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I have a Husky with a 24HP B&S. Some time back I fitted a dual temperature display to monitor the Transaxle temp (usually 65DegC) and the engine (oil filter) temp (usually 70DegC) and I have kept an eye on them both over the last few years. Tranny Temp is still the same but more recently I have noticed that when I finish mowing (the usual lawns) the engine temp is 99 to 105DegC.(221DegF).

Is that too hot? and any ideas what could be causing this heat creep?

Many thanks.
Neo

I would suggest that the transmission oil temperature is low and the engine is now about right.
In general - oils are engineered to be most efficient in the 95 -110 C continuous range and suffer no ill effects if they peak, for a short time, up to 130C.

The rise in engine oil temperature could be related to oil formulation change, dust/debris on the cooling fins, higher load (mowing faster/blunt blades, your weight, etc)

If in doubt, contact the oil manufactures technical advisory service for a more informed comment.

Skippydiesel said:

dust/debris on the cooling fins,

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yup.

Do you operate the engine at an idle slash slow speed?

I use an airline "in and under" that shroud after most uses. But just to be sure I will take the shroud off, take a better look and come back to you.

Neo7 said:

I have a Husky with a 24HP B&S. Some time back I fitted a dual temperature display to monitor the Transaxle temp (usually 65DegC) and the engine (oil filter) temp (usually 70DegC) and I have kept an eye on them both over the last few years. Tranny Temp is still the same but more recently I have noticed that when I finish mowing (the usual lawns) the engine temp is 99 to 105DegC.(221DegF).

Is that too hot? and any ideas what could be causing this heat creep?

Many thanks.
Neo

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Of course, be sure the engine fins are clean for good air around the cylinders. As your engine ages, the piston rings wear, as do, the cylinder bores. As they wear, there will be more "air" sneaking down into the oil pan/sump, past the rings causing the oil to gain temperature. When the engine fires, it actually is an explosion causing the piston to be forced "down". Some of that explosion is forced pass the rings into the sump and raising the temp....

Neo7 said:

I have a Husky with a 24HP B&S. Some time back I fitted a dual temperature display to monitor the Transaxle temp (usually 65DegC) and the engine (oil filter) temp (usually 70DegC) and I have kept an eye on them both over the last few years. Tranny Temp is still the same but more recently I have noticed that when I finish mowing (the usual lawns) the engine temp is 99 to 105DegC.(221DegF).

Is that too hot? and any ideas what could be causing this heat creep?

Many thanks.
Neo

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Do you know the ambient temperature at the same times. Could be dirt under the shroud.

If it was me and there was no obvious issue I would swap temp probe positions to determine if the temp probes are accurate. If readings are the same then ther may be an engine issue.

You can also use a IR thermometer and get instant readings at different place on the block. They are priced reasonable now days.

Let the engine set and run at fast rpms for awhile and monitor temp.

If you are a bit lazy, and want to check for fin blockage, you may be able to slide a hand under the cylinder, between cylinder and chassis, and feel for good airflow being blown from the flywheel blower down past the finnage and onto the top of the chassis. If the flow feels good and strong, you likely have little to no blockage of the fins by debris.
Be sure to feel for flow below the cylinder head area as that is likely the hottest spot, combustion and stuff, you know...
Oil a little bit above the boiling point of water is reasonable to me. Running an air cooled engine at idle diminshes the airflow and can lead to overheating. Idle rpms also decrease the oil splash and heat transfer capability. RIding back to the barn at slower rpm to 'give the engine a break' is not a good thing to do. Better to keep the rpms up.
tom

If this is a full pressure Vanguard.....https://www.ebay.com/itm/255464747799
There are adapters and coolers but at this stage you're not anywhere near too hot for an air cooled. 250F is generally max for conventional oils and synthetics will take that up a bit more, but not much. Beyond 250.....

Don't go looking for problems that don't exist.

I checked under the cowl but nothing but lite dust

In my very limited experience overheating is usually:

• Lack of cooling - As this is an aircooled engine, something restricting air flow.
• Running lean - carburettor not delivering the correct amount of fuel for the air : fuel ratio - something restricting fuel flow - "gunked" up jet or similar

Skippydiesel said:

• Running lean - carburettor not delivering the correct amount of fuel for the air : fuel ratio - something restricting fuel flow - "gunked" up jet or similar

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What about running rich? ... I fitted a new Air filter because the old one was quite dark with dust. ... I'll see how she goes on the next mow ;-)

No! A rich fuel air mixture will cool the engine. It will also carbon/soot up the plug(s).

One of the most common causes of a hot/cold engine indication, is a faulty thermocouple/sensor. As you have two (engine/transmission) is it possible to swap them around and see if they are consistent in their reading.

Neo7 said:

I have a Husky with a 24HP B&S. Some time back I fitted a dual temperature display to monitor the Transaxle temp (usually 65DegC) and the engine (oil filter) temp (usually 70DegC) and I have kept an eye on them both over the last few years. Tranny Temp is still the same but more recently I have noticed that when I finish mowing (the usual lawns) the engine temp is 99 to 105DegC.(221DegF).

Is that too hot? and any ideas what could be causing this heat creep?

Many thanks.
Neo

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Remove the shrouds and clean the fins regularly. As I recall, B&S has a bulletin to do that for these engines. Aside from that, use the correct weight oil for the temperature conditions.

I've already done that. I've been running the same grade of oil for ages. No recent changes there.

I know you have removed the top shroud, but what about the cover tins over the cylinders to make sure they are not packed full of dirt and chaff? I've seen too many have a clean topside and the fins were packed solid.

As I recall, B&S had a number of overheat issues with this design.

Next idea is to go up one size on the carburetor main jets so it will richen the mixture slightly and help cool the combustion slightly. These engines were tuned to run super lean due to emissions imposed on the industry.

As for the transmission(s) they have cooling fins and usually cooling fans. The fans are common for rounding out the spline teeth in the center and gradually slip and lose cooling efficiency.

Auto Doc's said:

I know you have removed the top shroud, but what about the cover tins over the cylinders to make sure they are not packed full of dirt and chaff? I've seen too many have a clean topside and the fins were packed solid.

As I recall, B&S had a number of overheat issues with this design.

Next idea is to go up one size on the carburetor main jets so it will richen the mixture slightly and help cool the combustion slightly. These engines were tuned to run super lean due to emissions imposed on the industry.

As for the transmission(s) they have cooling fins and usually cooling fans. The fans are common for rounding out the spline teeth in the center and gradually slip and lose cooling efficiency.

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I’ve rebuilt a few of these engines but I’ve never seen those rocker cover tins full of dirt. Assuming the tins are fitted correctly how would the dirt get in there?

I am referring to the metal tins that surround the outer cylinder fins.

Much of this depends on how dusty the condition is when moving. Around my area there is a lot of loose sand and dirt, but people mow at full throttle, and it looks like a small tornado.

I am referring to the metal tins that surround the outer cylinder fins.

Much of this depends on how dusty the condition is when moving. Around my area there is a lot of loose sand and dirt, but people mow at full throttle, and it looks like a small tornado.

Auto Doc's said:

I know you have removed the top shroud, but what about the cover tins over the cylinders to make sure they are not packed full of dirt and chaff? I've seen too many have a clean topside and the fins were packed solid.

As I recall, B&S had a number of overheat issues with this design.

Next idea is to go up one size on the carburetor main jets so it will richen the mixture slightly and help cool the combustion slightly. These engines were tuned to run super lean due to emissions imposed on the industry.

As for the transmission(s) they have cooling fins and usually cooling fans. The fans are common for rounding out the spline teeth in the center and gradually slip and lose cooling efficiency.

Click to expand...

I’ve rebuilt a few of these engines but I’ve never seen those rocker cover tins full of dirt. Assuming the tins are fitted correctly How would the dirt get in there?

Auto Doc's said:

I am referring to the metal tins that surround the outer cylinder fins.

Much of this depends on how dusty the condition is when moving. Around my area there is a lot of loose sand and dirt, but people mow at full throttle, and it looks like a small tornado.

Click to expand...

Oh Ok I get it now, sorry … No they are completely clear on my B&S engine

So have you checked out the thermocouples, as suggested in #15???

Auto Doc's said:

I know you have removed the top shroud, but what about the cover tins over the cylinders to make sure they are not packed full of dirt and chaff? I've seen too many have a clean topside and the fins were packed solid.

As I recall, B&S had a number of overheat issues with this design.

Next idea is to go up one size on the carburetor main jets so it will richen the mixture slightly and help cool the combustion slightly. These engines were tuned to run super lean due to emissions imposed on the industry.

As for the transmission(s) they have cooling fins and usually cooling fans. The fans are common for rounding out the spline teeth in the center and gradually slip and lose cooling efficiency.

Click to expand...

I’ve rebuilt a few of these engines but I’ve never seen those rocker cover tins full of dirt. Assuming the tins are fitted correctly How would the dirt get in there?

Auto Doc's said:

I am referring to the metal tins that surround the outer cylinder fins.

Much of this depends on how dusty the condition is when moving. Around my area there is a lot of loose sand and dirt, but people mow at full throttle, and it looks like a small tornado.

Click to expand...

Oh Ok I get it now … no they are completely cl

Skippydiesel said:

So have you checked out the thermocouples, as suggested in #15???

Click to expand...

No sorry Ive not had time to do that as I’m currently travelling.

Oh right, I get what you mean now ... thanks for your thoughts on that.... But yes they were clear, maybe because I often use a compressed airline (over the whole engine), underneath those cylinders, where the exhaust pipes comes out.

I've been away from home for some time but next time I've mowed the lawn I intend to use my laser temperature checker all over the engine to see if I have any unusually high hot spots and also to double-check the readings I've been getting from the temperature sensor (thermocouples) I have on there atm.

Best to remove the lower tin shroud that surrounds the cooling fins and clean away. Really need a visual inspection to rule it out. Mice and critters can drag debris in there. And YES they clog up all the time.

slomo said:

Best to remove the lower tin shroud that surrounds the cooling fins and clean away. Really need a visual inspection to rule it out. Mice and critters can drag debris in there. And YES they clog up all the time.

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Yes, thanks again, all clear, for sure ... Actually, this same point has been coved two or three time now. I guess that's the problem with long threads like this one, because none of us have the time to read all the previous posts.

Follow up report?

None yet, sorry

Ok today I've compared the thermocouple measured temperature with the laser type temp tester. The thermocouple actually measured about 4 degC lower (rather than higher) but that was just midday temperature (with the engine not running), so maybe thermocouples inaccuracies are not constant from low to high temps.
Anyway, I changed the thermocouple and should be mowing the lawn in the next couple of days, so I'll report back after that.