M11 suddenly running very cool

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M11 suddenly running very cool

December 14, 2018, 01:02:10 pm

Just left Yuma Proving Grounds headed for Ajo. Noticed the on the flats at 64mph and low 50's temps. My temp gauge dropped to 160. About half way between the 180 hash mark and the next lowest mark. So just guessing on exact engine temp. Stopped at Tacna on I-8 and looked at the overflow tank. It was nearly empty but the main fill tank was hot as were the hoses. So there is coolant flow going on. I topped up the over flow and I'm letting the engine cool off. I used my heat detector and after 15 minutes the main fill tank is at 134F. The cylinder head is 150F. The large silver coolant pipe on the engine side is 145F. Nothing is hot.

As an aside. This engine has always run at 180 and I don't think I have ever seen 200. (on the dash gauge)

Issues to look for??
Thanks

Re: M11 suddenly running very cool

Reply #1 – December 14, 2018, 01:26:28 pm

We've been above 200 many times pulling I-17 up to Flag, but the fact you are losing water is of concern: OR, have you been checking daily? At least, on our CAT, a little water loss is normal ( I follow CAT instructions and only add distilled water). Get on down here!

Re: M11 suddenly running very cool

Reply #2 – December 14, 2018, 01:49:20 pm

Thanks for the phone call Mike. I have never seen a drop of anything under the engine bay. The engine has shucked up a few inches of coolant from the over flow tank.

I'm going to restart and look at the temps with the infrared gun. Perhaps my gauge is going out.

Re: M11 suddenly running very cool

Reply #3 – December 14, 2018, 01:50:04 pm

Sounds like the thermostat stuck open

Re: M11 suddenly running very cool

Reply #4 – December 14, 2018, 01:51:42 pm

Actually as inexpensive as thermostats and gaskets are, I would just replace it. And they ARE wearing components (metal to metal contact).

Re: M11 suddenly running very cool

Reply #5 – December 14, 2018, 01:54:29 pm

Not unusual on over the road trucks to have the m11 thermostats fail. The "cage" corrodes and the "legs" break.

At least that's what I remember in my searches on m11 issues.

I think the symptom was over cooling versus overheat.

Three hours labor if memory serves me. There is supposed to be a disk in there I think that diverts? The flow for the retarder?

Re: M11 suddenly running very cool

Reply #6 – December 14, 2018, 01:55:07 pm

Quote from: mike leary – December 14, 2018, 01:26:28 pm

We've been above 200 many times pulling I-17 up to Flag, but the fact you are losing water is of concern: OR, have you been checking daily? At least, on our CAT, a little water loss is normal ( I follow CAT instructions and only add distilled water). Get on down here!

Mike, you should not need to add coolant (or distilled water). You should not have a leak. I would check hose clamps-- as temperatures cool, metal contracts, potentially making for tiny drips/leaks. Usually easy to spot as wet place where hose meets metal component.

A good way to check for this kind of leak (vs internal engine leak) is, when parked to fill to the "cold" mark. Check it a week later. If level is lower, very likely a hose/connection leak vs engine issue.

Re: M11 suddenly running very cool

Reply #7 – December 14, 2018, 03:49:40 pm

Big Dog,
Your at that point were the radiator may be leaking. Take a good look at it.
Also your cooling fans may be stuck on high.

Bob

Re: M11 suddenly running very cool

Reply #8 – December 14, 2018, 03:52:17 pm

Quote from: wolfe10 – December 14, 2018, 01:55:07 pm

Mike, you should not need to add coolant (or distilled water). You should not have a leak. I would check hose clamps-- as temperatures cool, metal contracts, potentially making for tiny drips/leaks. Usually easy to spot as wet place where hose meets metal component.

A good way to check for this kind of leak (vs internal engine leak) is, when parked to fill to the "cold" mark. Check it a week later. If level is lower, very likely a hose/connection leak vs engine issue.

I think, in the four years we've run this dear, I've added two or three cups, so it is not on my list. Being always parked on gravel, I'd never notice a leak, and I do inspect the compartment. BUT, before we head out, I look and look daily after that.

Re: M11 suddenly running very cool

Reply #9 – December 14, 2018, 04:44:31 pm

Bigdog just pulled in right next door! As being our style, we'll let him/her get landed before any 'lodge'.

Re: M11 suddenly running very cool

Reply #10 – December 14, 2018, 06:53:41 pm

So, do you think they say, "hey, I'm build # 5314 and you are # 4297, pleased to met 'ya ?

Re: M11 suddenly running very cool

Reply #11 – December 14, 2018, 07:08:29 pm

I suspect that it may have been environmental conditions that had me running cooler than expected. It was a cool 52 & cloudy with a quartering left tailwind. The engine wasn't working hard at all. After we sat for a spell the outside temp warmed up a bit and once back on the road. The temp never budged from 180F to one needle width above 180F.

A thermostat is a cheap thing and will be replaced. I suppose if my temp is off, To the low side would be preferable than the high side. In the end. We landed safely in Ajo.

Re: M11 suddenly running very cool

Reply #12 – December 14, 2018, 07:16:34 pm

Let the festivities begin

Re: M11 suddenly running very cool

Reply #13 – December 14, 2018, 07:24:02 pm

Quote from: gracerace – December 14, 2018, 07:16:34 pm

Let the festivities begin

Yep, From Mclintock. Where's the whiskey?
Anyway. We better end this as we are in the tech section.

I'll pop the radiator cap in the AM when the engine is stone cold and do a finger dip.

Re: M11 suddenly running very cool

Reply #14 – December 14, 2018, 07:41:23 pm

Quote from: gracerace – December 14, 2018, 07:16:34 pm

Let the festivities begin

Bigdog's lights are out now at 5.30 mst. I know that feeling.

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M11 suddenly running very cool

December 14, 2018, 01:02:10 pm

Re: M11 suddenly running very cool

Reply #1 – December 14, 2018, 01:26:28 pm

Re: M11 suddenly running very cool

Reply #2 – December 14, 2018, 01:49:20 pm

Re: M11 suddenly running very cool

Reply #3 – December 14, 2018, 01:50:04 pm

Re: M11 suddenly running very cool

Reply #4 – December 14, 2018, 01:51:42 pm

Re: M11 suddenly running very cool

Reply #5 – December 14, 2018, 01:54:29 pm

Re: M11 suddenly running very cool

Reply #6 – December 14, 2018, 01:55:07 pm

Re: M11 suddenly running very cool

Reply #7 – December 14, 2018, 03:49:40 pm

Re: M11 suddenly running very cool

Reply #8 – December 14, 2018, 03:52:17 pm

Re: M11 suddenly running very cool

Reply #9 – December 14, 2018, 04:44:31 pm

Re: M11 suddenly running very cool

Reply #10 – December 14, 2018, 06:53:41 pm

Re: M11 suddenly running very cool

Reply #11 – December 14, 2018, 07:08:29 pm

Re: M11 suddenly running very cool

Reply #12 – December 14, 2018, 07:16:34 pm

Re: M11 suddenly running very cool

Reply #13 – December 14, 2018, 07:24:02 pm

Re: M11 suddenly running very cool

Reply #14 – December 14, 2018, 07:41:23 pm

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