Timing question
06-12-2018
#31
If you think a good mechanic is expensive, try hiring a bad one
Re: Timing question
If it split the toothed area of the cam pulley, that might explain how it moved so many teeth away from correct.
If it had been assembled that far off, it would have never been able to run at all.
Somehow, it got from correctly timed and running for 3 minutes, to disastrously broken and wildly incorrect. What do you think?
All we can do is speculate based on the info you provide. Can't do much more unless you strip the engine down for true failure analysis.
06-12-2018
#32
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Re: Timing question
Your mistaken to think the timing belt could not skip few teeth without visible signs.
Most likely scenario, camshaft siezed up, engine tried to keep moving, timing belt start skipping teeth causing massive shock impacts to the dowel and cam sprocket which then broke free of the index and didn’t need to skip anymore teeth because the sprocket was free spinning at this point.
We have seen many cases of timing belt being off by 2-3 teeth resulting in a engine that can start but dies seconds later. Lots of times those cars got out of time due to a failed timing belt adjuster which allowed engine to jump time.
Most likely scenario, camshaft siezed up, engine tried to keep moving, timing belt start skipping teeth causing massive shock impacts to the dowel and cam sprocket which then broke free of the index and didn’t need to skip anymore teeth because the sprocket was free spinning at this point.
We have seen many cases of timing belt being off by 2-3 teeth resulting in a engine that can start but dies seconds later. Lots of times those cars got out of time due to a failed timing belt adjuster which allowed engine to jump time.
06-12-2018
#33
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Re: Timing question
Sure.
If it split the toothed area of the cam pulley, that might explain how it moved so many teeth away from correct.
If it had been assembled that far off, it would have never been able to run at all.
Somehow, it got from correctly timed and running for 3 minutes, to disastrously broken and wildly incorrect. What do you think?
All we can do is speculate based on the info you provide. Can't do much more unless you strip the engine down for true failure analysis.
If it split the toothed area of the cam pulley, that might explain how it moved so many teeth away from correct.
If it had been assembled that far off, it would have never been able to run at all.
Somehow, it got from correctly timed and running for 3 minutes, to disastrously broken and wildly incorrect. What do you think?
All we can do is speculate based on the info you provide. Can't do much more unless you strip the engine down for true failure analysis.
I don't know if I mentioned it yet. But here it goes. The engine was running fine except at idle I would get low oil pressure. I took block back and they replaced the oil pump. In doing so they had to take timing belt off. I think the mechanic might have not set engine to TDC before taking belt off. In the process of installing belt maybe move a gear without notice and tested fine(still enough in time). By the time i got it turned on ran for a bit until it hit wrong time. The only factor that changed was the shop taking belt off to change oil pump. If I had not taken the engine back, the engine would still be running great except at idle after warm up(low oil pressure).
06-12-2018
#34
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Your mistaken to think the timing belt could not skip few teeth without visible signs.
Most likely scenario, camshaft siezed up, engine tried to keep moving, timing belt start skipping teeth causing massive shock impacts to the dowel and cam sprocket which then broke free of the index and didn’t need to skip anymore teeth because the sprocket was free spinning at this point.
We have seen many cases of timing belt being off by 2-3 teeth resulting in a engine that can start but dies seconds later. Lots of times those cars got out of time due to a failed timing belt adjuster which allowed engine to jump time.
Most likely scenario, camshaft siezed up, engine tried to keep moving, timing belt start skipping teeth causing massive shock impacts to the dowel and cam sprocket which then broke free of the index and didn’t need to skip anymore teeth because the sprocket was free spinning at this point.
We have seen many cases of timing belt being off by 2-3 teeth resulting in a engine that can start but dies seconds later. Lots of times those cars got out of time due to a failed timing belt adjuster which allowed engine to jump time.
06-12-2018
#36
If you think a good mechanic is expensive, try hiring a bad one
Re: Timing question
My opinion, if the time is off by a little the the computer can still compensate.
If it's off by a single tooth, subsequent power loss might not be noticeable by most average people. It will start and run, but not great. It might set codes after a while.
If it's two teeth off, power and fuel economy goes to hell. Pretty obvious IMO.
3 teeth off and the PCM may not allow it to run at all.
The PCM on most 7th gens has the ability to shut down the engine if it sees cam-crank signals too far out of sync.
Let us know when you figure out that your camshaft is seized in the head.
06-22-2018
#37
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So, the cam shaft was not seized. The shop mechanics thought it might have seized due to overheating and air in the cooling system. Well none of that happened. The engine did not run long enough to even reach operating temp. Air locking was highly unlikely. The car didn't run long enough, it was up on my ramps and the radiator cap was off. The shop put another cam and sprocket on the head. Due to a badly written email I went and picked up my car before they could actually finish any work on the car. I decided to remove vavle train and see damage for myself. There was very little damage to cam bearings. No signs of seizing definitely no over heating. I put a straight edge on top of the valves and all touched. Did a compression test and all cylinders got about 200PSI. I took that as very good sign. So, I assembled the head, set the CORRECT TIMING, etc... and the engine started right up. Also did a leakdown test and got very little leakage (< 5%). So yeah, I believe I was right about them setting wrong time both times the cam got messed up. Once at their shop and last time in my car.
I am still getting low oil pressure but only at idle after warm up. Only sometimes though. I noticed that oil pressure would drop only when rpms went below 680 or so. I concluded that it was something else other than the engine rebuild. Just earlier I took the throttle off and cleaned it and the IACV. Had to burp car so put it back on ramps. Burped it for about an hour and the car never overheated or fell below 700RPMS. It is not definitive that the low oil pressure was fixed with thw cleaning just yet though. I still have to test drive and see.
*Note ---- the owner said he had another head he was going to put on it but I told him of my findings and really don't plan to take car back unless something else goes wrong.
I am still getting low oil pressure but only at idle after warm up. Only sometimes though. I noticed that oil pressure would drop only when rpms went below 680 or so. I concluded that it was something else other than the engine rebuild. Just earlier I took the throttle off and cleaned it and the IACV. Had to burp car so put it back on ramps. Burped it for about an hour and the car never overheated or fell below 700RPMS. It is not definitive that the low oil pressure was fixed with thw cleaning just yet though. I still have to test drive and see.
*Note ---- the owner said he had another head he was going to put on it but I told him of my findings and really don't plan to take car back unless something else goes wrong.
06-23-2018
#38
If you think a good mechanic is expensive, try hiring a bad one
Re: Timing question
So, the cam shaft was not seized.
I noticed that oil pressure would drop only when rpms went below 680 or so
You do understand oil pressure varies greatly because it is a direct function of mechanical pump RPM vs. viscosity vs. hydraulic leakage, yes?
06-23-2018
#39
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Barring the weight and viscosity; basically, the crank turns the oil pump therefore the lower the rpms the lower the oil pressure, right? To a certain point of course. That is how I understand it. When I give it some gas oil pressure goes up. And yes it only drops after reaching operating temp of 210 or so.
I do not have a gauge on it THIS time but when I did have it on, it would go as low as 7PSI. Here is something weird though. My drive way has about an 8% grade on it. I just had it on my drive way and the idiot light did not come on at all. Conclusions???
- what ever is causing the low oil pressure may be something else that is being covered up by the oil at that angle?????? The rpms will go less than 680 but the oil light doesn't come on. As soon as I put it on more level part of driveway the light will flicker.
I was just going to start another thread about the oil pressure but you asked.
I do not have a gauge on it THIS time but when I did have it on, it would go as low as 7PSI. Here is something weird though. My drive way has about an 8% grade on it. I just had it on my drive way and the idiot light did not come on at all. Conclusions???
- what ever is causing the low oil pressure may be something else that is being covered up by the oil at that angle?????? The rpms will go less than 680 but the oil light doesn't come on. As soon as I put it on more level part of driveway the light will flicker.
I was just going to start another thread about the oil pressure but you asked.
06-23-2018
#40
If you think a good mechanic is expensive, try hiring a bad one
Re: Timing question
I put it on more level part of driveway the light will flicker.
Did anyone plastigauge the bearing clearances before final assembly?
Suction leak in the oil sump pickup tube?
06-23-2018
#41
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-Only when level
-Wire looks ok.
-The shop swears they checked everything when rebuilding.
-Pick up tube is the same I have had for years. Never had problems with low oil pressure though.
btw I started another thread. Thanks for help and ideas.
-Wire looks ok.
-The shop swears they checked everything when rebuilding.
-Pick up tube is the same I have had for years. Never had problems with low oil pressure though.
btw I started another thread. Thanks for help and ideas.
06-23-2018
#42
If you think a good mechanic is expensive, try hiring a bad one
Re: Timing question
-The shop swears they checked everything when rebuilding.
Including the loose cam gear bolt. Yeah.
Based on everything you've described in this thread, I wouldn't trust a damn thing they say.
06-23-2018
#43
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