Date: Fri, 28 Apr 2000 21:50:17 +0200
From: Robert Brown <>
Subject: Re: Cracked cylenderheads on 900 regular

Hi, comments embedded below: Morgan Bullard wrote: > 1. The top of the engine block may not be flat. > 2. Are you tighting the bolts according to the manual. (the correct torque and in the correct order) > 3. Is the car over heating due to something else such as a bad radiator? > 4. Are you sure it is the head leaking and not the block? > 5. If you are taking this to a mechnic to do this, get a new mechanic. If you are > doing this yourself, you may want to consider taking it to a mechanic. 6 heads > is _way_ too many. > > I didn't know any 900s came with carburetors. My (US spec) 900 T has a > Bosch CIS fuel injection system. Single carburettors were available on 900's from 1978 up to 1987 or 1988. Twin carbs available through 1983 if I recall correctly. I myself have a 1983 900 single carb (called 900GL; the twin was called 900GLS, don't know why - maybe "Super") Back to the original problem: There are other things worth checking out, as well as the 5 excellent suggestions above: 6. Radiator fan not coming on in time, or at all. Two possible causes: 1) thermostat switch (embedded in radiator if I remember rightly) may be worn out or broken. 2) electric radiator fan broken? Make an electrical short across the contacts of abovementioned thermostat switch with a screwdriver and see if the fan comes on. The fan should come on when the temperature needle rises about 15-20 degrees (geometrical degrees, not temperature) above the horizontal. If you're close to the red, something's wrong. 7. (unlikely, but:) Thermostatic valve in front of head (near distributor) may not be opening sufficiently. Idea is that coolant is prevented from reaching the radiator as long as the engine is cold. Once coolant reaches 89 C (or 83 C turbo - not sure of the figures, use them with care), thermostat opens and allows coolant to flow to radiator. Thermostat is cheap to replace. 8. (even more unlikely) are you using the right gasket between cylinder head and intake manifold? Could get all sorts of flow problems if it's the wrong one. Which one to use depends on the year model. 9. Is the radiator in good shape (developing Morgan's point 3 above)? Even if it doesn't leak, you may have problems with its ability to cool. Especially if it's clogged (flush it out from both directions). Another thing to watch out for is the matrix material (the zig-zag stuff between the horizontal pipes that carry coolant). If the material becomes sufficiently corroded, it will not dissipate heat sufficiently. In which case you'll get plenty of advance warning because your fan will come on more often than it should (or not, see point 6 above). Anyone have any more ideas? I agree, six heads sounds a bit extreme. Regards, Robert, Gothenburg 1983 900GL 1999 9-3 200 > > > 4108 <gunnarjNOguSPAMnopsamis.invalid> wrote in message > > Troble with cylenderheads on my SAAB 900 with singel > > carburetor engine, model 1985, 2000 > > The cylenderhead will crack on cylender 1, between valves > > and the coolant will leak in to the combustion chamber, > > making smokes and illgoing when warming up. This is the > > sixth time I have to put a new/used cylenderhead on my > > engine, and the last one was from a car hardly driven more > > than 100.000 km. I have driven about 13.000 km. when the > > leaking starts. The car is driven 225.000 km. I have a > > new radiator for three years and no external cooling > > leaking. > > Is perhaps something wrong about cooling system, fuel > > injection system or something else? > > > > Yours sincerly > > Gunnar J˙fffff3nsson > > > > > > * Sent from AltaVista Where you can also find related Web Pages, Images, Audios, Videos, > News, and Shopping. Smart is Beautiful

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