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Old 01-31-2022, 09:42 AM
v8volvo v8volvo is offline
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Join Date: Jun 2009
Location: Montana, USA
Vehicle: '86 745, '83 764
Posts: 1,622
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Quote:
Originally Posted by Torbik View Post
When I use the old tappet (longer) with the new pump, I can't turn the engine over as the tappet in the pump will bottom out and it doesn't have anywhere to go.
So the new pump cant be used with the longer tappet.


Smart thinking on checking this rotating the engine by hand before trying to start it and destroying something!

Seems like this is a new issue we have never heard of before on here. I have had some situations where for whatever reason the vacuum pump pushrod length was too *short* for the pump (in other words it opened up a clearance with the cam, resulting in a tapping noise). I attributed that to a weak piston return spring in the pump though I could have been wrong, but a different pump solved my problem in that case. However I have never heard of this issue where the dimensions are too long and cause the cam to want to lock up.

This style of vacuum pump was used on many engines other than the D24 family (Audi 5cyl gas and diesel, TDI, etc) so maybe some of those other engines used different measurements and now the parts manufacturers are trying to consolidate all the applications into one part that is a poor fit for all of them? Seems to happen with older vehicles like ours sometimes unfortunately.

Can something be done with the pump itself to change the free protrusion of the pushrod?
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
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