M88/3 vacuum issue - help!
Discussion
I'm stumped.
Quick background - I bought an M88 from an M635CSi to fit into my race car that was previously running an M30. The engine is physically in, and it will run, but there's a pretty major issue in that if you run the engine with all the breather pipes connected, it'll turn over a bit then die.
If you pull the rocker cover -> plenum breather pipe off, it'll run fine. But, if you put your finger over the plenum outlet, it'll suck your finger in pretty hard (and then stall when it blocks) and if you block the rocker cover outlet it pretty much instantly will start forcing bubbles of oil out the rocker cover gasket.
If you go a bit further back through the hoses to the air valve under the TBs, the air valve seems to work fine but disconnecting the hose that goes into the flange under the cold start injector gives the same behaviour as above.
So, generally there seems to be too much vacuum in the engine.
I've got a couple of known issues to sort out, in that there's no exhaust connected from behind the manifold and the header tank is mounted too low.
So, does anyone have any idea why there's this surplus of vacuum?
Help!
PS - an indoor, un-silenced M88 sounds ridiculous, if a little painful.
Quick background - I bought an M88 from an M635CSi to fit into my race car that was previously running an M30. The engine is physically in, and it will run, but there's a pretty major issue in that if you run the engine with all the breather pipes connected, it'll turn over a bit then die.
If you pull the rocker cover -> plenum breather pipe off, it'll run fine. But, if you put your finger over the plenum outlet, it'll suck your finger in pretty hard (and then stall when it blocks) and if you block the rocker cover outlet it pretty much instantly will start forcing bubbles of oil out the rocker cover gasket.
If you go a bit further back through the hoses to the air valve under the TBs, the air valve seems to work fine but disconnecting the hose that goes into the flange under the cold start injector gives the same behaviour as above.
So, generally there seems to be too much vacuum in the engine.
I've got a couple of known issues to sort out, in that there's no exhaust connected from behind the manifold and the header tank is mounted too low.
So, does anyone have any idea why there's this surplus of vacuum?
Help!
PS - an indoor, un-silenced M88 sounds ridiculous, if a little painful.
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