High temp On climbs 2001 Dynasty 350HP ISC

[Coma]

Originally Posted by Jeff753

I think mine chatters around 202 also. I've never hit 210. My manual list 212 max. I seem to lose some power around 205 but I don't know for sure.
What temp thermostat is oem for the ISC 8.3 350hp?

My VMSPc says 178 when stable, somewhere I got the idea there are two, unconfirmed. There is another temp, 190 where it will stabilize under load. Maybe 180 is where the thermostat starts to open and 190 is fully open?

[jacwjames]

I have a 2002 Windsor, 2 slides so it's pretty heavy. I bought a Silverleaf system about 2 years ago and it lets me monitor the temps closely.

I run 180 unless climbing hills than then it will go up, can't remember if I've been higher then 200.

Have you cleaned your radiator lately, I know it's a side radiator but it still could have dirt accumulation, especially between the radiator and CAC. The thermostat is also a prime suspect. Have you witnessed the cooling fan running on high when you've pulled off the highway after a hard pull?

I was getting a little over 22 psi boost pressure until the CAC was rebuilt, just last month, I now see 23.2. I wasn't having a problem with the CAC but since the radiator was getting changed I took it and had it checked. It was leaking a lot.

[SteveLevin]

I don't have a Monaco, but I do have a side radiator and had a cooling issue last year.

Turns out the regulator that manages hydraulic pressure (for things like steering as well) was slowly going bad. So while the fan was turning at idle, when you actually spun the engine up, it didn't match up (i.e., as drag on the fan increased, it turned slower relative to engine rpm.

So I'd suggest testing to make sure that it is turning whatever RPM it is supposed to turn at say 2000rpm. Once we resolved that issue, I went back to being able to climb, etc., without exceeding 200 except on very long grades (such as I-5's "Grapevine" which is 6 miles of 6% continuous grade) on extremely hot (over 100 degree) days... and even them, 202-203 is about tops.

Steve

[Jeff753]

Mine has a wax valve that controls the fan. I know my fan runs but have no way of knowing if it runs correctly or not.
If 350 8.3 ISC dynasty drivers get hot unless they downshift then what I'm experiencing is normal. If they do not then I need to have cummins look into it.

So far it seems I need to downshift more aggressively to maintain Rpms above 1800. I have been downshifting but not that aggressively. Probably more like 1500 Rpms.
My coolant is two years old and I flushed the side radiator recently.

[Coma]

Originally Posted by Jeff753

Mine has a wax valve that controls the fan. I know my fan runs but have no way of knowing if it runs correctly or not.
If 350 8.3 ISC dynasty drivers get hot unless they downshift then what I'm experiencing is normal. If they do not then I need to have cummins look into it.

So far it seems I need to downshift more aggressively to maintain Rpms above 1800. I have been downshifting but not that aggressively. Probably more like 1500 Rpms.
My coolant is two years old and I flushed the side radiator recently.

Jeff, if it warm and I have been running hard then stop it howls, crack your driver window. You can easily tell the difference between idling up to temp and hot up to temp fan speed. When hot it will suck your hair off. Monaco probably has the specs.

I have no cooling issue below 5k in altitude. It could be pretty much ignored and recovery even at low RPM is quick. FWIW have you done a coolant analysis at JG Lubricants? It will give you a good idea of the sate of the inside of your radiator.

Try managing your RPM between 1900 and 2100 and see what happens.

[Jeff753]

Page 281-284 of my 2001 Dynasty Owners Manual has a good explanation of the ISC hydraulic cooling fan system.

Tomorrow I'm going to drive with higher Rpms as suggested (in the past I try for 1500) but I have been operating by downshifting already. If I downshift more aggressively I may end up going 25 mph.

I have to keep the load below 100% or it seems the temperature will keep climbing.
I have hit 203 and maybe 205 before hitting the top of the hills at black mountain and on i75.
Does the engine derate below its 212 max operating temp?

Reading about the switching valve that controls a spool valve and thereby fan speed I'm thinking that valve may be bad??
It says it's mounted to the fan motor but I don't think I've seen it or know what it looks like.
How do you test that?
Wow! Just googled it and found this. Irv2 to the rescue again!

http://www.irv2.com/forums/f115/side...nt-148331.html


Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[Jeff753]

Originally Posted by Mike Canter

If you are climbing step grades then you should be downshifting to keep your motor between 1800 and 2000 rpm. Your peak hp is at 2000 rpm and you are governed to a 2200 limit. Are you a rear radiator or a side radiator in 2001? I can't remember. If you bare a rear radiator then you should spray your radiator with Gunk Engine Degreaser and hose it down from both sides of the radiator. If you are a side mounted radiator then you need to check that your cooling fan is operating at high speed when the motor is getting up in temperature.

Mike I just wanted to thank you for the guidance. It's interesting what you can find in your manuals.
On page E-6 in my ISC Manual it says
ISC Engine Speed @ Maximum Power Output is 2200 RPM. I can't find anything about what it is governed at. I presume Maximum Power Output is the same as max horse power? That would explain a lot because I have not run between 2000-2200 if that's where I should be.

No doubt the 350 hp dynasty seems a bit underpowered with the 350 ISC.
Getting to merge speed on an on ramp is difficult even in flat Florida:(

I need to test drive a 600


Jeff
2001 Dynasty Regent tag axle
Cummins 350 8.3 ISC

[Jeff753]

Perfect today. Climbed Mont Eagle on I-24. Third gear about 20 pounds of boost and about 80% engine load. Got up to 202F.
Problem appears to have been attributed to poor downshifting. Could only get about 1700 RPMs but it seemed to help.

[Coma]

Cool!


You might try down shifting earlier, as once you fall off the HP step it's hard to get it back. Glad that no $$ to fix things.