Could Bad Timing cause hydro/vaporlock

[joseph.signore]

I need help please.

I have a 1991 Mercruiser 5.7 350 Magnum with Tbolt ignition. I just repaired some issues from water in oil and port cylinders as follows:

Replaced both risers, manifolds and gaskets with all Merc parts.

Replaced both heads, gaskets and intake gasket. (after finding a crack in the port side head)

Changed the oil twice since repairs done.

The motor runs great...

My problem is when the motor sits overnight it hydrolocks in the morning. (Not sure It's a loud clonk before she starts the same noise when I had water in my cylinders) I find no water in any of the cylinders except #7
has some gas or light oil on the threads only and the porcelain tip is redish brown but dry. I finaly checked the timming with a light this morning and it was way off...... The mark was not visible till I turned the distributor. My question is did the off timing cause some kind of vaporlock???

Thanks,

Joe

 

[Don S]

Re: Could Bad Timing cause hydro/vaporlock

Timing won't cause a vapor lock, but it can cause the engine to diesel when you shut it off. Water could enter the cylinder if the valves are open.

 

[joseph.signore]

Re: Could Bad Timing cause hydro/vaporlock

Timing won't cause a vapor lock, but it can cause the engine to diesel when you shut it off. Water could enter the cylinder if the valves are open.

No water found in any cylinders... No dieseling at all. Could my starter be bad and act up when motor is cold?

 

[Don S]

Re: Could Bad Timing cause hydro/vaporlock

My problem is when the motor sits overnight it hydrolocks in the morning. (Not sure It's a loud clonk before she starts the same noise when I had water in my cylinders) I find no water in any of the cylinders except #7

You just posted you had water in #7, now you say there wasn't. Which is it ??????????

 

[joseph.signore]

Re: Could Bad Timing cause hydro/vaporlock

Don,

No water... light oil on threads only.

 

[joseph.signore]

Re: Could Bad Timing cause hydro/vaporlock

FOUND THIS ONLINE:


At idle, your engine is turning relatively slowly, let?s say 1000 rpms. The throttle is closed, so very little fuel and air are being drawn in to the cylinders. This small amount of combustible mixture burns very quickly, so for maximum efficiency, the spark needs to start when the piston is very near top dead center. If the spark comes too early (too advanced), the pressure from the ignited mixture will hit the piston while it is still coming up the cylinder and be wasted trying to shove the piston down before it reaches the end of it?s travel. If you try to start an engine whose ignition timing is too advanced, the starter will try to turn the crank one way, and the combustion process will try to turn it the other way, and it will seem as if the starter hasn?t enough oomph to start it. Contrariwise, if the timing is set too late (too retarded), the pressure from the ignited mixture (and the power derived therefrom) will dissipate as the flame front chases the piston down the cylinder bore in the rapidly diminishing pressure of the combustion chamber. In other words, the piston is already on it?s way towards the bottom of it?s stroke, reducing the effectiveness of combustion. The is very fuel inefficient, since a larger throttle opening at idle (set by the idle speed screw) is needed allow extra fuel in to keep the engine idling. In practical terms, the position of the distributor which yields the highest idle speed is within a very few degrees of where it should be set. (If you retard the timing about 5 degrees from this point, you will be awfully close to spot-on.) Of course, this assumes your carburetor (or F.I.)is working well and that the idle mixture is correct.

 

[Maclin]

Re: Could Bad Timing cause hydro/vaporlock

That is an explanation of why an engine must have the distributor timing set correctly.

Hydrolock occurs when enough PURE LIQUID is in the cylinder and resists compression enough to cause the motor to not turnover with the starter. Water does not compress as well as air and the symptom resembles a siezed engine. Actually it is a good thing when an engine will not start with this condition because if enough power to turn the engine is applied or the engine catches from the other cylinders firing just before the water filled cylinder tries to compress then when it does hit the compression stroke the connecting rod bends from the force.

As for the original question as posted..."Could Bad Timing cause hydro/vaporlock" The answer is no.

If the timing is off then it will 1.) start hard and try to kick back and knock if it is too far advanced, or 2.) not start very well at all if it is too far retarded. Neither one of those conditions is ever called vaporlock or hydrolock.

 

[joseph.signore]

Re: Could Bad Timing cause hydro/vaporlock

Maclin thanks for your explanation... Im slowly learning. Whatever it may be called. Dose the cla-plunk noise sound the same as hydrolock?

 

[Maclin]

Re: Could Bad Timing cause hydro/vaporlock

A ca-plunk noise from a hydrolocked engine while trying to start usually means the rod just bent. Hydrolock is just that, the engine cannot turn over with the starter and acts like it is locked up. It sounds like your engine turns over ok. I cannot guess what the noise might be, I would have to hear and feel where it is coming from to get any kind of clue.

 

[thumpar]

Re: Could Bad Timing cause hydro/vaporlock

Hydrolock is when the cylinder is full of liquid, usually water and when you turn it over it will not turn at all or turn a little bit then stop. Liquid will not compress so the cylinder cannot move up any more.

Vaporlock is in the fuel supply. The fuel can get hot enough in the line to vaporize and prevent liquid fuel from getting into the carb. My dad explained this one better but that is how I remember it.

 

[joseph.signore]

Re: Could Bad Timing cause hydro/vaporlock

Thanks Guys!!!

After adjusting my timing the problem is gone. The advance must of been kicking my starter back on cold start-up. The boat runs great....

THANKS TO ALL!!!

 

[Maclin]

Re: Could Bad Timing cause hydro/vaporlock

Good deal