ACCUBILT ONLINE

Accubilt is a full service Automotive Machine Shop that specializes in aluminum cylinder head repair, driveshaft repair, and fabrication.

Aluminum cylinder heads and aluminum components were introduced by the manufactures to reduce vehicle weight and increase fuel economy. This change in materials has been very effective, but has had its down side for the consumer. Aluminum cylinder heads have problems with warping, cracking erosion, and annealing which is the softening of the aluminum. Some of these problems come from stress and the stress comes from thermo cycling for starters (heating up and cooling down). Just think how many times you start your car it warms up and then you shut it off and it cools down, each time your engine does this it acquires a little bit more stress. Another reason for the stress is the difference between the aluminum cylinders head and the cast iron cylinder block. The two different materials expand and contract at two different rates. This is known as thermal coefficient discrepancy.

The most common problem with aluminum cylinder heads is warping, which usually result in a head failure. The head warps away from the engine block because it is easier to stretch the head bolts than push the block down. Before reassembly check, your head bolts for stretch by measuring and looking for “necking down” or narrowing of the bolt diameter in localized spots. If your engine has “Torque to yield”, bolts (TTY) they need to be replaced. Accubilt has head gasket sets available with bolts included. Victor Rienz, Felpro, and Detroit Gasket.

In some cases, the failure of the head gasket will result in casting damage. The leaking combustion gases can cut the head removing material, or as the gasket fails and the composite core burns away the remaining, steel (“fire ring”) will flutter or vibrate between the head and block and etch the cylinder head in the area where the new gasket must seal.

Accubilt can repair these types of problems by welding and resurfacing the mating surface. This is a great way to save an expensive casting with great confidence and durability.

The real problem with warping is that the cylinder head warps on the top as well as the bottom. If you go to you local shop and just resurface the bottom, the top is still warped. If your engine has an overhead camshaft (OHC) then the camshaft bearing bores are still out of alignment. If you try to reassemble the engine and the cam bores are not aligned than, it will most likely have a failure.

If you have experienced a camshaft bore problem, Accubilt has the ability to salvage your cam bearing bores by align boring them by bringing it back to specification by reconstruction or the installation of bearing inserts or cylindrical bearings.

You say you don’t have an OHC engine but an overhead valve (OHV) engine you still have a chance for problems. Resurfacing a badly warped heads takes more material off the ends than the center. Making the Combustion Chamber Volume (CCV) smaller in the end cylinders this really increase’s cylinder pressure on these cylinders and promotes Detonation (Spark Knock), unexplained check engine lights, and overall efficiency. Sometimes a cylinder heads will warp to the extent that once it is resurfaced it is to thin per manufactures specification, and will effect camshaft timing on OHC engines.

Did I mention what the warpage does to the alignment of the valve guides and valve seats? This is crucial to the sealing of the valves and if they are allowed to run and leak compression then a “burnt” valve is most likely to happen.

There is only one way to repair these problems, and that is to remove the stress and let the cylinder head relax bringing it back to its original position. After this is done, and the cylinder head casting is done, and the cylinder head casting is straight, you can feel confident that a quality and durable repair can be done. Just Relax.

I mentioned resurfacing before, resurfacing is the renewing of the cylinder head-mating surface, and has become a more precise operation than that of the past. New technology has produced gaskets that require very smooth surface finishes. The measurement of these finishes is done with a prolifemeter and measures the RA (average roughness). Glass is the standard for smoothness and is considered zero. Some newer engines have recommended surface finishes of 9 to 13 RA. If the surface finish is to rough, it will reduce the performance of the gasket by ripping it every time it gets warm and expands.
Obtaining these low RA finishes is only possible with the correct equipment and the experience. Erosion as was mentioned earlier is the eating away of the aluminum around the water passages. This is caused by an electrical phenomenon that has positive and negative charges attaching your cooling System. It also attacks any aluminum part that has contact with coolant.

The damage it does can sometimes not be fixed with a gasket and sealer. We repair these types of problem regularly, by welding and putting new material in the needed areas.

Changing your engines coolant bi-annually will do wonders for keeping your cooling system in great shape. Don’t believe the claims about permanent antifreeze. THERE IS NO SUCH THING!

Cracks are another problem with aluminum cylinder heads some are symptoms of the stress, others are from localized heating and cooling. Regardless of the cause, we repair cracked castings. We use a controlled welding process along with a lot of skill and experience to ensure a quality repair.

Check out some of our repairs When looking for water related problems or structural crack we use different forms of detection. During the process of repairing a problem, the casting is checked numerous times to verify the location of the problem, to the quality of the repair after welding, and after the finished work is completed.

Many times repairs include the removal and replacement of valve guides and seats. This operation is a critical one and can be a potential problem if not completed correctly. The mating of non-similar materials brings thermal coefficients into consideration. Valve guides and valve seats come in different materials and alloys. Therefore, we use what is best suited for your application.

Accubilt can salvage most castings by our welding process. DON’T BE SO SURE IT CAN NOT BE FIXED. We have done repairs on all makes, models, and years – BMW, Mercedes, Volvo, Volvo marine, Jaguar, Porsche, Lexis, Acura, Honda, Nissan, Mazda, Volkswagen, Subaru, Audi, Hyundai, Chrysler, GM, Ford, Ford Motorsports, Mitsubishi, Duetz, Harley Davidson, GM Performance, Brodix, Dart, Honda M/C, Suzuki, and Kawasaki.

We not only repair cylinder head castings, we repair cylinder blocks, intake manifolds, water manifolds, transmission cases and modification to any aluminum housing. We have even done aircraft component repairs.

IF IT’S ALUMINUM, WE CAN HELP!

Do you have a sparkplug hole that’s been repaired before, but didn’t stay? Accubilt has many ways to salvage that sparkplug hole and head.

Have a piece broken off a head or any aluminum casting? We can help.

Have a broken bolt that after trying to remove it is worse now than when you started? We can help.

Accubilt has a group of experienced, talented, and quality mined ASE machinist that do the repairs. Quality is the number one concern with all our work. We have a one year unlimited mileage warranty on our reconditioned cylinder heads.

If you have a problem that you are in need of help or need some technical information in reference to aluminum casting of aluminum cylinder head repairs, please contact us at accubilt@accubiltonline.com. Or you can call us at 410-548-5700.

WE ALSO DO SUBLET WORK FOR OTHER MACHINE SHOPS.