Cast Iron Welding – BMW engine block welding

JW Portable Welding & Repairs supports car owners in need of Cast Iron/Cast Aluminum welding for their vehicles. We utilize our own welding equipment and advanced techniques in order to provide the strongest possible weld.


As seen in the photo gallery above, we repaired a BMW cast iron engine block. The top portion of the water pump seat was broken off from the seat. The broken off piece contained 2 threaded holes and one hole for the locating pin. The owner of the BMW faced 2 choices: replacement of the entire engine, or unconventional welding of the cast iron engine block.

*JW Portable Welding & Repairs was chosen for this service due to our portable machinery, mobility, and technical expertise. *


TIG welding was chosen by our specialists to rebuild the top portion of the water pump seat due to increased weld control on cast iron. Our TIG guns are equipped with pyrex cups and amperage control devices, which benefits the welder by offering increased visibility along with its ability to adjust welding parameters during the welding process. Such adjustments are necessary for cast iron welds due to the accumulation of heat during the welding process to avoid irregular distribution of heat in the cast iron caused by irregular cast thickness and the “sinking effect.”


During the welding process, an additional crack appeared, which usually happens when a damaged thin iron cast is exposed to heat. The otherwise invisible cracks widen when the iron cast warms up. We seemingly repaired the new crack at a much higher temperature than the operating engine temperature. Additionally, we added supporting welds at the back of the piece using SMAW since the entire cast was very thin near the crack.


After the entire piece cooled down, we started the slow process of smoothing the seat of the pump. Major attention was concentrated on the area where the gasket is placed to ensure the area was as plain as possible. The warpage played a difficult role in smoothing the middle of the piece but our persistent grinding, polishing, hand filing, and stoning insured acceptable results for the proper seal of the water pump.

This project involved a multilayered rebuild that had to increase the shoulder of the seat by about 1 inch while maintaining the thickness of the shoulder at about 3/8”. Selecting the proper welding rod that leaves the machinable welds and is slightly playable is a key component in ensuring that the machinist would be able to drill and tap the holes after our welding.


As we look back on this repair, a few suggestions to mechanical shops come to mind. If you are planning to weld something on your car, please make sure that the piece is accessible from all angles at a sufficient distance. Welders do require more space to work on the piece than a mechanic would. A mechanic is able to modify their tooling to fit the congested space and can locate positions of many pieces just by touching it. Welders are not able to modify their equipment to reach the congested areas and more importantly, they need to see the weld from all angles. Complete visibility of the “sinking effect” is especially important when welding on iron cast and aluminum cast.

Our technological advantage, efficiency and effectiveness sets us apart in the industry.

For further inquiries or to book services please contact:

Darek, @ (519) 872-2552