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Tandem pump cover swap - minor detail

Scholester

Well-known member
Joined
16 Jan 2012
Messages
1,357
I am still working on my car (work has been extremely busy) and part of my list of bits is a new Tandem Pump Cover.
The existing cover was in fact in pretty good order with only minor/moderate rusting but being swapped out it is for one of the excellent quality ACP covers (not over-cover).
The question is, when I removed my old cover, the blade and two end bearings slipped out with it. I get how it sits together and it may be a little tricky in ensuring that the new cover slips over the blade/bearings without them shifting (I was thinking elastic band until cover is partially on before sniping this away).
The actual question is whether there is any significance of the tiny little slot on one side of the blade as the other side is marked with a blue circle. Does this micro-slot engage with anything within the slotted pump shaft?
I will try and upload some photos which may help explain a whole lot better. Photos may follow as not uploading in this post.
 
Second time lucky?
 

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New cover
 

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Scholester
FYI - you might find that you have an issue following fitting of the ACP cover with getting any vacuum generated.

I purchased one of these covers and had it fitted at 9e - although the cover was well made, there was no vacuum following its fitment. Re-fitting the original cover solved the problem.

Apparently this is a common problem.

I gather it is more to do with the way the original vanes and covers have bedded together, rather than an issue with the replacement cover itself - if the new cover does not provide any vacuum the only options are to either refit the original cover or replace the entire pump.
 
symoonbeam said:
Scholester
FYI - you might find that you have an issue following fitting of the ACP cover with getting any vacuum generated.

I purchased one of these covers and had it fitted at 9e - although the cover was well made, there was no vacuum following its fitment. Re-fitting the original cover solved the problem.

Apparently this is a common problem.

I gather it is more to do with the way the original vanes and covers have bedded together, rather than an issue with the replacement cover itself - if the new cover does not provide any vacuum the only options are to either refit the original cover or replace the entire pump.
Thanks for this Sy.

Not being a particularly technical bod', how will this manifest itself in what I will notice/ what will not happen, that should happen!? Excuse my ignorance but I have never taken the trouble to understand what the pump actually does!

Any more contributors on the specific orientation of the blade itself with blue circle v small slotted grove?
 
The tandem pump provides vacuum pressure to assist the brake and (I think) clutch circuits so you will find that you have a very hard brake pedal and that it doesn't actually apply the brakes to any degree!!
 
symoonbeam said:
The tandem pump provides vacuum pressure to assist the brake and (I think) clutch circuits so you will find that you have a very hard brake pedal and that it doesn't actually apply the brakes to any degree!!
Quite important to get this right then!

Any views on the small slot on one side of the blade that holds the two outer bearings?
 
Im the first to admit ive never removed a cover from one of these .. ive always just changed the unit ..

Are you sure that part in the cover doesnt fit in the pump side as there are no locations for it in the cover and it REALLY looks to me like its part of the pump ..

Picture of the pump side if posible please .
 
Demort said:
Im the first to admit ive never removed a cover from one of these .. ive always just changed the unit ..

Are you sure that part in the cover doesnt fit in the pump side as there are no locations for it in the cover and it REALLY looks to me like its part of the pump ..

Picture of the pump side if posible please .
 

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Yes Demort, locates on the pump side then the cover slips over. Will be fun keeping the three items together whist pushing the cover in place but a rubber band may help initially before fully pushing the cover home.
 
Excellent .. thanks for that as ive never seen the inside of one before .

Probably teaching you to suck eggs here as you are doing what i havent but if you turn the engine over by hand would the pump bars end up sideways and stay in place a little easier to get the cover on :dont know:

I promise that the next time i change one ill strip it and see how it all works .. ill know what im talking about then :)
 
Demort said:
Excellent .. thanks for that as ive never seen the inside of one before .

Probably teaching you to suck eggs here as you are doing what i havent but if you turn the engine over by hand would the pump bars end up sideways and stay in place a little easier to get the cover on :dont know:

I promise that the next time i change one ill strip it and see how it all works .. ill know what im talking about then :)
Thanks again Demort.

I am good friends with The Finn on here and he changed his cover with little problem and did not experience any of the issues that Sy has raised with not getting a vacumm.

The fitting itself is not the problem, it was really whether the oriapentation of the little slot on the blade made any difference but I think it's down to me to experiment further.

:thumb:
 
Sorry for the ignorant question but is this tandem pump cover an issue for 997.1 as well as 997.2 ?

Also, the ACP cover seems a little pricey at £175?
 

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