Jump to content
Cee245

Temperature of cylinders on a 416h after mowing

Recommended Posts

Cee245

Hey everyone,

I have a 97 416h with 800ish hrs. I've done little to motor other than regular oil changes/cleaning of tins and cleaning carb a few times and my Dad helped fixing wires near fuse block and rear cylinder.

 

After reading all about

the heat related problems of the (P216) 416 and (P220) 520 Onan engines over the years, I thought I'd see what the temperature was on the cylinders after mowing my little half acre property @ 70f outside temp.

(This usually takes about 30-40

minutes as I have a lot of kid related objects in the way.)

 

This was roughly five-ten minutes AFTER getting done mowing when the idea occurred. 

 

I got about 310f for the rear cylinder and about 235f for the front. The temps change a lot when going over the fins, but I used the highest temp I seen on the gauge.

These aren't running temps, but after I got done. I used a laser temp gauge from harbor freight. 

I was wondering if anyone else has done this and was wondering what the temperature would be if I cut some holes in the right side drive belt cover like I think @Ed Kennell did on his snow machine to help keep warm.

I plan on tracking this info and sharing results more accurately as the summer goes on. 

Thanks 

C

  • Like 7

Share this post


Link to post
Share on other sites
 
Bert

The rear cylinder is shrouded and holds heat. Myself and other members have

noticed that the belt guard bracket is up against the fins near the valves. 

The valve seat failures are a common problem like you said you read. 

I trimmed my belt guard and brace and can feel a noticeable increase in the hot air blowing out the side. IMG_0849.JPG.9c8892ff2c789122589eb3c0fb91ed87.JPGIMG_0850.JPG.86644651b0f6557c00964dddaef5ee7c.JPGIMG_0851.JPG.ab1d3a3c5bbadf49aa2a9a2e08ed1c9d.JPG

 

Edited by Bert
  • Like 5

Share this post


Link to post
Share on other sites
 
Ed Kennell

Anything you can do to increase the air flow across that rear cyl can only help.    Those Onans really throw off a lot of heat.    That was one reason I designated my 520 a snow machine only.

It was too hot to use for mowing.      With the belt guard vented and a collector around the rear cyl.,  the cab stays about 35deg above outside temp. which is perfect for snow chucking.

  • Like 5

Share this post


Link to post
Share on other sites
 
lynnmor

Is the grommet in place around the oil filter?  Are the fins clean in the oil filter area?  Some oil filter mounts weep a bit of oil and that causes the fins to collect grime.

  • Like 1

Share this post


Link to post
Share on other sites
 
Cee245

Yes the grommet is in place and the tins were taken off last spring and cleaned. I almost always blow it off after mowing. 

Do those temps seem too high / about right?

 I'm not sure what they should be after mowing for 40min. 

Edited by Cee245

Share this post


Link to post
Share on other sites
 
artfull dodger

I have seen guys drill holes in the belt guard to allow hot air to pass thru instead of being obstructed.   Best place to shoot with a laser heat gun is as close to the spark plug part of the head you can get to.  That is where its usually the hottest, along with near the exhaust valve area of the jug.  You can get a dual needle heat gauge for cylinder head temps(used for snowmobiles mostly) that has thermocouple probes that mount under each spark plug.  Then you can monitor head temps on both cylinders the whole time you mow.     Mike

  • Like 3

Share this post


Link to post
Share on other sites
 
Cee245

@artfull dodger, Good thoughts.  I am not having a problem as of now, but I`m curious as to what a "normal temp" should be. 

 

I also have seeen guys drill holes in the drive belt cover to allow air to pass.  Regardless of my experiment, I will be doing the same at some point as it can only help with proper cooling of the rear cylinder. 

 

@Bert, I can see in your 3rd photo how much lower the drive belt cover is, how did you do it?  Do you have a similar photo further back on tractor? Thanks

Share this post


Link to post
Share on other sites
 
artfull dodger

On modern Vtwins, I have seen around 300-350 when running full power no load other than the hydro pumps. This was on a big commecial ZTR.   You want to try to keep the temps closer to each other as any unbalance can and does contribute to bad things happening.  

  • Like 2

Share this post


Link to post
Share on other sites
 
Cee245

Thanks Mike,

I was a little surprised at the temperature difference of the 2 cylinders. I guessed before reading them that it would be 30-40f different, not 75! 

 

And that was only ONE reading 5-10 min after shut down.  I know those numbers aren't accurate so my plan is to track the temps right after shutdown and I'll report back after the next few mowings and try some things to help with cooling. 

Share this post


Link to post
Share on other sites
 
lynnmor

I would think that the readings done immediately after shutdown would provide the best information.  With the engine running the fan is in play.  After the engine sits awhile, you are only getting information about which cylinder gets the best flow of air without any forced movement.

 

While the belt guard added holes are a good idea, understand that air is forced thru the fins and flow is only reduced by the sharp turns made external of the engine.

  • Like 1

Share this post


Link to post
Share on other sites
 
Bert
2 hours ago, Cee245 said:

 

 

@Bert, I can see in your 3rd photo how much lower the drive belt cover is, how did you do it?  Do you have a similar photo further back on tractor? Thanks

The belt guard is in the stock location. 

Unfortunately the tractor is at the family farm right now. However I have a pic of my 520 HC with 518 hood that may put a better perspective on the location of the parts in question. The belt cover was damaged so I just cut it off. 

Follow the belt and you can see it doesn't overlap the valves at all, in my opinion the belt guard bracket is more of an obstruction then the guard. 

IMG_0765.JPG.bdb2da6c70f623449cbab12191b39eac.JPG

 

  • Like 3

Share this post


Link to post
Share on other sites
 
ezeastside

The readings you get from the the infrared guns can be skewed very easily by reflective energy hence giving you the big difference in temperatures.

The key is to shoot the laser at an area that is similar to a matte black  area where you wont get the reflectance.

Find a spot on the front and rear and spray a dime to quarter size spot of high heat flat paint and shoot the laser in the same spot for 

your continued testing. 

I do Infrared thermal scans as part of my work in the electrical field for maintenance and problem solving.

The expensive cameras use a wide range adjustment factors to accurately measure actual temperatures.

Quite a science!!

I will follow this thread to see where the readings end up.

 

  • Like 2

Share this post


Link to post
Share on other sites
 
EricF

Has anyone checked cylinder temperatures with the plastic PTO/belt shroud introduced on later models vs without? It always looked to me like the plastic cover was a huge obstruction to airflow out of the entire engine area, so it would just magnify any little heat problems into bigger ones. I understand the safety (or more likely, liability) benefit of the shroud, but I prefer to leave it off of my 520H and let the engine fan work with as few obstructions as possible.

  • Like 2

Share this post


Link to post
Share on other sites
 
ezeastside

I decided to bring home the infrared camera tonight and check out CEE245's findings

I did a quick therma scan with pre set settings tonight after mowing. Approx one acre with 520H and 60" deck.

Take a look at the attached file

 

 

Wheel Horse Temps.pdf

Disregard the time and date stamp we take the batteries out of the camera and I didn't take the time to reset it.

The actual date is today around 7:00 PM EST

Edited by ezeastside
update
  • Like 6

Share this post


Link to post
Share on other sites
 
Cee245

@ezeastside,  Great info! That is really cool to see.

So there is almost a 9 degree difference between the front and rear cylinders correct? Do you think you could remove the drive belt guard next time you mow and test it with your equipment???

 

Obviously your equipment is a little more sophisticated than mine (lol) but I will still test mine the same way each time and go from there with drilling holes and possibly trimming the belt guard bracket. I would think as long as I test the temp the same way each time the actual temp isn't as important.

 

Share this post


Link to post
Share on other sites
 
Cee245

I must have been wrong with my original post when showing temperature but this is what I got.

 

Ok here are today/ tonight's results:

Mowed this morning with deck on highest setting  at 73f sunny. 

Front cylinder 267f

Rear cylinder 279f

Mowed this evening with deck at normal setting, 77f outside temp, sunny.

Front cylinder 270f

Rear cylinder 281f

 

Again, these are the highest numbers I could obtain from a $20 laser gauge. This was generally near the spark plug base.

 

I think those are solid numbers but I know @ezeastside has the proper equipment to really measure what I had intended.

Cory 

 

  • Like 1

Share this post


Link to post
Share on other sites
 
cleat

I would love to see a thermal picture of Bert's machine to see if cutting the guard away completely makes the temps more uniform.

 

Also would be nice to see one with a ventilated guard (all of mine are ventilated).

 

  • Like 2

Share this post


Link to post
Share on other sites
 
Cee245

After taking 3 more readings on my HF temp reader:

Front cylinder averaged 273

Rear cylinder averaged 282

 

After at least 30 min mowing 

 

One thing I noticed was the day I mowed and scanned the block on the pto side and it read 300f plus?

 

Got worried and I checked the oil to make sure it wasn't low. (Was full) It is much higher than readings from near spark plug.

 

Again my reader isn't high quality so, @ezeastside can I borrow your equipment to complete my test? LOL

 

I think my test gives a general idea of what the highest temp is on a 16hp onan should be measured by a HF temp gun near the spark plug.

 

 

Cory

On 6/11/2017 at 7:06 AM, cleat said:

I would love to see a thermal picture of Bert's machine to see if cutting the guard away completely makes the temps more uniform.

 

Also would be nice to see one with a ventilated guard (all of mine are ventilated).

 

 

 

Me too @cleat!

I'm planning on making cuts for more cooling. It can only help.

 

Share this post


Link to post
Share on other sites
 
cleat

9 degrees difference does not seem like much.

You must have good cooling to the rear cyl right now.

 

I imagine the higher temp at the PTO is because there is virtually no cooling there.

 

  • Like 1

Share this post


Link to post
Share on other sites
 
ezeastside

I Have not modified or ventilated my belt guard but I will get to this sooner or later and retest to see how close we can get the temperatures.

@Cee245 you can certainly bring your machine my way and I will test it with you!!

  • Like 1

Share this post


Link to post
Share on other sites
 
Bert
On 6/11/2017 at 7:06 AM, cleat said:

I would love to see a thermal picture of Bert's machine to see if cutting the guard away completely makes the temps more uniform.

 

Also would be nice to see one with a ventilated guard (all of mine are ventilated).

 

I'll look into a thermal camera, I'd also like to see the results of the mods on my other 520. 

Edited by Bert
  • Like 1

Share this post


Link to post
Share on other sites
 
doc724

Lots of good info here.  I tried to follow the thread carefully, but I am confused about the later readings.  Was this done with the engine running after mowing or with the engine off?  My  point is that when you have the engine running you have forced convection and radiation to cool the engine.  With the engine not running, you have only natural convection and radiation to cool it.  So the temps 5-10 minutes after shutdown will be hotter than while it is running.  The automotive guys call this post shutdown heat soak and the temps they measure become the design temps (with some margin of safety) for suppliers who make all the sensors and electronic things you find on today's modern engines. 

 

I have often thought about venting the belt guard-it would seem to make good sense.  Every time I cut grass with shorts on, however, I decide that it may not be such a good idea after all.

  • Like 1

Share this post


Link to post
Share on other sites
 
cleat
2 hours ago, ezeastside said:

I Have not modified or ventilated my belt guard but I will get to this sooner or later and retest to see how close we can get the temperatures.

@Cee245 you can certainly bring your machine my way and I will test it with you!!

You could just temporarily remove the guard and see if it makes any difference with it completely out of the way.

 

Just don't get caught up in the belt !!

  • Like 1

Share this post


Link to post
Share on other sites
 
artfull dodger

The acutal cause for loosing the valve seats most of the time is the exhaust or intake valve not fully closing.  Many guys never due the required valve adjustment and decarbon every 200-250 hours per the book.  Onan lifters tend to loose the gap between them and the valve stem.  This will continue once the gap is closed and start holding open the valve.  Obviously if the intake starts to be held open, that causing starting issues and such.  Its the exhaust valve and seat that gets into trouble fast.  When the valve is close, it helps disapate the heat from the seat, keeping its temp in check.  When the valve is being held open, you deprive the seat of this cooling effect.  Then you add in a temp boost of combustion flame getting between the partialy open valve and the seat.  This super heats the valve seat and it doesnt take long for this effect to start working the seat loose in the block.    This comes right from the engineers at Onan.  When I started small engine repair work, Onan was still in the engine building business.  They are one of the few that had adjustable valve lifters.  Briggs and Kohler you set the gap by grinding the valve stem during the rebuild process or replacement of valves.  Onans are a high performance engine, kind of like a sports car vs the family sedan.  And like a high end sports car of days ago, they demand routine maintance by the book.  Failure to do so results in issues, such as valve seats.  The 18 and 20hp Onans are more prone due to the larger bore and less "meat" between the valve seat and the bore to help with heat.  That said, I have seen Onans with over 4000 documented hours on RV gen sets.  Same B48 and P220's seen in GT's.  But most RV's see regular dealership maintance, so the genset gets the required valve adjustments  as needed.  And the engines are kept really clean.  While doing the mods to the belt guard do help.  I hope you all do your valve adjustment and head decarbon as well.  Mike    30+ years of small engine service work

Edited by artfull dodger
  • Like 3

Share this post


Link to post
Share on other sites
 
Cee245

@ezeastside, I would love to use your equipment for my test but I'm from north west Pa. The town I live in is North East, Pa which is near Erie by Lake Erie.

 

Your reader is obviously better than mine so we'd have to use your readings for accuracy.  I think mine might not be accurate but they are Consistent aside from my FIRST reading which was 5-10 min after shutdown. 

 

@doc724,

All readings except for the first were done by mowing full throttle for at least 30 min and then I shut it off and immediately grabbed my reader and took the highest number I found for each cylinder. The total time to do that took less than 1 minute.

Cory

 

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...