Tuesday, September 20, 2011

Engine compression and thermostat question?

My 98 Camry with 125,130 miles had a compression reading as follows: What do they mean? Should I keep the car? The specs is 178psi or more and the difference of 14psi or less per cylinder.



Cylinder: Dry Wet

1 220 220

2 220 220

3 215 220

4 210 215



I recently change the timing belt, accessories belts, and water pump without changing the thermostat. Would the thermostat create problems in the future? Thanks very much for your help.
Engine compression and thermostat question?
These numbers are very good. At this mileage, it would be good preventative maintenance to replace the coolant, the temperature sensor, and the radiator fan switch. Use only genuine Toyota parts and coolant. Do not use the typical %26quot;green%26quot; coolant, it will cause premature pump, gasket, and radiator failure. Also, if this were my car, I would do a de-sludging of the engine, and use only a good synthetic, like Mobil One. Good Luck!!!
Engine compression and thermostat question?
Babyface:

These are good readings. You state that 178 +/- 14 psi is the spec. The measured values are well above minimum and within the stated tolerance. Uniformity between cylinders is very important, which this engine shows.



With 125K miles, it shows good maintenance.



The meaning of these numbers is simply that the condition of the valves, pistons/rings and cylinder walls is (very) good. A special gauge can measure the 'pressure' produced in the 'compression stroke' of the engine.



You will know if the thermostat goes bad because the engine may not get up to temperature, or overheat, depending if it fails open or closed.



These are not expensive and easy to replace on a 4 cylinder camry. When you get some extra money, have it changed as a maintenance item.

Marc
Those compression readings are pretty even. if the spec says 178 (or whatever) the guy testing it probably did not open the throttle plate to allow more air into it. It sounds like you did NOT have it tested at the Toyota dealer!



For a 10 year old car, the compression readings are very close together so I would not worry about it.. A careful valve adjustment might get them even closer.



Dont worry about the thermostat, its an easy fix, and they dont go bad all that often.



Toyota engines last a very long time, 125,000 miles is NOT BAD!!
150 psi and up is excellent its a Toyota and thermostats are cheep your good to go.
I would say keep the car. The reading you have are dam good.Your oil lose past the rings is minimal.And with a new O2 censer and a new catalytic converter, should pas any I.M. test.
compression is good keep the car but do change the thermostat after and during a water pump change not cause the other is bad just for safety reasons it might just not be the right size for the pump and its like changing the front door on a old house you would want to change the locks just cause there old you get my drift
theese are normal readings, actually better than normal. dry readings is the psi in the cylinder normally as it is. wet reading is with a squirt of oil. this is done to see if the piston rings are good. ur engine is fine will last u 300K or more without a problem as long as u take care of it. wouldnt worry about the thermostat those are replace as needed. yes keep the car as long as the rest of its ok. the engine is fine.