Oil pump chatter???

[Dolomitejohn]

Hi all. Got a strange issue. My sprint engine has been prefessiinally rebuilt. It drives like a dream but it has one minor issue. I seem to be getting a rattkev/ chatter from the dizzy / fuel pump / oil pump area at abou 800 to 900 rpm when hot. The pump had a new impellor fitted but case and relief valve were not touched. Dizzy was recon by dizzy doc before the rebuild and the fuel pump is electric. I have noticed oil pressure above 60 psi at times ( def when cold). Is 40 psi when rattling. I assuming it's the pump, so any ideas why it might be doing this? Cheers all.

[Mad Mart]

Probably the oil pressure relief valve chattering away. You may need to replace the spring. There has been problems with new oil pumps having the incorrect spring fitted, causing excess oil pressure.

[xvivalve]

Similar thoughts to Mart: New impeller gives higher oil pressure, old pressure relief spring can't cope and breaks causing chatter as pressure subsides...?

From memory, you can access the split pin, spring and piston situ, but it's a bit of a faff...I did the spring on the Quicksprint whilst it was usefully sitting on my trailer that I used to be able to just shuffle under!

[Dolomitejohn]

Thanks gents. Yes starting to think the same. I think I will go for a new pump (robsport) with a new correct spring fitted. Was thinking my spring could be worn and maybe the valve plunger or sleeve could be worn also. Runs like a dream otherwise.

[xvivalve]

...and maybe the valve plunger or sleeve could be worn also.

Were that the case, I doubt you'd be seeing 60 psi...?

A new pump will be County brand...I'd investigate the spring first before settling for County!