About the two tests:

Compression test will tell you whether you have leak cylinder or head gasket or not.
The oil gallery pressure test will tell you if you have engine oil leak or not.
You should have the oil pressure test first. If there is a leak, then follwed by testing the frequency of the engine noise, you will tell whether it is camshaft or crankshaft problem or not.
You can mention the tests to the shop person. But they should know what to do. By the way, if your car is not under warranty, do not go to dealer.

所有跟帖： 

• my car is not under warranty(2nd owner) -IDM- ♀ (157 bytes) () 08/20/2007 postreply 11:21:21

• 回复：my car is not under warranty(2nd owner) -biglow- ♂ (783 bytes) () 08/20/2007 postreply 11:40:35

• we have changed time belt. it is strange that -IDM- ♀ (334 bytes) () 08/20/2007 postreply 11:59:09

• Did you notice the fuel efficiency lately? -biglow- ♂ (72 bytes) () 08/20/2007 postreply 12:14:22

• it seems no different. we drive mostly in local. -IDM- ♀ (0 bytes) () 08/20/2007 postreply 12:43:23