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Help with vaccuum leaks on rover v8

To: buick-rover-v8@autox.team.net
Subject: Help with vaccuum leaks on rover v8
From: "Stuart Goggin" <SGOGGIN@au.oracle.com>
Date: 08 Jul 99 15:11:12 +1000
Hello All.


Sorry if this is a little off topic for this list, I really just want some
feedback from some rover v8 experts...

Looks like I have to replace the inlet manifold gasket on my 84 RR.   I am
getting some severe flat spots about mid throttle when the engine is cold. 
I can fix the problem by warming the engine up and then switching it off for
ten minutes.   As the manifold warms up the flat spots dissappear.  But it
only takes a few minutes of driving for the problem to reappear as the
manifold cools. The RR has a 3.5 v8 with twin strombergs,  I have checked
the carby diaphrams and they looked OK.

I took it to a local RR specialist who diagnosed an inlet manifold leak and
an electronic ignition module failure.    Apparently they took it for a test
drive and then swapped ignition modules, the problem  disappeared.   So they
concluded that the electronic ignition was faulty.   They wanted $300 AUD
for  an used ignition module.    Did some ringing around and found that
Rangie Spares in Melbourne had the modules NEW for $75.  Ordered it and it
arrived the next day.   Took all of ten minutes to fit and find out the
problem did not change.   Finally realised that the heat soak from their
first test drive had fixed the problem temporarily, and that switching the
modules did not.   Luckily I did not spend the $300 they wanted on their
second hand module.....  

So now I am going to look at the inlet manifold leaks.  I find it a little
hard to believe that a small vacuum leak can cause such major performance
problems.   Every car I have owned previously would run OK with leaks large
enough to hear the hiss.  So is it really possible that what must be a
fairly small leak can cause big flat spots?

I have also noticed that the PO has removed the third crankcase input
breather filter, and replaced it with a screw.  This means that the crancase
is always running with a high vacuum.  I guess this might have sucked the
inlet manifold gasket in and caused an air leak...

I will be replacing the gasket myself,  mainly because I want to learn how
to do it,  but also because I can't afford to spend the $250 they want for 
replacing
the $20 gasket.

Any comments/hints/flames welcome....
Regards 
Stuart

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