Rough Engine IO550 at COLD start only

[Healthpilot]

Outside temperature 40 degrees F. This happens only for the first 3 to 5 min.  I pulled the engine data.

EGT on one and three are slow to climb. 

Could this be an issue with one of the sparkplugs on cylinder one and three?

 

 

[Brandt]

1 hour ago, Healthpilot said:

Outside temperature 40 degrees F. This happens only for the first 3 to 5 min.  I pulled the engine data.

EGT on one and three are slow to climb. 

Could this be an issue with one of the sparkplugs on cylinder one and three?

 

 

https://www.aopa.org/news-and-media/all-news/2020/july/pilot/savvy-maintance-valves

[Ibra]

Does it get there quickly (EGT1) if you lean aggressively after startup ?

Worth checking Cyl1 valves 

Edited February 13, 2023 by Ibra

[Healthpilot]

2 hours ago, Ibra said:

Does it get there quickly (EGT1) if you lean aggressively after startup ?

Worth checking Cyl1 valves 

Yes i did. If I lean aggressively the engine dies on me. 

[Fly Boomer]

4 hours ago, Healthpilot said:

Could this be an issue with one of the sparkplugs on cylinder one and three?

@kortopates is one of our most knowledgeable members on topics like this.  If he has time to look at it, you will almost certainly get an answer.  I'm still learning how to read these things, but if there is no heat, it seems to me that either there is not enough fuel, or the ignition system is not setting the fuel on fire on every compression stroke.  Sometimes these big-bore Continentals like a few taps on the primer/boost pump immediately after start -- have you tried that?  Also, I would probably pre-heat at 40 degrees.

[PT20J]

Preheat is never a bad idea, but only affects starting. After a few seconds, the combustion chambers warm enough to vaporize the fuel well.

Cylinders have two spark plugs. When only one fires, combustion progresses more slowly so the exhaust gasses leaving the cylinder are hotter and EGT rises.

A rough running engine for several minutes after a cold start with low EGT and low CHT on specific cylinders could indicate a sticky valve. It’s more common in Lycomings, but can happen in any engine. 

Skip

[Healthpilot]

38 minutes ago, Fly Boomer said:

@kortopates is one of our most knowledgeable members on topics like this.  If he has time to look at it, you will almost certainly get an answer.  I'm still learning how to read these things, but if there is no heat, it seems to me that either there is not enough fuel, or the ignition system is not setting the fuel on fire on every compression stroke.  Sometimes these big-bore Continentals like a few taps on the primer/boost pump immediately after start -- have you tried that?  Also, I would probably pre-heat at 40 degrees.

Yes I have tried boost pump no joy.  I will check valves with borescope at annual. Although I thought big bore Continentals did not have this issue. Cylinders have less than 200 hours on them since top overhaul. I will also try pre-heat. 

[Healthpilot]

4 hours ago, Brandt said:

https://www.aopa.org/news-and-media/all-news/2020/july/pilot/savvy-maintance-valves

Thank you I will borescope cylinder 1 and 3 at annual coming up. 

[Fly Boomer]

7 minutes ago, Healthpilot said:

Yes I have tried boost pump no joy.  I will check valves with borescope at annual. Although I thought big bore Continentals did not have this issue. Cylinders have less than 200 hours on them since top overhaul. I will also try pre-heat. 

If, as @PT20J (Skip) suggests, valves are suspect, I wouldn't wait for annual inspection to get a borescope in there.  It's not invasive, it's cheap, and it's quick.  Also, I wouldn't allow the "200 hours since top" to influence my diagnostic steps -- we all want a big expense like that to go the distance, but sometimes it doesn't turn out that way.  I wish you the best of luck.

[PT20J]

If you suspect valves, I would definitely work to eliminate that sooner rather than later. If a valve sticks hard closed, something has to give and it will bend the pushrod. Then, you'll know for sure! But it's not good if it happens in flight.

[dzeleski]

This is what a sticking valve looks like and sounds like. Based on that EGT graph you have a sticking valve. As said above this is something that needs to be looked at today, not in a few weeks or in a few months.

 

 

[Healthpilot]

No plans to fly before checking. Annual is scheduled for week after next. This is the first time it happens. Does anyone know a good A&P in the Seattle area expert on Continental big bore engines that has access to a decent borescope? if not I will purchase one and give it to my mechanic. They seem to be quite cheap now. Is this one ok or not good enough?
5mm Ultra Fine Dual Lens Endoscope Camera, Hiacinto 5inch IPS 1080P Digital Inspection Camera with IP68 Waterproof, Automotive Scope Camera with 7 LED Lights, 16.5FT Semi-Rigid Cable, 32GB Card: Amazon.com: Industrial & Scientific

[rickseeman]

I would buy the borescope like Mike Busch uses. It's cheap and I like it. Can't remember the name. Sorry

[rickseeman]

I think it's a Vividia VA-400

[Fly Boomer]

52 minutes ago, Healthpilot said:

No plans to fly before checking. Annual is scheduled for week after next. This is the first time it happens. Does anyone know a good A&P in the Seattle area expert on Continental big bore engines that has access to a decent borescope? if not I will purchase one and give it to my mechanic. They seem to be quite cheap now. Is this one ok or not good enough?
5mm Ultra Fine Dual Lens Endoscope Camera, Hiacinto 5inch IPS 1080P Digital Inspection Camera with IP68 Waterproof, Automotive Scope Camera with 7 LED Lights, 16.5FT Semi-Rigid Cable, 32GB Card: Amazon.com: Industrial & Scientific

As @rickseeman suggested above, get the Vividia recommended by Mike Busch:

https://www.aopa.org/news-and-media/all-news/2017/may/pilot/savvy-maintenance-borescope

Also, be sure you are getting the latest version.  They keep improving it, but they don't change he model number.  I don't think there is a way to tell by examination either -- you just have to buy from a supplier that has lots of turnover, like Spruce.

[ilovecornfields]

17 hours ago, Fly Boomer said:

@kortopates is one of our most knowledgeable members on topics like this.  If he has time to look at it, you will almost certainly get an answer

And if you sign up for Savvy Analysis , he will almost certainly look at it!

 

[rickseeman]

I would feel better if anything Mike Busch says about cylinders would be chiseled in granite for preservation.

To the OP:

You started a gasoline engine without a choke on a cold day. (Without EFI.) It's not supposed to start idling and run perfectly smooth. After a little bit, it gets some heat in it and runs fine. I say this is perfectly normal and there's nothing wrong with your engine.

 

[PT20J]

12 minutes ago, rickseeman said:

I would feel better if anything Mike Busch says about cylinders would be chiseled in granite for preservation.

To the OP:

You started a gasoline engine without a choke on a cold day. (Without EFI.) It's not supposed to start idling and run perfectly smooth. After a little bit, it gets some heat in it and runs fine. I say this is perfectly normal and there's nothing wrong with your engine.

 

3 minutes rough at 40 deg F doesn't sound normal to me.

[rickseeman]

Maybe, but it is an Ovation. Which sure does seem like a cold natured engine.

[Guest]

4 hours ago, rickseeman said:

Maybe, but it is an Ovation. Which sure does seem like a cold natured engine.

Then there’s something wrong with it.

[Guest]

The engine monitor data is already telling us which cylinder is unhappy.  Unless borescope technology has changed recently, I don’t know how it will tell us the valve is sticking.  Always ready to learn more.

[Healthpilot]

2 hours ago, M20Doc said:

The engine monitor data is already telling us which cylinder is unhappy.  Unless borescope technology has changed recently, I don’t know how it will tell us the valve is sticking.  Always ready to learn more.

Great question. This is all I could find: Anatomy of a Valve Failure - AOPA

[Pinecone]

Here is the borescope that Mike Busch uses:

https://www.amazon.com/gp/product/B01MQPC6U1/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&psc=1

Last year, they changed the unit to a higher resolution camera.  But they did not change the model number or anything.  I ordered mine in July 2022, and the one I got is the higher resolution.

BTW, a borescope is not going to show you a sticking valve or why.  That occurs inside the valve guide.

One more thought, if your A&P does not have a borescope, I would be thinking about finding an A&P that has joined the 21st Century.

[Healthpilot]

11 hours ago, Pinecone said:

Here is the borescope that Mike Busch uses:

https://www.amazon.com/gp/product/B01MQPC6U1/ref=ppx_yo_dt_b_asin_title_o06_s01?ie=UTF8&psc=1

Last year, they changed the unit to a higher resolution camera.  But they did not change the model number or anything.  I ordered mine in July 2022, and the one I got is the higher resolution.

BTW, a borescope is not going to show you a sticking valve or why.  That occurs inside the valve guide.

One more thought, if your A&P does not have a borescope, I would be thinking about finding an A&P that has joined the 21st Century.

If borescope cannot diagnose, what do you guys propose as a way to diagnose the potential sticking valve problem?

Just to be clear this may be just me be overzealous since my A&P thinks this is just oil fouling, and the cylinder is just slow to come up to temp and burns off the oil the problem simply goes away. He is recommending monitoring and flying since this has never happened before. He thinks that it is VERY unlikely that this is a valve issue. 

[Healthpilot]

On 2/14/2023 at 7:37 AM, dzeleski said:

This is what a sticking valve looks like and sounds like. Based on that EGT graph you have a sticking valve. As said above this is something that needs to be looked at today, not in a few weeks or in a few months.

 

 

Interesting. When you increase RPM in the video roughness seems to decrease. In my case it doesn't. If I increase RPM in the first 3 minutes roughness increrases.