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Toyota 1hz piston failure

Posted by Ashley Wilson on

This poor customer is about to rebuild his engine for the 3rd time
The 1st time he never checked the installed piston heights. The engine ran 1/2 hrs before it started missing.
The valves were hitting the pistons, and had bent all the valves.
All the pistons were damaged with indents of the valves on the top of the pistons and 1 also had abroken ring land. All the valves were bent and guides cracked or broken.

The 2nd time the engine ran for 10 minutes before it started to seize.
On inspection of his engine the customer has put 4 out of the 6 top rings in upside down. As they are tapered rings they will only fit I way. (One side or the ring is flat and the other side tapered as per attached pictures)
He advised me 2 pistons went in really easy, and the other 4 were pretty hard to get in, this should have of been a concern.
But I suppose anything can be installed with the right hammer
Another indication would have been tensioning up the piston spring compressor the extra resistance as they would not have of been compressing correctly.

http://parts.noordeman.com.au/collections/tools-misc/products/trg5126-4-ring-compressor

When rings are fitted to pistons correctly they normally fall into the groove as per attached pictures.

We have offered to rebuild his engine with trained engine rebuilding tradesman at a reduced price to assist. But have helped him all the way with the price.
We do feel sorry for you Rob if you’re reading this.

Image Below :You can see the rings have been installed the correct way . As the top ring is flush with the piston.

Below: The Top ring has been installed upside down and has to been forced into the ring groove.

below you can see the top of the piston has started to seize.Also the unusual wear ring wear above the yellow line.Piston and rings have both started to seize in the cylinder bore


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