Intake manifold gasket leak

[Blzr6.2'83]

I read in my Haynes Diesel book that it is important to get a perfect seal on the intake manifold gaskets. What would happen if you got a leak? I know on a gas car it would affect the vacuum by letting more air in, but the throttle on a diesel is controlled by the injection pump right. The book said it would leak oil and that is a good reason to get a good seal, but it also said it could affect the vacuum. With my limited knowledge it does not seem like a vacuum leak would do much unless it was big enough to let in dirt or something. I am just a newb and want to know what would happen.
Oh, yeah, this is on an NA 6.2 because I know you could loose boost if you have a turbo.

[Tatraplan]

Vacuum is not affected at all, since these
engines have a separate vacuum pump.

A really big leak could result in dust etc
being sucked in through the leak, since the
air would bypass the air filter.

/Robert

[CleviteKid]

In general there is not much vacuum in the intake manifold of our diesels, but there is just enough to draw the blowby vapors from the crankcase through the crankcase depression regulator (CDR) valve and burn them in the engine.

The CDR is the thing about the size and shape of a tuna-fish can, with a hose or two hoses going to the intake manifold just under the aircleaner (on a non-turbo engine). A leaking intake manifold gasket with a BIG leak could reduce the vacuum at the CDR connections, and the crankcase ventilation would not be quite perfect. But no one would notice.

On the other hand, it is sometimes convenient to run your engine with the intake manifold completely off, if you want to check the high pressure injection pump and fuel injection lines for leaks, for instance. There is a set of screens made to keep "rocks and rats" from getting sucked in, but you can make your own from window screen and duct tape for a one-time test.

Dr. Lee :cool:

[Blzr6.2'83]

OK, that is what I thought.
Thanks