2001 XKR Sudden Rough Idle and Tons of Codes (all on Bank 1)
#21
Is did see in this thread that the car ran only about 75K. (or was it 65K)
Reading this thread makes me hope that it is understood that a cilinder that gets fuel but does not combust, will get bore-washed, which impacts compression on that cilinder badly. (with throttle closed will give only ~60PSI)
Diagnosing piston/cilinder/valve damage just by "dry" compression test is not the way to go.
Just hoping engine has not yet been directed towards the scrapyard yet.
Off course, it may still (just) be a dropped valve seat due to tiny leakage that over time has been forming a large air bubble in the engine, not visible in coolant level:-(..
Heater hose described in this thread could have been leaking a bit for some while...
My experience with AJV8S is that the tine hose to the reservoir from the coolant manifold lets air in the cooling system when the engine cools down. (fixed 2 overheated yr 2000 XKR's and both showed this leak in vacuum test)
Normally the vacuum in the system (when cooling down) pulls coolant back in from the overflow tank. (That is why you should top up completely in cold state)
This pulling back in from overflow coolant tank does not happen when that tine hose next to temp sensor takes in air.
Somehow that connection is not leaking coolant when pressurized (by expansion of the plastic warm hose in the reces?)
I strongly believe that the problem I am describing is responsible for many overheating AJV8S engines. (So not by failing pumps and not by failing thermostats)
Driver wont get a low level warning, and we all know temp gauge is useless.
Al you get is (slightly) dropped valve seat(s). (Can also happen at engine shutdown, when really HOT and pump stops)
Mine was hammered back in (not straight..) by the valves and luckily piston was not hit.
Compression was also 60PSI on my cilinder.
Take care.
Wish you luck.
Reading this thread makes me hope that it is understood that a cilinder that gets fuel but does not combust, will get bore-washed, which impacts compression on that cilinder badly. (with throttle closed will give only ~60PSI)
Diagnosing piston/cilinder/valve damage just by "dry" compression test is not the way to go.
Just hoping engine has not yet been directed towards the scrapyard yet.
Off course, it may still (just) be a dropped valve seat due to tiny leakage that over time has been forming a large air bubble in the engine, not visible in coolant level:-(..
Heater hose described in this thread could have been leaking a bit for some while...
My experience with AJV8S is that the tine hose to the reservoir from the coolant manifold lets air in the cooling system when the engine cools down. (fixed 2 overheated yr 2000 XKR's and both showed this leak in vacuum test)
Normally the vacuum in the system (when cooling down) pulls coolant back in from the overflow tank. (That is why you should top up completely in cold state)
This pulling back in from overflow coolant tank does not happen when that tine hose next to temp sensor takes in air.
Somehow that connection is not leaking coolant when pressurized (by expansion of the plastic warm hose in the reces?)
I strongly believe that the problem I am describing is responsible for many overheating AJV8S engines. (So not by failing pumps and not by failing thermostats)
Driver wont get a low level warning, and we all know temp gauge is useless.
Al you get is (slightly) dropped valve seat(s). (Can also happen at engine shutdown, when really HOT and pump stops)
Mine was hammered back in (not straight..) by the valves and luckily piston was not hit.
Compression was also 60PSI on my cilinder.
Take care.
Wish you luck.
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xjrwithproblems
XK8 / XKR ( X100 )
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11-09-2013 02:56 PM
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