Help Needed With Compression Figures - V6!
I have recently noticed that the coolant temperature has been getting hotter than usual, when in traffic or in slow moving traffic. Obviously it is going to be higher than usual under these conditions, although with the temperature gauge reaching 110 degrees, and then even when clear of traffic it can take a good while to get back down to 90 degrees, and even then it isn't particularly stable!
So anyway, after eliminating fan, thermostat, radiator, low coolant, waterpump issues etc, I decided to do a compression test. I done a wet and dry test, and the results were as follows:
Cylinder Dry Wet
1 15.5 Bar 21+ Bar
2 14.1 Bar 21+ Bar
3 8.0 Bar 21+ Bar
4 14.2 Bar 21+ Bar
5 14.5 Bar 21+ Bar
6 14.1 Bar 20+ Bar
Obviously cylinder 3 is very low on dry test, but I noticed cranking the engine for an extra second made the pressure increase to 10 Bar, which is still obviously low.
With regards to the wet test, 21 Bar is the maximum my gauge reads up to, and the needle was hitting the stop, so it was obviously trying to read higher still! It was also noted that on the dry test, number 3 cylinder was emitting vapour from the spark plug hole!
I done the tests with all spark plugs out, all injectors and coils obviously disconnected, and on a warm engine. All wet tests were done with 10ml of oil directly applied down each plug hole.
I'm a little concerned to say the least about the low reading on number 3 cylinder, but such a massive increase between the dry and wet tests surely isn't good. Not jumping to conclusions, but is this likely to be a complete engine rebuild? I cannot understand this as the car drives spot on, doesn't smoke and there is no gunge in the header tank or round the oil cap either!
Any ideas anyone?
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