Engine Overheating on 8% Grade

[deasnealy]

Can you explain or point me to how to reroute the engine breather? I am not sure exactly what the engine breather is.

[garykk]

If you have a rear hatch to the engine, remove that and you can access the radiator and can easier get to the area you need to clean.Using an aluminum friendly solution in a spray tank, start your engine and spray into the fan area, all around, the fan will push the solution into both the radiator and CAC. Be generous. By this time the engine is probably warmed up. Shut it down, spray the engine and let the whole thing sit for 20-30 minutes. Restart the engine and from the hatch use a garden hose and gently spray water into the fan area, do this till you don't see anymore soap coming out of the rear of the radiator. You'll see bubbles for a few minutes

The slobber tube is the breather tube on older MH Diesel engines. It's usually located just ahead of the radiator and over time, oil and mist from the tube accumulates in the radiator and CaC, attracting dirt and clogging the radiator and CAC. Some folks either extend it or run an extension to the rear of the radiator.

[deasnealy]

When you say rear hatch, I assume you mean from within the RV coach and not the hatch on the exterior of the coach. On my RED I cannot see the fan or reach it without crawling under the RV and not sure I will be able to get much coverage from that angle. I know some folks can access the engine from the Bed or closet. I am not aware of my coach having that option.

[bikerdavet]

when I drove a semi many many years ago it was common to have to reduce speed and adjust RPM's when pulling long grades to keep the temperature in an acceptable range. Just because I could pour more fuel into the engine didn't mean it was a good idea to do it. I expect there are some current or former semi drivers on this forum who can explain it better than i. More fuel burn equals more temperature. There may be absolutely nothing wrong with your setup, it could be physics.

[garykk]

Originally Posted by deasnealy

When you say rear hatch, I assume you mean from within the RV coach and not the hatch on the exterior of the coach. On my RED I cannot see the fan or reach it without crawling under the RV and not sure I will be able to get much coverage from that angle. I know some folks can access the engine from the Bed or closet. I am not aware of my coach having that option.

Yes, the hatch inside the rear of the MH. I am not familiar with your model but I would be very surprised if it did not have a rear inside access hatch.

[tiffanman]

Originally Posted by Tony Lee

No it doesn't but the engine has to run the compressor and when you are running out of options, turning off the aircon AND turning ON the dash defroster can make all the difference. Long grades in California have signs suggesting turn off AC in hot weather and it is a sensible suggestion.
When conditions are marginal you need to start driving by your engine and transmission temperature guages and forget about all the hoons burning you off in their 600HP rigs
I spent a couple of hours and a gallon of degreaser in a truck wash in Whitehorse getting the radiator and CAC clean and when Betty and I pulled the radiator and CAC out on the side of the road in Mexico a couple of trips later it was still clean. Now a mild clean once every trip is more than enough to keep it that way especially now the slobber tube isn't making a mess

The turn off AC signs you see on the highway are specifically for AC systems where the condenser is in front of the radiator,Just running a compressor will not add to a engine overheating no way no how if the condenser has its own stand alone electric cooling fan

[deasnealy]

Cleaned the radiator with light low impact pressure washer using Simple Green. From the engine side as best I could and then rinsed the engine and ran the engine a between rinses to high RPM's until I saw no bubbles. Called Freightliner and they had me remove a fuse. Just ran 2 small grades. Got to about 3/4 on the gauge on the first one. On the second one, I saw a market uptick in heat on the gauge but kept the RPM's around 2200. Never hit a high alarm, but I never had it get this hot before and would run it hard. I wonder with the fuse removed what else could be the problem. It was my understanding that removing the fuse put the clutch in high mode.

[Lt Dan]

I would recommend you get a ScanGauge D monitor. That way you can see the exact temperatures on the engine. I watch mine and the analog gauge goes well above the halfway point and the ScanGauge shows 210, then the fan kicks in and the temperature starts to drop. The analog gauges are not always accurate.

[deasnealy]

I will consider the scan gauge. I heard it was very useful. However, I should not get near the red regardless. I used to get about a clip over the half mark on the gauge and it would drop. Now it does not seem to drop until I slow down or take the pressure off the engine.

[BigBillSD]

My cummins 400 ISL almost hit that 220 degree mark going up that hill from the desert floor to mountain springs with the AC off and the heater blowing.

At the I didn't know about keeping the engine RPM @ 2200. Now I go up that grade and the grapevine and my coach doesn't get over 206 degrees on 90 degree days. The Original owner of my coach had an electric fan installed to exhaust the heat out the back louvers. Obviously he didn't know about going up the hills at that RPM either.


If you are still in San Diego you might check out the happy cow self service car washes. But not the one on Mission Gorge road as there isn't enough room to drive out of the bay, you would have to back out onto that busy street.

[timjet]

Does anyone know if a Dec 2006 Cummins ISL has a slobber tube that could be re-routed. I have a side radiator so if it does have a slobber tube would it be helpful to relocate it?

Also at what coolant temp should action be taken to cool it down, like downshifting and turning off the air cond. I'm thinking of getting a Silverleaf monitoring software.

[Old Scout]

Think the 2006 Cummins [manufactured in 05 maybe] has a tube on tranny end, above starter. Terrible location, oil vapor above starter collects and holds dust/dirt over time. With the fuel lift pump located just above, if you ever have a starter issue [eg, locked up solenoid], its a perfect set up for a fire. Side-mounted radiator not an issue, potential fire is--IMHO.....
PS--think the Cummins will de-rate itself around 227-230. With my 2003, I have never seen anything over 215--but like others have mentioned I pay attention to the RPMs and gear down to ensure adequate coolant circulation. Really doubt if adjusting A/C and dash heat will do much for an ISL overheat issue.......

[BigBillSD]

Originally Posted by timjet

Also at what coolant temp should action be taken to cool it down, like downshifting and turning off the air cond. I'm thinking of getting a Silverleaf monitoring software.

220 degrees is where my 2006 ISL 400 starts flashing its over temp. I have only seen that once. My freightliner chassis has a small info center that lets you scroll thru some readouts. I usually have it on the Oil Pressure screen, but when I head for the hills I change it to the temp screen.

Once I read about keeping it at 2200 RPM I no longer get anywhere near that temp. I also use the silverleaf vmspec on a tablet for lots of temps and pressures but I still concentrate on that info center screen of the temp when climbing hills in hot weather.

[timjet]

Thanks Bill.

My info center also has a bunch of engine parameters including coolant temp, but the contrast is so weak and size of the print so small I can't read it with sunglasses.

Why are you not depending on the Silverleaf software on your computer to monitor the coolant and oil pressure? I'm thinking of getting the Silverleaf VMSpc, any reason I shouldn't?

My engine is a 400 HP ISL with a build date of Dec '06.