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Poor Cranking? Check Your Solenoid!

Ironflight

Ironflight

VAF Moderator / Line Boy
Mentor
With close to 1600 hours on the Valkyrie, it is no surprise that some of the original components might be ready for replacement. For the past few months, I have noticed some intermittent starting (actually cranking) issues on some flights. I remember a few months back when I hit the starter switch, and got nothing but a ?click?. But when I tried it again, it cranked fine?.so I kept an eye on it, and kept flying. Occasionally, the cranking seemed slow?but then it got better. Again, I watched it. Just before this current trip, I gave a call to SkyTec to see what they thought about the performance of the starter, and they (rightfully) said that they have had great luck with the Flyweight installed on the airplane, and that they would be happy to go through it if I sent it in ? but they bet it would be fine.

Well sure enough, it worked just fine all the way to Oregon ? and then on the ramp at Aurora, all Louise got was that ?click? ? over and over. SHe and Joe rolled it in to the Van?s hangar, and we pulled the cowl. I grabbed a piece of hinge pin and bent it into a ?U? shaped jumper wrapped it in a rag, and jumped across the solenoid terminals ? and got the best cranking prop I?ve seen in a long time! Now seeing as I was sitting in the mother ship?s hangar, I had a hunch that it might not be hard to find a brand new starter solenoid?.and I could even save on the shipping! Sure enough ? Daryl had one in my hands by the time I had pulled the old one, and we were putting things back together in no time. I can?t say enough good things about the ?magic door? in the back of the Van?s hangar. Rap on the door and say ?1/2 box end??and one magically appears?. ;)

The Prototype Shop guys seem to have a good life!:D

I saved the old solenoid, and will do an autopsy on it when we get back to Houston ? I expect to see burned and pitted contacts providing a high resistance. Pictures when I have them?. In the meantime, if you have a lot of starts on your system, and you are experiencing problems, it might be a good time to suspect the solenoid- they are actually pretty cheap!

Paul
 
Solenoids are an often overlooked source of problems. They "usually" give some warning signs of an impeding failure such as slow cranking like you experienced or intermittent operation (you will see this when you first activate the relay and nothing happens, it takes a second or third time of activating it to get it to work).

I also replace these in pairs, if the master or the starter relay fail, I replace them both. These are relatively inexpensive parts that play a critical role in aircraft operation.
 
Is the a better than average chance that my "one blade, then it just stops for a second or two, then multiple blades and start" - is solo iod related ? I've already changed the battery.
 
Why bother with an external starter solenoid when there's one built in the starter. A few millohms of resistance at 350A equates to a drop of several volts across the circuit. So what if the starter cable is hot all the time, its hot to the starter solenoid. As long as the cable is supported correctly it will never be a hazard.
 
rocketbob said:
Why bother with an external starter solenoid when there's one built in the starter. A few millohms of resistance at 350A equates to a drop of several volts across the circuit. So what if the starter cable is hot all the time, its hot to the starter solenoid. As long as the cable is supported correctly it will never be a hazard.
Click to expand...

Agree. Requires a switch rated for 20+ amps or a relay, but it works great. I use a rewired Skytec NL series, with a 30 amp automotive relay triggered by a start button (with hidden cutout) on the stick.

http://www.skytecair.com/Wiring_Diag.htm
 
Tighten the connection

It is important when you tighten the nut on the stud, that you back up on the locking nut so the stud does not turn. The connection inside the solenoid is two flat surfaces and if the stud turns you loose that good connection.
 
Follow-up ? the Post-Mortem

First, I tend to agree with the guys who say that we should think about doing away with the starter solenoid, now that we are all using non-Bendix starters. Heck, Sky-Tec actually comments on their page that they don?t know why Van?s still show them on their drawings. Well, some habits die hard?.and rewiring takes time, so maybe I?ll get rid of mine someday. In the meantime, here are some autopsy photos:

This is the solenoid with the top ripped off. Looks Ok from this vantage point:

P1010787.JPG



Ahh?.but take out the plunger and take a look at the contacts! They are nicely pitted ? and not symmetrically.

barryrv10 said:
It is important when you tighten the nut on the stud, that you back up on the locking nut so the stud does not turn. The connection inside the solenoid is two flat surfaces and if the stud turns you loose that good connection.
Click to expand...

I think Barry hit the nail on the proverbial head!

P1010789.JPG



And here is the ?underside? of the plunger contact ? note the pitting, and the fact that it clearly rotates during its life:

P1010790.JPG



I cannot believe how much changing a $21 part changes the character of a 1500+ hour airplane! Whereas I was beginning to think I had to baby it on every start because it barely got over TDC, now I can once again practically taxi on the starter. The thing is, these go bad gradually over a lot of hours, so you just don?t notice how bad it is getting ? like boiling a frog. So if you have a slow starter ? think about changing your solenoid (or eliminating it). And remember, we have to put SOME parts in to keep the aviation economy going?

Paul
 
Thanks very much for the tear down report. I think I'll get that on the list of time limited replacement items.
 
Me Too

I KNOW WHAT I AM DOING THIS WEEKEND. For some time now, I have had slow turn over speed or not at all. Some times I have to turn the key several times to get through one compression stroke. I just replaced the battery, but didn't make any difference.

Steve
 
I replaced my starter solenoid a few years ago for some reason. It may have been a continuous duty type and the starter solenoid needs to be intermittent duty...or something like that.

A clarification of that could be useful for people like me who do not always know this technical stuff.
 
My SkyTec is still turning strong but I have suspicion I turned one stud a bit several years ago. Thank for autopsy and clear picture :)
 
At 750 hours starter solenoid quit

Starter solenoid quit on me in the middle of a wonderful weekend before a glorified crowd what a shame. :D It was still operational later but I had to knock on it or press the start button several times.


Autopsy revealed similar to Paul's problem here are Xrays
















A young Pepboys manager did a good job locating the right match. They don't know anymore how the relay looks and what it does. He asked me several times what kind of car is that and what year etc... if I knew. I showed him ACS analog on my iPad and he found something Ford like.






A bit of mismatch on mounting bracket but it works. Love experimentals!



 
Are you folk not using diodes to reduce the internal arcing in the contactor? Vertical Power has a good writeup on the issue here.

Also, I replaced a battery last year due to poor starting but saw no improvement. Investigation revealed that the stud at the starter had broken free and the starter had to be repaired. If you're having starting problems, check the entire circuit.
 
flion said:
....Also, I replaced a battery last year due to poor starting but saw no improvement. Investigation revealed that the stud at the starter had broken free and the starter had to be repaired. If you're having starting problems, check the entire circuit.
Click to expand...

I agree completely. In 2011 I had a starting problem and replaced the battery. Didn't do any good. I then removed every connection from the battery to ground and through the relays to the starter. I found some corrosion on almost all of them. I wire brushed everything, put on new washers and nuts, and everything has been fine since.

The old battery? Since it was still good it is now in the Panther airframe, working perfectly!
 
flion said:
Are you folk not using diodes to reduce the internal arcing in the contactor? Vertical Power has a good writeup on the issue here.
Click to expand...

The diode suppresses the arc generated by the collapsing magnetic field of the relay coil, it protects the switch contacts that activate the coil not the main contacts.
 
While the "a piece of hinge pin and bent it into a 'U' shaped jumper wrapped it in a rag, and jumped across the solenoid terminals" sounds completely doable, can someone suggest a safe[r] test for a single-person shop ?

I have a suspicion I may be suffering this symptom but I am not completely comfortable holding onto a 'U' shape of hinge pin :confused:
 
humptybump said:
While the "a piece of hinge pin and bent it into a 'U' shaped jumper wrapped it in a rag, and jumped across the solenoid terminals" sounds completely doable, can someone suggest a safe[r] test for a single-person shop ?

I have a suspicion I may be suffering this symptom but I am not completely comfortable holding onto a 'U' shape of hinge pin :confused:
Click to expand...

You can always do it the way SkyTec woudl like you to - connect a voltmeter across the terminals and check the drop while cranking. Of course, you'll have to do some rigging to get the wires clipped on and the meter mounted so that you can see it while cranking if you want to do it alone. You'll get more precise data that way!
 
Thanks Paul. I can definitely manage the volt meter method. I'll be pulling the cowl to check a few other things next weekend and will as this test to the plan.
 
Vlad said:
A young Pepboys manager did a good job locating the right match. They don't know anymore how the relay looks and what it does. He asked me several times what kind of car is that and what year etc... if I knew. I showed him ACS analog on my iPad and he found something Ford like.
Click to expand...

In a pinch that will work but I prefer something like this to the "economical" version from PepBoys (china).

http://www.aircraftspruce.com/catalog/elpages/solenoidx610030.php

or

http://www.bandc.biz/bandcstartercontactor12v.aspx

07-01875.jpg
 
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Ironflight said:
First, I tend to agree with the guys who say that we should think about doing away with the starter solenoid, now that we are all using non-Bendix starters..............so maybe I?ll get rid of mine someday
Click to expand...
Paul
I just starting to wire my -8. Can you point me to a reference on how to eliminate the starter solenoid? I'm intrigued and willing......
Thank you
 
I used a ford starter contactor for few years and about 1700 hrs.on my s7, they are a good alternative,if that is not what Vans is actually selling, they do look alike. Can't remember which car it came off of though.

Bird
 
Vlad said:
Starter solenoid quit on me in the middle of a wonderful weekend before a glorified crowd what a shame. :D It was still operational later but I had to knock on it or press the start button several times.

Autopsy revealed similar to Paul's problem here are Xrays

Click to expand...

Next time grab the drill and not the hammer. Drill out the four rivets and lift out the plunger and look inside. You will see the problem, and it can be fixed in minutes, on the spot. And four little screws and nuts will have the sol cover back on and ready to go. You can clean the contacts with a knife or sandpaper. And you can rotate the studs back to make good contact.

These have a 20+ year life span if installed without rotating the stud. The nut that is on the stud is there to hold the stud in place. You must use another nut to secure the eye of the wire. Use a wrench to hold the inside nut in place as you tighten the outer nut. Do not rotate the stud. But you already know that.
 
bird said:
I used a ford starter contactor for few years and about 1700 hrs.on my s7, they are a good alternative,if that is not what Vans is actually selling, they do look alike. Can't remember which car it came off of though.

Bird
Click to expand...
30 years of reliable engine starts; about 3,000 hours on my LongEZ/Ford solenoid. Spruce was selling 'em for about $8 then. If/when it breaks I can replace it at NAPA.
 
Add another starter solenoid to the pile ...

20140615-171130-61890390-575x431.jpg


Only 310 hours on it but it's been hurting for about 100 hours.

I'll do as Walt suggested and swap out the master solenoid for good measure.
 
Good thread

Just had issues starting, occasional nothing on first key turn, turn again and starts fine type of issues...then just nothing at all. No buzz or click or anything. Solenoid was the issue $30 fix. Funny issue in that new solenoid case did not ground. Seems always something to learn, small ground wire. Life is good again. Got 500hrs on first. Just glad it didn't go t/u on a trip!
 
580 hrs

I had to change out my starter solenoid this year with 580 hrs on it. I changed batteries, got a different battery charger then finally then fnally pin pointed it to the solenoid. WOW what a difference. Now it cranks over like it did when new.
 
Could a faulty solenoid result in Voltage to drop to 6 or so Volts during engine cranking?

I am experiencing slow cranking and have been for a while. In the summer it does start (although slow/weak cranking), but in the winter, no way. I have changed starters (from automotive to skytec LS) and have changed the battery. I also changed the negative/ground from the battery (was 4 ga now 2 ga). I took my battery to a autoshop and it tested ok. My voltage at the battery with no load is 12.65 volts. When I turn my master on, the voltage reads 12.1 on my Dynon.

When I crank the engine, the voltage reading on my Dynon shows the Voltage quickly drops to 6 or so Volts and the prop blade won't go through the compression stroke. Same result on both starter and battery configuration.

When I connect a battery booster to the battery, it starts quite nicely. I'm not convinced it's not a battery issue as my replacement battery was not a brand new one. I'm just wondering if these symptoms could point to a faulty solenoid as well.
 
You should measure the voltage drop across the terminals of the solenoid. That will confirm a solenoid issue. Voltage is typically tapped at, or near the battery, so unless it is on the starter side (not likely) you will probably find it is the battery in your particular situation. Meaning: the voltage is low to the starter contractor, so it would be the battery.
 
I haven't had a chance to check for voltage drop at the solenoid yet but I did take a picture before I left the hangar so I could reference it while I did a little research. It looks like my starter solenoid is similar to the vans one. The two larger terminals with the two smaller ones. One of the smaller terminals is connected to the ignition switch, and the other smaller terminals has two wires connected, one wire connected to the firewall grounding location and another wire connected to the negative on the battery. I notice that wiring diagrams don't mention to connect it to the battery but in my mind, I think due to how close the starter solenoid is to the battery, the previous owner made that redundant connection. Correct?
 
Small Post Markings

Are the two small posts marked? If yes, are they marked S & I? If yes, your wiring may not be correct. If you have that type of contactor, the S post is the "switch" post and gets the 12 vdc input voltage to energize the coil, ground is through the steel mounting "T" at the end of the case. The "I" post is the ignition post and receives 12 vdc when the coil is energized and then, during the start cycle, provides 12 volts out at that post. This style of contactor was designed way back in the 1950's when automotive ignition systems required a coil to generate spark through the distributor contacts. The "I" post supplies battery voltage to the coil during the start cycle for this purpose. If your contactor is of this style, when you ground the "I" post, thinking it is the ground, what happens is that the wafer shaped copper strap that connects the plunger to the "I" post becomes a fusible link and is (almost) instantly vaporized - so now the "I" post has not function whatsoever, essentially the ground strap to nowhere. All this is being masked by the contact of the mounting "T" with the firewall (or whatever metal surface it is attached to) to provide a ground source to complete the coil energizing circuit.

You can confirm for yourself the functions of the two posts with the use of a multimeter. With the coil not energized - you should get continuity between the "S" post and the steel mounting strap. There shouldn't be continuity between the "S" & "I" posts. With the coil energized there should be 12 vdc between the "I" post and the steel ground strap - if the copper wafer connector strip inside the housing has not been comprised.


If you don't have the the ignition style solenoid, then all above is only good for reference.

YMMV

HFS
 
After reading Paul's original post, I had bought a pair of solenoids (Master and Starter) with the idea that I would replace them when I started having starting issues.

Well, a few months back at 641 hours, I had the same slow starting issue described in this thread.

After replacing both solenoids, I pulled the plane out of the hangar and pressed the starter button. Same slow prop turning problem as before. What???!

After thinking about it a little bit, I removed each of the big power leads, gave them a light sanding with some 1500 grit sand paper, and put them back on.

Then when I hit the starter, the engine cranked right over.

Lesson learned! Check the simple stuff first.

I still have the old solenoids on the shelf as an emergency backup.
 
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If you install your big load connections using dielectric grease, it will make an oxygen free connection and eliminate this problem...... check with a electric utility lineman.

Can be used on any size connection.
 
Solenoid problem

I have never been happy with how my 8a cranked over when I turned the key. The battery is behind the baggage compartment and wondered if positive wire was too long? I turn the key and engine might partially turn over and stop. Always figured it was high compression. Turn key a second time and engine would turn over but not what I would consider fast, like a car. Will look at the part.

Allan, 8A waiting for 3rd class medical elimination or I am going to start building an RV 12.
 
FWIW, SkyTec PM, LS, and HT starters don't actually require a start solenoid. There is a positive and a negative to eliminating it.

The positive is having one less set of contacts adding resistance to your high amperage circuit. It is a big deal...consider "amps delivered = volts/resistance". As Bill demonstrated, it takes very little additional resistance to drive amps way down, and amps spin the starter.

The negative is having a live high amperage cable running alongside the vibrating/moving engine all the time. Cable routing and fixation must be excellent, or there is a risk of the cable's insulation being damaged, creating a very big short circuit. The issue is mostly one of craftsmanship.

http://www.skytecair.com/Wiring_Diag.htm

NL inline mod:

http://www.skytecair.com/images/PDF/Rewiring NL Solenoid.pdf

I use a re-wired NL, triggered with a 30 amp automotive relay, activated with a low capacity cockpit switch.
 
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Solenoid part number??

Anyone got that AutoZone/NAPA/Pep Boys part number for that "Ford" solenoid now residing on their firewall?
 
HFS said:
Are the two small posts marked? If yes, are they marked S & I? If yes, your wiring may not be correct. If you have that type of contactor, the S post is the "switch" post and gets the 12 vdc input voltage to energize the coil, ground is through the steel mounting "T" at the end of the case. The "I" post is the ignition post and receives 12 vdc when the coil is energized and then, during the start cycle, provides 12 volts out at that post. This style of contactor was designed way back in the 1950's when automotive ignition systems required a coil to generate spark through the distributor contacts. The "I" post supplies battery voltage to the coil during the start cycle for this purpose. If your contactor is of this style, when you ground the "I" post, thinking it is the ground, what happens is that the wafer shaped copper strap that connects the plunger to the "I" post becomes a fusible link and is (almost) instantly vaporized - so now the "I" post has not function whatsoever, essentially the ground strap to nowhere. All this is being masked by the contact of the mounting "T" with the firewall (or whatever metal surface it is attached to) to provide a ground source to complete the coil energizing circuit.

You can confirm for yourself the functions of the two posts with the use of a multimeter. With the coil not energized - you should get continuity between the "S" post and the steel mounting strap. There shouldn't be continuity between the "S" & "I" posts. With the coil energized there should be 12 vdc between the "I" post and the steel ground strap - if the copper wafer connector strip inside the housing has not been comprised.


If you don't have the the ignition style solenoid, then all above is only good for reference.

YMMV

HFS
Click to expand...

Thanks HFS. I will crawl under and look for the S and I. I know that aircraft spruce sells a solenoid with 2 small posts where the one of the posts is for the starter and the other is for the ground. I've had the airplane for 5 years and bought a new battery shortly after I purchased it due to weak starts. I did see a slight improvement but it never started like I thought it should, and the winter months (-10 F) with preheat were always a struggle.

With the research and reading I've done on the Forum, it seams like it could be any or a combination of a weak battery, dirty / corroded contacts, high compression cylinders, a wood prop, a permanent magnet starter (skytec LS), degraded solenoid.

Here is a question...I brought my battery again to get tested. The battery temperature was about 20 F and the results were 170 CCA. Now, the Oddysey website and other websites that sell the battery list it as 170 CCA but on the battery itself it says 220 CCA. Is this battery shot or not? In the summer, the plane starts. Although it's still not what I would consider very strong, but the warmer battery is producing more cranking amps (or enough cranking amps).

Even if it came in at 220 CCA, another thread in here says that the Skytec LS starter draws 320 amps so maybe it's just not going to happen.

What I do know though is that if I connect a battery booster pack to start the aircraft, it starts nicely. But the booster has 500 cranking amps.

Either way, whatever I need to order will only arrive 2 weeks after I order it so I guess I'm deciding whether I buy a new battery and see or if I buy a new wire wound starter, or both.....and clean contacts.
 
Battery sounds ok.

The skytec LS starter will always make the situation worse due to the very high current demand of the permanent magnet design. I would still check all the connections, cable crimps and replace the relay (cheap and easy). If that doesn't fix I'd replace that starter with a good wire wound unit.
 
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FWIW

I just recently purchased the starter solenoid from AC Spruce (P/N 11-03162) as part of my "fact finding" mission. I wanted to see what they were selling and how it was being represented via a wiring diagram. What I found out - the unit I received was a "Ford" type solenoid that I described in an earlier post. There was no wiring diagram. Without prior knowledge about the "I" post being for the ignition coil during starting, and thinking it to be the ground post to complete the coil energize circuit - I can see how it could easily be incorrectly wired. As long as the unit was bolted to something that carried the return load back to the battery, and the "I" post now "non-op" (if wired as ground - connector ribbon severed internally), the contactor would operate as advertised, but under false circumstances.

In all fairness to AC Spruce - I may have gotten an incorrectly identified part (maybe) from the factory where they are produced. But the unit I took apart for testing (not from my airplane) came from them and was an "I" type contactor and the one installed to replace the test unit was also a "Ford" type. If they are selling this style, I think there should be some sort of wiring diagram to help clarify what everything does. Sometimes what you see is not what you get.

YMMV

HFS
 
Solenoid Part Number

Cole-Hersee, a long time manufacturer of contactor products, sells this item under part number 24021 and is listed as "12V Resistor Shorting Solenoid".

Hope this helps.

HFS
 
Crank73 said:
Thanks HFS. I will crawl under and look for the S and I. I know that aircraft spruce sells a solenoid with 2 small posts where the one of the posts is for the starter and the other is for the ground. I've had the airplane for 5 years and bought a new battery shortly after I purchased it due to weak starts. I did see a slight improvement but it never started like I thought it should, and the winter months (-10 F) with preheat were always a struggle.

With the research and reading I've done on the Forum, it seams like it could be any or a combination of a weak battery, dirty / corroded contacts, high compression cylinders, a wood prop, a permanent magnet starter (skytec LS), degraded solenoid.

Here is a question...I brought my battery again to get tested. The battery temperature was about 20 F and the results were 170 CCA. Now, the Oddysey website and other websites that sell the battery list it as 170 CCA but on the battery itself it says 220 CCA. Is this battery shot or not? In the summer, the plane starts. Although it's still not what I would consider very strong, but the warmer battery is producing more cranking amps (or enough cranking amps).

Even if it came in at 220 CCA, another thread in here says that the Skytec LS starter draws 320 amps so maybe it's just not going to happen.

What I do know though is that if I connect a battery booster pack to start the aircraft, it starts nicely. But the booster has 500 cranking amps.

Either way, whatever I need to order will only arrive 2 weeks after I order it so I guess I'm deciding whether I buy a new battery and see or if I buy a new wire wound starter, or both.....and clean contacts.
Click to expand...

A picture is worth a thousand words, but, DATA is worth a thousand DOLLARS. Measure the voltage drop across the solenoid, and connections. Battery to starter.
 
I'm just trying to get all my ducks in a row for a productive troubleshooting weekend.

Can I trouble one of you guys to give me a Lehman's explanation on how to check voltages across the start circuit? Where do I take the readings from? Positive lead on the positive post and work my way down the circuit with the negative lead? I assume I have to check voltages while engaging the starter? It's -20F here and my aircraft is not in a heated hangar. I'm a little reluctant to hammer on the starter many times on a cold engine. I do have an oil pan heater but I would prefer the engine eventually starting to warm it up and cycle oil.
 
Skytek has a great troubleshooting picture and verbage on their web site. It shows step by step where to place your voltmeter probes.
 
Disconnect at the starter and connect something else that is 12V and draws a load (like a landing light or something). Engage start solenoid and volt check the big solenoid terminals to ground. The downstream side should be within one or two tenths of the upstream side.
 
Great idea with the headlight instead of the starter. Here are my results which lead me to it being frikken cold (lower cranking amps), a wood prop, and a permanent magnet type starter.

Battery Voltage with everything off - 12.3
Battery Voltage with Master on and Dynon D10A and MicroEncoder ON- 11.7
Battery Voltage with Starter engaged- 11.55
Battery Voltage at Starter with Starter engaged- 11.4

So that's a 0.15 Volt drop across the Starter solenoid.

Should I expect lower voltages if my starter is connected vice the headlamp because there is more resistance. With the battery, I was seeing 6 Volts or so at the battery.

Will a wound starter (instead or permanent magnet) make a world of difference.

Maybe a new wound starter is the way to go.
 
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