Over the winter I did a timing belt change (lock and swap) and the recent warm weather prompted me to start the car: - It started right up but ran rough for a few minutes, then died - Two further attempts resulted in running for a few seconds then dying. - Last attempt resulted in engine not turning over When I pulled the timing belt covers off for a visual inspection, things looked normal--no sheared belt teeth, no debris, normal belt tension, all bolts (tensioner bearing, tensioner) are tight. When I tried to turn the engine over manually, I discovered that I hit a mechanical stop in both directions and the "free range" between the two stops is approx 185 degrees of crank rotation. When setting belt tension with my Motoriva frequency meter, I had the opportunity to manually roll the engine over at least a dozen times while getting the frequency/tension correct so I know that there was no interference prior to starting the engine. I assume pistons are hitting valves somewhere but am at a loss as to what went wrong. Any ideas/suggestions/theories would be appreciated. Barring any better ideas on how to proceed, I would start by removing valve covers to look at factory timing marks in attempt to define what bank or banks are screwed up but I don't know if I can get #1 piston to TDC with the limited rotation.
I am in Minnesota. I have done the lock and swap on my old 308 a couple of times with success and it seemed even easier on the 575
OK. do you understand the otto cycle theory and how engine is setup and what you have to do now or did you also lock and swap because of lack of knowledge? I'm not trying to put you on the spot just trying to assess your knowledge level so I can help.
Great! Marks on cams are assembly not timing marks! Car will run on assembly marks and often cam timing = assembly marks but often they are a few assembly mark widths off. If you truely have a stop in your motor then don't turn it anymore. You may already have done significant expensive damage and need heads off repair. Take plenum off take valve covers off. remove belts. remove cams. that retracts valves in head. use piston stop or dial gauge to find #1 TDC. replace cams with assembly marks at the #1 journal cap marks. replace belts to this new position. don't worry about exact cam timing or exact belt tension yet. Now leakdown the motor to see if you bent any valves. no valves bent then get new belts and tension accordingly. bad leakdown = heads off and rebuild. Got it? or need more details? This is a lot of work. I can only assume you have diagnosed the reason for engine stopping as you describe. I can only assume something moved during lock and swap was not so locked.
I should have interjected by replacing everything as described above you should be able to turn the motor by hand gently and not feel anything crunch. The quicker way to do a leakdown is do it before the cams go back in...your choice.
Chessie- Unlike the 550s FBB and Dave work with, the 575M has timing marks scribed on the backs of the cams that can only be seen with a mirror, since the cam timing was done at the factory with the engine removed. When we checked mine against actual cam timing by degreeing the cams, they were exactly correct. Probably not always correct, but another check to see if something is really wrong.
Taz My workshop manual shows the timing marks on both ends of the cams. I was hoping that was correct but I have read before that they are only on the back end of the cam so mirror it is I guess. FBB I understand your comments and next steps--thank you for that. Do you (or anyone) have a theory as to what went wrong assuming my "mechanical stop" is pistons against valves. It is awfully difficult to screw up lock and swap. I am sure nothing moved because all my marks that were transferred to the new belts lined up to the marks on the cam sprockets and drive sprocket. I had two on each cam sprocket and one on the drive sprocket for each belt. I also turned the engine over by hand many times after installing belts and while setting tension and there was no interference felt. Somehow all that changed at startup but I don't know why
Taz another question on the cam timing marks---My shop manual which shows both ends marked, shows the marks on the bearing cap and the shaft but they appear to be viewable from the top of the camshaft. When you say need a mirror, it appears that it is on the backside of the back bearing cap and backend of the shaft but only visible after you remove the cam covers. Is that correct?
I suspect it is a bit late for this but get the valve covers off, get the cams out to prevent further problems. At that point a leak down can be done to see if or what got bent. I can pretty much tell by looking at the cams where the pistons should be but that is a bit hard to explain so just taking them out is best at this point. Pay attention to how it all comes apart. The answer to your problem is there somewhere. Sorry to say but it sounds like you missed something. If it really was as you say and the cams are indeed out of time there is no other answer. When the belts were changed did you have the crank pulley off? It is a common mistake to tension the belts with the pulley loose or off and when the belts are tensioned or the crank turned the helical gears will spit the crank gear down the snout of the crank and when it is all bolted back together the cams are out of time. Seen that happen a number of times.
Rifledriver I understand your comment on being able to tell where the pistons are and I accept that a mistake has been made but what ha me perplexed is why was I able to turn the engine by hand with no interference. Can you explain your comment about the loose balance pulley? I am sure I had the balancer back on because I had to turn the big bolt and didn't want just the bolt on the crank
Chessie, there's also the (remote) possibility that the motor is simply hydrolocked due to a leaking fuel injector. The fuel "should" have evaporated by now and you should be able to turn the motor, but as others have said, it's best that you not try, until you get the cams out and can confirm what's going on. Be careful when removing the cam caps as they're under a fair amount of valve spring pressure. The cams will want to pop out of their saddles as the caps are loosened, which could result in launching some nuts & washers, so be prepared, and have all the usual openings (oil drainback holes, etc.) well covered. I have a set of tools that I made that makes cam removal very straightforward and eliminates the possibility of them popping out of their saddles. If you'll PM me your email address and physical address details, I'd be happy to loan them to you.
Without being there all we can do is guess and I kind of already did that. John makes a good point about hydraulic locking. Take the spark plugs out as well. We may be able to say more when it is certain why it isn't turning. But then again, not being there maybe not. Find out why and go from there. Also tell us EVERYTHING you did to it since it last ran. What was apart, what was serviced, what was replaced.
DO THAT The easiest thing (most non-invasive) to do first is to inspect the timing marks to see if they are reasonably close to being lined up ---- see if you can get the engine to rotate to #1 TDC. If not, let us know.....there are some work-arounds there if you have a goniometer and a plunger dial indicator (a borescope would be very useful as well). Even though they are only the "assembly" marks, and not meant to be used to precisely set correct timing, they are certainly accurate enough so that if they are lining up w/TDC, you can be assured that the problem is NOT valves hitting pistons. As to how / why the timing went off during your procedure (assuming you find that to be the case), I would suspect something got "lost" when you were locking down the tensioners --- so some slack inadvertently got in the system, and things went out of synch by a few teeth / degrees of rotation. Also --- how did you "lock everything" during the belt swap ?
I did a lock swap on both cambelts, replaced the tensioner bearings, cleaned the tension mechanisms, replaced the remaining aux belts, changed engine oil and coolant, and changed brake fluid
Seeing that the car did try to start I would lean toward the having a cylinder filled with fuel. By removing all of the spark plugs you should see which cylinder it is, and pressure will be released. Sometimes it's just the simple things. Hopefully! good luck.
If it was hydraulic lock, then when I hand cranked the engine 180 the other direction (CCW) wouldn't I push the liquid out the exhaust ports?
Finnerty To lock the system, I put the car in 1st gear and used a small vicegrip between the two camshaft sprockets
Not necessarily, if only a small amount of liquid is present ---- just enough to air-seal the rings and not enough to create a large puddling volume on top of the piston. Also, the hydraulic lock could be occurring at both ends of an individual cylinder / piston cycle --- approaching TDC on the compression stroke, with all valves closed, against positive pressure build up in the cylinder and approaching BDC on the power stroke, with all valves closed, against negative pressure (vacuum) build up in the cylinder. And, that would coincide nicely with the 180 degrees of stop-to-stop crank rotation you are observing........ however, I doubt that is the problem --- but, I do hope I am wrong for your sake .
I thought about that and about something getting sucked into the intake while the air cleaners are off. My locking vicegrip is accounted for and Ferrari puts screens at the intake tubes that remain in place when you remove the air cleaners. I checked thoroughly for misc things before buttoning up and more recently after removing the cambelts covers.
Yes it should, and too, if you remove the plugs, it'll provide a relief path for the fluid that doesn't depend on the cam positions at all. However, one of the serious problems/results of hydrolocking is that you could have bent a rod, and that may be what's preventing you from making the full 360. But all this is conjecture until you get things torn down a bit more.
