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Re: Open the cam cover and check the cams for movement Posted by CMyles [Email]  (#1126) [Profile/Gallery]
(more from CMyles) on Tue, 10 Apr 2007 09:54:03
In Reply to: Re: Open the cam cover and check the cams for movement, Travis, Tue, 10 Apr 2007 08:56:45 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Travis,
You have the spark plugs out, right? Take a good look at your clutch cover and ancillaries but most likely this is valve-piston interference. This would occur if one or both cams were significantly out of time. In that event there may or may not be a bent valve. If the cam(s) timing shifted that much while the engine was running then there are almost certainly bent valves. The next thing to do is to remove the cams and see if the engine will turn. When you remove the cams you allow all the valves to close at once and stay closed so unless there is a bent valve, which will not close, you should be able to turn the engine. With the cams out if you still can't turn the engine then take a piece of heater hose that fits tight into the spark plug hole (3/8" I think) and try to blow into the combustion chamber. If you can easily blow air into a chamber then some valves are stuck open and that's because they're bent. On occasion I have taken good valves from trashed heads and used them to replace bent valves in a good head without any grinding, lapping (or even cleaning;-) and had total performance success. You couldn't do that with most engines and expect good performance but Saab engines aren't like most engines. If you end up doing that, after you install the good used valves set the head upside-down on the bench and do a "leak-down" test. Just fill each combustion chamber dome with mineral spirits and see if it leaks past the valves into the ports. Give it some time. If some valves leak then you may have to get a machinist involved or just find another head. One cause of cams getting out of time is that the cam sprocket is indexed to the cam by a single small "dog". That "dog" can actually shear off and allow the cam to ignore it's spinning sprocket. One way that I know of to cause that to happen (don't ask) is to roll the engine by putting a wrench on a camshaft. Never roll a B202 that way, always find some way to turn the crankshaft directly (turn the flywheel or the crank pulley bolt). So when you remove your cam sprockets see whether one of those "dogs" is sheared off. If so just get a good used sprocket and throw it on there (after you deal with any bent valves). Good luck.
posted by 206.123.221...
, Mon, 9 Apr 2007 23:18:06, Tue, 10 Apr 2007 09:54:03 <-- Viewing This Message, Tue, 10 Apr 2007 10:05:32
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