B7100D Over Heating?

[mik1315]

I have a 1979 B7100D, 16hp. Any ideas why the engine is running at 230 Fahrenheit? Both the radiator and engine have been flushed and the radiator does not appear to have mineral deposits inside, no damaged cooling fins, or plugged up. The fan appears to be drawing outside air through the radiator. The engine is missing the high temperature whistle.

 

[85Hokie]

I have a 1979 B7100D, 16hp. Any ideas why the engine is running at 230 Fahrenheit? Both the radiator and engine have been flushed and the radiator does not appear to have mineral deposits inside, no damaged cooling fins, or plugged up. The fan appears to be drawing outside air through the radiator. The engine is missing the high temperature whistle.

Let me run some questions by you:

What are you doing when it overheats? Bushhogging? FEL work?

How are you gauging the temperature ? Infrared laser ?

What is your coolant ratio?

How much fluid is in radiator? 3/4" - 1" from the top lip?

Have you taken any temps at the bottom neck of the radiator? SHOULD be a 50 degree drop through the radiator

How do you know the fins are clean? Looks can be very deceiving. I would wash them down with soap and water hose, after I blew them out with compressed air.

Any chance you have a small head gasket leak? Check open radiator for bubbles?

How fast does it take to get to 230?

Mine runs at 210 dead balls when working the hell out of it, then back to idle after 5 minutes will settle in at 180.

Report back

 

[mik1315]

85hokie,
Thank you for the reply.

"What are you doing when it overheats? Bushhogging? FEL work?"
Using my finish mower, Woods RM48 or Caroni TC590. Grass wasn't too tall, third gear; guessing on engine RPM 2/3 throttle setting?

"How are you gauging the temperature? Infrared laser?”
Installed temperature gauge. Discrepancy of 25 degrees between with infrared laser and gauge.

"What is your coolant ratio?"
It's around 60/40, rated for -30 below, need that up north.

"How much fluid is in radiator? 3/4" - 1" from the top lip?"
The level is about 1” from the top.

"Have you taken any temps at the bottom neck of the radiator? SHOULD be a 50 degree drop through the radiator"
Good question, the temperature drop is around 90 degrees Fahrenheit.

"How do you know the fins are clean? Looks can be very deceiving. I would wash them down with soap and water hose, after I blew them out with compressed air."
Pressure washer, on low setting, followed by compressed air.

"Any chance you have a small head gasket leak? Check open radiator for bubbles?"
I checked no bulbs in the radiator.

"How fast does it take to get to 230?"
About 18 minutes or so but will time it next time.

"Mine runs at 210 dead balls when working the hell out of it, then back to idle after 5 minutes will settle in at 180."
Mine will cool down to 190, according to the temp gauge. I will measure with infrared. I estimate the throttle at about around 2/3 or less.

Respectfully,
Mike from Medina, Ohio.

 

[North Idaho Wolfman]

"How are you gauging the temperature? Infrared laser?”
Installed temperature gauge. Discrepancy of 25 degrees between with infrared laser and gauge.

Is the gauge higher or the IR?
Sounding like your gauge my be wonkiee and just off temp.

 

[torch]

Installed temperature gauge. Discrepancy of 25 degrees between with infrared laser and gauge.

Infrared temperature probes are notoriously inaccurate, despite their high precision. The lens is looking at a cone, not just the spot indicated by the little red dot, so they indicate the average of an area that increases with distance. They measure radiant heat from an object, which can vary from the actual temperature of that object depending on it's emissivity (how efficiently the object radiates heat) and reflectivity*. Plus, most IR probes are made of Chinese electronics so even under ideal conditions they are only accurate +/- 5° or so!

They are a great tool, but understand their limitations and don't be fooled into unquestioning belief of the accuracy.

*I work with IR thermal imaging cameras regularly and it's amazing to see how a piece of glass or steel will affect the image compared to the surrounding structure. A pot of boiling water might only show as 100°F because the shiny metal pot is reflecting the room. Flames can be visible behind a window, but the camera will show the window as completely opaque.

 

[mik1315]

Wolfman,

Thanks for everyone's help. My gauge is reading higher than the Infrared, 25 degrees Fahrenheit. By the way, the gauge's sending unit is spliced into the top hose, from top of engine to top port of the radiator. I will check the temperature by dipping a mercury thermometer inside the radiator cap and report back.

By the way does anyone have an extra over temperature whistle? At what temperature does the whistle go off?

Mike from Medina

 

[85Hokie]

Wolfman,

Thanks for everyone's help. My gauge is reading higher than the Infrared, 25 degrees Fahrenheit. By the way, the gauge's sending unit is spliced into the top hose, from top of engine to top port of the radiator. I will check the temperature by dipping a mercury thermometer inside the radiator cap and report back.

By the way does anyone have an extra over temperature whistle? At what temperature does the whistle go off?

Mike from Medina

If you take the infrared laser and point to ALL points on the housing in the radiator upper hose - and the top neck of the radiator, it will give you a closer reading of the hot water at that point. Those infrared pointers can be off too, but only +/- a degree or two.

Is your gauge a mechanical or electrical (I might have missed that info) IF electrical - make sure the housing has been grounded, otherwise you dont get an accurate reading at all!

If you gauge is off 25 F (205 F)- then that places you right inline as to the right temps when the engine is at it's proper temps.

 

[D2Cat]

Last year I installed a mechanical water temp. gauge on my L305. I couldn't get the gauge to read above 140deg.

After a while I replaced it with a new one, different brand. It read about 165 deg after mowing for a hour. Then one day, while mowing, the gauge seemed to be climbing. I could almost see the needle edge upward. It went past 200deg and kept climbing. I then let the engine idle and checked various locations with an infrared thermometer. Engine was around 180 deg. so I continued mowing with the infrared in my pocket to check every few minutes.

The needle kept moving. At the bottom of the gauge is said "WATER". The needle went all the way to "A", and stayed there. (A little further and needle would have hit the back side of the stop pin)

Needless to say, I replace that gauge also!

I installed a 15 years Old Stock Caterpillar gauge with the colors in it. I mower a pasture yesterday with 5'-6' tall grass/weeds for two hours and the needle on this gauge was mid green. (normal)

So I think a large percentage of the gauges sold today are made in a Chinese factory. Their quality control is not what is should be. And it does not matter where you buy the gauge, including the old stand by NAPA---they all come from the same place, Sunpro, Bosch, it doesn't matter.

 

[85Hokie]

"So I think a large percentage of the gauges sold today are made in a Chinese factory. Their quality control is not what is should be. And it does not matter where you buy the gauge, including the old stand by NAPA---they all come from the same place, Sunpro, Bosch, it doesn't matter."

Better words have not been said - excellent point!

 

[mik1315]

Update:

I tighten the fan belt and replaced the radiator cap, the old cap's rubber seal looks like a mouse had nibbled on it. Engine is operating around 215 degrees Fahrenheit. I did notice antifreeze seeping from a bolt on top of the head. It is a bolt connected to the head puller or some type of bracket, see photo. Any ideas what the bolt is for and the leaking anti freeze?

Mike from Medina, Ohio

 

[North Idaho Wolfman]

mik1315,
It's time to break down and put a head gasket on it!

 

[torch]

That's a cylinder head bolt. A/F leaking from there indicates one of 3 things:
1. bolts not adequately torqued
2. head gasket leaking between water jacket and bolt hole
3. head or block cracked between water jacket and bolt hole.

Assuming the bolt is tight, then the "right" way to fix it is tear it down and replace head gasket, head, and/or block, as required. But...

If everything else is ok -- no sign of coolant in the combustion chamber, compression OK, etc, then I'd suggest trying a can of CRC Block Seal first. Use is more involved than most leak sealants that are just added to the coolant, but it's also more likely to work -- if you follow the directions properly.

You have to flush the coolant out with plain water thoroughly; it won't bond to the metal in the presence of coolant. (After it's set then you drain the system and can fill with coolant.) An old mechanic put me onto this stuff years ago and I've used it quite successfully twice now. It's much cheaper and easier than option A.

 

[North Idaho Wolfman]

If everything else is ok -- no sign of coolant in the combustion chamber, compression OK, etc, then I'd suggest trying a can of CRC Block Seal first. Use is more involved than most leak sealants that are just added to the coolant, but it's also more likely to work -- if you follow the directions properly.

You have to flush the coolant out with plain water thoroughly; it won't bond to the metal in the presence of coolant. (After it's set then you drain the system and can fill with coolant.) An old mechanic put me onto this stuff years ago and I've used it quite successfully twice now. It's much cheaper and easier than option A.

Because of the b7100 not having a normal water pump operated system, my understanding is that a block sealant will not work as it should and will just sit in the bottom of the radiator, then as the temp rises it bonds to the lower radiator causing it to be less efficient and if really bad cause the tractor to over heat.
I have see CRC and it looks very fine and looks like it might move with the thermo siphon but I worry.

 

[85Hokie]

is it holding at 215? and these are measured with IR thermo?

215 is a normal hot temp for most engines, cars run between 210-220 because the efficiency is higher with a hotter engine.

What is your mixture ? 50-50? IF you are using 50-50 and want to try it, use straight water for a week and see if there is ANY change in temps. If there is - you might not have a major problem as others have said, then again - you might have all those problems.

Water is by far a better agent for heat transfer than 50-50. And on a thermosyphon system, the heat needs to transfer easily and efficiently. Give it a shot, you can save your old fluid and replace if/when you need to use it again.

 

[torch]

Because of the b7100 not having a normal water pump operated system, my understanding is that a block sealant will not work as it should and will just sit in the bottom of the radiator

That is an interesting point, I forgot about the lack of water pump. There must be some circulation in the system, but is it too low a velocity to stir things? The CRC MSDS lists the SG as 1.37, so it is denser than water.

On the other hand, looking at my tractor, the cores run vertical instead of horizontal, so the cooled water will be falling into the tank below. Not much chance of plugging those. The lower tank of the rad has enough volume to accommodate the entire can of sealant, which is itself about 50% water, so I don't think it possible to plug that either. And finally, the MSDS shows the primary sealant is sodium silicate, which doesn't cure in water, it requires heat and air. It may leave a coating behind, but I believe the bulk of the active ingredient is drained out with the water at the end of the process.

Personally, I think there is nothing to lose by trying it, but, yes, I can see where it might not work in this application.

 

[mik1315]

85 Hokie,

I think you may have busted my overheating. I drained the anti-freeze and replaced with fresh water. Ran the tractor for over an hour it ran up to 195 degrees Fahrenheit. Also, it idles at 180 degrees. The tractor is running 25-30 degrees cooler with the water. I never checked the anti freeze ratio other than checking for freezing temperature. I will report back next week.

85 Hokie thanks for the simple check before I rip open the engine.

Mike from Medina, Ohio

 

[North Idaho Wolfman]

mik1315,
You didn't "fix the issue" you side lined a problem that if not addressed soon could cost you a lot more in the long run.
If the leaking head gasket is leaking any amount into the cylinders it will scar them and eventually kill the useful operation of the engine.

 

[Big Kahuna]

And $4000 later you'll have a new motor, been there done that.

BK