Hot cylinder advice needed on IO-360

My RV-8A has 11.8 hours flight time. It's powered by an Aerosport Power IO-360B2B engine. The engine had an additional 3.5 hours of test time at Aerosport Power before it shipped seven years ago. Until today the engine ran just fine. I have a dual Lightspeed ignition.

Today, during run-up prior to take-off, the number 4 cylinder suddenly spiked very hot - both in CHT and EGT. I immediately shut it down. After letting the engine cool down for about 30 minutes I re-started it and taxied back to the hanger. At low idle for a couple of minutes the #4 temps seemed normal. Anything above idle causes #4 to get quickly very hot again.

I changed the oil at 10 hours and flew the plane last week after the oil change for 1.4 hours without any issues. I don't think my problem has anything to do with cowling or baffling. Normal temps during the prior engine break-in flights are CHT 375 and EGT 1270 degrees with less than a 30 degree spread between the four CHTs.

The plugs on #4 look normal compared to the other plugs (just a slight amount of carbon fouling) and the engine didn't seem to run rough - it's just a hot #4. So, I'm thinking the problem with #4 is a clogged or restricted injector. Or perhaps a sticky valve.

Anything else I should be looking at??

Test changin the cht probe to other cylinder it could be the probe

One plug not firing will cause the EGT spike. You can determine that quickly doing a ignition check. If you have a cold cylinder start with checking all your plug wires. Then check the coils. I have had just one side fail. When you check each ignition stay on that ignition long enough to insure you see a rise in EGT for all cylinders. It can take a bit to see a dead cylinder EGT fall off and my engine runs amazingly smooth on 3 cylinders at 1700 rpm.

George

I'm skeptical about bad readings from the two probes since both the CHT and EGT showed hot at the same time. And both CHT and EGT showed hot when I briefly ran the engine a second time. Wouldn't the odds of both a CHT probe and a EGT probe failing in the same cylinder at exactly the same time be pretty unlikely?

This will be a partially blocked injector or intake leak. To test it run it with the high EGT and lean the engine and if that cylinder peaks long before the others and then starts going cold and rough running it is a blockage in the injector or a massive intake leak leaning that cylinder out.

It will not be a failed plug. That will give higher EGT but lower CHT.

If you have an engine monitor, and you should, send me the data file.

This is yet another reason why I suggest you guys do an APS class. They pay for themselves in this one area alone.

brown is right imho

he read your post, some did not read very close at all.

Please define "very hot" during runup. I.e., what were the approx temps of all four?

#4 hot

When I noticed #4 hot during the run up the CHT was 420 and the EGT was at 1750. The other cylinders were at 220-240 CHT and 800 EGT. I'm sure the temps on #4 were in the green before I started the run up.
I have a Dynon D-180 Flightdeck that can record the data if hooked up to a laptop but I didn't have it connected for this flight.

Ouch, those are high, that's not a plug for sure. I would not run it again until you take a look at everything on that cylinder.

George

At low power it would be nearly impossible to get the temps that high in a few minutes. I would borescope the cylinder first and check with the plugs out that the engine rotates without undue drag (piston possibly siezing in the cylinder).

glider4 said:

When I noticed #4 hot during the run up the CHT was 420 and the EGT was at 1750. The other cylinders were at 220-240 CHT and 800 EGT. I'm sure the temps on #4 were in the green before I started the run up.
I have a Dynon D-180 Flightdeck that can record the data if hooked up to a laptop but I didn't have it connected for this flight.

Click to expand...

Interesting - thanks. Something fishy - hard to imagine these could be correct readings. How long was the runup, and what was the OAT? 200 degree rise during a fraction of a minute, at runup power, seems unreasonable. If the readings are indeed correct, I'm skeptical it is low fuel flow to that cylinder (or normal fuel flow, but high air flow due to intake leak on that cylinder). CHT's are obviously affected by mixture, but I do not think to that degree so quickly, and certainly not at runup power.

Could it be ignition noise into the probes? Any coupling of the high intensity output of the LS ignition might make readings go haywire. Did you happen to look at the engine monitor when the engine was just shut down? I've chased radio noise, and others have had their transponders reply to the ignitions...

To those more knowledgeable, if an exhaust valve were hanging, I can see the egt going up, but wouldn't the cht then also drop?

Run-up

My hanger is uphill from the taxiway and runway. I can pretty much coast downhill at 1,000 RPM to just before the runup area. Time from engine start to runup area was probably four minutes.
When doing the runup this time I fairly quickly went from 1,200 RPM (RPM needed to swing the plane around in the runup area) to 1,700 RPM and checked both "mags" which seemed fine. Like I said, the engine seemed to be running pretty smooth. After the mag check I then ran the engine up to full static 2,230 RPM for just a few seconds. That's when I saw the #4 readings in the red and immediately shut down. Time from start of "mag" check to shut down was under two minutes.
Prior to runup all cylinders CHT and EGT were "in the green". That said, I don't get into yellow until the CHT is at 400 degrees. I could have had #4 at 370 to 390 degree prior to the start of runup and not noticed it.
OAT was 51 degrees.

High EGT and CHT

It is very rare to have a single cylinder have high EGT and CHT suddenly with everything else being normal. I had this happen in my RV-8 with IO-360A3B6 years ago. Cylinder 3 went from 330 to 509 and EGT from 1310 to 1425 over a period of 2 minutes while in cruise.

In my case if was definitely caused by pre-ignition which was being caused by a helicoil that had it's inner (closest to the piston) portion spring out several mm. It eventually eroded to a fine wire causing the pre-ignition. If it were not for the EI limits and aural warning, I would have destroyed the cylinder very quickly in my case.

I'm not at a computer where I can figure out how post pictures right now, but I have the engine analyzer data and pictures of the 'tang' if you are interested send me a PM with real email address.

Electronics International has a pretty good engine diagnoses guide on their website that i'd recommend reading. A scope and very close inspections for anything that could be creating a hot spot in that combustion chamber as a start.

Greg

Ok, not the injector. Fuel flow to the injector is fine and the injector itself was very clean. More investigating this afternoon.

Re time you ignitions.

This was the cause of our high CHT's.

At least it benchmarks and rules that out.

Check your CHT temps right after shut down then a couple of minutes after shut down. If they all appear okay you probably have electrical interference.

Now we have some more data....but not enough. Your D180 will have logged this event I hope, use the Dynon Support program and "Retrieve Logged Data" and email it to me.

A pre-ignition event by definition should result in a drop in EGT, and a rapidly rising CHT in the order of 1-2dF per second. All the pre-ignition data files we have do not show a jump in EGT except when it was a failing plug prior to the event.

I would be surprised if you can induce one on the ground though. If you can, well do not do it again, they will survive a quick event but too many too often will trash it.

If the CHT went from 230 to 420 in a few seconds.....then this is a probe issue or something else. You just can't do that short of setting off an atomic weapon in there. You did not do that did you

Data file will tell us a lot.

More info

I spent 5 hours trying to get a better understanding of what happened to the engine yesterday. Looking at the injectors on #3 and #4 showed no contamination or blockage. A fuel flow test right to the injector showed plenty of fuel. The plugs on #3 and #4 looked normal with some slight carbon fouling. Nothing observed on the plugs in #4 indicated they had been recently overly hot.

The compression was informally checked swinging the prop two full cycles with everything feeling normal to our resident engine expert. Both CHT and EGT probes were tested with a heat source to confirm they were working. No leaks were observed in the #4 intake plumbing. The #4 exhaust pipe looked normal and the #4 EGT probe looked exactly the same as the #3 probe.

I will check tomorrow to see if I can download the D180 data. I had been using a PC to update the firmware but not to record flight data. I was doing that by hand on a knee board during the prior flights.

To end the day, the engine was started and run for about 8 minutes. It ran at idle for about 4 minutes and then I slowly increased RPM to 1,200 and then for about a minute to 1,700 RPM. "Mags" were checked as well and mixture varied and boost pump checked. While the engine wasn't purring it wasn't running rough.

As typical for prior engine runs and flights, #1 was the hottest cylinder (by CHT) with #2, #3 and #4 within 25 degrees of #1. All CHTs did not exceed 270 during the 8 minute run.

The EGT on #4 ran hot after a few minutes. It climbed to 1400 degrees while the other cylinders were in the 1200 degree range. The EGT reading on #4 did swing several hundred degrees up or down in a matter of just a few seconds when the mixture was leaned or the throttle increased or reduced. None of the other EGTs were moving as rapidly as #4 did today. I had not observed this manner of quick swings in any EGT readings before. Not saying it didn't happen before, just that I never noticed it changing as fast as it did today.

I appreciate all the input everyone has offered. and hope to download the D180 data tomorrow.

Problems identified!

Today I reached the conclusion that my high EGT and CHT readings in #4 were due to two different issues just coincidentally happening at the same time.

After we had cleaned the plugs off of #4 yesterday the CHT ran normally during the engine test run at the end of the day. What I thought was minor carbon fouling was apparently enough to cause one of the #4 plugs to fire erratically or not at all. Will be ordering eight slightly "hotter" plugs today.

The continued problems with the EGT noted again yesterday by rapid swings in the temperature readings showed up again today - with the engine off! Just before the start of a logged data download from the D180, the panel showed for a EGT on #4 at 54 degrees ambient temperature. When the data download was completed the #4 EGT was showing 2033 degrees. I have believe an intermittent short in that sensor wiring that needs to be tracked down. Not a fun task I'm guessing but a lot better than having to deal with a major engine malfunction.

Thanks again for all the input and advise!

This reminds me that we are both blessed and cursed by the information available today. After all, these engines flew for decades with essentially zero health information available to the pilot. Yet when presented with information that is essentially impossible in the real world, we are inclined to believe it. Not saying that the OP did anything wrong by shutting down with 420/1750 temps displayed - just mentioning that you can't believe everything you see.

Runups were a lot easier when we only had oil pressure and oil temp to look at, weren't they?

You have explained why the EGT may have been randomly high in two ways. The first being a connection issue. The second being a fouled plug. Both of these are valid for EGT excursions.

The CHT excursion is still not explained. Perhaps it was a connector issue, but normally they drop not skyrocket. But a failed probe can do anything I guess.

By the way a fouled plug will not give you a CHT rise, it will give you a drop in CHT along with a rise in EGT.

I would also caution you in selecting a higher heat range plug. Better ground leaning practices would be a good start, not using full rich on descent and landing or when taxiing.

Did you manage to get that data file?

Toobuilder said:

This reminds me that we are both blessed and cursed by the information available today. After all, these engines flew for decades with essentially zero health information available to the pilot. Yet when presented with information that is essentially impossible in the real world, we are inclined to believe it. Not saying that the OP did anything wrong by shutting down with 420/1750 temps displayed - just mentioning that you can't believe everything you see.

Runups were a lot easier when we only had oil pressure and oil temp to look at, weren't they?

Click to expand...

Michael, there is only one statement in your post that is true. We are blessed by the available information today. The rest of your post is possibly dangerous to the untrained eye. Until you know how many peoples lives have been saved by an engine monitor and knowing what it was telling you, it is easy to make your assessment. Believe me, an inop EMS is a NOGO item for those of us who know better.

For a start, if you (and you should) have an EMS, it helps understanding what it is telling you. 99% of pilots are dogs watching TV. Simple as that. All the threads on VAF prove this. Don't feel like it is just VAF, same on Mooneyspace, Cirrus COPA, Beechtalk although the %age there is way better and by a long margin, pprune, the Cessna pilots association. Despite this, having an EMS and not knowing what it is telling you but taking action to not fly, investigate and seek help is far better than just blasting off.

I have had people with one CHT only tell me that they had a preignition event in a C172, and fortunately they had the probe on that cylinder, and he amazingly noticed the needle moving up quickly, he made the right call and even though it was trashed he made it. Had he had the probe on another cylinder, he would have been so far off the coast he would have been swimming in a section of coast known for the worlds apex predator. Then of course I compare this to all the data files APS have collected over the years where EMS's have saved the day.

I did a short lecture at an AOPA safety conference in the nations capital recently and used one real life scenario, we play back the JPI in real time, displaying everything, and paint the scenario as it happened. Out of a lecture room with 60-70 pilots, safety folk, ATSB and CASA folk.......how many survivors? I exclude the two past APS students coz they know the answer, but we killed every single one of them and their wives and kids in the back seat. All of them. I even had one guy telling me if we just switched that mag off it would save them.....sorry....it will not help. He and his family died twice!

So you can hopefully see why I am passionate about these things, when you have coached round the world pilot Ryan Campbell, and realise what can give you a bad day, when you have lived on the sidelines to the Whyalla crash and subsequent ballsup of an ATSB report and you know folk who have been a part of the Cessna twin exhaust AD, and how some lives are saved and others not, it becomes a very real thing.

If your EMS is telling you something....Believe it until proven otherwise!!

Now lets look back at the good old days, A&P's had plenty of work to do and parts and labour were cheap. Well not so, but lets assume so. Runups today are far better because if you always fly your plane and you do a mag check at TOD on the way in, your runup is already done. Better to find the bug today on descent than next Monday morning when you have a meeting to attend and you are at the runway end. Besides knowing what was wrong it is a direct hit on exactly the plug not just one of twelve.

What happens if you have two faulty plugs, and the old mag drop is about the same on each mag. You take off, but a LOP high power mag check will find this long before it is a problem found later and likely not doing an old rpm drop check.

Yes the old days were great. But in terms of an EMS, today is far better.

I hope you do not feel like I am picking on you or starting a fight, this is not the intention, but for those others reading this thread and easily (because it is convenient) take the view who cares about the EMS, the truth needs to be told. I was thinking over a beer I could tell you more....but it would take a carton or two

Cheers!

Follow-up question

I'm still learning a lot about engine management so forgive me is this is a dumb question.
In a dual ignition system, if, in one cylinder, one plug is firing and one is firing inconsistently, wouldn't the CHT tend to rise when there was just one spark per cycle instead of two? I understand that if I was just on Left or Right "mag" and not on Both that CHT would drop when the single spark stopped sparking in one cylinder.
My local engine guru who saw the #4 plugs before cleaning thought this could explain the higher CHT during the run up. During my taxi to the run up area it was full rich at low RPM.
Also, he said it was not unusual to get some moderate levels of carbon fouling, especially in the lower plugs, during the first several hours of operation in a brand new engine until the rings seated. I spent today cleaning all the other plugs. They were all somewhat carbon fouled.

Yes, David, EMS are a good thing. And I also understand you are passionate (and have a financial interest) about it.

However, the point is, even by your own admission, this event is impossible. You said: "If the CHT went from 230 to 420 in a few seconds.....then this is a probe issue or something else. You just can't do that short of setting off an atomic weapon in there..."

So we have become slaves to numbers on the screen. On the balance, more info is better, but only if it is right. If pointing out this neutral observation constitues blasphemy or spreading "dangerous information" then so be it. Better start gathering up the firewood and hay bales... It certainly won't be the last time.

EGT CHT VIDEO

glider4 said:

I'm still learning a lot about engine management so forgive me is this is a dumb question.
In a dual ignition system, if, in one cylinder, one plug is firing and one is firing inconsistently, wouldn't the CHT tend to rise when there was just one spark per cycle instead of two? I understand that if I was just on Left or Right "mag" and not on Both that CHT would drop when the single spark stopped sparking in one cylinder.
My local engine guru who saw the #4 plugs before cleaning thought this could explain the higher CHT during the run up. During my taxi to the run up area it was full rich at low RPM.
Also, he said it was not unusual to get some moderate levels of carbon fouling, especially in the lower plugs, during the first several hours of operation in a brand new engine until the rings seated. I spent today cleaning all the other plugs. They were all somewhat carbon fouled.

Click to expand...

Watch this video presented by mike Busch on CHT,EGT and how they relate.
http://www.eaavideo.org/video.aspx?v=1316946190001
It will help you with your questions.

Toobuilder said:

Yes, David, EMS are a good thing. And I also understand you are passionate (and have a financial interest) about it.

However, the point is, even by your own admission, this event is impossible. You said: "If the CHT went from 230 to 420 in a few seconds.....then this is a probe issue or something else. You just can't do that short of setting off an atomic weapon in there..."

So we have become slaves to numbers on the screen. On the balance, more info is better, but only if it is right. If pointing out this neutral observation constitues blasphemy or spreading "dangerous information" then so be it. Better start gathering up the firewood and hay bales... It certainly won't be the last time.

Click to expand...

Michael, if and only IF the event went from 230-420 in a couple of seconds, then yes it is impossible....but so far we do not have proof of that, it is not a data file in the guys memory, so what do you do? What if you are flying along and you see it.....just assume it is a bad probe? What about if you have your alarm set at 500dF (which is stupid but many do) and you see 480? Is it a bad probe? What do you do?

I agree, more info is better but only if it is right......but how can you tell? If you can't, you need to assume the worst and hope for the best, or be able to diagnose it on the spot. This is where 99% of pilots fall down. And some problems are not easy to find the exact fault in flight even with a lot of knowledge. This is why a data file is so valuable. Most folk do not study them on regular occasions or just prior to doing maintenance or an annual. And they should. This can be the payback time. Most do not get it.

Lets say you are flying a turbocharged plane, and for no good reason you have lost a couple of inches of MP. Do you just say....ohhh must have bumped the throttle and just push it forward and reset say 32"? No other data available and you can't diagnose that in the air........until it is too late.

Your NTSB has lots of dead people to verify this one.

By the way Michael, I am calling you out on this one (And I also understand you are passionate (and have a financial interest) about it.), and if this is the first time for you and I am confusing you with others I apologise, but it needs putting to bed. If you or anyone else anywhere else in the world does a live or online APS course.......I do not see one cent. Not one. Is that OK?

This notion that because a business unit is set up (which it has to be) and I am passionate about it, I must be making a fortune from it, is one of the most irritating aspects of the human condition. If and I say IF the course costs were sent to me 100% ....so what? I bet not one of the students would begrudge it. I am yet to meet a person who says afterwards they paid too much and many say too little or one recently, "where were you guys 20 years ago when I started out as a commercial operator and engineer" (A&P). Also RV8 builder/owner and a fleet of piston twins.

Why is it that Mike Busch who makes it his business, and wilfully plugs his SAVVY business in all his articles does not cop this stick? And I do support Mike in plugging his maintenance planning business, because nobody else will and he gives away much for free. (By the way he attended APS THREE times and learned most of what he teaches from there). George Braly, John Deakin and Walter Atkinson have given away so much for free, and contributed so much to GA safety that is taken for granted, and they too have been accused of similar things. The small amount of pocket money made over the years amounts to cents per hour. But they still do it because they enjoy it, and most appreciate it.

As for APS -Oz......still not drawn a cent (residual leftovers are reinvested), in fact it has cost me thousands, the AOPA safety seminar last week cost me in after tax (non deducted) dollars about $2500 plus a day of work and all my weekend.

I am sorry that in trying to help and educate I have to be this defensive, but it gets right up my nose when the kind of comments about having a commercial interest are made in such a way to discredit the facts and are likely to be revered by others yet are completely false. I sure don't see Stein, Don at Airflow, Dynon, or others who have a significant financial interest get pasted.....and nor should they. All I ask is the same respect.

I also noted that someone posted that the various EMS manufacturers manuals are a good source for diagnostic advice.

Well.......that might apply to the instruments features etc, but most have some very poor and some completely wrong information contained in them.

But how can you tell?

I reckon there is far more and better advice here on VAF than there is in many of those manuals.

EMS

I like having an engine EMS in my RV but to tell you the truth I don't have a problem getting in any plane that does not have any engine EMS AND FLY IT ANYWHERE and lean it out till it runs rough and enrich it a little till it runs smoothly worked since the beginning and works just as good today in most planes that are used for training and the majority of the GA fleet.
Bob

That is fine Bob, and still many do. And for a VFR jolly in the local area I will jump in the Cub or a mates RV6 no problem. But I will not fly them IFR in IMC or at night.

My question to you is what kind of car do you drive? If it is a 1950's Chevy Impala with no seat belts, my argument is going to be shot down now, but you could. I bet 99.9% of us prefer a 2013 model and wear their seat belts.


As a follow up, to the OPs problems, the data shows some connector problems and some plug fouling from taxiing too rich.

Data, Data, Data. It can tell you a lot more than just a number.

RV10inOz said:

This will be a partially blocked injector or intake leak. To test it run it with the high EGT and lean the engine and if that cylinder peaks long before the others and then starts going cold and rough running it is a blockage in the injector or a massive intake leak leaning that cylinder out.

It will not be a failed plug. That will give higher EGT but lower CHT.

If you have an engine monitor, and you should, send me the data file.

This is yet another reason why I suggest you guys do an APS class. They pay for themselves in this one area alone.

Click to expand...

Agree with David on this. You have a clogged nozzle. A fouled plug would give an EGT rise, but a lower CHT reading.

I had the same thing happen on my engine about 6 months ago. I called a local company, QAA, and they helped me troubleshoot everything. Turned out to be an injection problem. Vanessa and her techs were super helpful though. If you are still struggling glider, it can't hurt to give them a call 877-833-6948
Best of luck with the diagnosis!