Timing Belt & Cyclinder #4
Posted in Ignition Systems | Asked on May 24, 2010
My timing belt broke and I do not have an interfering engine. I took it in to get fixed, along with water pump, motor mounts, some other belt, not to mention a few months ago I replaced my ignition coils, spark plugs and wires, and cam sensor. Now the mechanic is telling me that Cyclinder #4 has low compression (70) and the other three are normal at (180), they said the car will have misfire which im not sure what the means but he said ill see when i drive it. The car is 6 years old and I have had it all 6 years and keep up with it as much as I can. Now he is saying I need a complete head job, to replace the head gasket in order to fix the cyclinder with low compression and that the head gasket parts alone are 329.00. not incl labor. I honestly do not feel I need that done, the vehicle has over 150+ miles of course its going to loose HP. I just dont know what to think. No where does it say that a broken timing belt will lower compression on a cyclinder. Can you help me understand this whole low compression cyclinder thing?
There are 3 Answers for "Timing Belt & Cyclinder #4"
It would be very helpful if you included the YEAR, MAKE, MODEL, and COUNTRY OF ORIGIN. Many modern cars can run for more than 150,000 miles. I have a neighbor with a Saturn that has 250,000 miles. Euro and Asian cars usually last much longer than would be expected compared to US cars. You might try re-torquing the head before replacing the head gasket. This may restore compression. Do it with engine fully warmed and use the torque sequence listed in a Haynes manual. Aluminum heads may warp when they are over-heated and cause a space to form around the gasket, creating a compression loss. TO replace a head gasket correctly involves removing the head, having it professionally cleaned and heated and un-warped, and milled back to straight edge. Then, install new head gasket and use torque sequence. Good Luck!!
I highly suggest you take your car to a different mechanic for a second opinion. Low compression on 1 or more cylinders at only 6 years old is pretty rare.
Yes, you do need cylinder head job. You have bent valve. Bent valve will lower compression, because valves must be seated correctly.
Lower than specific compression can cause misfiring condition.
A misfire condition is similar to extremely rough idle and it can cause major loss of fuel economy and no power.
Anyway, the purpose of a timing belt is to provide a quiet, flexible connection between the camshaft and crankshaft to keep the valves opening and closing in phase with the movement of the pistons.
Timing belts are used in two types of engines designated “interference” and “non-interference”. If the timing belt breaks on a non-interference design, there is enough clearance between the pistons and valves to prevent damaging contact. An interference design does not have sufficient clearance between those parts and engine damage would result from a broken timing belt.