Usually utilized to check for cracks in the cylinder head and block. In the event that the vehicle has overheated, or you have purchased a part and you are unaware of the history, it is advised that you pressure test the head/block. Often confused with a compression test. Compression tests check for compression in the valves. Usually heads that require pressure test should also be skimmed.
Otherwise known as a service. The head (also known as a “top”) is stripped, cleaned and serviced. We skim the head (unless otherwise asked) and replace the valve stem seals. Apart from the valve stem seals, the complete head is meant to service the existing parts and not replace them. Unless there are evident spares that need replacing (e.g. visibly bent valves) the quotation for the complete head will not include the replacement of parts (e.g. valves and guides). Assessing the damage on a cylinder head is difficult without stripping the parts, and it is therefore common that initial quotations on the complete head will include additional costs. A compression test is performed to ensure that the valves are seated properly and that there is compression. In the event that your head has shims, then the service will include setting the shims.Compression tests check for compression in the valves. Usually heads that require pressure test should also be skimmed.
These processes apply to the engine block. Rebore is when the block is bored to the next available size. Resleeving the block is used sleeve the block to the original size. In the case of reboring, the customer will have to purchase new oversized pistons to match the oversized bore. When a customer elects to Resleeve the block, the customer can use the existing pistons, provided that they are fit for use. Customers may also elect to resleeve specific bores (e.g. one or two) but are advised to let us check that the rest of your bores are not worn/damaged.Compression tests check for compression in the valves. Usually heads that require pressure test should also be skimmed.
Due to many reasons, the crank journals (big ends and mains) experience wear from friction with the big end and main bearings. In this case the journal becomes worn and no longer maintains the same size. As with the pistons all journals must measure the same the size (i.e. the big ends must all match, and the mains must all match), and so even in the event that one journal is worn, the rest of the journals must be cut to the next available size. The size depends on the available bearings for the engine.
The process of build up is different to welding and is used on parts such as the crank. Build-up therefore takes a bit longer than welding and can take anywhere between 1 -2 weeks per journal/thrust build up. Build up is required either either to the journals (Mains or Big Ends) or the Thrust. In the case of the journal, build up is required when a journal has run, and has been reduced beyond any oversized bearings. Undersized bearings are only produced to specific sizes and should the bearing run beyond this size, you will be required to build it up by adding material to the journal. Building up a journal can also be used in the case that you do not wish to cut your crank and wish to maintain the size of the other journals. E.g. if one Big end has run, and will be cut to 30 thousand, then the rest of the big ends will need to be cut to the same size (all bearings must have the same size). In this case one can build up the journal and either cut to the Standard size or 10 thousand. The thrust is located on the crank and in the case that it has been worn over time, build up will be required to fill the thrust with material.
The “sizes” generally refer to the pistons, rings and bearings. Most of the parts are measured on the metric scale which means they are measured in inches and thousands. This is strange for South Africans as we are used to the imperial system that used mm and meters. Certain parts do use different measurements in the imperial system (some French and Italian makes) but majority use the metric system. When you purchase a new car, your pistons and bearings are all “Standard Size”. The exact size varies from product to product, but essentially standard size means as you received the parts from when they were manufactured. If your block needs reboring and crank needs cutting, this basically means that you will be grinding the part to allow for bigger pistons/smaller bearings to fit in place of the standard part that you are now replacing. The size that blocks and cranks are ground, depends on the available part sizes. The part sizes for bearings vary from 10th, 20th, 30th, 40th, 60th. Pistons and rings rang from 20th, 40th, 60th. The availability of the sizes depends on each part. For example if you own a 3Y Toyota engine, you will be able to find bearings and pistons up to 60th, but most engine parts do not cater past 40th. The thrust is located on the crank and in the case that it has been worn over time, build up will be required to fill the thrust with material.
The short sub involves completing engineering to the engine block, crank and conrods and supplying the new parts (e.g. bearings, pistons, rings, thrust-washers). After that we build the short sub (which is the crank, block and conrods).
A long sub includes the short sub, with the addition of the rest of the engine parts to provide you with a full engine. This way we engineer the other parts as well (e.g. cylinder head) and provide new parts (e.g. gaskets, oil pumps etc.) to provide you with an overhauled head.
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