nz4runner

I've searched through and read all post I could possibly related to this.

Anyways I have a 1994 manual 2.8 diesel 4runner. It's got a recon motor with less than 5000km on it.

I purchased the truck just over a month ago since I started noticing a noise which appeared to becoming from the rear of the truck a few weeks ago.

Since purchasing it it's had a good run in 4wd and been up and down some rough tracks.

It's noticeable on the road when I hit 50-55km/hr (30-35mph) once I go over 60km/hr I struggle to notice it. On flat seal I can hear it more easily. It's almost a tyre type noise but not/ tyres are an A/T tyre with 5mm tread left. - like a woomp woomp or a boomp boomp or a doomp doomp (hopefully descriptive of the noise haha) it doesn't sound like something loose etc. When I take it out of gear and free wheel the noise is still noticeable but it drops off slightly but I'm guessing that's because I'm losing speed.

I had a leak from a rear axle seal noticed by oil around the flange plate of the diff/axle and oil in the drum and the oil that had been spun into the wheel arch, so the bearing has been replaced and new seals put in. I also changed the diff oil. There was small filings on the magnet on the diff plug no big chucks etc.

I've also had a leak coming for the transmission stick I'm waiting for a new transfer shift lever oil deflector and gasket. I thought the seal between the transmission and transfer might have gone when I checked the oil levels in the transmission and transfer the transmissions level was a fraction lower than the plug hole and when I removed the transfer fill plug oil dribbled out slightly.

Universals have been greased. The drive shaft feels good with no play at the diff end - where it comes out the back of the transfer I can get a little fraction of movement back and forwards in terms of movement the way it would normally spin it's not slack/bearing play side to side etc.

The woomp woomp is still there.

If it's the original diff / rear axle assembly which is guess it is it has 300,000km / 185000 miles.

I'm stuck as to what's causing it

stanprophet

Most of the time, a noise making a womp womp sound is a tire that is out of round or cupped causing the noise. I have heard bearings making a not constant sound, but they will usually cause a roar or grinding noise. Usually like there is a jet aircraft following you down the road.

Now there is always that sound that sounds like one thing and turns into something different. Usually I test drive the vehicle then put it on the lift, and see if the noise is there on the lift. A bearing will make the noise while stationary, tires will not.

You could put the rear axle up on some stands, and run the truck up to the speed you hear the noise at the most. But PLEASE be very careful, if it were to fall of the stands it could be very bad. Also when applying any throttle or brakes, be very slow and ease into them. If the noise is there you know you have a bearing or U joint failure. If it is gone then it is a tire issue. I have had U joints make that droning sound. It is usually due to a needle bearing getting dry and tearing up the cup. They can be tight, and no visible sign of a failure. Pulling the propeller shaft (drive shaft) out, and articulate the joints by hand. If there is any binding, then the joint in question is bad.

So I would run it on the stands, if the noise is there, I would pull the drive shaft and check the joints. If the joints are fine, I would find someone with a lift where the truck can be put in the air and ran, and use a stethoscope to pinpoint where the noise is coming from, and go from there.

By the way, I thought the 4Runner was called a Surf in NZ and Aussie land? Hope you get it figured out. Oh and Welcome to Yota Tech!

nz4runner

Thanks for taking the time to answer.

Yeah in New Zealand we have an abundance of 2.4l turbo diesel surfs, 3l turbo diesel surfs with mainly auto transmission and there is also the 3l v6 petrols.

On top of that there is the odd 4runner floating around. At a guess it would 95% surfs to 5% 4runners most being the 2.8 manual diesels.

I chose the 4runner because of the 2.8 diesel engine it's a sturdy work horse look after it and it will look after you type thing. I didn't like the sound of the frequency of the heads cracking on the 3l turbo diesels. I don't need to go anywhere fast and it's used to get me into my hunting spots -river bed travel off road tracks etc.

I'd thought about putting the truck up on stands and running it up to speed to see if the noise was there - the thought of it coming off the stands puts me off at this stage.

I'll get someone to ride in the back and put their ear to the floor in the back to see if they can pinpoint it first.

Second I might rotate the tyres and see what happens.

Then I'll think about putting it up on stands etc.

Thanks for the input this forum is great.

stanprophet

Interesting.

All the toyota folks here in the states wished we had a non petrol option in these trucks. Rotating the tires may help pinpoint the noise.

nz4runner

I rotated the tyres - no change.

A mate had a look and says the drive shaft is pretty solid UJ's etc feel good.

I did notice if I grab the back wheels and rock the tyre sideways there's a slight tap/knock coming from somewhere in the there - it's probably from either where the axle splines seat in or from the bearing knocking in the bearing housing. My mate put his hand on the bottom of the axle housing and said he could feel the knock.

Here's a vid/recording with the phone sitting on top of the tyre while I rock it back and forwards.
http://youtu.be/2Cnizb2om_U


Removed the drums and grabbed the axle shaft and pushed it in and out it moves a fraction - that's the same on both sides.

Anyways I recorded the noise by leaving the phone in the back over the axle. It starts to be noticeable after 30seconds once I get up to 50km/h. A lot easier to hear with ear phones too.

http://youtu.be/RSoD-RmCWsM

FGZ

The u-joints may feel good, but those or the drive shaft spline itself are my guess at the source of that noise. Try swapping the rear drive shaft out with a spare. Also, can you put the rear on jack stands and recreate the noise? A bent rim that is letting the rear tires wobble left/right would be easy to see like that, and maybe you can pinpoint the noise while you're sitting still.

nz4runner

I haven't put it up on stands yet. I guess tomorrow I'll drop the rear drive shaft out and run it in 4wd and see what happens without the drive shaft there.

daved5150

iTrader: (1)

Welcome to Yotatech there, nz4Runner! I really can't give any more ideas as Stanprophet is more knowledgeable than myself. You'll get it figured it out.

Is it constant or intermittent? I'd check out the u joints as the guys here have said. Getting the tires off the ground and running it will hopefully solve it for ya.

And yea, by the way, count me in as one of those Americans who would give my left --- to have a diesel powered old school 4Runner. That 2.8 oil burner sounds like a cool little motor.

Terrys87

iTrader: (1)

I have something similar in one of my runners. I have had the driveshaft u-joints replaced and balanced. My guess is one of two things. With the high mileage, I wonder if my gears are just worn or if I have a bearing starting to go out or just worn out. I do not know gears or about rebuilding them. I have a friend that does am trying to set up a time with him to help me figure it out and maybe rebuild/repair it. In the mean time I do have another differential I am going to try and see if that helps eliminate it.

I have done all of the above mentioned and am 99% sure it is in the diff and most likely in yours as well. Swapping the differential out is easy on these if you have one laying around. Undo your brake lines, the four bolts on each axle/brake cover and the bolts that hold it to the axle housing.

I have driven some Toyota diesels in my travels and you are lucky to have them. Great motors and great on petrol.

nz4runner

The noise is barely noticeable/if at all from 0-30km/h I've heard it a couple of times when I've got to 30km. It's most noticeable at 50-55km/h once you get over 70km/h it's unnoticeable it still might be there but due to the speed of driveshaft and wheels etc it's not recognisable.

If I drop it into neutral from 60km/h and let is coast down to 50km/h the knocking is there but it's a lot quieter than if I was accelerating from 50km/h or driving at a constant speed at 50-60km/h

The 2.8 are a great motor some have been known to do well over 500,000km with little to no work. They were a standard motor in Hilux utes from 1989 till around 1999 when they went to the 3litre motors. They have a unique sound to them and anyone could pick out a 2.8 going down the road with their eyes closed. Check out some of the YouTube "2.8 hilux" clips.

I grew up driving a 2.8 hilux so it's a little nostalgic having a 2.8 now

nz4runner

Put the truck on stands and ran it with the wheels and drums off. No noise from the drive shaft, wheel bearings sounded good.

Put the drums and wheels back on and tried it again. No noise from driveshaft, wheels were all good. Slight vibration resonating through the diff but no knocking noise... I'm none the wiser..

Been for a drive and it's still the same..

I'll chuck up some YouTube clips later

nz4runner

http://youtu.be/oHTif0p3Azg

When I go to the left side you can hear the knocking slightly from 17 seconds onwards - it's faint and a lot quieter than if it was moving on the road.

http://youtu.be/EbpvMVE5rDM

Towards the end of the clip when I point it at the driveshaft you can just notice the whomp whomp or knock knock. Drive shaft appeared good though.

http://youtu.be/jawNDMRpCrg

This is from the back of the diff at the very start you can hear a vibrating noise - it did that when I touched/pushed on the diff felt like it was coming from the centre maybe pinion or something?

http://youtu.be/Jm6OaTTnGfo

23-25 seconds can hear a whoom whoom noise which could be linked to the noise I'm hearing which may isolate it to the left side.

daved5150

iTrader: (1)

Just watched your videos. A bearing in the third member?? Two things to try...put a different third in and see if noise goes away. If not, install a spare driveshaft in with good u joints and see what happens. It definitely sounds like a bearing to me.