BLOG 2: 74 series restoration - Engine Inspection
When we bought the car we were originally told there were no engine problems apart from a possible compression issue, which would be the reason that the engine would not idle. Although after a small test we thought it may not be the case, we decided to still test the compression anyways.
We used our own compression gauge to test the cylinders, the first 3 had good compression after being tested, but when we came to the 4th one we soon discovered it had low compression and were unfortunately unlucky with the whole situation had we hoped that this was not the problem.
In order to fix the compression of the last cylinder we began stripping the engine to get to the pistons out of the cylinders. The two possible problems that we thought could be causing the compression issue would either be 1. the rings of the piston were damaged, or 2. the actual cylinder for the piston is damaged. The difference between issues 1 and 2 are that piston rings were a cost effective and easy to fix problem, whereas with an issue regarding the piston cylinder, a full recondition of the engine would need to be performed and done by a professional which could set you back a couple thousand $.
We began by removing anything above the engine in order to disassemble it, we then took all the injectors out before removing the engine head. To get the pistons out without removing the whole engine, we drained the oil from the sump underneath the car and removed it. We manually turned the engine with a ratchet to push the pistons all the way down, this allowed us to go underneath the car, unbolt the bearing caps off the conrods and push the pistons up through the top.
We manually turned the engine, releasing each conrod and piston, and pushing them up until they were all out. Once done, we covered the top of the engine with a towel so no dust or dirt could get into the cylinders and onto the crankshaft etc.
After removing the pistons, it was a clear sign that on the 4th piston the rings were in fact broken, this is what caused uneven fuel compression throughout the engine and the reason for the original problem. We could also see in the piston cylinders that the last cylinder had a visual sign of how high the combustion explosion was going, with burnt carbon line being much lower than the other pistons chambers. Now that we knew this was the case, we sent the pistons, as well as the engine head into Engine Specialties to take a closer look.
Interestingly this vehicle has just over 300 000km on the clock, and closer inspection to the cylinder linings revealed that the original honing marks from the factory were still visible, and that there was no "ridge" formed by the rings. This makes you realise how some of these Toyota Land Cruisers manage to do 1 million kilometres without reconditioning the engines.