UNDERSTANDING THOSE KNOCKS AND NOISES

We have all at some time or another had one of those annoying noises under our 4WDs that whatever you do, you can’t seem to find. When you have a truck that is built to use, you are bound to develop squeaks and bangs from time to time.

If you are like us with your trucks you will know that there is nothing worse than having a noise that you can’t pin point whatever you do. We feel your frustration. Which is why we are going to show you how to identify and fix five annoying issues on your old bus this weekend.

SQUEAKS

Pinpointing the squeak can be done easily with soapy water or water dispersant spray. Keep in mind that bushes may only squeak when they are cold, so you will have to do this first thing in the morning to get an accurate diagnosis.

WHERE TO START

First, wind down all four windows and try to identify which corner of the 4WD the noise is coming from. Then, simply look over the bushes in that area and see if you can see signs of wear or damage (usually clean areas where two components are rubbing). You will have to do this one-at-a-time to see which one is making the noise and possibly needs replacing.

WHAT TO DO NOW

Once you know where the noise is coming from, spray the bush with soapy water or water dispersant spray and go for a drive. The moisture from the soap should quiet minor squeaks, but won’t make any difference to worn bushes.

THE OUTCOME

If the noise is gone, you know which bush needs replacing. This trick can work on all types of bushes, but may not work for metal-on-metal rubbing.

BANGS

Having a bang come from under your 4WD can be very off putting, especially if it is against the floor under your feet.

WHERE TO START

Bangs can be a bit trickier to diagnose as they usually happen when something is under load. Gearbox, engine mounts and diff backlash as a perfect example of banging under your 4WD.

WHAT TO DO NOW

An easy way to see if you have broken a gearbox or engine mount is a stall or load test. This is when you put your foot on the brake and select a gear. Then slowly let your foot off clutch and watch the gearstick. If it tilts towards the right hand side of the 4WD significantly there is a good chance that either an engine or box mount has broken. If you have a bang from around the rear of the 4WD, it may be an indication of too much diff backlash, broken rear trailing arm bushes or even a flogged out uni on the tail shaft. You’ll usually hear this when you let the clutch out too quickly.

THE OUTCOME

If you do have the stick come over and whack you in the leg, you can then climb underneath with a torch and visually inspect all of your mounts. If a mount or bush has split, you can see a crack in the rubber or the rubber has broken away from the mount. Pry on it with a lever bar and if it moves more than normal it’ll need to be changed. If you suspect it’s a diff tailshaft or uni, work your way from the transfer case backwards checking each joint for movement or free-play.

GRINDING

Grinding is one of those sounds that can confuse even the most experienced mechanic as grinding noises have a nasty habit of resonating through the vehicle where a problem in the back could echo up the front.

WHERE TO START

Grinding can be caused by everything from a rock in between a brake rotor and the dust cover up to a bent cross member rubbing on a tail shaft. The first thing you need to do is to replicate the noise. Figure out when it happening. Then, have a mate jump in every passenger seat listening for where the noise is the loudest. Front, back, right or left. If you can identify, for example, that it is happening when you brake and it’s loudest in the front left – that’ll be where you start looking.

WHAT TO DO NOW

Once you have found the origin of your grinding noise, get a mate to drive your truck slowly and walk beside it so you can hear exactly where it is from. Each problem will require a different fix, but start from the most obvious, simple explanation and work your way through from there.

THE OUTCOME

Okay, so you have found you’re grinding and it isn’t anything major, in fact it is just the dust cover on the rear rotor touching on the rotor, all you have to do is pry the cover off the rotor and see if the grinding noise has gone.

WHISTLES AND WHINES

Finding whistles in your truck can be a long painful process, as it can be caused by anything from a loose hose clamp on your turbo to a rear axle bearing with a dry roller. There are a few little tricks to keep in mind when trying to find them.

WHERE TO START

Knowing the general location of the noise is the starting point on any noise, but whistles or whines can be tricky especially when they come from the engine bay. A spray bottle with soapy water is your friend again with leaks. Take for example a boost leak, just get your mate to give the old bus a couple of pumps on the throttle while you spray them with soapy water. The pressure will push out and cause bubbles in the soap. This will work on in of the pressure side of your turbo system.

Another whistle that can catch you out is a door seal on your truck, this usually happens as the seal get old and compress, which allows the pressure to come inside the cab and make a whistle. Sometimes these leaks can be found by hosing around the outside of the doors with one of your mates inside watching for water entering the cabin.

WHAT TO DO NOW

So after you have found your leak, it’s time to fix it. When it comes to your doors whistling, a quick and cheap fix is to just adjust the door striker on the pillar in a little, this will allow the door to closer tighter up against the seal again. Your turbo system leaks can be different; you may get away with tightening the hose clamps if they will go up otherwise just replace them.

If it is a split hose, obviously replace it and do the clamps at the same time. If you repair the hoses but still have a whistle, get your intercooler out and get it pressure test to see if it may have split a core, this is hard to see on some intercoolers as they are not always accessible.

THE OUTCOME

So, you have found your leaks whether it be a hose or a torn door seal, what do you do now. If it is a torn door seal and you need to fix it ASAP, you can fill it with silicone and stick the seal back together for now and then chase up a new seal when you get back. A hole in the intercooler can get pricey, so for a temp fix you can get some Dynasteel or something similar and patch up the hole and then when the funds allow for it you can get a new intercooler. As for a torn hose, you can find silicone hose to suit at most good auto parts stores.

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