Brake booster pump drive noise, please help

Hi,

I’m taking the liberty to start a new thread since it was not really the timing chain or valves (as per my other thread) that made the noise.

I have a sharp rattling noise that comes from the brake booster attached to the right hand side cam shaft. It is only audible at around 1000rpm and not under or over. I have today listened to the engine with an engine-stethoscope and there is no noise from the chain or the valves. It is easily reproducible by revving the engine from idle to about 1000rpm. Once the revs climb over 1100rpm’s it fades away. Same thin below 900rpm’s. Weird.

We have also done a timing chain adjustment today, without any problems. It not the alternator/AC/steering pump belts either, because there is no noise in the stethoscope when listening down there.

It is a bit difficult to pin-point the exact noise source, but it seems to come from the vacuum pump drive side, ie not the pump but the coupling between the cam and the pump.

It sounds like valve clatter but having gone through all cylinders with the stethoscope I’m pretty certain that it is not the valves.

According the Ferrari work shop manual there is a short drive shaft between the cam shaft and the pump and it seem to be secured by a wedge or something like that.

The brakes work just fine so the pump seems to work as it should. The car is 1980 400i with 25k on the clock.

If anyone on this fantastic forum has input on this topic this would be much appreciated. I guess that I will have to take it apart, but having some insight would make life much easier.

Best regards and thank you

//RoB

 

You'll probably have to get the whole assy. as I don't see a detailed IPB of its inners, Eurospares 'supposedly' has them for $255. EU (I've discovered that just because they show "NEW to order $255. EU" doesn't mean that they have them in stock or able to get them).
I believe you're referring to part #2 in the IPB...
http://eurospares.co.uk/partTable.asp?M=1&Mo=652&A=1&B=37700&S=

& the part specific...
http://eurospares.co.uk/searchResult_one.asp?S=100493&TM=1&TMo=652&TA=1&TB=37700

I'd consider yourself lucky because the ones that are in the Boxers are around $3K, & if you're lucky, $1700.+ if you can get it at TRutlands (2011).
Certainly, it wouldn't hurt to yank the thing off & check its inners.

 

Could be wrong but try this.
The brake booster vacum pump has damper pads on the driving joint between the cam and pump (so you dont get rattling noises!!)

They cost aprox breathtaking £1.75 each and come from ferrari/eurospares you need 2 of them. Dont drop the driving joint into the timming case!!!!!!! or ££££££.

Regards
Alastair

 

I'm pretty sure Alistair is correct here - the early cars don't have this feature IIRC, but 400i models do, and what you describe is exactly the noise you get. Not only that but I have 'done' the same job myself and it takes about 30 mins!

Press on,

Howard.

 

Anybody got part #s for these silencing pads?

 

I, too, am very curious of part #'s as well as what part it is on the 1st link I provided from Eurospares (page 37).

 

Item 18 (116420), used on both ends of the "crossed" drive coupling, item 1, seems to have the right description ("Tassello in gomma" = Rubber block) and functional placement.

 

Brilliant!

Thank you. Good news. I was a bit worried that something worse was at play here...

When removing the pump to get to the drive shaft is there any particular way to do this to avoid things falling into the timing chain compartment or will it all come out as one unit?

-Anyone having pictures of the pump taken off?

I checked the part no's and all the parts I need are in stock. –And with very affordable prices as a change.
101025 gasket
116420 pads, 2 of them

All the best
//RoB

 

I don't have any specific recommendation for how best to do this operation, but the parts drawing shows that item 1 is not really attached to anything and is captured between item 16 and what's on the end of the pump when everything is in place -- so don't just pull the pump off quickly, rather, withdraw it just a small distance until you can see item 1 and either grab hold of item 1 or keep it pushed into item 16 so it doesn't fall down.

 

Yes, absolutely - just gently ease the pump forwards to see the drive coupling orientation, then if necessary turn the engine by hand to get the adaptor (with the rubber bits in) horizontal so it can't 'slide' out. It would be best to also have a magnet handy to catch the little b*gger if it makes a bid for freedom...

Good luck with a rewarding job - for a very small investment, normal service will be returned.

Howard.

 

Hi.

Thank you very much.

That seems pretty straight forward. I will order parts today and have a go next week. I will revert here with the results and possible some pictures for the benefit of the next Ferraristi facing the same challenge.

Best regards
//RoB

 

Hello Rob
All good the gents are spot on with the description. Let us know how you get on.
The forum is great for these things.
Regards
Alastair