oil pump

[ampwhu]

whilst working out what I have and don't have, I thought i'd look at the oil pump prior to my engine build. Something isn't quite right here...…..

The gasket looks to go in only 1 way. I guess so the flow and return holes aren't blocked by the gasket.

oil pump 1.JPG (48.12 KiB) Viewed 277 times

If i offer the pump up to how the gasket sits, then there is a small cut out at the base of the pump (picture is upside down).

oil pump 2.JPG (67.7 KiB) Viewed 277 times

with the new oil pump held in position, there will be a small hole at the bottom where oil will just pour out. I cant see how the pump would fit any other way.

oil pump 3.JPG (45.43 KiB) Viewed 277 times

the old pump was held on by 4 bolts and the new pump only 2. but there is no small hole in the base where oil will run out.

oil pump 4 old.JPG (60.96 KiB) Viewed 277 times

what the hell am I missing here. im puzzled!

[philthehill]

The gasket only is there to seal between the oil IN and oil OUT passages.
Oil will get to the rear of the pump and that is why there is the gasket/pump rim cut out to allow any oil to drain back to the sump. There are no seals fitted to the oil pump so there will be oil loss from the pump body/pump lid.
The rear of the pump/pump housing is sealed by the rear engine plate gasket.
Your oil pump should have a small bleed hole in the block face of the pump. This provides lubricant to the rear of the camshaft and camshaft drive.
The five oil pumps I have all have the cut out in the pump body rim to allow oil to drain back to the sump. Your Hobourn-Eaton oil pump should have had the rim cut out. Why it did not I cannot say.

This is a good read - https://www.calverst.com/technical-info ... oil-pumps/ Note the comment about oil pump gaskets.

[ampwhu]

I think its wise to replace the pump when rebuilding. Do you?

good read that Phil. I think the pump depths are the same so the 2 long 1/4 unf bolts should be the right length.

[philthehill]

I replace the oil pump every time I rebuild an engine unless I know what the oil pump is like and its history.

The oil pump should be considered as the beating heart of the engine.