How to replace a cambelt on a mk2 megane 1.6l vvt
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- Опубліковано 21 жов 2024
- In this video I get a bit closer to get the new daily back on the road by installing a whole new cambelt kit
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Great video, and very helpful ... but ... there is one big catch!
The toothed drive sprocket is not keyed to the crankshaft at all, it is only held there by friction when the accessory pulley is tightened to full torque (40Nm + 135 degrees). At 04:47 you buzzed the accessory pulley off the crankshaft and replaced the bolt to allow you to turn the crankshaft. In many cases the crankshaft bolt without the accessory pulley won't give enough friction to hold the toothed drive sprocket stationary relative to the crankshaft. So if you then turn the crankshaft bolt, often the crankshaft will turn and leave the toothed pulley (and hence the camshafts!) behind, ie the engine will go out of time.
Better to put the engine in time by turning the crankshaft around to meet the locking pin BEFORE you remove the crankshaft pulley. Then when you insert the camshaft brace the engine is locked up and you can take off the crankshaft pulley. Scary thing is that once you do so, the toothed drive pulley can turn on the crankshaft. When you replace the belt and check crank position, it is the belt that re-establishes relative position between cams and crankshaft. The toothed crankshaft pulley is then only held in place by friction. Scary design, but that's how it is.
I’ve been struggling re-inserting the timing belt on an F4P engine (same design) and I saw on another video a guy just putting the belt without the crankshaft bolt this is indeed a very scary design…
@@KokahZ777 That is in fact how I ended up putting the timing belt back on, too. Many manuals say to put the belt around the crankshaft sprocket and camshaft pulleys first, and then use the tensioner for the final stretch, but I found that difficult - mostly due to space constraints. It was much easier to but the belt over both camshaft pulleys, idler and tensioner rollers first, and then do the final stretch by pulling the belt (together with the crankshaft sprocket) down over the crankshaft itself. Provided you are careful not to damage the end of the crankshaft, this works well. You can then rotate the crankshaft inside the crankshaft sprocket to put the engine back in exact time (if necessary) before tightening the accessory pulley and crankshaft bolt to the final spec. It goes without saying that you need to check and re-check this meticuloulsy to be ABSOLUTELY sure the engine is back in perfect time.
I suspect that many people who do this job will - as I did - accidentally get the engine out of time by turning the crankshaft inside the loose crankshaft sprocket, thereby leaving the cams behind. It is scary to be in that place - you will actually feel the pistons touch the valves as you turn the crankshaft. However it is not difficult to recover. Once you understand what is happening it is actually easy to position cams and timing belt first, and then turn the crankshaft inside the sprocket to put the engine back in time (against the locking pin). But yes - the whole scheme depends on that one critical crankshaft bolt being (and staying) tight. Scary design indeed!
Speaking of that, there is some conflicting information around on the tightening spec for the crankshaft bolt. The SKF kit I used states 20Nm + 135°±15° as opposed to 40Nm + 135°±15°. This turned out to be an error : 40Nm + 135°±15° is the correct spec on the K4M engine. However in practise it makes very little difference, the 20 or 40Nm is almost irrelevant - it is the final 135° that actually does the job. For an average size guy with an average socket wrench, 135° will be about as tight as you can get it anyway. So start at 40Nm with confidence - it's a healthy size bolt and you won't easily break or strip it.
Another good tip is to pull out all 4 spark plugs before you do any of this. Turning against any compression makes it more difficult to feel what's going on and increases the chance of damage if you have accidental valve contact. With no compression you will be able to feel exactly what's happening.
Going to be changing the belt on my twing rs tomorrow. Not the same car, but the same engine.
Thanks for the demonstration 🤌
that trick with the cable ties is genius
I used a cable tie to de- tension the tensioner before installing. I then managed to get the belt on without to much pain and after it was fitted, I used a screwdriver to break the cable tie off the tensioner. I then proceded to tension the belt till the arrow was in the middle.
Thank you so much you have saved my life and my bank
Great video mate, keep up the quality content bro
Nice video kidda, now go an check how many cuts you have on the back of your hands 😁😁
great video.My megane still makes rattling noise after replacing pulley,Oil pressure light still appears on display.Please help.Thank you.
thanks champ
Nice!
Is there an easy way to see if the cambelt is broken?
Yes. The engine won’t start
👍👍..? Ford fiesta mk3 ...??. Saludos ...
Couple videos in the making on the fiesta the first one should be coming this week hopefully and it I will be repairing the front passenger wheel house and installing the wing thanks for the comment and support