O-360 Engine Help

[Marauder]

I figured if Mike's Savvy group can't figure this out, the collective brain trust of the Mooney site could. I have a friend who owns a Cardinal with an O-360. This is the first time I flew with him as a safety pilot. He told me to watch his #1 cylinder temp during our take-off climb since he rexperienced this cylinder going over 400 over the past months. Sure enough, it got a little over 400 within a couple of minutes and he pushed the Cardinal over to climb a very shallow climb and bring the temps down to the 380 range.

He told me this has been going on for several months. The Savvy guys told him to suspect an induction issue and he had the #1 tubing rebuilt. There was also recommendations to have the baffling redone. Which he did.

What I noticed was that both front cylinders were running hotter than the rear cylinders. In fact, the rear cylinders were running 50° cooler than the front ones during level flight. The fronts for running in the 370° range while the rears running in the 310 to 320 range

The engine has about 1750 hours on it and is the factory original engine! Any suggestions or ideas?

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[DS1980]

Maybe the CHT gauges are installed incorrectly.

Maybe there's something that's causing the air to redirect above the front cylinders and back down over the rear cylinders.

 

Did the fronts run warmer than the rears even before the baffling was redone?

[Marauder]

Maybe the CHT gauges are installed incorrectly.

Maybe there's something that's causing the air to redirect above the front cylinders and back down over the rear cylinders.

Did the fronts run warmer than the rears even before the baffling was redone?

I should have added he has a JPI 830. The problem came about rather sudden and the baffling work was done to try to alleviate the issue.

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[Hank]

Bird nest? not likely on both sides of the engine. Ditto a double induction leak. If the baffling is good, is there something new / different / changed / replaced / damaged at the front opening? Like the vintage Mooney guppy mouth that was reduced by STC to improve engine cooling, or the oil cooler piece on J's that is often notched to improve engine cooling?

 

Or did the sudden change begin with warm weather? Winter lasted a long time and spring was short before the advent of summer warmth.

[takair]

Can we assume that the #2 always ran a little hot and did not suddenly change as did #1? Can't recall on the 0-360, but some of the engines have o rings at the bottom of the induction tubes, where they go into the air plenum. It can occur that, even with a new o ring, the metal is worn away and will not seal.

Another thing to look for is an exhaust leak blowing onto the thermocouple. This one can sneak up rather fast. Would tend to be worse at high power. Could happen on multiple cylinders as well..... Look for grey soot at each exhaust gasket.

I've seen many planes with good baffles, new baffle seals, etc....but the baffle seal flops the wrong way when the cowl is installed. This is hard to detect unless you specifically look for it. This can actually be a bigger problem with new seals, because they have not taken a preset to the correct orientation.

[kmyfm20s]

Check the exhaust gasket, it may be leaking and giving the CHT probe some heat.

[N201MKTurbo]

With the top cowl off, do a full power run up until your hottest cylinder gets to the high 300s. Because there will be essentially no cooling you can tell if it is a baffling issue or something else. If they all heat up evenly, then you have a baffling problem. If they don't then something else is causing the imbalance.

If you see an imbalance doing this test, quickly shut down the engine and use a handheld IR thermometer to compare the cylinder temperatures. This will tell you if the problem is real or if you have a sensor problem.

[Marauder]

Bird nest? not likely on both sides of the engine. Ditto a double induction leak. If the baffling is good, is there something new / different / changed / replaced / damaged at the front opening? Like the vintage Mooney guppy mouth that was reduced by STC to improve engine cooling, or the oil cooler piece on J's that is often notched to improve engine cooling?

Or did the sudden change begin with warm weather? Winter lasted a long time and spring was short before the advent of summer warmth.

From what I gathered, it began sometime over the winter. I looked the plane over after we landed and could not see anything suggesting any mods were done on this Cardinal. Or that anything was obstructing the air flow.

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[Marauder]

Can we assume that the #2 always ran a little hot and did not suddenly change as did #1? Can't recall on the 0-360, but some of the engines have o rings at the bottom of the induction tubes, where they go into the air plenum. It can occur that, even with a new o ring, the metal is worn away and will not seal.

Another thing to look for is an exhaust leak blowing onto the thermocouple. This one can sneak up rather fast. Would tend to be worse at high power. Could happen on multiple cylinders as well..... Look for grey soot at each exhaust gasket.

I've seen many planes with good baffles, new baffle seals, etc....but the baffle seal flops the wrong way when the cowl is installed. This is hard to detect unless you specifically look for it. This can actually be a bigger problem with new seals, because they have not taken a preset to the correct orientation.

I agree on the #2 may be normal. It never got past 380, but did run hotter than the rear two. I am also making the assumption that the probes were wired correctly and in the right order since it sounds like the JPI was there a while.

I like the exhaust leak theory. Makes perfect sense.

I will ask that he double check the baffling. It was changed out but could have been done wrong.

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[Marauder]

With the top cowl off, do a full power run up until your hottest cylinder gets to the high 300s. Because there will be essentially no cooling you can tell if it is a baffling issue or something else. If they all heat up evenly, then you have a baffling problem. If they don't then something else is causing the imbalance. If you see an imbalance doing this test, quickly shut down the engine and use a handheld IR thermometer to compare the cylinder temperatures. This will tell you if the problem is real or if you have a sensor problem.

Great suggestions. I'm a little concerned with the mechanic he is using. He told me that the plane had the famous nose wheel shimmy and that it was "repaired" recently. On landing, it was there and pretty violent -- a lot worse than those I experienced flying Cessnas during training. Wonder if the mechanic is missing some obvious things. Sent from my iPad using Tapatalk

[pinerunner]

With the top cowl off, do a full power run up until your hottest cylinder gets to the high 300s. Because there will be essentially no cooling you can tell if it is a baffling issue or something else. If they all heat up evenly, then you have a baffling problem. If they don't then something else is causing the imbalance.

If you see an imbalance doing this test, quickly shut down the engine and use a handheld IR thermometer to compare the cylinder temperatures. This will tell you if the problem is real or if you have a sensor problem.

What I really like about this post is its something any owner could do!

[Hank]

I've seen many planes with good baffles, new baffle seals, etc....but the baffle seal flops the wrong way when the cowl is installed. This is hard to detect unless you specifically look for it. This can actually be a bigger problem with new seals, because they have not taken a preset to the correct orientation.

 

There's a post in another thread showing pictures of this. With the cowl on, the baffling should be folded forward, and there should be no gaps/bends in it. Byron gave advice on fixing any that may appear.

[jetdriven]

Air has to go through fins to do any work. Just last week I helped re-do baffles on a couple Cherokees. Both had the original 40-year-old baffle seals stapled to the bottom front baffles. One was missing some on both sides. I guess they get overlooked until the owner or mechanic actually singles them out. But anyways, if these are shot or installed incorrectly the air sneaks past this area instead of cooling the front two cylinders. Both had several square inches of completely open area in that location. So check this area very carefully for sealing. The air pressure in the cowl pushes these out against the forward part of the lower cowl to form a good seal. I'm not real familiar with fixed gear cardinals but the seal usually is fastened to the baffle by the bottom edge, pointing forward.

Another thing about one of the Cherokees. He just installed a new engine monitor but used spark plug washers on the top plugs. He thinks he has a CHT problem, the cylinders push 400 in climb and over 380 in cruise. He disagrees but I read the top spark plug washer CHT thermocouples read 40 degrees too hot.

The other, an Arrow, actually, doesn't even have a CHT gauge installed. Curiously, another Cherokee owned by a different friend, has no CHT gauge either. He the AC removed and they didn't close up a grapefruit-sizes hole in the front baffle where the compressor was. The logs revealed a replaced cylinder on every annual. Six in all on a Cherokee 140 in 1200 hours.

[Guest]

I would suggest that you verify that the probe locations correspond to the correct cylinder numbering or location. As stated gasket probes read differently than bayonet probes. It seems strange that the front cylinders are hotter than the rear.

Clarence

[Marauder]

 

 

Did the fronts run warmer than the rears even before the baffling was redone?

 

Yes. But not this high.

[Marauder]

I would suggest that you verify that the probe locations correspond to the correct cylinder numbering or location. As stated gasket probes read differently than bayonet probes. It seems strange that the front cylinders are hotter than the rear.

Clarence

 

Agreed. He may have repaired the wrong induction tube!

[DS1980]

Yea, I'm leaning toward baffling as well, assuming the connections are correctly located. It's either running the air upwards or sideways. I like N201s ground test idea. I think that has the answer.

 

When will you be able to do a ground run?

[Marauder]

Yea, I'm leaning toward baffling as well, assuming the connections are correctly located. It's either running the air upwards or sideways. I like N201s ground test idea. I think that has the answer.

 

When will you be able to do a ground run?

 

I passed along the recommendations to the owner. I will report back when he lets me know how things worked out.