How to Install Gearbox & Differential Breathers

Revision 1.1

The Test Vehicle

The test vehicle was 1994 manufacture (Australian version) with the following running grear; The success of these modifications on your vehicle will depend upon any variations from the configuration used to provided these instructions, components used, and your mechanical engineering ability. Given those variables, I can not provide any guarrantee as to the level of success of failure you may achieve.

Background Details

There has been a lot of talk about the effectiveness of the differentrial and gearbox breathers used on the 80 series Toyota Landcruiser. I started to look in detail when oil was noticed coming out of the front differential breather valve.

The front diff breather enters the axle housing about 25mm above the axle centreline. The rear breather is connected to the top of the rear axle housing. It is interesting to note that the 60 series Landcruiser had the breather entry at the top of both axle housings.

When the axle housing breather hoses were removed ther was a noticable induction of air into the axle housing, which had been under vacuum.

A number of small modications have been made to (hopefully) resolve the discharge of front diff breather, and prevent the breather or seals from sucking in water or dirt during river/creek/mud hole crossing.

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Options

The only options, not detailed here, are to; These are sub projects that others may consider investiagting, and writing the approriate methodologies.

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Modifications

The modiciations are simple, and can be carried out with normal hand tools These modifications include;

The Breather Valve

The breather valves are designed to permit gas (and liquid) exit the axle or transfer case housings. A modification needs to be carried out on only one valve.
Below is a cross section of the original breather valve. The valve body is brass, with a steel cap, spring, and rubber flapper.
Diff Breather Valve
The 60 series Landcruiser used a plastic body and cap, without either the spring or rubber flapper. You may wish to purchase one of these if you do not wish to modify one of the original breather valves.

The 80 series breather valve after modification is shown below;

Modified Breather Valve

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Tools

Tools required to carry out the task are listed below. Most of these tools are probably already in your tool kit. Goto top of Document 

Parts

The following parts are required to complete the modification. Most are available from auto parts or brake repair shops. Goto top of Document 

Modification Procedure

Overview

The procedure is simple, and will take about 2.5 hours once you have all the tools and parts required. No attempt has been made to connect into the main grearbox breather, as the gearbox needs to be lowered to get access to this breather (unless you have minute hands, and double joined arms/hands).

Then new breather line will run from the rear axle housing, to the inner rear cross member, along the inside of the left chassis rail to the transfercase cross member. From there it will split to run up the side of the transfer case to the transfer case breather outlet, and forward along the chassis rail to front axle house breather valve hose mounting point on the chassis.

At this point the new breather line will split to connect to, the front axle housing breather outlet, and the other remaining leg will run up into the engine bay.

The new breather line will be secured to the chassis with P clamps, and cable ties were access to the bolt onto the chassis is extremely diffucult (like behind the fuel tank).

Brass "T" pieces are used at the transfer case cross member, and just forward of the left engine mount. Hose clamps are used at each breather outlet and each "T" piece.

Work is commenced from the rear axle housing towards the from of the car. Breather lines are always mounted above the brake lines.

Please read ALL of the modification details before commencing. There are a lot os steps involved, but most are just reasonable engineering practice.

This proceedure has worked fine for me, on 1FZ-FE engined '94 model. Your milage may vary, so use these instructions as a guide.
 
 

Detail

Clean the underside of the car with degreaser and a pressure was, then find a level, and preferably clean dry hard surface. Get the car on the ramps or jack stands. Proceed as follows;

Rear Axle

  1. cap one end of the new breather line
  2. feed the breather line (capped end first) rearwards from the transfercase crossmember along the inside of the chassis rails, above the brake lines) past the main fuel tank
  3. slip one P clamp (tail pointing rearwards on thre right side) over the new breather line
  4. slip one hose clamp over the new breather line
  5. remove the original rear axle housing breather hose (completely)
  6. remove the cap in the new breather line
  7. push the new breather line onto the rear axle housing breather outlet, and secure with the hose clamp
  8. ensure that there is sufficient hose to allow full articulation of the suspension without fouling or rubbing
  9. secure the new breather line to the fuel tank cross member using the existing parking brake cable guide bolt
  10. remove the bolt holding the brake lines to the chassis at the rear of the fuel tank
  11. install a P clamp over the new breather line, tail outer most and pointing down
  12. loom the new breather line neatly across the rear of the fuel tank, and secure with cable ties
  13. secure the P clamp and brake lines with the original bolt
  14. remove the bolt holding the brake lines to the chassis at the front of the fuel tank (and behind the transfercase crossmenber)
  15. pull any excess new breather line forward from in front of the fuel tank
  16. install two P clamps over the new breather line, tail outer most and pointing down, just forward of the fuel tank
  17. secure the new breather line to the brake lines behind the fuel tank with cable ties at each brake line clip
  18. secure the rear most P clamp and brake lines with the original bolt

Transfer Case

Here you have two options, one is to leave the original forward breather in place, the second is to remove it completely
 
Option A 
Follow this process if removing the forward breather hose 
Option B 
 Follow this process if leaving the forward breather in situ 
               or
Remove the forward breather hose at the base of the main gearbox gear lever and plug with 8mm bolt. Remove the main gearbox breather just forward of the T piece.
Cap the port that the hose came off with the 3/8" blanking cap Insert the 8mm bolt into the end of the hose and secure with the hose clamps.
Install brass T piece into the breather line between the main gearbox  and transfer case. Secure with hose clamps Tie the hose to the top of the main gearbox to avoid it snagging while on the trail.
NB: small hands are an advantage here, and its a fraction easier if you work from the left side of the car
  1. slip one P clamp (tail down and forward most), and one hose clamp over the unused end of the new breather line
  2. secure the new breather line to the  T piece on top of the gearbox using the hose clamp
  3. route the new breather line down the left side of the transfer case
  4. remove the second lowest transfer case housing bolt
  5. secure the new transfer case breather line with the P clamp against the transfer case using the bolt just removed
  6. loom the new transfer case breather line along the transfer case cross member, and up to the top of the chassis rail
  7. cut the new transfer case breather line at the top of the chassis rail
  8. cut the rear axle housing breather line just forward of the transfer case cross member
  9. slip one hose clamp over each of the new rear axle housing breather and new transfer case breather lines
  10. trim each new breather line to permit a tidy fit of one brass T piece
  11. secure the new breather lines to the brass T piece with the hose clamps, with the new transfer case breather line connecting to the terminating portion of the brass T piece
  12. slip one hose clamp over a the remaining section of new breather line
  13. secure the remaining section of new breather line to the remaining unused portion of the brass T piece
  14. secure the rear axle housing breather line to the chassis using the mounted P clamp and bolt from the original rear axle housing breather support

    15. Front Axle

  15. slip all but one of the remaining P clamps over the new breather line
  16. route the new breather line forward from the T piece, under the engine mount, to the front axle housing breather support
  17. secure the new breather line to the chassis using bolts from the brake line mounts and P clamps
  18. use cable ties were appropriate
  19. cut the new breather line approximately 15cm forward of the left front engine mount
  20. remove the front axle breather hose from the front axle, and chassis rail. Listen for the suction!
  21. slip a hose clamp over the unused section of new breather line
  22. install this section of new breather line onto the front axle breather outlet, and secure with the hose clamp
  23. allow sufficient breather line for full front axle articlutaion from the front axle housing to meet up with the breather line from the rear axle and transfer case.
  24. cut the new front axle housing breather line at this point
  25. slip one hose clamp over each of the the new front axle hosuning breather line, and rear axle/transfer case breather line
  26. clamp the rearaxle/transfer case breather line to the terminated part of the remaining brass T piece with the hose clamp
  27. clamp the new front axle housing breather line to the brass T piece using the hose clamp
  28. route the remaining section of new breather hose down along the left inner gaurd in just in front of the left engine mount
  29. slide one P clamp and one hose clamp over this section of breather line
  30. secure the breather line to the remaining outlet of the brass T piece using the hose clamp
  31. secure the P clamp using the original front axle breather hose support bolt and chassis mounting hole

    32. Engine Bay

  32. route the section of breather hose to a convenient location in the engine bay which has an 8mm bolt hole. This will depend on the extra equipment installed on your car
  33. rework either the front or rear breather hose support bracket to hold the new breather line
  34. mount the breather line support bracket
  35. install the breather line into the support and secure by compressing the metal loop slightly
  36. cut the breather line, leaving sufficient to install an original breather valve
  37. slip a hose clamp over the endof the new breather line

    38. Breather Outlet

  38. non distructively remove one of the original breather valve caps
  39. re-assemble the breather valve without either the rubber flapper or spring, as per the modified 80 series breather valve drawing
  40. remove the breather valve from the original breather hose
  41. install the modified breather valve into the open end of the new breather line in the engine bay
  42. secure the modified breather valve onto the new breather line using the hose clamp

    43. Completion

  43. ensure all clamps are tight
  44. inspect brake lines for any damage
  45. account for all unused clamps and hose
  46. account for all tools used
  47. clean the tools
  48. clean thy self
  49. remove the car from the ramps or jack stands
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Pictures of the Installation

Below are pictures which show various parts of the completed installation.

The following photo shows a view forward from the transfer case cross member to the front brass T piece, were the breather line splits to go down to the front diff, and up into the engine bay. The hydrauldic line seen in the picture is the clutch line. The white object on the right is the engine sump.

Front Axle

The second photo shows details of the area around the transfer case T piece. You will notice the P clamps using the same bolts as the new breather line, and the support U bolt for the ARB side steps (left of the picture) routed under the brake lines and new breather lines. Fuel lines can be seen on their way to/from the engine in the centre of the photo.

Transfer Case from under the car

If you have a full time 4WD (as most are) you can possibly trace the breather hose from the 4WD servo motor as below;

Transfer Case - Rear View
or from the actual transfer case (all versions) to the T piece on top of the transfer case itself, as below.
Transfer Case - Top View

The main gearbox breather connects at the base of the shifter tower. A hose connects to the transfer case from the rear, and then runs forward to a flapper valve at a point behind the motor. You need small hands to access these from under the car.
 
Option A Option B
 
Option A - Main Gearbox Breathers
Option B - Main Gearbox Breathers
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Copyright D.J. Zilm 1998, 1999
Press here to mail meMail the author for more info.