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New (to me) Supercub... Running hot? Charging issues too

Find a brand/model on the alternator & reg. and it will help with troubleshooting. Alternator doesn't narrow it down much.

Assuming a digital voltmeter?

Web
 
Find a brand/model on the alternator & reg. and it will help with troubleshooting. Alternator doesn't narrow it down much.

Assuming a digital voltmeter?

Web

No, it's an analog gauge. I'll get a name off the alternator tomorrow. Thanks. Supposed to be -2 in the morning. I sure won't be flying it! Ordered my insulated covers and reiff heater today.

JP
 
Before you adjust the voltage, verify bus voltage with a digital voltmeter. Then, if adjustment is needed, set it while monitoring voltage with the digital unit. Analog is NOT accurate enough for this.

Web
 
Did you ever say what type of battery you have? I use B&C alternators and regulators in both planes. With the Odyssey the voltage is 14.4 99% of the time. It shows 14.5 the other 1%. With the EarthX I see 14.1. My batteries seem to be happy in both cases.

What engine monitor are you using? Just curious. In my engine monitor experience I haven’t had probe accuracy problems. Connections? Yes, but that’s all or nothing. Testing probes on old analog temp gauges was common. I don’t know anyone who does it with digital instruments. Swap a probe to validate, maybe, but that’s it.

1300-ish EGTs sound normal. The only CHT that’s high is #3. It looks like you’re getting it straightened out.
 
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It's an odyssey. New one now.

Engine gauges are non powered. has a rotary switch with 1 thru 4 for each gauge. CHT and EGT

JP
 
You’d probably be a lot happier with digital.

I agree. Looks like 7 or 800 for a single gauge that would do all of what 4 gauges are doing now. It's on 'the list' but it's down a ways. I'm thinking Pmags is higher priority. Skis, Reiff are bought and going on in a couple weeks. After that.. I'll see where I'm at. Woke up to 0 degrees. Will take my dad for his first ride today when it warms up.. a bunch!

JP
 
Pmags are pretty cool. I love how they're timed!

Enjoy the cold air performance but watch the cold air mixture until you get this thing sorted out. :) You do have a CO detecter, right?
 
OK.. some answers.

Analog gauge for voltage isn't worth much. What looks like 15+ is really right on 14.5

This came down shortly after start. However.. while monkeying around with it.. (loading up with lights and such) I routinely saw just 11.5V. I could shut off the field current with the left half of the master, and it would slowly come down on voltage.

I guess I was surprised that 1500rpm was not holding steady voltage at 12+ . It seemed sporadic as to if it was charging or not.. load or not. At times it would go back to 13+ . but the behavior wasn't predictable. I took pictures of the components. I'm guessing that the voltage regulator is incorporated into the alternator? When the cowl is off, I can get some better images. I'll share some other stuff in a different post. Thanks Much

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As for temps. I made it a point to fly out faster. 60 to 70kts. This kept #3 down into the 450 to 460 range at full power. This was yielding right at 2500rpm.

Cruising around.. 1, 2 and 4 were all in the 350 area. 3 stayed around 395 to 405

EGT are suspect. Most of them are in the 1300 to 1400 range. #3 was 1500 to pegged 1600+... however.. when messing with the selector switch, I would occasionally see it bouncing around in the 1300 to 1400 range... not steady, literally bouncing.

As for mags... I got a close up picture. Hard to read the tag. However... what I could see said made in Sidney NY.. which makes them bendix I believe.

On the plus side.. Gave dad a ride for the first time in it. Saw a bald eagle just taking off in a field. I could tell it had a real big wingspan. I turned around to see where it was headed, and it had perched in a tree top, along with a second one. Cool sighting.

JP
 
Your charging system is failing. Could be as simple as needing brushes but I suspect the regulator. Voltage should be much, much more stable. Right after startup it's common to see the voltage a few tenths of a volt lower than normal. This is because the alternator is trying to recharge the battery along with running anything else that happens to be turned on. Otherwise you should see 14.2 volts, +/- .2 volts. That's ideal. Anytime you see 12 volts or less, you are running on battery only and your alternator is not working. Have you checked for good connections on the alternator? Do you have a brand/model?

Web
 
No brand/model I can see currently. If I have to pull the lower cowl... I might just as well pull it for rebuild. Happen to have a local pilot that owns a shop. Last time I went in to get the snowcat alternator checked.. by the time we were done BS'ing.. He handed it back to me. I asked.. Is it good? He says.. It is now.. I rebuilt it, didn't even bother to test it.

Thanks.

With the realization I have Bendix mags.. My priorities I think have shifted from going to Pmags to getting a EDM350 engine display.

JP
 
JP11;734240With the realization I have Bendix mags.. My priorities I think have shifted from going to Pmags to getting a EDM350 engine display. JP[/QUOTE said:
When you check the mag timing, if it is off have the mags pulled and get the Egap checked and corrected. It's a quick job.
 
I think the charging system gave up today. After start, it showed the 14.5

That didn't last long.. and before half an hour it was down into just over 12.. which means it was really 11.5

They are going to pull the alternator when I'm gone next week.

JP
 
Ask them to do a 500 hr inspection on the mags.

Web
Oh my, yes. Your problems are nagging me to think that your aircraft spent a lot of time in the "if it ain't broke, don't fix it mode". I think you may have significant preventive maintenance items to catch up on. I like to avoid magneto failures that result from no maintenance.
 
What's the history of this setup, firewall/forward? You said in the first post that there's about 40 hours on this build? If so, what is the history of the engine? Used engine on a new built airframe? Overhauled engine? How about the mags, alternator, exhaust system, oil cooler, etc? All new or used?

If you need to replace the alternator, I highly recommend the Plane-Power stuff. Also make sure to replace the wire harness if changing out that old charging system. It's not much more effort than cobbing the old wires onto a new system and it eliminates any problems with old/crap wires.

Web
 
Web

It was an overhaul in 2008. Yes.. overhauled engine on a new built airframe. I wish he had kept receipts.. but it doesn't appear so. Log appears to say mags were overhauled then as well.

I had given up on the charging system.. as it APPEARED (I know.. with the crappy gauge) like it wasn't charging after I'd been flying it around for a while today.

I decided to start it later this afternoon.. and confirm that it really wasn't charging. Fired it up, right up to what I know now is 14.5v

Alternator and starter look new. Starter is a sky-tech.

Yes.. it does have just 45 hours on it now. Exhaust is new. I'm going to take a few pictures for 'what is it?' identification.

It's LOUD! like 127db according to the display on the garmin radio.

I think I'm doing a much better job of managing temps. If I let it accelerate to 60 to 70.. CHT on 3 is staying at 450 or under. Others about 100 less. Once cruising around.. #3 is just over 400.. and others 325 or so.

Oil seems to stay in the 120 to 150 range. You think I should put one strip of foil tape over the front of the cooler? I have the cooler mounted on the back of #4
 
You know, sometimes a little short or bad ground will make your charge circuit do strange things. Chase the simple stuff first to make sure you don’t bolt a lot of money on it to see it doing the same thing. I chased an intermittent alternator for years. It went away when the plane was re-wired. Nothing stood out as bad.
 
I never had good luck with tape holding on the rear cooler but give it a try. You can use thin washers to offset the cooler from the baffling and then make simple metal plate to slide between the cooler and baffling, I have a thin and wide one works great. If you have bendix bags they tend to be pretty bulletproof. I would just check timing, If number one is 325 you can try some metal tape 1 inch on front of cylinder to push more air back to number 3. Do you have a big hole above number feeding a scat tube to the muffler?
DENNY
 
I have a scat tube in front of 2 that feeds muffler. I was going to try a bit of foil tape on #1 to see if I can force more air up and over. Just using the eyeball, it seems like the block off plate is under half way up the jug. I've seen others with more 'ramp.' Mine is just a 90deg angle. I've bought some black silicone and will seal the aft baffle to the accessory case per Dan Dufalt's suggestion.

The mechanic wants to set the cooler back half to 3/4 of an inch, he thinks it ran hot in summer due to the cooler being up against #4.


As for chasing the wiring.. Being that it's so cold, and I just bought it. I haven't had much chance to just poke around it. I should have the datums in a few weeks, and when it's inside for that, I plan to address a few little things.

I'm learning a lot as I go.

JP
 
A bit of follow up.

I swapped the probes. #3 is still the issue. It's running about 50 hotter than #4. A short climb to say 1k feet that is keeping the speed down around 50 is yielding CHT in the 460 range.

It does cool of at cruise.. but it's always hotter than the others by 50. I'm still tweaking the baffling around that one.

Charging issue, isn't. Gauge reads a bit off. I think it pretty much charges right to 14.5 or so... checked with multi meter.

Loving the new Datum skis.

I've put 15 hours or so on it since I bought it. Not bad for winter. I'll keep digging on the CHT issue.

JP
 
Hopefully I’m not rehashing something that’s already been put to bed, but what do your baffles around #3 look like?

Where’s your oil cooler mounted? How’s the seal around your oil cooler if it’s on the cowling?

Google this: “CHT washer mod site:vansairforce.com”

I clearanced my baffles behind #3, ensured my cowl was sealed tight, and added the spacer and my #3 came much closer in-line with my other CHTs.
 
If you still have no drop in RPM with carb heat you are way too lean. You should see about 75-100 degree drop at 2400 rpm.
DENNY
 
I'm gonna repeat what Denny said because I think it's worth repeating. If you don't have a drop in RPM when you apply carb heat, something is wrong there. Could be the carb or improper carb-heat rigging. Fix this and test fly it again.

450, 460 is way too high for such a short climb out. Until the culprit is identified and corrected, the only flights that plane should be making are test flights.

Your engine is not running properly.
 
I am getting 100 rpm drop from carb heat at full power.
Oil cooler is behind #4 .

My baffles had been touching at the aft, lower corner of #3. I've got some space there now, but it's not quite what I'd like yet.

JP
 
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