Oil leaks are a real pain in the backside, aren’t they? They’re hard to diagnose, time consuming to repair and make a hell-of-a mess in the shed. Which is why knowing how to choose the right seals, gaskets and sealants for the job is vital if you want to fix it right the first time.
When it comes to seals, gaskets and sealants everyone has their own preference. Some people like using genuine seals and gaskets while others swear by ‘this’ or ‘that’ aftermarket brand. A handful even question whether you should run a gasket at all; claiming that you’re better off just using gasket goo in its place. But how do you know what’s best for the job you’re about to attempt?
To find out how to ensure your 4WD never leaks oil again, we caught up with Justin Malaponte from NQ Crash & 4WD Spares who’s going to help steer you in the right direction so next time you have to do a repair you can make sure you only have to do it once.
When you look at the majority of genuine seals you’ll find that many are made by an outside manufacturer and readily available through aftermarket bearing and seal suppliers. So the next time you are shopping for that front crankshaft seal to go in your TB42 Patrol or 1-KZ HiLux, instead of paying a premium or waiting weeks for the genuine parts, take the seal down to your local bearing supplier and see what they can do. You’ll find most common seals are kept in stock and will cost a fraction of the price.
There are hundreds of types of seals on the market and they all have a specific job. Take the front crankshaft seal on any engine; it is designed to be a specific thickness so it sits into the front case in the correct position. There are two basic designs of seals, a narrow seal will have a single wiper – this is the sealing surface around the inside of the seal – or wider seals which have two sealing surfaces to ensure nothing leaks.
If you ever have an issue with a leaking crank seal (or any seal for that matter) you will often find it is due to scoring on the mating surface where the seal runs. A cheap fix for this is to get a wider seal, this will change the position of the seal runner and allow it to seal correctly. Alternatively, you can sleeve the balancer to restore the sealing surface to new again, or replace the entire part.
The seals used in the automotive industry are made of Nitrile rubber because Nitrile has a high oil resistance. If you do ever need to buy new seals for your 4WD, always shop around as the majority of seals can be sourced through a bearing supplier for much cheaper than you can get them from the manufacturer.
The amount of different sealants on the market these days is unbelievable and they each have a specific job to do. When choosing the right sealant for the job at hand you’ll need to look at things like its oil resistance, temperature rating, whether it is recommended for use with gaskets and to seal parts where electrical sensors are used, its curing time and what pressure it will withstand.
How you apply the sealant also plays a huge part in ensuring a quality bond. Too much and it can spill inside the part you’re sealing and potentially cause blockages. Too little and it won’t seal at all. Unfortunately there’s no golden rule except to refer to your workshop manual to find out how much should be applied. Generally there will be an application method described which will explain how much sealant should be applied in what areas.
“Copper sealant is a great sealant for very high temp situations. For example cylinder head, turbo or exhaust manifolds. Normally good for up to and exceeding 500°c. The metal content in the sealant helps to control heat dissipation and promotes even heat transfer between the two surfaces.”
From paper to shim steel and rubber to copper; gaskets can be made to any thickness using a number of different materials. A gasket can be one of the most important parts in any repair to ensure it doesn’t leak.
Take your diff centre for example. We hear people say, “Ah bugger it I will just seal it with gasket goo; it doesn’t need a new gasket” all the time. The truth is, that gasket is there for a reason, whether it to be as a shim to space a part out or even just to give it a good surface to seal on. The materials used to make gaskets are chosen for a reason, too.
Manufacturers used to use cork gaskets back in the day as they thought that it was the best option because a cork absorbs moisture and swells and this would have had to give a better seal. Right? At first yeah, it did, but as cork dries out with the heat of an engine it cracks and goes porous and leaks. So instead of cork manufacturers started to use metal or Neoprene (rubber) as they are oil resistant and could be re-used more than once.
“Using the correct sealant on a gasket can sometimes increase the gasket’s longevity. The sealant will often protect the gasket from an engine’s heat and also provides a barrier against other corrosive elements such as fuels, oils and other chemicals that cause premature failure of engine and transmission gaskets. Adding a thin smear of sealant can also help fill minor imperfections in the sealing surface.”
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