Hey Guys and Girls,
Bit of a puzzler! I was braking hard up to some traffic lights on a 60Mph road when my engine died with a short grinding sound. The engine did not restart and i thought it sounded like a cambelt break. But when i took of the oil filler cap, i could see the inlet camshaft rotating. Is it possible that the exhaust camshaft has stopped rotating even though the inlet is still going? I'm pretty sure the grinding sound means bent valves right?
If i could have your thoughts and comments, they would be much appreciated!!
Cheers
Jon
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Very unlikely I would have thought - unless the exhaust cam has somehow come loose from the pulley - can't see it happening really...
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As Aprilia says, the only way this could happen is if the exhaust cam pulley bolt has loosened and the pulley has become unseated from its taper (these pulleys are not keyed to the cam at all).
I have never heard of this happening before. Have the belt or pulley been disturbed recently?
Cheers
DP
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No i've not touched anything so it's unlikely the exhaust pulley bolts have loosend.
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Yeah thats what i thought. Maybe the camshaft has snapped somewhere near the top. I'll have a look thursday anyway!
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Jon
Apart from the - very untypical - grinding noise; what else points you in the direction of the valves?
Is the engine spinning over with little obvious compression? Have you done a compression test? Is there still a spark? Is the spark still lining up with a, say 10 degree before TDC, timing mark marked on the front pulley? Can you smell fuel from the exhaust?
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To Screwloose - I havent done a comp test yet. i need to borrow one from a friend tomorrow. As for fuel in the exhaust and spark, i haven't yet checked as i am revising heavily for exams, however, if no fuel (or fuel smell) is exhausted then surely that means the ex vales are not openning. The plugs i will earth out tomorro to see if they spark. As for the 10 Deg before TDC, i don't have a gun to check - unless there's another way?!
As for the grinding noise, it sounded similar to brake pads that are thouroughly worn. i thought this was maybe my valves being damaged?
Jon
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Jon
It's unusual to hear anything when the valves meet the pistons following a cam-belt failure. They're bent like straws in an instant - probably before you've even registered the cut in power.
If it's valves; the injectors will still be working and the fuel smell from the exhaust will be very strong. Unless it's taken out the cam sensor [which is on the back cam] then it should still be sparking.
The sound of a valve-damaged engine is very distinctive; instead of the usual resistance, the engine just whines turning over. If you can borrow a Zetec-capable [deep plughole] compression tester, that would be your best next move.
Come back with the results and we'll take it from there.
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Screwloose -
Hey. Yeah the engine whines the same as if there are no spark plugs present. Like very little resistance so the Starter motor runs a little quicker. I'll get back to you in the week concerning the comp. test.
Thanks
Jon
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