Blown stator on 1982 90hp v-4

[baiwan]

Can a blown stator cause the following:
a. no charging
b. double reading on tachometer on board and a tach on the spark plug leads(1500 rpm instead of 750)
c. ignition timing trouble.
I face these three problems and found only this fault.
I wonder what could lead to stator damage, could it be a damaged volt regulator and how I can check mine without the engine runnuing?
Has any one come up to things like that?

 

[Rory140 V4]

Re: Blown stator on 1982 90hp v-4

IMHO, sounds more like a faulty rectifier than stator and for the tacho check if it is set for the number of cylinders you have?

 

[emdsapmgr]

Re: Blown stator on 1982 90hp v-4

The factory service manual describes test procedures for the stator, both volt and ohms. A bad rectifier causes erratic/incorrect tach readings and may not recharge the battery properly.

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

Rectifier is ok, I checked it.
Stator has deformation with cracks at two opposite coils.
I checked with a seperate device on spark plug wires and have double rpm metered there compared to readings of a mechanical rpm meter on flywheel.
I have serious ignition problems and change of timing doesn'f effect much.
It seems there are double sparks or something messing up ignition.
Engine knocking higher at higher r.p.m : no mechanical cause.
I worked a couple of days to find a blown stator.
I think the magnetic field is changed where the blown coils and fools tach and ignition - is that possible?

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

Resistance of stator (yellow leads) is less than 1 ohm.
Ignition coils (brown leads)on stator are ok.
I know the stator is blown, I asked if it could lead to said trouble (specially ignition trouble)?

 

[jonesg]

Re: Blown stator on 1982 90hp v-4

Can a blown stator cause the following:
a. no charging
b. double reading on tachometer on board and a tach on the spark plug leads(1500 rpm instead of 750)
c. ignition timing trouble.
I face these three problems and found only this fault.
I wonder what could lead to stator damage, could it be a damaged volt regulator and how I can check mine without the engine runnuing?
Has any one come up to things like that?

yeh, double firing might be why the tach is showing it going very fast,
shorted isolation diodes ( if yours has them) can cause continuous firing, could also be bad power pack on later models anyways.

Sounds like the stator is toast anyway ...if you did the proper troubleshooting.

 

[CharlieB]

Re: Blown stator on 1982 90hp v-4

The stator may be bad, proper testing with a DVA Meter will verify that.

The tach problem is NOT caused caused by the ignition system, the tach is strictly alternator driven, counting the pulse of the charging coils from the stator. Usually and erratic tach is caused by a dying diode in the rectifier.

The ignition double firing is a serious problem and left uncorrected will cause piston and cl damage. Usually double firing is caused by a fault ignition module Firing one cyl while also firing the other cyl. Verify this with a timing light, and/or an inductive tach. As for possible damage, if left unrepaired the second spark will cause that cyl to run lean, soon to cause major damage.

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

I have:
1. Toasted stator
2. Double RPM on tacho
3. Double RPM on all cyllinders - double firing.
Could it be possible the stator is causing the trouble?
Rectifier is O.K. (damaged rectifier lowers RPM twice - I had that experience)
I checked timing with timing light - fine on left and right hand side cyllinders.
Switched power packs: left to right and v.v. - no change.
I think that toasted stator cheats tach, and power packs and causes double fire?
Gone coils on stator mess up magnetic field and signals in power pack?
Does this sound possible?
I only have not checked voltage regulator, could it be possible reason for stator blowing?

 

[daselbee]

Re: Blown stator on 1982 90hp v-4

Resistance of stator (yellow leads) is less than 1 ohm.
Ignition coils (brown leads)on stator are ok.
I know the stator is blown, I asked if it could lead to said trouble (specially ignition trouble)?

Just to be sure...a resistance of less than one ohm between the two yellow leads is normal on a good stator. Should be about .4 ohms, but that low a resistance is hard to measure without a very good meter.
Both yellow leads should be open to ground.

 

[ezeke]

Re: Blown stator on 1982 90hp v-4

The most common damage to the stator is from a rectifier with bad diodes allowing the battery voltage to flow to the ignition.

When you replace the stator, replace the rectifier as well.

It sounds like you may have sheared the flywheel key. Sure you torqued the flywheel to spec?

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

It seems you don't understand me.
I have checked every thing the routine way, except the voltage regulator.
I have two blown coils on stator - cracks in resin indicate that.
Can damaged coils on stator influence tacho and ignition by disturbing magnetic field, or I should replace power packs as well.
I checked rectifier by metering resistance both directions.

 

[CharlieB]

Re: Blown stator on 1982 90hp v-4

A rectifier diode can test fine with a low voltage as in most Ohms Meter, and yet fail at higher voltages and loads in use.

Remove the stator wires when testing rectifiers, leave the battery connected, touch post on the rectifier with a test light, if either stator post on the rectifier lights the light, then the rectifier is bad.

I am trying to understand how a stator could cause a double fire. The stator simply charges the cap in the box, it is the scr that is switched to signal the discharge by the trigger.

The old Force black boxes had a bad habit os developing a double fire on one of the pair the box controlled. The SCR would go bad, switching one cyl then BOTH then the first again, then BOTH.

I could see this happening on ONE BOX but I seriously doubt TWO at once. Not impossible but very improbable. UNLESS there was an outside voltage source (like switched battery cables for a heartbeat) or pulse that came in on the kill wire and damaged BOTH boxes. In which case I would be double checking that ignition switch to be certain that it cannot happen again.

Lastly, the epoxy potting on stators has a terrible history of melting, cracking from thermal expansion, yada, yada, yada. If the stator passes DVA Voltage tests I wouldn't worry about it, yet. If the stator will NOT pass DVA Test, then by all means, replace it.

If you do not have access to a dva meter you can cheat.

WARNING, Never, Never, NEVER< EVER attempt this test on a trigger, you WILL smoke it.
Disconnect the stator leads from the box.
Connect one terminal(winding set)to the battery ground
Connect the other terminal to your test light
Connect the test light ground lead to battery +.
The light lights and remains lit, that stator winding is probably good.
A broken winding will NOT keep a test light lit. Period.
Disconnect the stator winding from ground, retest BOTH stator leads with the charged test light, any light and the winding is shorted to ground. (BAD)
Repeat with each set of stator windings.

Actually triggers may be tested similar to this but only using a single flashlight battery and bulb (1 & a 1/2 volt)

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

Stator coils are eight, parallel connected I guess, if there is one, two or four coils blown, there is no way to get it by metering.
Burnt coils might change magnetic field and effect power pack power supply.
This I thing happened to my motor.
There is:
1. No battery charging;
2. Double reading on tacho;
3. Double firing on all cyllinders.
Similiar trouble one source - stator.
I have checked every thing else, except voltage regulator which is a separate unit from rectifier (two seperate boxes) but regulator can't influence tacho nor ignition.

 

[CharlieB]

Re: Blown stator on 1982 90hp v-4

The stator is actually THREE sets of winding coils, each set independant of the rest, all sharing a common steel frame and the rotating magnetic field of the flywheel.

Charging coils
Lowspeed coils
Highspeed coils

A voltage regulator MAAY influence the field within a stator in that the ouput voltage set point of the regulator IF failed and NOT operating, not charging......

Disconnect regulator AND rectifier and retest for spark.

Did you test stator conductance as I spelled out how to use your test light?

This is a very visual proof of a failed stator.

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

I did the said test. Stator shows no short to ground.
its resistance is less than 0.5 ohms coating broken on two opposite coils,
I put a working transformer to create magnetic field in front of each coil
there was reading on the ignition coils - some 18 V and no reading when I tested the charging coils. Befor removing stator I ran motor with disconnected rectifier and regulator - ignition still bad, and no readings on the tacho, I tested rectifier + to both yellow wires one by one - normal one way a little resistance and open the other way, the same with the ground.
I didn't check regulator, because I couldn't find where the purple wire goes and how it operates. I think the purple wire goes to ignition key and to plus when switched on and when voltage rises yellow wire consumes power from stator to reduce voltage, but I am not sure.
I intend to change stator and check up every thing again, unless someone who had this problem gives a hint.
What do you think?

 

[daselbee]

Re: Blown stator on 1982 90hp v-4

With so much crap flying on this thread, I think I will add my crap too!

How about this: Disconnect the two yellow stator wires, and wire to a house lamp with a 100 watt bulb in it. Use alligator clips, or some method to attach the lamp to the stator yellows.
Start the motor, the bulb will glow dimly if the stator is outputting on the alternator coils. It should be about 30v AC if you want to measure it. Well, it is that voltage on my V6 loopers.

How about that crap?

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

Stator is blown, It's off the motor and I'm looking for a new one. I want to check V-regulator; the lamp won't do; I have a DVA is that sufficient to check up regulator and how?
I want to make sure I won't blow the new one.
If I manage with that, I''ll go the routine way to improve ignition.

 

[daselbee]

Re: Blown stator on 1982 90hp v-4

Biawan you have a PM.

 

[baiwan]

Re: Blown stator on 1982 90hp v-4

Thanks. When I'm angry I stutter.

 

[wilde1j]

Re: Blown stator on 1982 90hp v-4

Rectifier/voltage regulator is very easy to check once you're sure the stator is OK (normal test for stator is to check for AC voltage across yellow leads with motor running (> than 25 VAC is OK). If you have that established, just measure DC voltage across battery terminals with motor at a fast idle. You should get 14 VDC +. If + or < 12.7 VDC, the rect/reg is cooked.

The above assumes all wiring is correct and you have good terminations.