Author Topic: Advice on cylinder head - Phase1 GTV Twinspark - Material and Welding  (Read 2657 times)

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Hi all,

Does anyone know what type of aluminum alloy was used to cast these heads? And if it is possible to weld this material?

I have a cylinder head that has had the water pump impeller come loose from its shaft. It looks like it was still being driven and unfortunately has worn down the casting. This was discovered after finding water in the engine oil. I did a pressure test and could hear a leak near the top of cylinder 1. The head was removed and pressure tested again, where a very small hole was found, small but large enough to cause trouble.

The photos show where I have drilled a hole hoping I could plug it with a threaded insert, but thanks to the wearing the material is now approx 1.5mm thick. My luck for beliving the previous owner when he said the pump was changed with the timing belt... date code on the impeller says 98' so it turns out.

I think my only solution now is to find a talented tig welder to build up the surface from the impeller side to block the hold and restore the original wall thickness, what I am not sure is if this can be done successfully. I am sure there are welders that could do the job, but I know that welding cast alloy material has many challenges.

Any insight on this problem is greatly appreciated.


I hope others can learn from my mistake here, and change that pump regardless of how good the bearing feels or what you have been told. It appears that its replacement is recommended because of the life span of the impeller and not on the seal and bearing. I did try to find an alternative part that uses metal for the impeller instead but was not successful.

..Also, how do I post images in this forum?

Thanks again.


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Hi Sylvio
I would be speaking to a cylinder head reconditioning specialist in your area for what can be done. I am sure they would be able to carry out the proper repair (weld) back to original standard. With regard to loading photos on the forum, I have provided you the following link on “how to” (max of 4 photos per post after downsizing).
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Is there a reason to weld it rather than sourcing one from wreckers?


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Re: Advice on cylinder head - Phase1 GTV Twinspark - Material and Welding
« Reply #3 on: August 22, 2021, 09:37:03 PM »
Was looking for similar answer and yes, it can be welded. If you`re doing it by yourself - just need a welder like Hobart for proper material.
« Last Edit: August 22, 2021, 10:50:41 PM by RobRi »
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