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Subject Supplemental Notes: 120k T-Belt Servicing
     
Posted by jzack on March 14, 2008 at 7:37 PM
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SUPPLMENTAL NOTES – 120K T-BELT SERVICING


This is a supplemental guide for doing the 120k T-Belt servicing – basically my little cheat sheet of tips, notes and pictures. It’s intended to be a companion to these helpful documents:

- TT.Net FAQ document >>>CLICK HERE
- 60k Addendum by TT XTZ (Ashley): >>>CLICK HERE

Introductory Comments:

Ever since purchasing this car I’ve had doubts that the t-belt servicing was ever done. For peace of mind I decided it was best to order the full 120k servicing kit from Coz ([ www.czp.us ]) given that the car had 95,000 miles on the odometer. In addition to the kit you may want to consider replacing these too:

- Radiator (my car still had the original)
- Fan blade – blade had a number of stress cracks on the body
- PCV hoses that go between the upper plenum and intake pipes (easy to access during this servicing)
- Power steering reservoir hoses
- Short fuel line hidden under the throttle plate pulley (easy to get at -- but didn’t need to do mine!)

From all the postings I’ve seen my 1991 2+2 Z seems to be fairly typical in terms of repair issues (i.e., stuck parts, tight locations, etc.) and the difficulty in performing them. I’m pretty sure that if I’ve run into these problems while doing the t-belt servicing others will too! This document is divided into two main sections:


Taking Things Apart
- PS Pump and Belt
- CAS and Mounting Bracket
- CAM Sprockets Bolts
- Crank Shaft Sprocket
- Removing Old Seals
- Pulling Idler Studs
- Belt Wrap Technique

Putting Things Back Together
- VTC Gears Cleaned Up a Bit
- Installing New Idler Studs
- Installing New Seals
- Tightening Bolts on CAM Sprockets
- T-belt Positioning and Tension


Additional Helpful Tools:

- Small Rubber Mallet 1.5 – 2 inches diameter head
- Stud Puller – 10 mm (see write-up for tip to avoid purchasing this)
- Steering Wheel Puller – AutoZone has loaners, can keep them for at least 3 weeks.
- 2mm Small Flat Precision Screwdriver
- Small C-clamps (2.5 – 3inch)
- Dental Inspection Mirror (for looking at CAM shaft scoring)
- 8/32 Tap and Drill Bit Kit
- 10mm, 1.5 Pitch Metric T-Tap
- 4 Medium Size Binder Paper Clamps
- 90 Degree Industrial Dental Pick (Home Depot, ACE Hardware – General Probe 3 Pack Set - # 862)


>>>Tear Down<<<<

Two things that gave me some challenge on my way to the t-belt: Rotating the Power Steering Pump and Removing the CAS Mounting Bracket.

Power Steering Pump: Rotating the power steering pump to remove the drive belt.

PSP – Issue #1: There was a wire tie holding a harness bundle to the hi pressure hose connection.

PSP – Issue #2: Old, hard power steering reservoir hose…

Note: I did replace the lower reservoir hose later in this servicing since access to that area was good with everything pulled apart!


CAS + CAS Mounting Bracket: The CAS mounting bracket was really stuck on good.! I could NOT get enough wiggle movement to break it free! The problem is with these two locator pins (small yellow circles below) – which isn’t apparent until everything had been removed – so here are some pictures:

Pin on the block fitting...

Tip #1: In order to get the mounting bracket off I had to remove the CAS sensor first – removing the sensor allowed the bracket to wiggle a bit more (and hitting with a rubber mallet seemed to help as well). Prior to removing, I made sure to carefully trace out the CAS position on the lower bracket using a pencil – this made it easier later to reinstall the CAS close to its original position. However, you’ll still need to check the timing with a light – CAS final adjustment is very sensitive.

Tip #2: I made sure to use some anti-seize compound on the CAS bracket/block locator pins during reinstallation.

Note: The CAS was no fun to get off the sprocket gear either. It took a lot of finger tip tugging to get it to break free. I used some white grease lube on the re-install – wow, what a difference! Pops-up by itself.


CAM Gears – Bolts and Tension: I found that that the easiest way to remove the bolts holding the CAM gears was to loosen them while the OLD t-belt was still in-place. As long as the crank shaft is kept from moving (i.e., car in 5th gear or flywheel jammed with screwdriver) – this is an easy way to get things undone. For added strength – I used some c-clamps to make sure the belt didn’t jump a tooth when tension was applied to the gear bolts.

Tip #1: Use a breaker bar to get them loose, tighten firm again by hand, then remove the belt. Also -- SAVE THE OLD TIMING BELT – I used this same method to tighten everything again once the CAM and crank seals had been replaced. Preferred using the old belt, didn’t want to stretch or stress my new one!

Tip #2: If you have followed the TT-Net FAQ instructions (step #15) for setting the initial crank shaft position, you’ll see a mention that once the old t-belt is removed the CAM gears will want to rotate (violently) and come to a rest. The ONLY two gears that will want to do this are on the passenger side of the engine and both wanted to turn counter-clockwise about ¼ of a turn. In my situation (which I think is typical) – the exhaust CAM (one on far left) moves as soon as the t-belt is removed. The VTC intake CAM gear didn’t move until I started to put a little tension on the 17mm center bolt to remove it. What’s the good news here? - even if they get away from you and end up “slapping to a rest” there’s nothing to worry about in terms of damage. Many have reported this with NO issues afterward – same story for me!

Tip #3: I’m not a big fan of tensioned gears randomly spinning and possibly catching my fingers or tools – so getting them to rest “nicely” is a good thing! Here are some steps for keeping the drama to a minimum:
- When removing the t-belt from the CAM gears – assume that the passenger side Intake( (VTC) gear will stay put and just worry about the exhaust gear.
- Take a small breaker bar (with 11mm socket) and attach to one of the 4 exhaust sprocket bolts – apply some pressure in the clockwise direction (like trying to tighten the bolt), and ease it to rest.

Here’s the general idea (sorry – accidentally deleted my picture showing the Exhaust sprocket)…

Crank Sprocket Removal: Found out after removal just how rusted the shaft was underneath!

TIP: Naval Jelly works wonders in getting this mess cleaned up. Just apply a little, let it sit for 20 minutes or so and rinse off. Do a second time if needed. Once the rust is all removed, apply some grease to the shaft to protect it – I used anti-seize compound to make sure the gear would easily come off with no drama next time…

As suggested by others on TT.net – there are two ways to deal with a stubborn crank sprocket:

- Use a Dremel cutting wheel to split the gear and work it off.
- Use a steering wheel puller, tap the gear and pull it off.

I decided to go the steering wheel puller route – was a little worried about having a cutting accident that messed up either the crank shaft or the oil pump housing. If I ever have to do this again – I’ll use the cutting wheel and save time.

For the tap and pull method: I used an 8/32 tap and my Dremel tool to drill two 5/8 deep holes. Carefully tapped the holes and then used a boat load of different sized washers to make sure the 3.5 inch x 8/32 bolts wouldn’t slip through the puller arms. My sprocket gear was so rusted – it had to be ratcheted the whole way off via the puller push bolt.


This portion of the write-up will address issues prepping for the seal installs, removing the old seals as well as removing the crank sprocket. Access to the CAM seals requires removing the Intake and Exhaust CAM Sprockets which for the most part is pretty straightforward – take out the holding bolts and slip the gears off the shafts.

Stubborn VTC Gear: I had no problems with three of the gears – but one of them wouldn’t budge! Tried slipping two large flat screwdrivers down behind and prying but really couldn’t get good leverage. Instead, I used the AutoZone steering wheel puller and did it like this (don’t laugh, was easy to setup – it worked well). It did take a few bolt turns to get the puller to free the gear!

Intake (VTC) Gear CAUTION: – The shafts on both removed VTC sprockets are what comes in contact with the oil seals! Be gentle when removing these gears and use care to not to place the shafts down on gravel or dirt! Find a safe place to store them and rest them on plenty of rags – a fair amount of oil will leak out over time.

Removing the Damned Seals: Before this job – I had never removed an engine seal in my life! I couldn’t find any consistent advice recommending the right seal remover tool for our engines – so I decided that making a custom tool was the best approach. FYI – There are seal pullers available for purchase, but the ones I found really weren’t designed for the tight space issues encountered with the Exhaust and Crank Shaft seals.

This was the custom toolset starting point that I purchased at Home Depot – it came as a 3 pack with a 90 degree pick and two other styles (pack ran around $7 or so) :

Tool Bonus Tip: This toolset 3 pack comes with another pick that works really well on the injector connector spring clips. Take a look at the white square (illustration) on the packaging – see pick on the far left side. Pick tip has two 45 degree bends and the tip-end is swiveled by about 30 degrees. Makes it easy to insert and twist to pry up the connector clips.

I used a Dremel cutting wheel to shorten the 90 degree pick tip size. Be sure to cut the tip on a 45 degree angle rather than flat -- helps later when pushing the tool tip into a seal body.

This shows how my custom tool grabs a seal. On a real seal, the cut-down probe tip isn’t long enough to push up beyond the seal’s outer ring either…

Here’s the general idea on how the pick-puller works…

Step #1:

Step #2:

Step #3: Once the pick handle is close to being parallel with the CAM shaft, give a good tug to pull it out.

Tip #1: Using the puller is a two handed affair, they put up a real good fight! Hold the pick tool handle with one hand while using a finger to push (and hold) the tip end up into the seal body, then use both hands to pull on the pick’s handle.

Tip #2: I did find the TT.Net FAQ tip helpful about “dimpling” down the seal’s outer ring using a 2mm metric flat bladed screwdriver -- held on a 35-40 degree angle and struck once or twice by a small hammer. Bending the seal ring reduces outer surface area contact and even allows for the spraying in some lubricant (10-w40) as needed. The crank shaft seal was the hardest to get free – I ended up “dimpling” it in two places, spraying in some lubricant and then pulling from two “non-dimpled” seal locations to finally get it out.

I first tested my new tool on the Intake (VTC) CAM seals. As you can see from this picture, with the sprocket gears removed there’s easy access to the bottom lip of the seal with little worry of hitting the shaft.

Once I had them out – I had the confidence to move on to the more difficult exhaust and crank seals..

Exhaust CAM Seals: Keep in mind – I had never done anything like this before (all newbie territory)!!! I was a little worried about possibly scratching the CAM shaft – so I used a thin piece of (orange) Lexan plastic as a shaft protector.

Note: I ONLY used that orange Lexan once – realized it was silly and did the rest without it. Unfortunately these were the only engine bay pictures I had snapped.

Overall my custom seal puller worked well – I’d also suggest slipping a few washers over the handle for better leverage.

Once the seals have been removed – be sure to inspect the seating surfaces. I did find some kind of RTV debris behind a few of them (look closely at end of red straw). I didn’t think it was a big deal but I did clean all of the RTV out of the area.


Removing the Idler Studs: I wasn’t able to get the double-nutting technique to work, instead I spent $15 on a stud puller tool.


TIP: I didn’t realize this until later, but here’s another way to get the studs out without buying an extractor tool – Remove the nut, washer and idler pulley. Replace the nut using RED Loctite (or epoxy) on the nut threads – let dry for a while. The RED Loctite will pretty much permanently bond the nut to the stud – making it easy to get enough leverage on the stud via a breaker bar + socket. I never tried this method myself but it seems reasonable and cheaper than buying a stud puller.

Belt Wrap Technique: I’ve seen postings about using the “belt wrap technique” as a way to secure the crank shaft from rotating – especially for cars with automatic transmissions. While I had things apart – I decided to give it a try just to see how it’s suppose to work. Here are some pictures with a few ways I tried wrapping the belt – posting these pictures to assist others who may not be familiar with what it means. I can’t say how easy this would be to do with the crank pulley still installed? Note -- wrapping can also be done on the Intake and Exhaust sprockets as well…


Meshing/locking the teeth together to keep the belt tight...


PUTTING THINGS BACK TOGETHER


Cleaning Up the VTC Gears: Once the VTC sprockets had been removed I noticed they had some wear marks from the CAM seal lip. Decided it would be best to polish them up a little and make the surfaces nice and shiny. Used some Micromesh polishing cloth (4000 grit) and in a few minutes things looked great!

Note: Pretty sure I didn’t need to do this – but figured with everything all apart, why not?

Installing New Idler Studs: Nothing too special here – prepped the holes with a tap tool.

I installed the new studs using BLUE Loctite on the block side threads. Once the studs were attached to the block and the idler wheels were slipped into place, I applied RED Loctite to the top threads/nut and torqued everything to spec. I’ve run across a few online postings where folks had issues with the studs and/or pulleys coming undone – figured this was the best solution. In addition – the RED Loctite should make it easy to remove the studs in the future since it pretty much permanently bonds the nuts to the stud threads!

Installing New Seals: Here are some pictures of the Lexan trick mentioned in the TT.Net FAQ (step #36) for the crank shaft. The plastic I used was a sheet of overhead vu-graph material (for those that still remember vu-graphs!). For those that don’t – it’s an 8.5 x 11 piece of paper thin plastic sheeting found at office supply stores.

I rolled up the sheet, applied some grease, slipped the CAM Seal over the plastic and moved it into place over the crank shaft…

Things are almost ready to go --- you need to allow about ½ of an inch extra for the plastic sheeting to fit inside of the oil pump housing.

Tip: DO NOT pull the plastic sheeting out from the inside of the seal until you are fully satisfied the seal has been set properly. It will help greatly in removing a mis-set seal should you need to do that (don’t ask how I know this!).

I ran across this tip somewhere – using a PVC fitting to set the new seals. Worked like a charm for all 5 of them --- sets them perfectly flush. This PVC is a conduit coupling from the electrical section of Home Depot (yes electrical, not plumbing!).

For just the crank main seal a short length of PVC pipe is needed to clear the crank shaft. The white PVC mated up against a smaller diameter lip inside of the gray electrical coupler. A small rubber mallet was just the thing to tap the seal into place (look closely it’s in the picture too).

Installing the CAM Gear Bolts: Similar to what was done during the tear down – I temporarily re-installed the OLD timing belt onto the engine. I didn’t worry about any of the timing marks or position of the CAM sprockets. I just wanted everything held tight while I torqued the gear bolts to specification. Just like before, 4 small C-Clamps (one per gear) were used to keep the belt from jumping a tooth on the gears.

Tip: I did apply Blue Loctite to these bolts – seemed as if that’s what was done during factory assembly?...

Installing CAM Gears - CAUTION: Both the intake and exhaust sprockets have locator pins which insure that the gears are installed correctly on the CAM shaft ends. Make sure these pins are orientated correctly when the gears are pressed into place. There have been forum postings where these pins have been damaged due to mis-alignment issues.

Installing the New T-Belt and Tensioner: It’s important to insure that the new timing belt is installed correctly – all the new belt marks must be lined up with the marks on the various gear sprockets. DO NOT worry about the marks on the sprocket backer plates – they mean nothing!

Starting with the crank gear – position the belt correctly (note: I painted a white alignment dot on the side of the belt too). A wood shim worked great for holding the belt firmly against the crank sprocket while the belt was installed elsewhere...

Moving onto the passenger side exhaust gear -- pre-install a small C-Clamp, thread the t-belt underneath and tighten the clamp screw a bit (still should be very loose). Rotate the gear to line-up with the belt mark and then fully tighten the clamp.

Tip: Instead of a C-Clamp, I’ve seen advice for using a 1-handed wood working pressure clamp. >>>>>>>>>>>>>>

For the intake gears -- I used these paper clamps to hold the belt in position…

Once done on the passenger side, move to the driver’s side and repeat. Once the belt is in place begin setting the tensioner.

I found that a metric Allen Wrench was a good way to measure the tensioner’s gap. In general, the setting and adjusting of this gap was fairly time consuming. It took a number of tries and several manual belt rotations to get the gap where I wanted it (just a slight amount greater than 4 mm but not more than 5mm)

Call me anal – but I checked for this too!!!!

Note: It’s very easy to move the belt back and forth – use a large flat screwdriver to gently pry the inner edge away from the gear backplate. Tap the outer edge of the belt with a small wood block + rubber mallet to move it in towards the backplate.

Optional Sanity Check: After many tries at getting the tensioner gap where I thought it should be – I used this technique as a final check to verify belt tension was set correctly. Scribed a line on the gear backer plate that was even with the belt line (belt wasn’t under deflection pressure), then measured for maximum deflection.


FINAL WORDS

I’m very satisfied with how this job turned out! The new belt has been installed for two driving seasons and no issues to report. Overall this project is pretty time consuming but not all that hard to complete. Hopefully -- others will find these pictures and commentary helpful?



DISCLAIMERS…

READ AND FOLLOW ALL SAFETY PROCEDURES RECOMMENDED IN THE NISSAN SERVICE MANUAL FOR WORK ON THE 300ZX Z32 ENGINE AND FUEL SYSTEM. MAKE SURE CAR ENGINE IS COLD, RELIEVE PRESSURE IN FUEL LINES AND DISCONNECT THE BATTERY BEFORE STARTING ANY WORK.

YOU ARE RESPONSIBLE FOR YOUR OWN SAFETY WHEN WORKING ON YOUR CAR. THIS WRITE-UP IS AN EXAMPLE OF ONE WAY TO PERFORM THIS MAINTENANCE, IT MAY NOT BE THE SAFEST OR BEST WAY TO DO IT. YOU ARE RESPONSIBLE FOR DETERMINING HOW THESE REPAIRS SHOULD BE EXECUTED IN A SAFE AND CAUTIOUS MANNER -- AUTHOR IS NOT RESPONSIBLE FOR ANY HARM TO YOU, YOUR CAR, FUTURE GENERATIONS, YOUR PROPERTY OR TO OTHERS WHILE OR AFTER PEFORMING THIS OR ANY OTHER AUTOMOBILE SERVICING... .

     
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