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brenthg · 06-09-2016, 06:19 AM

On a new to me 2005 Discovery 39S, I was out for a day trip to get familiar with the new ride. It ran like a top all day and then a bunch of engine lights came on and I saw the Temp Gauge pegged. I immediately slowed down and found a place to pull off for a cool down.

After cooling off, I took the cap off the overflow tank and added maybe a 1/2 gallon of water and headed back to town. Temp Gauge increased again at higher speeds, but came back to normal when I slowed down, so I stopped and bought a gallon of coolant and added maybe a little less than 1/2 gal of coolant and it seemed to be fine after that.

I suspect that the radiator was low on coolant and needed to be topped off. Hoping to get back out on the highway this weekend and run it up to 65mph and see if that's what it was.

I've read all the threads here about cleaning CAC and radiator and I'm planning to setup a regular maintenance schedule to clean and degrease with SimpleGreen as a precaution.

Tha_Rooster · 06-09-2016, 10:01 AM

My question would be where did that gallon of fluid go?

brenthg · 06-09-2016, 02:10 PM

Like I said, maybe it was low on fluid and hadn't been topped off in awhile. I just became the new owner a few weeks ago and there weren't any maintenance records with it.

With an older coach like this, not knowing its history, I purchased an extended service policy to protect it just in case.

gatorcq · 06-09-2016, 05:31 PM

I hope you used distilled water

palehorse89 · 06-09-2016, 05:46 PM

Quote:

Originally Posted by brenthg

Like I said, maybe it was low on fluid and hadn't been topped off in awhile. I just became the new owner a few weeks ago and there weren't any maintenance records with it.

With an older coach like this, not knowing its history, I purchased an extended service policy to protect it just in case.

Coolant systems are a sealed/pressurized system.........should never need topped off.........if coolant is needed, there is a leak some where.
If you have a "Over flow" bottle, when cold it should be around the low level mark, and when hot it should rise to the high level mark or a bit above........when it cools down, if the level goes below the low mark, and adding coolant is necessary so as the bottle/tank does not go dry and suck air into the radiator system, there is a leak.
On my way home from Florida last fall, I noticed the level was not holding at the low mark when cold.......added a bit and when home, sure enough a heater hose clamp up over the rear axle had a small drip........tightened the hose clamp, all has been good, holding a perfect level in the over flow tank from hot to cold.

Bigd9 · 06-09-2016, 06:14 PM

Same thing happened to me on my 2006 Discovery. After buying it and getting home the low coolant light came on. I added a gallon of mixed proper coolant to it. It never needed any more after that day which was close to 20,000 miles ago.

Just as a word of information, that tank is a Surge Tank and should be under pressure at all times when hot. That white plastic tank is known to develop cracks at about your coach age and leak coolant all over. Lots of forum post here in this group about that issue.

Brent, congratulations on your Discovery purchase! I'm on my second one and loving it. Any questions, just ask.

brenthg · 06-09-2016, 07:24 PM

Thanks BigD....ill keep my eye on the tank.

brenthg · 06-14-2016, 03:37 PM

So out again today for a long test drive and I monitored the coolant temp on the Medallion as I was driving. It ranged from 205-215 deg F at 55-65 mph. Today was in the mid 90's. Is that what I should expect for normal temps running out on the hwy?

I suspect that the CAC and radiator needs cleaning and maybe new thermostats and I plan on doing that in the next couple of days anyway.

Just wanted to compare the coolant temp I'm seeing on my Cat C7 with others. BTW, coolant level is showing normal in tank.

stuhly · 06-14-2016, 04:45 PM

In my opinion that is too high. 190-195 should be normal.

Bigd9 · 06-14-2016, 06:12 PM

I agree, I believe the two Cat regulators (Thermostats) are rated at 190 degrees. So that should be very close to the displayed engine temperature.

Your engine could have a higher temperature regulator for some reason. Or clogged radiators or other things like a faulty water temperature sending unit.

I'll have to look at mine on this trip next week. Temperatures are supposed to be in the 90's. Up to now we normally see 187 +-

brenthg · 06-14-2016, 06:39 PM

That's what I've been reading on other Cat owners posts. I think it's time to get new coolant and new regulators.

brenthg · 06-15-2016, 10:19 AM

Since this coach is new to me, without any maintenance history, I took it to a Truck/Catapillar shop this morning. After telling them about the high temps out on the road, they suspected either the fan actuator or thermostats. They will hook up to diagnostics and observe on a test drive to see what the problem is.

I'll feel a lot better knowing what the problem is and having a certified mechanic resolve this issue than me hunting and poking around by trial and error.

I will report back when I find out what they discovered.

brenthg · 06-16-2016, 12:29 PM

Truck shop reported back today and as I suspected, the radiator is coated with dirt and needs cleaning. They want to pressure test also to confirm there are no leaks.

Hopefully cleaning and while they're at it, install new thermostats, I'll be on my way next weekend for a week's stay at Jetty Park at Port Canaveral to watch the cruise ships come and go...maybe even a rocket launch.

Bigd9 · 06-16-2016, 02:46 PM

Are they going to remove the radiators for cleaning and testing? Or attempt to clean them from the outside? If they are really clogged, removal may be the best option. Check and make sure the breather tube has been extended to below and reward of the radiators otherwise oily stuff will re-coat the radiators and attract dirt again.