Low compression on a 4.0 A27 motor
#1
Low compression on a 4.0 A27 motor
I did a compression check on my 2003 A27 motor. The car had sat for over a year in a wet garage. The engine ran well and the plugs appeared normal. I did a compression check, six of the cylinders were at 175# the other two were 125# The compression came up after I put oil in the cylinder. Could I have some stuck rings? Is there any way to free them up or am I looking at an overhaul?
#5
I would suggest you run the engine and perform a compression test at or near operating temp since this is when the engine is normally operating!!
A cold engine test may be useful as an indication of failed components but is not accurate as far as a good running engine is concerned. Parts expand with heat and an engine is supposed to be most efficient at operating temp.
The rings might be sticky but may free up after a good run???
bob gauff
A cold engine test may be useful as an indication of failed components but is not accurate as far as a good running engine is concerned. Parts expand with heat and an engine is supposed to be most efficient at operating temp.
The rings might be sticky but may free up after a good run???
bob gauff
#6
What's the chances that all our V8s would have one or two cylinders down if we checked them?
If it runs OK then I agree with Bob - just use it.
My Wife's MR2 1ZZ was run for 3 or 4000 miles with the oil control rings glued solid into the pistons (common fault with these engines). It didn't do any harm or affect performance and the only reason I eventually swapped the engine out was I got tired of buying oil every couple of weeks.
If it runs OK then I agree with Bob - just use it.
My Wife's MR2 1ZZ was run for 3 or 4000 miles with the oil control rings glued solid into the pistons (common fault with these engines). It didn't do any harm or affect performance and the only reason I eventually swapped the engine out was I got tired of buying oil every couple of weeks.
#7
It's possible that several valves have deposits on them from sittiing in that moist environment undisturbed for a period of time. The fuel may have also started to spoil. I am with Bob; run the engine a bit to get everything functioning normally again, and recheck the compression. Even if it still shows several low holes, I would consider just driving it before shelling out a small fortune to correct it. Even if you do decide to eventually correct it, at least you will get some time to save your money up!
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