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Old 01-23-2016, 09:42 PM   #1
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Default Nissan D21 1987 VG30i 4x4 V6 timing belt replacement and coolant system maintenance

1987 D21 Nissan VG30i V6 4x4 230,000 miles

I recently replaced the timing belt and cooling components on this truck and had a few thoughts, part numbers, and pictures I wanted to collect in one spot.

I'll write as all of it comes to mind, get started and organize and post pics later. Pardon spelling and grammar.

This truck uses a 60k style timing belt. I ordered mine from the local dealer, paid a mint for it, but it was a Japanese belt and supposedly came from fresh shelf stock. Order by your vin number. The later style belts have different teeth and will not fit. Go by the number on the belt, not the number on the box!! Been screwed there, too.

I ordered a pile of new radiator hoses. I had two styles of bottom radiator hose but neither fit. Took more time, but I decided to stop playing darts and order the part from an online dealership.

I noticed a bulge in the hose coming off the top of the thermostat housing 60k miles ago. I thought this was probably casting flash since it was on the housing neck, but I knew I should check it next timing belt change, which is now. Turns out, it was a corrosion cell on the thermostat housing which has also been eating away at the hose. They call this electrochemical degradation. Newer coolant hoses are supposed to be made from a rubber resistant to this. I shouldn't have let this go so long.

Here is a picture of the old hose, showing the bulge:

Inside of the hose at the bulge:

I had to replace the thermostat housing. They are not expensive. Here is a picture of my old one, showing the corrosion:

Old metal pipe flange. Zinc plating is gone, corrosion has set in, on its way out:

New thermostat housing, gasket, metal pipe flange, and new hose and clamp:

The main problem doing this is that the coolant pipe bolted on the backside must come off, and to do that is not easy. That pipe must be loosened from an anchor underneath the EGR, one bolt, and it is a bear. This allows the pipe to come forward so it can be unbolted from the housing.

I used an anaerobic sealer on the gaskets. Gasket dressing is listed as a use on the tube. Some #2 or #3 would have been ok to use as a dressing, as well. I like dressings on aluminum because they reduce corrosion.

There are a couple heater hoses on the throttle body. I replaced those. It is bulk heater hose and cost is not an excuse. Fortunately, the steel nipple fittings, while showing corrosion, were still acceptable. The best time to replace those would be on an engine rebuild.

The manual says line-up the cam sprockets with the dots on the backing plates. I found the dot placement is not precise, so I lined up the passenger cam sprocket and the crank sprocket, then painted a white dot where the driver's cam lined up. It was a half-tooth off.

Using a factory timing belt with the white indexing marks on the belt is great insurance that you have the cams and crank sprockets aligned. Barring that, you can count teeth between the sprockets. I used plastic zip ties to hold the belt onto the sprockets for the alignment process:

Factory timing belt. HNBR is the type of rubber:

New tensioner. Slight design difference compared to old one:

This truck did not have an index mark for the crank sprocket as shown on the manual. That area might be part of the coolant pump housing. I made one with a Dremel metal rasp.

The distributor cap rotor will tell you for sure if you are on TDC of cylinder #1 compression stroke. The bottom fin of the rotor button will be nearly lined-up over a raised fin on the distributor shield plate underneath the rotor. Picture of how the rotor lines-up when flywheel is at TDC:

It is a big mistake not to remove the radiator before pulling the harmonic balancer. I promise you will bend the fins. The radiator removes in one minute once the hoses are off. You have to drain it regardless, and the top bottom hose must come loose on either end, as well.

Install the fan shroud BEFORE installing the fan. If you try to squeeze the shroud between an installed fan and the radiator, I promise you will bend lots of fins, and if you have a new radiator, you will hate yourself.

Corrosion on the fat metal radiator pipe exiting the timing belt areas was enough this time for me to replace it. It is fairly expensive, but I promise it will be much more in the future.

The wire bail radiator hose clamps are still available from Nissan. They are cheap, but there are probably better clamps out there if you have the money. I have never had one fail or cause a hose to fail, however.

I now routinely smear a very thin coating of silicone grease on the inside of the coolant hoses so they won't stick to the nipple.

Judging the proper tightness of a clamp is difficult but lubrication of the threads helps one judge the feel. I stop when I feel torque greatly increases and I can't rotate the hose end by hand, even with silicone grease on the hose innards.

I would not use anything but a genuine Nissan thermostat. These have a clocking requirement so entrapped air can escape the top of the thermostat--there is an alignment mark on the housing and one on the thermostat flange (see pic below). Compare the temperature stamped on the new thermostat to the temperature on the old thermostat to make sure they have the same opening temperature. Picture of a genuine Nissan thermostat. The jiggle vent is just to the right of the arrow mark:

I found I could not install the timing belt without first leaving the tensioner wheel off--the belt is too tight to get over all the sprockets. Once I had the tensioner on, I rotated it with an allen wrench one revolution clockwise to put it under its spring tension.

Sometimes the crank sprocket is hard to remove, especially if no anti-seize was used on the shaft in the last belt replacement. It should be pried off using TWO screwdrivers or similar device. The danger here is that the belt shield behind the sprocket could be bent or nicked in the process. Another likely danger is that the edges of the sprocket could be damaged by the pry tool. Badly damaged backing plates (there are two) can be ordered as parts and the sprocket teeth edges can be cleaned up with a couple passes of a file.

If replacing the seals, I strongly discourage use of a tool not designed for the purpose. I christened a Lysle seal removal tool for all three seals and I was astonished at how perfectly it worked; it is too easy for the seal lands on the shafts to be damaged by indiscriminate seal removal techniques.

Using the Lysle seal removal tool:

The new seals may or may not be pre-greased on the inner lip. If no grease, you have to add it yourself. Also, the shaft land MUST be greased too with a thin coating, otherwise the chances are very good the seal lip will turn inside out while you are pushing it in.

Use a seal installation tool so the seal seats evenly.

The passenger side cam has a land to stop the seal at a depth just at the edge of the entrance taper on the seal well. Here is what that seal looks like installed to the stop:

The drivers cam does not so the seal can be installed at a greater depth. This might help if there is a prior screwdriver gouge you need to keep the seal lip away from. Here is what that seal looks like fully seated (note the shaft would have oil or grease on it during actual installation of seal). Note the greater depth than the one pictured above:

Tensioning the timing belt: I followed the manual instructions, including the part about turning the engine over by hand for a few revolutions. But, heed this, before doing that, double check the alignment of all the sprockets with the white index marks on the belt, because the belt marks will not align again for many more revolutions--I think that has something to do with the belt having an odd number of teeth--something about reducing wear on individual teeth if there is an irregular tooth on a sprocket.

Coolant: John Deere Coolguard II. Compatible with anything and everything. Pre-mixed. 6 year life.

While I have read about the coolant being changed or flushed only using the radiator drain, you don't know how much coolant is in the block until you remove one of the two block drains. They are nearly impossible to remove and you may need careful pinpoint heat on them and perhaps candle wax treatment. Plug is a M14 x 1.25 and I think it has tapered threads. Probably only available from Nissan, unless you have find an oil plug, but those are a little different and I don't know if they would work as well, or at all. Definitely use anti-seize back on the threads and don't go crazy on the tightening torque.

Access to the plugs is difficult. Driver side plug access is better with the alternator removed. I could not remove that plug. I removed the passenger side plug with oxy-acet brazing tip torch and wax treatment on the threads. If some sort of thread sealant was used on the threads, wax might not be much help. I had to go faint red glow and use a swivel socket on an extension with a flex head 3/8" drive to move it, and it was hairy.

Picture of one of the block drains:

I used an ** OSC radiator. It fit well and seemed to be nearly identical to the original radiator. I bought the model without the transmission cooler, which is 3/4 inches wide. I did have to slightly enlarge the attachment holes in the plastic shroud because they did not exactly align with the pre-drilled holes in the radiator. Also, I used smaller diameter screws than the stock screws for the top attachment. I felt the pre-drilled holes in the radiator might crack open with the larger stock screws--it was just too hard to turn the screws. If you have to force them, you are going to have trouble.

The original radiator had 230,000 miles on it, and I changed it as preventative maintenance, but it has held up remarkably well. There was a patent on it pertaining to an anti-corrosive coating or brazing, I think.

Check the radiator fan viscous clutch for leakage of fluid and replace it if you see that or dirt stains as evidence of leakage.

Painted timing belt covers are a nice way to dress up the engine bay. Color in an engine bay helps to differentiate parts and recognize problems faster I believe.

The block and heater core can be flushed using the air hose with air vent over top of the engine. Make sure the heater lever is open, the block drain removed, and use a garden hose nozzle. Replace that plastic air vent with a new one if you have not needed to already.

Inspect the radiator cap gaskets for any cracks in the rubber and replace the cap (13psi) if any found.

I let the coolant pump go twice the timing belt life, 120,000 miles, but I also use a Nissan pump. So far, so good.

I would suggest replacing or rebuilding any original alternator with more than 260, 000 miles, judging by the brush life left on mine at 230k.

Alternator Belt Tension: follow the manual tensioning instructions. My tendency is to have belts too loose at first. If you hear a slight squealing when your headlights are on, but the sound disappears when the lights are off, the belt is still a little bit too loose.

That is all I can think of right now.

There is always more than meets the eye!

Adding information: the two plates or disks on either side of the crankshaft sprockets are called "Crankshaft Sprocket Plates" by Nissan and are part number 13022-V5001 , run about $2.50 @ (2016)

Also, I put anti-seize on the shafts for the crank sprocket and the cam sprockets.

When the belt covers are off is a good time to replace the cylinder head temperature sensor harness. See my thread here on a way to save some money doing that: http://www.infamousnissan.com/forum/...ad.php?t=36698

Last edited by chickenfriend; 06-25-2017 at 12:12 PM.
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Old 07-11-2016, 01:36 PM   #2
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Originally Posted by chickenfriend View Post

The distributor cap rotor will tell you for sure if you are on TDC of cylinder #1 compression stroke. The bottom fin of the rotor button will be directly over a raised fin on the distributor shield plate underneath the rotor.
So this is my dilemma currently. I've always seen the rotor button on numerous other vehicles (american V8's) point to the tab on the cap for that cylinder. The fin that you speak of is close but doesn't point to #1 when #1 is at TDC. This holds true with all 6 cylinders. Are these things different?
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Old 07-11-2016, 02:08 PM   #3
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I always verify timing with a timing light as the final say.

I made a mistake by using the word "directly". "Roughly" would have been correct.

Certainly, if the #1 cylinder is not on the compression stroke, the rotor is going to be nearly 180 degrees from that fin--a dead giveaway!

A rotor is basically an extension of the camshaft, intermediate shaft, or indirectly, oil pump. It will move a little if there is a vacuum advance or centrifugal advance, but for the most part, it can be thought of as being part of the engine.

What can be adjusted is the distributor housing. The cap is screwed-down to the housing so you might as well consider the two as one unit. The mark on the housing does not actually represent the TDC position of the flywheel, but instead it tells you where the #1 cap electrode is.

If the distributor has to come out (and there is no need for that in a timing belt replacement), then make sure to make your re-installation mark on the block/head, indexing it with the housing and the rotor position. Then, also realize the rotor will rotate some as it is being pulled out or re-installed since the shaft gear is helical.

When the flywheel is at TDC for piston #1, then the rotor should be close to lining up with the mark, but not quite. If the timing is, say 4 degrees BTDC, the rotor to be closer to being exactly lining up, compared to more advance, 15 degrees, for example.

We would expect the center-point of the rotor disc to have already moved beyond the cap electrode when the piston is at TDC, because by TDC, the plug has already fired; the ignition fires before TDC.

The truck is timed at spec of 15-18 degrees BTDC. I think the picture I posted above of the rotor and the shield ridge is reflective of that.

Last edited by chickenfriend; 06-25-2017 at 12:09 PM.
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Old 07-13-2016, 01:38 AM   #4
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damn good idea with the zipties on the belt.
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Old 07-13-2016, 02:06 AM   #5
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Sticking this. Good info in this thread
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