Now that we have left summer and are accelerating towards winter at a vast rate of knots you may wonder why your Yanmar TNV engine fitted to your Takeuchi, Thwaites, Volvo, Wacker Neuson or the vast myriad of other OEM’s that fit it won’t start, especially when it’s been fine up until recently.

It may puzzle you but the answer is air temperature…………not the cause of your Yanmar TNV not starting but the reason behind it.

The Yanmar TNV engine is a really reliable, well built piece of equipment but it has one drawback. It likes the air that is sucked in to be as pure and clean as an 18 year old Exeter virgin (good luck finding one of those). If you don’t change your air cleaner regularly (I don’t mean removing it and banging it on the side of your digger to remove the big lumps) with a nice new clean one or have a hole in the intake system hose it draws dirty air in. All those lovely particles of minute dirt enter the combustion chamber on your Yanmar TNV engine and turn into a wonderful grinding paste which then wear the bores on the block rather than the hardened piston rings. You then lose compression as the piston ring gap becomes too big and all that lovely ‘bang’ you get from compression fizzes out like a marriage when you come home and find your partner in bed with the next door neighbour. Worse than that  your engine won’t start!!!

Now here’s where the temperature bit comes in. The drop in ambient air temperature means that the air being sucked in is that little bit colder, the Yanmar TNV glow plugs that are fitted to the machine heat this air up to aid initial combustion but because it’s colder it doesn’t get hot enough and coupled with the drop in compression caused by the worn bores it won’t start. You can turn it over and over and your Yanmar TNV just won’t have it and fire.

If that happens to your Yanmar engine, let’s say a Yanmar 3TNV88-XWA2 fitted to a 3 tonne Thwaites dumper, don’t let the driver over crank it and burn the starter motor out or, worse than that, use too much Easy Start so a con-rod comes out through the side of the engine. Simply follow the following steps following all relevant safety procedures.

  1. Remove each Yanmar glow plug and attach it to a battery and make sure it glows, if they all glow up nicely it’s not a glow plug issue.
  2. Remove an injector pipe, then the injector from your Yanmar engine. Re-attach it to the pipe so the injector is outside of the engine and turn the engine over. If you have a good spray pattern refit and try the other two. If they all spray nicely you haven’t got an injector fault.
  3. If its not a glow plug or injector issue the chances are your Yanmar 3TNV88-XWA2 is down on compression and will require a complete overhaul.

As the largest Yanmar TNV engine supplier in the UK even we can’t cost-effectively re-condition the smaller Yanmar TNV engines, in fact anything below the Yanmar 4TNV88 has gone down the path of your telly inasmuch as when if goes wrong you put it in the bin and nip down to Curry’s and buy a new one. However if you need a new Yanmar TNV engine don’t ring Curry’s as they don’t do them, ring PES who have the largest stock of new Yanmar TNV engines for sale in the UK and normally have a cost-effective solution to make your problem go away in the shortest possible time frame therefore keeping your machines working and earning money.