Strange engine timing issue
Discussion
I’m currently replacing the cambelt on a 2.2 JTD Multijet (fitted to a Jeep).
There was no reason beforehand to suspect the engine was mistimed. Yesterday I inserted the spring loaded camshaft locking pin and turned the engine over until it engaged, thus locking the camshaft. At this point I stopped work for a few hours. When I came back to it, I noticed that despite the locking pin being in place, the timing marks didn’t look quite right. I then tried to remove the pin, but it was very stiff. When it came out it was bent, and with a notched dent where there must have been a lot of force applied as if the camshaft was trying to turn. I then tried to turn the engine by hand but it stopped just short of TDC. This seemed inexplicable at first, but now I’ve had a play around it seems the engine timing is out and the resistance is pistons hitting valves. Now, with the camshaft pin back in, the corresponding timing mark is about 5 or 6 teeth out. The three timing marks on the crank, camshaft, and fuel pump do seem to be in sync with each other, ie belt not slipped, but with the camshaft locked in the correct position, none of the timing marks are in their correct positions. The only explanation for this I can think of is if the camshaft pulley and the camshaft itself have gone out of sync.
So what the hell has caused that? It’s as if whilst I was away from the job someone came with a big breaker bar and forced the crank round, but with the camshaft locked, the pulley has slipped and the locking pin sustained damage. Obviously this didn’t happen, so what could possibly have caused the engine to try to turn over whilst I was out? The only movement is that perhaps the engine sank down slightly on the jack and came to rest on the axel stand, but would this generate rotation in the crankshaft?
Has anyone ever encountered anything similar before?
Thanks!
Tom
There was no reason beforehand to suspect the engine was mistimed. Yesterday I inserted the spring loaded camshaft locking pin and turned the engine over until it engaged, thus locking the camshaft. At this point I stopped work for a few hours. When I came back to it, I noticed that despite the locking pin being in place, the timing marks didn’t look quite right. I then tried to remove the pin, but it was very stiff. When it came out it was bent, and with a notched dent where there must have been a lot of force applied as if the camshaft was trying to turn. I then tried to turn the engine by hand but it stopped just short of TDC. This seemed inexplicable at first, but now I’ve had a play around it seems the engine timing is out and the resistance is pistons hitting valves. Now, with the camshaft pin back in, the corresponding timing mark is about 5 or 6 teeth out. The three timing marks on the crank, camshaft, and fuel pump do seem to be in sync with each other, ie belt not slipped, but with the camshaft locked in the correct position, none of the timing marks are in their correct positions. The only explanation for this I can think of is if the camshaft pulley and the camshaft itself have gone out of sync.
So what the hell has caused that? It’s as if whilst I was away from the job someone came with a big breaker bar and forced the crank round, but with the camshaft locked, the pulley has slipped and the locking pin sustained damage. Obviously this didn’t happen, so what could possibly have caused the engine to try to turn over whilst I was out? The only movement is that perhaps the engine sank down slightly on the jack and came to rest on the axel stand, but would this generate rotation in the crankshaft?
Has anyone ever encountered anything similar before?
Thanks!
Tom
It’s possible but highly unlikely. No one in my household could have, so unless a stranger did then I really can’t explain it.
I’ll get the cam pulley off tomorrow, but I’m now worried that it’s slipped far further than the notch on the pulley should allow. Therefore, will I find that something has sheared to allow this?
I’ll get the cam pulley off tomorrow, but I’m now worried that it’s slipped far further than the notch on the pulley should allow. Therefore, will I find that something has sheared to allow this?
I’m not sure about the remote start, but maybe. I did see the boot opening the other day when the key was in my pocket.
I also thought of rolling back, but the car is chocked (could still move a little) and is connected to a ZF9. Would the torque converter transmit such a load at almost standstill? Also the car would’ve moved backwards, and from what I can tell, the crank has advanced forwards relative to the camshaft.
Today still discover is as expected. The locating tab on the camshaft pulley had sheared to allow the relative movement. New one ordered from Greece, starting to worry the engine might be goosed when I put it back together.
Just very frustrating that I cannot understand what has caused it. And that it almost certainly wouldn’t have happened if I’d just removed the pin before leaving it (not that I had any reason to suspect the problem).
I also thought of rolling back, but the car is chocked (could still move a little) and is connected to a ZF9. Would the torque converter transmit such a load at almost standstill? Also the car would’ve moved backwards, and from what I can tell, the crank has advanced forwards relative to the camshaft.
Today still discover is as expected. The locating tab on the camshaft pulley had sheared to allow the relative movement. New one ordered from Greece, starting to worry the engine might be goosed when I put it back together.
Just very frustrating that I cannot understand what has caused it. And that it almost certainly wouldn’t have happened if I’d just removed the pin before leaving it (not that I had any reason to suspect the problem).
Scrump said:
This was my first thought on reading the OP.
Odd situation, do keep us updated.
Fingers crossed that it goes back together without damage.
Odd situation, do keep us updated.
Fingers crossed that it goes back together without damage.
Will do, and thanks!
My next worry is that if the camshaft tab has sheared, who’s to say the crank pulley hasn’t suffered the same fate? It looks like a bugger to take that off. 320nm and LH thread. I think I’ll pop something down the glow plug hole and feel for TDC.
Wire down the glow plug hole test completed, and it seems the crankshaft and pulley are fortunately still in sync with each other.
I’ll carry on with the job, and just hope and pray that the mystery rotation, plus me finding out the hard way that valve and pistons were meeting when turning over by hand, hasn’t done any further damage.
Thanks all for your thoughts so far. It’s sort of relieving that no one has suggested something bloody obvious that I just over looked.
I’ll carry on with the job, and just hope and pray that the mystery rotation, plus me finding out the hard way that valve and pistons were meeting when turning over by hand, hasn’t done any further damage.
Thanks all for your thoughts so far. It’s sort of relieving that no one has suggested something bloody obvious that I just over looked.
oakdale said:
The starter motor must have operated to cause the damage you have, I just hope no electrical damage has been done as well.
Does your key fob have the rotation x2 button similar to this one?
No it doesn’t. So probably not that. Does your key fob have the rotation x2 button similar to this one?
I did turn the car (not engine) on before I inserted the pin, so had to turn it off again when I left it. I was very aware of the risk of attempted start and so was being careful not to press anything I shouldn’t have. Although with the symptoms as they are, and the need to press the brake pedal to move the gear shifter out of neutral into park, there is the chance that I inadvertently activated the starter. Though I have absolutely no memory of doing so and as I say I was being very careful.
I realise now, there was no need to be in neutral to turn the engine over, but I’m not that familiar with the ZF9 and was working on the worst case assumption that for some reason the input shaft would also be locked in park. I’ve disconnected the battery now so hopefully zero chance of reoccurrence.
As you say, it looks most like that the starter motor had activated for reasons unknown, hopefully no damage to motor or flywheel.
mrtomsv said:
No it doesn’t. So probably not that.
I did turn the car (not engine) on before I inserted the pin, so had to turn it off again when I left it. I was very aware of the risk of attempted start and so was being careful not to press anything I shouldn’t have. Although with the symptoms as they are, and the need to press the brake pedal to move the gear shifter out of neutral into park, there is the chance that I inadvertently activated the starter. Though I have absolutely no memory of doing so and as I say I was being very careful.
I realise now, there was no need to be in neutral to turn the engine over, but I’m not that familiar with the ZF9 and was working on the worst case assumption that for some reason the input shaft would also be locked in park. I’ve disconnected the battery now so hopefully zero chance of reoccurrence.
As you say, it looks most like that the starter motor had activated for reasons unknown, hopefully no damage to motor or flywheel.
What an awful situation you've been put in, modern "convenience" electronics are a trap waiting to get youI did turn the car (not engine) on before I inserted the pin, so had to turn it off again when I left it. I was very aware of the risk of attempted start and so was being careful not to press anything I shouldn’t have. Although with the symptoms as they are, and the need to press the brake pedal to move the gear shifter out of neutral into park, there is the chance that I inadvertently activated the starter. Though I have absolutely no memory of doing so and as I say I was being very careful.
I realise now, there was no need to be in neutral to turn the engine over, but I’m not that familiar with the ZF9 and was working on the worst case assumption that for some reason the input shaft would also be locked in park. I’ve disconnected the battery now so hopefully zero chance of reoccurrence.
As you say, it looks most like that the starter motor had activated for reasons unknown, hopefully no damage to motor or flywheel.
oakdale said:
What an awful situation you've been put in, modern "convenience" electronics are a trap waiting to get you
Thanks, it’s nice to have a sympathetic and understanding ear on here. When I try to talk stuff like this through with my wife, she looks at me like the dog would if I tried to teach him algebra.Lying in bed last night it occurred to me that the sequence of events to put the car back in Park; with the ignition on, press the brake, then shift from neutral to park, would momentarily satisfy the logic for the auto stop start. I’m now thinking this is a feasible theory.
New cam pulley should arrive from Greece today.
Edited by mrtomsv on Tuesday 20th May 20:11
Got it back together with a new cam pulley, it's working so hopefully I've got away it. Something must have caused the starter to try to turn, but I've no idea what or when it happened. I'll always follow step 1, disconnect the battery from now on.
Thanks for everyone's help and ideas.
Thanks for everyone's help and ideas.
Hope you have got away with it. Usually good practice to disconnect the battery before carrying out this level of work.
I once took a gearbox out of a rear wheel drive old car. Had a complete brain fart and put a spanner on the starter terminal.
I now always remember to disconnect the battery first.
I once took a gearbox out of a rear wheel drive old car. Had a complete brain fart and put a spanner on the starter terminal.
I now always remember to disconnect the battery first.
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