accord will not start

[92redex]

was driving down road about 45 car died came back on died again and nothing tried cranking nothing. Thought it was timing belt tore it down belt not broke but hold down bolt was gone belt was real loose. Replaced belts and everything marks are on , will not start just cranks.

[Losiracer2]

readjust timing. you're prob. 3 teeth off or something...like I was when my car wouldn't start.

[PUMASTi]

A bad Distributor can cause this.

[DaGrk1]

check if ur getting spark and fuel and then work from there

[batever]

Before I get going, I didn't understand what you meant by "the hold down bolt was gone?" I'm not sure what you mean by the "hold down bolt" and it would help me get a clearer picture. But I did get that the timing belt was loose and slipping so here we go:

Ok, here's my disclaimer: a couple really experienced forum members just commented and didn't mention this, so maybe I'm wrong (I just started studying internal engine operations recently so I could be totally off, if so, please be gentle on me!).

But, the thing is, from everything I know (not a super lot, as I just said, but something) what you described (both the sequence of events and the fact that the engine won't turn over now) is consistent with valve damage.

I don't know for absolute certain why the car would die at 45 mph and then come on again before finally going dead, but what I'm thinking is if the timing belt was slipping a lot that could have happened. The camshafts would get out of alignment enough to mistime the spark and combustion might stop, but you're still coasting down the road and in gear, so the crankshaft (and pistons) keep going. If the timing belt is still slipping, at some point in the revolutions the timing could line up well enough (happens to be at the right place) so taht the engine starts firing again. But since the timing belt is still slipping , it goes out of time again and the car engine just stops.

Here's why I think you probably have valve damage:

While most of this is happening, valves are going to be getting hit by pistons. Here's why:

If the timing belt slips badly, pistons will keep moving because they're being driven by the combustion in the block and the inertia of the crankshaft alone will keep it going for multiple revolutions (not sure how many) even if the engine stops getting spark all of a sudden. And because the camshafts aren't moving at all or are moving too slow because the timing belt is majorly slipping, some valves will be open at the wrong time. For example, if the camshaft is too slow it will push valves down into the combustion chamber at the wrong time so the valve sealing bodies collide with the pistons as the pistons travel up to top dead center. Even if the camshaft is completely stopped, there still might be a valve poking down there when it shouldn't be. If it gets hit by a piston and flies up against the rocker arms, it might have enough force behind it to then move the camshaft! which will push another valve down and--well you get the idea, it's a mess.

Okay, so now because the valves got distorted/bent by being hit by a piston they stay sealed at least partially open. The valve springs will try to pull them up but since they are bent the valve seats won't seal the intake and exhaust ports.

Now if you set the timing belt back and put the engine back together like you have, then the distributor will make spark and the injectors will inject fuel but the flame edge of the combustion won't compress the pistons in the cylinder because the valves are letting all the expansion pressure escape out both the exhaust ports and the intake ports instead of driving the pistons. Essentially, not enough compression will build up to drive the pistons. So that's why the engine won't "turn over" or start working on its own power separate from the starter motor.

Someone correct me if I'm missing something (I really mean that). Even though the timing belt didn't break, if it slips far enough the same damage can happen to the engine as if the belt actually broke. We could even actually look and figure out how many degrees out of alignment the camshaft would have to be to cause that, and how many timing belt teeth that would equate to, but I won't do that right now.


At this point, i think the thing is to check and see if you actually do have valve damage. I would suggest three ways to move forward and diagnose it. The first way, the way that I think is best and safest but is more work than the other two, is to take the valve cover off and check the valves. Get a valve spring compressor and some compressed air and/or nylon rope (if you don't know how, the Haynes manual explains it very well) . Keep the valves from falling into the cylinders by using compressed air (actually, this won't work because the valves are all gonna be messed up, I would go with the nylon rope method.)

Compress the springs on each valve and then see if they slide freely up and down, and spin the valve bodies to see if they have out of roundness(eccentricity) . My guess is some of these valves, maybe not all, are bent from getting nailed by the pistons.

Only thing to do in that case if you want to keep the engine is pull the head and put in new pistons, or buy a new head, I think. I've never done that so I don't know exactly what it involves.

A second way to diagnose it, if you have the equipment, might be to do a compression check. If you have this kind of valve damage you will have wicked low compression readings if the compression builds at all.

A third way, which is really simple, is to manually rotate the engine counterclockwise from the crankshaft bolt a few times. It will tell you something about the compression, because if the valves aren't sealing properly , you won't feel the compression resistance that you normally would feel every time you turn the crankshaft 180 degrees. Also, while doing this you could potentially feel the physical resistance/impact of a piston on a bent valve seat.

The only reason I might not use either of these last two methods is that I'm very careful by nature and wouldn't want to further damage anything by rotating it more if it is damaged. But you would feel something hit I would guess if you did this. Also, one could ask, if you've turned it over by the starter already a few times, as I'm sure you have, what's the harm of doing it by hand?

People who have actually done engine work instead of just reading about it like me might have better advice about which way to go. For me, I'd say go and look at the valves.

If others know that my analysis is off or have other advice, please comment, but to the best of my current knowledge and abilities I think that's what happened, unfortunately. Your timing belt doesn't have to break for you to incur valve damage, it can also slip and when the camshaft gets far enough out of time you are in trouble.

Probably this happened because the tensioning spring on the timing belt adjuster arm failed. It's a good idea to replace them, if not every timing belt change, every other one.

I'm really sorry about your car and hopefully I'm wrong, and good luck with it.