Does the front cover have to be removed to fix jumped timing or is it possible to just remove the valve covers and correct it? Specifically on a 4.6 3v engine
You have to remove the front cover.
I do not mean to offend you. but if you need to ask that then you need to bring it to a mechanic to do the work.
Couldn’t you just remove the valve covers, wedge tool the secondary timing chain in position and remove the bolts from the cam phaser and rotate it?
The cam phaser can be removed and repositioned on the chain without removing the front cover.
That doesn’t solve the problem, the timing chain should not “jump time”. The chain must be loose, soon the valves will be bent.
Something is worn or broken, fix it.
Are you certain the timing chain has jumped a cog, rather than what seems more likely, some part of the VVT system has failed? VVT mechanisms are very sensitive to oil level and oil quality. What is the oil change history ? Miles between oil and filter changes?
Let’s assume for a minute the timing chain has jumped a cog and someone tries to start the vehicle. can piston/valve damage occur even if the engine isn’t turning over?
“turning over” is an ambiguous term. “cranking” is when the key is in start and you hear that rrr rrr rrr sound, then it catches and the key is returned to on, & it continues to run.
When the engine is cranking – that rr rrr rrr sound – the crankshaft is rotating, which means the pistons are going up and down, and yes, that could result in a collision between the pistons and the valves if the valve timing was incorrect.
If the cam sprocket is off by one tooth it will likely run without a noticeable problem other than the check engine light. If the chain jumped one tooth it will jump 6 more.
Did you miss-time the camshaft when you replaced the cam follower?
What’s the best/easiest way to do diagnostic to tell if the pistons/valves collided? I’d want to do this before paying someone to tear off the front cover to fix the timing, no point in doing that if the whole engines bad
I had a mechanic that one of my friends used before replace the cam phasers and after he did the repair and the car wouldn’t start he refused to fix the issue claiming that the car was like that before he did the work which is total bs because I started the car and ran it for 5 minutes in front of him before he even opened the hood. I have filed a CPA case against him but this is off topic.
I have tried to start the car twice (once when he was here and again after he left) and both times it cranked and then it made a loud rattling noise before refusing to turn over.
Do you think it’s unlikely damage occurred since the engine is turning relatively slowly when it’s cranking and only tried for a few seconds before shutting it off
A cylinder leak-down test.
No, a starter motor is plenty strong enough to bend valves. If it made a noise and now refuses to turn when the starter is energized one of 2 things happened. The timing chains fell loose and locked up or the valves and pistons made contact. If you can’t turn the engine by hand, you can’t check for bent valves so the timing cover must come off.
That is the sound of engine damage. If the camshaft timing is off by so much the engine won’t start then engine damage occurred. 25 hours to remove and install the cylinder heads. Valves can break off and go through the pistons, plan on replacing the engine.
Time for a Coyote…
If I had this problem I’d just assume the engine has been damaged. The question is : How much? Next, remove the engine and place it on an engine stand and start taking it apart. It’s much easier and faster that way. If at some point during the disassembly the damage is found to be very minor (definitely possible), fix what’s broken and re-install the engine. If the damage is severe, then still no worries, you’re already set-up to install another engine .
For that there are three options:
- an exact match, used, from a wrecked vehicle
- used aftermarket engine, such as a coyote
- new (or factory rebuilt) engine, such as a coyote crate engine
The first two above, the price for the engine is probably not going to be overly expensive. A little Googling will provide the price ranges. A visit to Summit Racing’ s website is probably in order as well.
If you simply don’t have time for all this & need something to drive, of course you can always just junk the vehicle or sell it to a mechanic, and buy another.
If the chain is worn out then odds are everything else is also worn out. Most chain failures are due to irregular oil changes, low oil levels, and so on.
Used engines are a crap shoot at best unless they can be tested or heard to run; and yes I know the boneyards always claim everything in the inventory to be “guaranteed good”.
Not a coyote, that is the later 4 valve engine, the OP has a 3 valve. The coyote is not a drop-in replacement, it is a big investment in parts, wiring and time. Better stick with a 3 valve replacement.