The danger of long grass  

There are few things in Africa as beautiful as long grass waving in the soft afternoon sun.  As lovely as this may be, you have to be aware that it poses serious hazards for your vehicle.

Blocking your radiator

Grass seeds can block your vehicle’s radiator, leading to a rise in engine temperature.  If this happens it can cause serious overheating which could lead to damage to the rings, pistons or rod bearings, blowing a head gasket and even cracking the cylinder head.

It is quite a challenge to clean a blocked radiator and virtually impossible to do it out in the bush therefore you must have some form of seed screen handy if you travel off-road where there is grass.

However, you should only use it when you drive through long grass as it could increase your vehicle’s fuel consumption by almost 10%, especially for turbo-diesels that rely on cool intake air.

There are different types of seed screens on the market but the most popular seems to be a net which you can easily attach and detach from the front of your vehicle.  Get a net that is long enough to cover the radiator at the bottom as well and not only the front of the vehicle as most of the seeds are sucked up from below.

Remember to remove your seed screen when you are not driving in long grass.
Remember to remove your seed screen when you are not driving in long grass.

You may be concerned about a seed screen interfering with the airflow, but if the radiator is blocked with grass seeds, insects, grasshoppers, leaves etc the chances increase tenfold that your vehicle will overheat. Also, you will only attach the seed screen where grass is a problem.

Fire hazard

When driving through long, dry grass you have to be very aware of the danger of vehicle burn out. Grass may collect underneath the car around the exhaust pipe. In a short time it can catch fire and your vehicle can burn out.  This risk is higher with a petrol driven vehicle because exhaust temperatures are much higher than with diesel engines.

In places where the grass is long you should stop frequently to check for grass collecting near or on the exhaust. The exhaust will be extremely hot, so always have a thick glove in the car, similar to those used by welders.  Alternatively you can also make yourself a rake-like tool for removing grass from your undercarriage and take it along on your trip.

Whenever you stop make sure that you don’t stop over grass and always have a fire extinguisher in the vehicle.  If you travel with Tracks4Africa GPS Maps, be on the lookout for Grass Burn Out Risk warnings on the map.

Don't stop over long grass as the heat of your exhaust might ignite the dry grass.
Don’t stop over long grass as the heat of your exhaust might ignite the dry grass.


Regarding vehicle burnout; never install any additional electrical equipment to your vehicle without a proper fuse. Not only is it better for the protection of the apparatus, but it also ensures the safety of your car. Always verify the safety of any aftermarket work yourself by checking for any loose electric wiring underneath your vehicle. Sparks combined with a hot exhaust pipe and dry grass are like putting a match to a pile of, you guessed, grass!


5 thoughts on “The danger of long grass  ”

  1. You are missing a vital point. Long dry grass being broken up by the front bumper and then going over the top of the engine and coming to rest on the wiring loom of the gearbox right up under the transmission tunnel. Toyota Landcruiser 105 was within 30 seconds of major fire in central Kalahari when white smoke noticed in wing mirrors. Good fire extinguisher and squeezy bottle of water saved the day. DO check all round the gearbox, not just the exhaust!

  2. Braai tongs are also handy to pluck trapped grass out. Covering the area below the bumper is really important. Remember that if air cannot pass through the main grill area it must be sucked in from elsewhere!

  3. Any advice on the best brands and availability of grass seeds? I got one, but indeed the seeds are sucked in from beneath. Valid point you make here.

    1. Frank, it seems to me like the net screen (see the top photo in the blog) is the best option as you can make one yourself according to the size you want.

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