2550 Melting hood!

JSharp · Jul 1, 2007

Well, I tried to mow today. I got 3 passes and noticed the left rear deck wheel laying on the ground thanks to the shoulder bolt/axle breaking. I figured I'd run the deck wash anyway and noticed one headlight out and the other one flickering...

More for the dealer to fix when they come pick it up. I'm done fixing things for the 2 remaining years of my warranty. I've already done a number of repairs on this mower not limited to the POS press in zerks and straightening out the steering wheel after the steering recall.

Here's a few photos for those not familiar with how the '06 2500 series is setup. You can see the oil cooler I added to the Kohler and see that there no ducting of any kind to the engine cooling fan inlet.

It just draws air from where it can and sends it over the engine after exiting the engine shrouding. No ducting in, no ducting out. No control of airflow at all and no way to keep the hot underhood air from being drawn back into the cooling fan or into the engine intake.

What we have here in effect is a heat source with fan, the engine, and an almost closed "box" that is the hood. Opening the lower rear sides of the box and adding a few louvers to the top of it doesn't change the fact that there's not enough air actually being forced through the box by the cooling fan with no ducting arraingment nor does the cooling fan or carb inlet have direct access to cool air. They just pull in whatever is under the hood. And if that's hot re-circulated air, then that's what they get. Ultimately some gets out of course. We see that in the burned spots on our lawns. But judging by the temp readings I've taken, it's not nearly enough IMO.

Folks are free to believe my temp readings or not. They're as real as they can be. They were taken with an almost new Raytek MT-6 IR thermometer and an older remote thermistor thermometer made my Computemp. And I've been designing and implementing instrumentation since the 70's so I do have some idea how these things work.

One thing I'm pretty sure of though - The *many* folks that have had hoods melt and the others that are already seeing high oil consumption at low hours are likely to believe me...

CCinCT · Jul 1, 2007

Your last photo does a great job of showing where most of the air is drawn in from, for those that aren't familiar with the hood. Why you keep insisting that hot air is being drawn DOWN from the engine compartment is beyond me, but whatever. I've had no problems with cooling, nor has anyone that I know of in the area.

I'll snag a temp gauge in the next day or to and see what I get for temps at the same locations you measured at.

JSharp · Jul 1, 2007

I was going to ask you a similar question. Why do you insist that air flows from the louvers under the steering wheel when there are 2 steering system cover plates in the engine compartment that almost completely block that area? I'll post some pics of that area being blocked if you like but anyone with a 2500 series can see them.

I can also post another photo if you like that shows just how enclosed the engine really is. The vast majority of it, where the cooling air actually exits the engine shrouds, along with 100% of the hot exhaust system, is under the hood. But again, anyone who's seen one can see all this is true so there's little need to post more pics.

I'm not insisting that air flows just downward. I'm insisting that heat builds up under the hood since there's no real mechanism I can see to prevent it. Then the engine fan and intake can draw that hot back into and over the engine.

I'm also insisting that oil filter and and sump temps of almost 240ºF to almost 250ºF are TOO HIGH for a lightly loaded engine on a 90ºF day. Especially when that engine has an additional oil cooler.

Anyway, those numbers may look just peachy to Cub Cadet dealers and the factory "engineers", but they don't to me. And my hood agrees...

Fordlords · Jul 1, 2007

Now that I see the picure, what is wrong with that? It's got a wide open area on both sides of the tractor, right by the fan, to draw in fresh air- adding ducting there would not help it any. The warmer air under the hood will rise to the top. If you are concerned that the fan can draw in some warm air in from the top, yes it can, but these type of tractors have been doing that for ages. Some warm air gets back in, it's not a problem.

I don't know of any lawn tractor out there that has a fresh outside air draw for the intake or carburetor.

I don't think the ducting on my older Cub works better, if anything I'd say it would be worse. I can take temperature measurements with my Extech thermocouple thermometer if we want to compare. One thing I know is worse is the screen under the tractor with my setup has to be cleaned, and it is much harder to get at than having the fan shroud right there up top easy to clean. These have to be cleaned on every air cooled lawn mower engine every few hours.

Looking at the 2006 setup in those pictures, I really don't see what is wrong with it. The plastic hood is just the plastic hood doning the things that plastic hoods will do. See the dealer, get the mods and the problems repaired. You put on the oil cooler, so you are doing the best you can do to keep it as cool as possible, you might just be worrying too much.

-Fordlords-

JSharp · Jul 1, 2007

I'd agree with you Fordlords had 2 things not happened in the last week. I was playing around with my Raytek and noticed what I thought were high filter and sump temperatures. Then I noticed my melting hood...

<shrug> I'll call the dealer in the AM. They can come get it and can replace the hood along with everything else that's broken on the tractor right now. If they fix those things enough times, maybe it'll motivate them to do something different in the future...

Fordlords · Jul 1, 2007

This is what the "ducting" on the 682 looks like, with an engine that really is completely boxed in. All air is drawn in from underneath, and ducted out front. Kind of makes you more comfortable with the 2500's now, I hope

-Fordlords-

CCinCT · Jul 2, 2007

JS, in this quote:

JSharp said:
Quite a bit of "sag" around the the hole cut for the exhaust pipe and the grill is looking bad.

... you point to the hood melting around the exhaust. This is a know issue with the latch failing, not with a cooling issue. The latch fails and causes the hood to ride higher than normal, partially (or coming very close to) blocking the exhaust. which would cause any hood to melt. This would also result in much higher engine compartment temps, and eventually higher oil temps. Is it possible that this is what's going on?

If your latch has indeed failed in this manner, than it's also probably that you don't have the additional exhaust shields in place, These two things would explain why your experience is different than mine. Mine was made in early '06, but my dealer has performed all TSB's that have been issued, at least that I know of. I don't have any unexpected heat build-up, and I don't get brown grass even after letting my 2544 idle at full throttle for 15 minutes (which I did yesterday because of this thread, just so I could see firsthand). The only thing left to check is oil temp, which hopefully I can do this week.

JSharp · Jul 2, 2007

CCinCT said:
JS, in this quote:

... you point to the hood melting around the exhaust. This is a know issue with the latch failing, not with a cooling issue. The latch fails and causes the hood to ride higher than normal, partially (or coming very close to) blocking the exhaust. which would cause any hood to melt. This would also result in much higher engine compartment temps, and eventually higher oil temps. Is it possible that this is what's going on?

If your latch has indeed failed in this manner, than it's also probably that you don't have the additional exhaust shields in place, These two things would explain why your experience is different than mine. Mine was made in early '06, but my dealer has performed all TSB's that have been issued, at least that I know of. I don't have any unexpected heat build-up, and I don't get brown grass even after letting my 2544 idle at full throttle for 15 minutes (which I did yesterday because of this thread, just so I could see firsthand). The only thing left to check is oil temp, which hopefully I can do this week.

Mine is also early '06. I would have done the TSB before except I didn't know about it. It's not like Cub sends out notices.

Here's a photo of what mine is doing -

My latch is fine but it won't be soon since the whole front of the hood is starting to deflect. And though it's not easy to see in this photo, the exhaust pipe is still centered in the hole through the hood and protrudes slightly.

You can see in the photo where the lower part of the hood is starting to twist and deflect downward, pulling away from the grill. On the inside you can see ( not in these pictures though ) where the grill is also deflecting. What would help here is a longer exhaust pipe but, it's not possible because then the hood wouldn't open.

In the first pic you can notice too how the headlight reflectors are sagging and the lenses are turning white already. 1 year old and always garaged so it's not in the sun except when it's being used. That doesn't bode well for the longevity of the headlight assemblies either.

I'm liking Larry's header wrap idea more all the time even after they fix all of this stuff with the latest factory scab-on.

I must be lucky since mine got it all. High oil temps, brown grass, and now a melting hood...

JSharp · Jul 2, 2007

Fordlords said:
This is what the "ducting" on the 682 looks like, with an engine that really is completely boxed in. All air is drawn in from underneath, and ducted out front. Kind of makes you more comfortable with the 2500's now, I hope

-Fordlords-

Check out a current 3100 if you get a chance. It has a sealed engine fan inlet sized flexible duct that ties to a plenum under the steering column. That plenum has a screen below the dashboard as it's inlet.

It's really done right. Nothing but cool outside the engine compartment air makes it into the cooling fan.

Nice tractor by the way. I've liked it and the Honda engine retrofit since I've been here.