake | ||
635097 | CLAMP, hose, 2-9/32” I. D. (USL-461389) | 1 | 0301-D | intake | Air intake hose to air cleaner | |
800830 | CLAMP, support, air intake flexible hose | 1 | 0301-D | intake | ||
A-5449 | CLIP, 5/16 | 2 | 0301-D | 6,7 |
||
52868 | *SCREW, rd. hd., No. 10-24 x 3/4 | 2 | 0301-D | 6,7 | Tee to tee vent tube assembly to dash | |
52651 | *NUT, hex., No. 10-24 | 2 | 0301-D | 6,7 | Tee to tee vent tube assembly to dash | |
53762 | *WASHER, plain, No.10 | 2 | 0301-D | 6,7 | Tee to tee vent tube assembly to dash | |
53381 | *WASHER, lock, No. 10 | 2 | 0301-D | 6,7 | Tee to tee vent tube assembly to dash | |
A-5449 | CLIP, 5/16” | 1 | 0301-D | 7 | Mounted to oil gage tube clip screw | |
A-5449 | CLIP, 5/16”, ventilation tube to dash | 1 | 0301-D | 6 |
||
52868 | *SCREW, rd. hd., No. 10-24 x 3/4 | 1 | 0301-D | 6 |
||
800603 | CONNECTION, flexible, air tube, 74” long | 1 | 0301-D | intake | Air intake to air cleaner | |
53667 | CONNECTOR, 5/16, flared tube (GM-137404) | 1 | 0301-D | straight 3/16 tube x 1/8 pipe | 2,6,7 |
Air cleaner to air cleaner vent tube |
53667 | CONNECTOR, 5/16, flared tube (GM-137404) | 1 | 0301-D | straight 3/16 tube x 1/8 pipe | 7 | Master cylinder to master cylinder vent tube |
800921 | CONTROL, dual, crankcase ventilating valve, assembly | 1 | 0301-D | 1 | Air cleaner and crankcase ventilation vent valve | |
801085 | *NUT, special | 1 | 0301-D | 1 | Mounting dual conrol | |
801084 | *WASHER, special | 1 | 0301-D | 1 | Mounting dual conrol | |
53670 | ELBOW, 3/16, inverted flared tube, 1/8 pipe | 1 | 0301-D | 90* brass | 6 | Fuel tank to fuel tank vent tube |
53670 | ELBOW, 3/16, inverted flared tube, 1/8 pipe | 1 | 0301-D | 90* brass | 4 | Timer to air cleaner vent tube to timer |
53670 | ELBOW, 3/16, inverted flared tube | 1 | 0301-D | 90* brass | 2 | Transfer case vent to vent tube |
53892 | ELBOW, 5/16” x 1/8-90*, flared, ventilating tube (GM-111284) | 1 | 0301-D | 3 | ?carb vent ?? | |
A-17444 | LOOM, 30” long | 1 | 0301-D | 6 | on fuel vent tube inside cab | |
A-17445 | LOOM, split, 3/16 x 1” | 1 | 0301-D | 7 | Master cylinder vent tube to dash | |
A-17445 | LOOM, 3/16” x 1”, split | 2 | 0301-D | 6,7 |
Tee to tee vent tube assembly to dash | |
A-17122 | NIPPLE, 1/4”, pipe | 1 | 0301-D | 1 | For vent valve hose connection | |
53668 | NUT, 3/16”, flared tube | 12 | 0301-D | all |
flare nuts, part of all the tubes | |
384526 | NUT, ventilating tube (5/16” flared) | 2 | 0301-D | 3 | part of tube 648126 | |
A-17842 | PIN, swivel, ventilator valve | 1 | 0301-D | 1 | ||
53890 | *SCREW, rd. hd., No. 6-32 x 3/16 | 1 | 0301-D | 1 | Valve shut-off control connection | |
53843 | *WASHER, plain, 1/4 | 1 | 0301-D | 1 | Valve shut-off control connection | |
53891 | *PIN, cotter, 1/16 x 7/16 | 1 | 0301-D | 1 | Valve shut-off control connection | |
648452 | RING, anti-rattle, air intake tube | 1 | 0301-D | intake |
||
800860 | SPACER, air intake pipe bracket (Up to Serial No. . ) | 2 | 0301-D | intake |
||
A-17380 | SPACER, flexible pipe to support tube clamp, 5/16 I. D. x 5/8” long | 2 | 0301-D | intake |
||
53751 | *SCREW, rd. hd., 1/4-20 x 1-1/2 | 2 | 0301-D | intake | Air intake flexible pipe to support tube | |
53741 | *NUT, wing, 1/4-20 | 2 | 0301-D | intake | Air intake flexible pipe to support tube | |
53340 | *WASHER, lock, 1/4, internal | 2 | 0301-D | intake | Air intake flexible pipe to support tube | |
800778 | SUPPORT, carburetor air intake tube | 1 | 0301-D | intake | ||
53931 | *BOLT, hex. hd., 5/16-18 x 7/8 | 2 | 0301-D | intake | Support and clamp to cowl side | |
52558 | *WASHER, lock, 5/16 | 2 | 0301-D | intake | Support and clamp to cowl side | |
53671 | TEE, 3/16”, flared tube | 1 | 0301-D | brass | 6,7 |
Tee to tee vent tube, master cylinder and fuel tank vent tube. left dash tee |
53671 | TEE, 3/16”, flared tube | 1 | 0301-D | brass | 2,6,7 |
Transfer case vent tube, air cleaner vent tube and tee to tee vent tube. right dash tee |
A-17742 | TUBE, fuel tank vent to tee, assembly | 1 | 0301-D | 3/16 copper | 6 | 54-1/4” long |
648081 | TUBE, transfer case vent to tee, assembly | 1 | 0301-D | 3/16 steel | 2 | |
800059 | TUBE, vent, air cleaner to dash tee, assembly | 1 | 0301-D | 3/16 steel | 2,6,7 | |
A-12935 | TUBE, vent, assembly, 17-1/2” long | 1 | 0301-D | 3/16 steel | 6,7 |
Tee to tee on dash |
A-17866 | TUBE, ventilating, carburetor, assembly | 1 | 0301-D | 5/16 | 3 | Carburetor to housing tube |
648080 | TUBE, ventilation, assembly | 1 | 0301-D | 3/16 steel | 4 | Timer to air cleaner tube |
648704 | TUBE, ventilation, master cylinder to tee, assembly | 1 | 0301-D | 3/16 steel | 7 | 23” long |
A-17840 | VALVE, ventilation, air cleaner tube, assembly | 1 | 0301-D | 1 | ||
A-17082 | VENT, transfer case | 1 | 0301-D | 2 | pipe bushing? | |
384569 | ELBOW, connector, 1/4 flared tube | 3 | 0302-A | 1/4 tube x 1/8 pipe | 5 | 2 vacuum tube connectors at pump, 1 for fuel |
A-1694 | CLIP | 0304 | 5 | illustration p50 shows 4 clips holding vacuum tubes together | ||
800161 | TUBE, vacuum, intake manifold to pump | 1 | 0304 | 1/4 tube | 5 | |
387891 | UNION, 1/4, inverted flared tube (interchangeable with GM-145474) | 1 | 0304 | 1/4 tube x 1/8 pipe | 5 | Vacuum tube to manifold |
GM-145474 | UNION, 1/4, inverted flared tube (interchangeable with 387891) | 1 | 0304 | 5 | Vacuum tube to manifold | |
800911 | PIPE, tail, exhaust, assembly | 1 | 0401 | exhaust |
exhaust pipe snorkle | |
800912 | CLAMP, exhaust tail pipe to body, assembly | 1 | 0401 | exhaust | exhaust pipe snorkle to body bracket | |
117608 | ELBOW, 90*, inverted flared tube | 1 | 0603 | 4 | ?vac tube at dist? | |
117609 | ELBOW, 90*, flared type, .042 orfice | 1 | 0603 | 90* 3/16 tube x 1/8 pipe | 4 | distributor vacuum restriction at wiper tee |
648144 | EXTENSION, windshield wiper tube, assembly | 1 | 1811-D-1 | 1/4 tube | 5 | Tube extension to tee |
GM-178910 | TEE, inverted flared tube, 1/4x1/4x1/8 pipe | 1 | 1811-D-1 | 1/8 street tee, 3750x2 | 5 | Windshield wiper tube, extension and distributor vent tube. wiper tee |
800162 | TUBE, windshield wiper, assembly | 1 | 1811-D-1 | 1/4 tube | 5 | Vacuum pump to tee |
Special thanks to Harold West for all his help in writing this article.
He has spent countless hours researching the CJV-35/U and has been
incredibly generous with his time and efforts.
More information and comments are
welcome,
Bob W.
Click
here for contact information