Too hot? Oil Temp' at 240+

[Kunkies]

I have a question regarding "normal" operating temperatures of our Valks.

I have one of those fancy smancy oil temp gauges that replaces the stock oil dip stick.  I have validated the gauge is accurate.  For the first time in 4 years, and during a 9 day trip last week, I noticed the oil temp' was not 205'ish like I'm use to seeing, rather almost 240.  This makes me anxious.   

I'm to understand oil temp' mirrors coolant temp', true.  Also, radiator fan works, and I'm religious about coolant changes.

Should I be worried?

[sandy]

Air cooled bikes (Harleys) get up to 265 with no engine damage. However I've never seen more than 222 on my Trutel gauge when I pulled a 400lb tent trailer. Maybe you can get a contact temp gauge and measure the water temp entering the top of the radiator.

[Jess from VA]

My understanding (limited) is that water/coolant temp is a quicker indicator than oil temps (which lag behind water temp), though they are clearly related.  I also understand that to be most useful, water/coolant temp should be measured (just) before it enters the radiator, not after.

I have the same Tel Tru oil temp gauges.  One of them needs recalibrated.  YOU say you have checked it.  Was that in boiling water (sea level) at 212F?   (it boils sooner at higher elevation, like 200F at 6,600 ft altitude.)  I would double check this before you go elsewhere.

I have been lead to believe that 220F is as high as you want your bike temp.  I've been over a couple times in really hot weather, but not for long, and not much higher (never 240).  I'm in VA and usual summer operating temp is not 220, closer to 200-10.  I won't ride in 95-100*.  In cooler/cold weather I never worry.

If you were really running 240 (moving), I'd be concerned.  Unless you sat and idled in hot weather for a long time.  I won't let that happen.  I get stuck in heat, I shut it down.

[Kunkies]

Wow, great input. . . thanks everyone.

Yes, my Tel-Tru oil dip stick therm' has been calibrated.  211 in boiling water at 827' above sea level (Charlotte, NC).  1 Degree off, close enough.

Conditions for the 240+ temp is as follows:  I-77 northbound from Charlotte to Roanoke, 90+ degree temps and humid, running ~75MPH'ish.  This was the beginning of a 9 day road trip.  Tool bag mounted on the front forks right up underneath the headlight bucket partially blocking the top of the radiator (possible cause?).  On my return, I monitored oil temp's and they were normal 205-215'ish, until I jumped on the slab and started running 75MPH again.  I was carrying about 80lbs worth of stuff on my pillion and saddlebags.

What precipitated my note was I checked my oil level the day after I returned and the oil went from virtually clear (changed oil right before I left) before my departure to a much darker color.  Not empirical, yet I don't think I've seen my Amsoil 20W-50 oil get dark that fast, ever.

[Bagger John - #3785]

The oil is beginning to coke up.

Your temp indicator says 240 degrees in the sump but I'll bet you have localized hot spots.

Pull the plugs and see what's going on with the fuel/air mixture. Are they excessively white and possibly blistered?

[The emperor has no clothes]

You are making me check mine more often now. It's always been about 210*, even here in the desert. Kind of quit looking much anymore. I think I'd pull the tool bag and see if it helped.

[Kunkies]

What is "coke up"? 

[Bagger John - #3785]

What is "coke up"? 

When oil is excessively heated it begins to break down. The lighter aromatics come out of solution, leaving behind the heavier solids.

Coke itself is a product of cooking coal in an oven. So...the same principle applies here.

[Savago]

On top of the all good advice people posted, here goes my 2cs: assuming your radiator fan is ok (and the radiator is not blocked/insanely dirty), I would have to ask:

a) Which oil are you running in your bike?

b) Which oil filter you got?

c) When was the last time you flushed the coolant?

d) Is the air filter clean?

Even with a bad fan, if the bike is moving you shouldn't reach 240F.

[Hook#3287]

I think I'd pull the tool bag and see if it helped.

Agreed, anything blocking airflow to the radiator is not good.  Not saying it will cure you're issue, but I'd move the tool bag.

[Kunkies]

Tool bag off!   

Answers:
a) Which oil are you running in your bike?  A.  AMSOIL 20W-50

b) Which oil filter you got?  A.  OEM

c) When was the last time you flushed the coolant? A.  ~ 8 Months ago

d) Is the air filter clean?  A.  1 year old, due for replacement

[Paladin528]

Noticed a 15 degree difference between running high speed on the highway and slower speeds on the other roads.  Slowing down runs around 200-205 and on the slab looking at 215-220.  Thats on a relatively cool day in the 70's.

[WintrSol]

Grain of salt time, but this page: https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=19&ved=0ahUKEwiO2tSMn-HUAhWEOT4KHRH3ArIQFgh_MBI&url=http%3A%2F%2Fwww.hotrod.com%2Farticles%2Fengine-oil-temperature%2F&usg=AFQjCNG2_PgwN1Qd0Dp0KwVpHUR9ZHj6rw&cad=rja
says oil should be over 220F to remove water and "A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees."

[Bagger John - #3785]

..."A quality conventional motor oil will tolerate oil sump temperatures of up to 250 degrees, but starts breaking down over 275 degrees. The traditional approach is to try to hold oil temperatures between 230 and 260 degrees."

That works if there are no hot spots in the engine. Which I'm thinking there may be in this case - ergo, the need for a plug read.

[WintrSol]

No arguments here. The real question here is, why is the oil getting so hot in a moving bike at relatively cool ambient temperatures.

But, if you search around the Amsoil site, they claim they ran a HD engine to temperatures as high as 500F at the head, without their oil failing (whatever that means). I'm sure there was some cooking off of the oil, but their claim is it didn't lead to failure.

[Bagger John - #3785]

No arguments here. The real question here is, why is the oil getting so hot in a moving bike at relatively cool ambient temperatures.

But, if you search around the Amsoil site, they claim they ran a HD engine to temperatures as high as 500F at the head, without their oil failing (whatever that means). I'm sure there was some cooking off of the oil, but their claim is it didn't lead to failure.

Which is about what I'd expect from an air-cooled Harley engine. Our motors - being liquid cooled - should exhibit a much lower thermal variance. When temps do become elevated, something's amiss.

A few ways to cause overheating of any engine:

1) Overly lean condition;

2) Retarded or improper engine timing;

3) Excessive load;


And with a water-cooled engine in particular:

4) Coolant system failure (restricted radiator passages, blocked airflow, air bubbles - voids - in the coolant, clogged water pump, faulty thermostat).

Items 1-3 are a fairly easy diagnosis, assuming you have a timing light. Item 4...requires a bit more investigation.

I had a couple of GL1100s over the years which exhibited the higher-than-normal temp condition as the OP described. Plug colors (mixture) were ideal, timing spot-on (I bought the special little inspection plug to verify) and airflow through the radiator was good. Even swapped radiators on one of them with a low-mileage, clean example. Still no joy. The problem lay deeper than I went at the time. 

[WintrSol]

I'd try air bubbles first: put the front wheel higher than the rear, radiator cap off, and run until the radiator warms up, then rev it a few times. Use a catch basin for any coolant that expands out, and top off the radiator after the bike is cool again. If the radiator is slow to warm up - it should just take a couple minutes - I'd say the water pump is next. New pump and bubbles aspirated would mean deeper issues; can you thoroughly flush this engine?

[Kunkies]

Update for those following:

Well, I had an opportunity to ride Sunday and I put ~240 miles on her.  90+ degree day with high humidity, normal for North Carolina summers.  Prior to, I remove my tool bag from the front forks (right under headlight bucket), validated my oil temp' gauge was working properly, checked to ensure no air bubbles in cooling system, and checked coolant effectiveness.  Check.

When my engine got up to normal operating temperatures I noticed a sudden drop in temp' on the oil gauge from ~215 to ~205; thermostat working, check.    

Net/net:  my Valk' oil temp ran at ~204 degrees on average, ~220 was the highest for I was running up twisty/winding mountain roads in lower gears [primarily] for engine breaking.

Issue resolved.  It appears my tool bag was not only blocking a portion of the radiator, but also creating indirect wind turbulence disallowing direct air flow even to the bottom of the radiator.  Not good.

Lesson learned:  avoid tool bag use. 

Thanks for all the suggestion and feedback.  Couldn't have diagnosed without this awesome forum!