Got the plenum off today, valve cover off and 1-6 bank plugs pulled and have some hard data: --#4 plug tip was "mashed". the pin is demolished, the matching tang is bent into the center of the plug,the ceramic is not there, and there is a chip out of the first few threads at the leading edge. --When I pulled the cam cover off and observed, the bucket on #4 cylinder is stuck down into its well creating a space between the bucket and the cam of approx 3/16 to 1/4 inches. I am able to line up the cam timing marks (its within my 180 degree rotation limitation) but as of now, I have no way of measuring TDC of #i cylinder to check valve timing. I will start to work that issue tomorrow but it looks like there is a bad valve or more on that bank and the head will have to come off. I have not pulled cams out yet to see if the remaining valves are closing. I will do that in the next few days.
Did you notice the square drive in the top? For 10mm size it's hardly relevant to use a torque wrench if you know what you are doing, although I am somehow sure I will get comments on this. To each their own, these are imho easier to work with than sockets because they save you switching ratchet accessories and are tinier so you can get to fasteners in all angles and hard to reach spaces. Easy to find in the toolbox too. Ouch Chessie, that sounds expensive, good luck with the repair. Hope it's not a valve head that broke off! Was this really the first time it was started with the new belts?
The piston could not impact the end of the spark plug unless the spark plug was the wrong type --- too long --- any chance of that ? Or, unless the rod cap broke or the bolts came loose / backed way off --- which is highly unlikely, and maybe impossible, given the relative geometries of the piston crown and the combustion chamber. Also, you would have had the same interference in all 12 cylinders (assuming they all had the same plugs installed). If the plugs are correct length, and the damage only occurred in one (the #4) cylinder, it sounds like something got loose in there or fell in --- a nut, a pebble, a small piece of something, etc. --- and got smashed between the piston crown and the spark plug tip. Or, perhaps the plug was structurally defective and broke off a good sized piece of itself, and that then got jammed up. Another possibility could be that the valve seat dropped out of the head, and then got broken into a few pieces that got tossed around in the cylinder. Also, if one of the valve tappets (buckets) is stuck down that means the valve is also stuck down (open), so perhaps a piece of the debris then got stuck in between the valve head and its seat ? If that valve is really stuck hard (seized) in both directions (won't go up or down) for some reason, this could explain the "hard stop-to-stop" you are experiencing when you try to rotate the crank --- as it is actually the tip of the that valve's cam lobe that is rotating around CW / CCW until it contacts the seized tappet. This could be near to a +/- 360 degree (of course, it would have to be somewhat less than full 360) range of rotational freedom of the camshaft --- which would correspond to a nearly +/- 180 degree rotational freedom of the crankshaft. If it were me, I would NOT pull the head, or even the cams, just yet..... Instead I would use a borescope to look inside that #4 cylinder to see if any debris can be found and to see what may be sticking that valve open. If found, I would extract all of it, if possible, and if everything looked reasonably clean and not too banged up, and the valve appeared to be traveling and seating well........then I would try to run the engine. You MAY, JUST MAY, get lucky
You can determine and set #1 TDC by measuring the piston depth (height) through the open spark plug hole
The same plugs have been in the car since before I bought it. I have owned it for two years and put on 1600 miles in that time
I think, when we looked at the geometry, that a few degrees of crank rotation only results in a couple of thou of measure of the piston at TDC so, without a proper TDC apparatus one could only approximate TDC. I have thought about checking the cam timing on the other bank to see if they are equal as a check whether the cams jumped time on the "bad" side.
I could also lay a long rod into the #4 hole and see if that piston is coming up and if the cam lobes are approaching. The cup as I hit my mechanical stop.
There are inexpensive TDC plunger tools available from Snap-on, etc. for screwing into the plug hole and giving at least an indication of piston travel and full up / full down position. What is your location ? I am about 225 miles South of Minneapolis, and I would be happy to loan you my scope and TDC tool if you're close enough to make a road trip or have any other reason to be in the area.
1st let me tell you how sorry I am about the engine damage. No matter how it happened it isn't a good day to find that out. Second let me disagree vehemently about trying to find debris and trying to start the motor. I have had before me many times a motor in exactly the same condition. The piston will be damaged and the head will be damaged. All that is left to know is why. The head needs to come off, the motor will probably need to be removed. Trying to run it at this stage cannot achieve anything but possibly cause more damage. It will be a help in the repair to know what cylinders are effected. If it was me, at this point It would remove all 4 cams and do a leak down test. Armed with that information and a visual inspection of the motor once the head or heads are off you will know what steps to take next.
Agreed. NOTHING good can come of running that engine now. Brian knows what the hell he is talking about. Listen. Leakdown testing with the cams out is a very safe way to assess the rest of the engine and decide if the problem exists in multiple areas or just this #4 area. Regards, Pete
I really feel for Chessie. An awful situation to be in. While the cause of the problem has not yet been identified, what can the experts tell us about the risks of doing a 'lock and swap' and how to avoid them? Thanks. Frank
I have said it more than once already, this had nothing to do with doing a so called lock and swap timing belt change. Did everyone get that this time?????????????
Brian, Guess I missed it along the way. May I ask for a brief summary of your thoughts? Would be great to have your thoughts in one place. Feel free to PM me if that's easier. Thanks. BTW, good Q&A in the latest Forza. Frank
I have both cam covers off now so I can see the original timing marks. We looked to see of the alignment marks were the same for both banks on both cams. We also cobbled a homemade TDC gage (a quarter inch stainless rod that I had and wrapped with masking tape at the point where it extends from the head with a series of pen marks on the masking tape as a reference, What we found: --I have the original timing marks on all four cams on BOTH ends of the camshafts and both saddle bearings. My manual shows it this way but I was expecting only the blind end to be marked. --The timing on the drivers(left bank) does not match the passengers (right) bank. It appears to be different by one or two sprocket teeth. --When we lined up the cam marks on the pass side and checked for our TDC on cyl-1, it appeared to be short of TDC by about 5/8 inches which seems to be several degrees of crank rotation --When we "found" TDC with the homemade TDC stick, the timing marks on the Drivers bank lined up but the pass side was off. Conclusion theory now is that the bank exhibiting the mashed plug on cyl-4 is out of time. After I remove belts and cams and pressure test for more damage, I will examine my original belts and their markings with my new ones against marks on pulleys to see if I can determine how I got off or if it "just slipped". It still bothers me that no problems were exhibited when I manually rotated the engine multiple times prior to starting. I need to resolve that in my mind so I can sleep.
I try hard not to add insult to injury but at this point some things need pointing out. People work on their own cars for a number of reasons but no matter the reason you need adequate tools. You don't have them. For that there is simply no excuse. If you can afford a Ferrari you can afford the correct tools. You are not a starving secretary driving a broken down 20 year old Toyota. One thing so far you are going to buy prior to reassembly is one of a couple different types of tools made for accurately finding TDC. Your popsicle stick isn't cutting it. You may or may not have the requisite mechanical knowledge and understanding to do this job but it is clear you are lacking in some work habits. If you really methodically did everything you say I don't think we would be having this conversation. I could be wrong and I apologize in advance if I am but exhibit A is the cams on one bank are out of time. I have personally done this job hundreds of times and overseen it done hundreds more and one thing I know for sure is they don't get out of time all by themselves. After turning it through did you go back to TDC and recheck? It really at this point sounds to me like one of two things happened. Either the crank pulley was off or loose when the belts were installed and tensioned and the drive gear slipped down the snout of the crank and then when the pulley was reinstalled the drive gear was pushed back in place and due to being a helical gear repositioned the cams to where they are or the belt was installed with slack on the long run and when tensioned the cams turned. At the end of the job the motor was not reTDC'd and mark position confirmed. Again if none of it went the way I just outlined this conversation would not be taking place. Now, if you do not have a leak down tester and a compressed air source, get both.
Common error that catches many of us DIY'ers on timing belt swaps as it's not written in the swap procedure (Ferrari), or there's only a vague reference to doing it (Porsche). Toyota/Lexus do spend a fair amount of space in their WSM manuals on this point.
Ferrari does not write their manuals for us. They expect that the reader already knows how to fix the car.
Lock the crankshaft so that it does not rotate during the subsequent procedures. Mark the two driven pulleys and the driving one with respect to the front cover, in order to highlight any possible shifting when fitting the belt. Lock the two driven pulleys with each other using a self-locking plier.
Seems a bit harsh to me..... Speculating that a retired ME, who also apparently has a fair amount of DIY auto repair experience (including a successful belt change on another Ferrari engine -- his 308), "may not have the requisite mechanical knowledge and understanding to do this job" and asserting that "it is clear you are lacking in some work habits" is very condescending. As far as the "popsicle stick" check goes....... I am quite confident that the OP knows full well that is not a proper, precise method to measure TDC --- but, he is just doing something quick and easy to get some preliminary information about the general relative positions of things in order to point him in the proper direction to proceed. Nothing wrong with performing a rough approximation of things to get started.....then following up later with more precision when appropriate.
