Question Ted... having a tough time here. Had an electrical problem with my daily driver Audi, so I picked up an old 97 Celica ST with the 7AFE. This seemed like a great idea as I have a long commute, and am very strapped financially at the moment. After purchasing, I drove for only 90 miles and the vehicle lost all power. It was running perfectly to this point. Upon cranking the engine, I heard what I knew was a broken timing belt. In an attempt to save money, I had it towed to a friend of a friend who was to replace belt/H20 pump and seals for about $500. Tonight I am told that it will not start after the repair. He rechecked to ensure he was not 180 degrees off, verified spark, etc. He stated that after all the basics he checked and that the engine has bad compression and that he is going to need to get me an estimate on a head gasket replacement. While I'm no tech, I know a little. I cannot imagine any reason whatsoever that a timing belt breaking would cause a head gasket to fail, nor low compression. I was on the highway at high cruising speed and it was running fantastic. Naturally, I think he has made an error in the timing marks. If the timing is set to the wrong marks, can that cause a situation that would allow compression to read low? Any information you can give me would be greatly appreciated. I am more than happy to donate for your knowledge. Thank you for your time and effort. Respectfully, Jeff
Answer Hello, the 7AF-E engine is a 'non interference' engine which means that even if the timing belt breaks there can not be any contact with the pistons and valves, so, no it does not have an effect on compression, did you ask if the timing belt was broken when you took it in? If the belt broke and the car ran normally before then replacing the belt should fix the problem, I doubt very much that it's a head gasket issue, the low compression is probably caused by the timing belt being installed incorrectly.
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Toyota technician since 1979,expert in electrical systems,OBD systems,engine repair, driveability problems,EFI systems,ASE certified,Toyota master technician. Certified Hybrid Vehicle technician.
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Toyota technical training:
Brakes and chassis
Engine performance and diagnostics