XO POWER ENGINE MACHINE SERVICES INCLUDE THE FOLLOWING

Complete engine overhaul

Fortunately or unfortunately, depending on how you look at it, most Japanese cars are so old and worn out by the time the engine needs a rebuild, the value of the car will not support the cost of a full rebuild. Most of the time we only get to do engine repairs rather than full rebuilds. However, from time to time we find an owner who loves their car and wants the engine to perform like new. We now offer nearly every machine operation necessary to restore an engine to like new condition in-house.
 

The advantage to rebuilding here rather than having a rebuilt motor shipped to us, is we have control of all aspects of quality. We can be sure top quality nitrided rings are used instead of plain cast iron. We can make sure surface finishes not only meet, but exceed manufacturers requirements. We can seal the engine in a way we know will work. We can spend as much time as necessary to get the clearances just like they were when the engine was new.

There are production engine manufacturers out there that do great work. Many are even better than us. Unfortunately, there are also some very bad engine builders out there, some of them with major OE remanufacturing contracts. With some makes, you can't even trust a high cost motor purchased from the dealer. When we do it ourselves, at least we know exactly what we are warranting.

Valve Seat grinding

The valve seats are steel inserts pressed into the aluminum head. The seat to valve contact angle is cut to 45 degrees. The width and contact position on the valve are usually adjusted with a 60 degree "throat" cutter and a 30 degree "top" cutter. Some cars use different angles; we always follow the manufacturer's original specs when grinding the seats. The attention given to getting the seat cut to match the manufacturer's specifications exactly will have a direct effect on how long the rebuild will last. We have the necessary experience and the commitment to quality to ensure your rebuilt head will perform the same as it did when it was new.

Crank Regrinds

The crankshaft undergoes high loading due to the fact it transforms the linear loading of the pistons into a usable rotational motion. In time it will wear. Rather than replace this relatively expensive forged item the surfaces can be reground.

Valve Grinding

We charge £2  to grind a valve. Most new valves cost between £15 and £35 each. On a 16 valve head, grinding instead of replacing could save you as much as £475. It still makes sense to grind whenever possible. Many valves found in newer cars are tiny, and don't have much of a margin. We only grind valves when the manufacturer says it's an acceptable procedure and we always thoroughly inspect the valve for wear before machining and maintain the manufacturers minimum margin specification.  We also have reducing collets and can machine valves with stems as thin as 4mm.

Cylinder head milling

Cylinder Boring

When the cylinder wall is worn beyond the manufacturer's tolerances, it must be bored oversize for use with oversized pistons. Boring must be followed by several honing steps in order create surface finish that will both hold oil for lubrication and provide good sealing. When available, we will follow the manufacturer's procedure for boring and honing. For instance, for the 5SFE motor, Toyota recommends boring to .0008" (just under .001") below the finished size. Then using a 400 grit rigid hone to finish the bore to size. However, frequently there is not a published procedure. When we don't have access to a procedure we bore to .002" under finished size, remove an additional .0015" with a 280 grit Sunnen Hone, then remove the final .0005" with a 400 grit Sunnen hone to create a plateau finish. We follow that with a nylon ultra finish soft hone in counter clockwise direction to remove folded or torn metal left by the honing process. After the boring and honing is complete, the cylinder walls get a serious scrub-down with hot soapy water.

Decking cylinder blocks

Occasionally, the cylinder block deck will need to be resurfaced. Deck warpage is more common on Subarus and other aluminum blocks with sleeve inserts, but can happen to any type of block. We can surface almost all blocks inline or V6 etc

Valve guide replacement

If the valve guide to valve stem clearance is excessive it causes two problems: one, the valve seat can not be cut concentric and two, the engine will consume more oil than necessary. The condition of the valve guides can not be known until cylinder head is out of the car and the guides are measured. This means when we find worn guides, we need to call you for additional authorization to replace the guides. Worn exhaust guides are more common than worn intake guides because the exhaust valves get much hotter than the intakes. To remove the guides, we heat the head to 200 degrees (F), then we drive the guides out with a driver powered by a pneumatic hammer. To install the guides, we reheat and chill the valve guides before driving them back in.

Penetrant Dye Crack Checking

The first step is to clean the cylinder head. Care must be taken to prevent covering cracks by wire brushing. Aluminum is a fairly soft metal and a vigorous brushing can actually cover cracks, making them undetectable with dye. Next a penetrating dye is sprayed on the area to be checked and allowed to soak in for 5 minutes or so. After soaking all of the dye is wiped off using shop towels. Once the head is cleaned, a developer is sprayed on. Cracks will show up as red lines. Just going though the motions of a penetrant dye test does not guarantee you'll find a crack. The key to success is very careful inspection. The dye is just a tool that makes finding cracks a little easier. The real way cracks are found is through the thoroughness and experience of the person doing the test, not the test itself.

Now that we own a cylinder head pressure tester, we almost always pressure test instead of dye checking. The pressure tester will locate cracks or porosity under valve seats that would be impossible to detect with dye.

The dye still comes in handy though. It's good for checking the plastic cam gears found on the 1996-1999 Subaru 2.5 DOHC EJ25, as well as other parts other than cylinder heads.

Cylinder Head Pressure Testing

Pressure testing is the best method of testing for cracks because cracks in areas that are not visible can still be found, areas like under the valve seat or half way down a head bolt hole. This is an Axe pressure tester we purchased used. It does not require a special plate set for each new head. It uses 20 universal deck plates and universal port block off plates in various sizes. It covers 95% percent of all heads and 100% of the heads we repair here at Art's. To check for cracks, we block all of the cooling system ports, then we pressurize the water jacket to 40 PSI (about 3 times normal cooling system pressure). We then submerge the head in heated water to bring the head up to its normal operating temperature, and to make leaks easier to spot by following the bubble trail.

Pressing bushings and bearings

Many bushings are available to repair control arms and other suspension components. Our customers can save a lot of money by repairing their suspension parts rather than replacing them.  Being able to perform this type of work in house means we can get cars in and out on the same day  We also press our own bearings and gears.

(TIG)

TIG welding is similar to oxy / acetylene welding in that the torch is held in one hand and the filler is added with the other. Heat can added without added without adding more filler. If you notice poor fusion in a section you've welded, you can just go back and re-melt the section. The amperage can be modulated with the foot control to compensate for heat build up in the work piece as you weld. Any filler material can be used without need to change spools or liners.