4D56 engine reliability: strengths, watch-outs, and known issues

This diesel unit is afraid of overheating and the cylinder head gasket blows regularly. But replacing the gasket is not enough; you have to grind the mating surfaces. After a couple of blowouts, cracks are often found near the valves or prechambers.

Another serious problem of this engine is crankshaft breakage, and this often happens during prolonged driving at low engine speeds. In engines with Common Rail, the crankshaft journals are thicker and breakage is less common.

For obvious reasons, the fuel system causes the most trouble for owners of such diesels, both for swirl chamber and Common Rail versions. Listing all the problems is pointless; this is a topic for a separate and very large article.

The timing belt does not have a long service life and does not always last the prescribed 90,000 km, especially if it is not tensioned every 30,000 km. With a break, only the rockers break off, but in Common Rail versions, the mounting bolts of the camshaft bearing caps are often torn out. The balance shaft belt, when broken, usually gets under the timing belt and also breaks it.

Also, oil leaks are common here, almost all gaskets and seals sweat, the crankshaft pulley and vacuum pump have low service life, the EGR valve clogs, a lot of trouble is associated with air ingress, and at the slightest tuning the pistons crack. Also, do not forget to check the valve clearance every 20,000 km or they will simply burn out.