Still running hot

[JaminSamin]

Originally Posted by OurNextRVAdv

Thanks for the suggestion. Called CAT this morning and it seems my engine most likely had the old temp regulators, part #119-3075 that opened at 201F. CAT has upgraded the regulators to part #115-4223 which now open at 206F. For maximum efficiency, CAT said the C7 should be running around 200F, which is why they upgraded the regulators. So, it looks like I put too much thought into it and everything is now the "new normal:-)"

Thanks for everyones input!!!

I would double check that upgraded regulator number they say opens at 206F. I installed new regulators last year, part number 115-4223 and they open at 190 degrees, same as the old ones. Just got back from a trip and my ScanGauge D coolant temp only left 190 when I was climbing a grade. Here is a pic of the old ones with 88C stamped next to the part #.

[Ted DuPuis]

When I check those part numbers, 119-3075 is listed as a 180F thermostat and 115-4223 is a 190F thermostat. However that's the temp the thermostat starts to open. I've read that somewhere over 200 is where the thermostats fully open, so 201-206 (for colder vs. hotter) makes sense and I've heard some Cat folks list it that way.

I have 115-4223s and a BlueFire to monitor coolant temp and other engine parameters on my 3126B. For normal city/highway driving below 85F it pretty much is at 190F on the dot, and then if I have a higher power run up a hill or accelerating it'll go up to 195F or so before dropping back down.

For 90-100F temps it'll run hotter. I am intending on some other improvements to help with this. 210F is where I start to really pay attention to temps and backing out of the accelerator. A lot of times just downshifting and getting the revs up will help.

[ftodaro]

Just make sure you do not install the regulators backwards. The radiator hoses have wires in them to prevent collapse. If you have never removed the CAC for a good cleaning that would be on my list along with a pressure test.

[OurNextRVAdv]

Thanks FTO,
I was unaware there was an orientation so I thank you for bringing that to my attention. I have the pins facing towards the front of the coach. Can you take a look at the attached photos.

[Bigd9]

My Cat C7 runs between 190 195 all the time. Rarely do I ever see 200


One thing not mentioned in this forum post is the water pump belt. The pump is driven by a V belt, and I found the belt on my engine so loose I could almost pull the belt off of the tensioner pully or sheave. The tensioner is not spring loaded and it is a bear to adjust. I've mentioned this to others and they too have found their water pump belt loose.

Here are a few pictures"

• Picture of the access hole I cut. See while rectangle cover.
• Picture taken with a endoscope showing the area between the two radiators.
• Picture I found showing the two regulators and their proper orientation.
• Picture taken of the water pump tensioner and the V-belt

[ftodaro]

Originally Posted by OurNextRVAdv

Thanks FTO,
I was unaware there was an orientation so I thank you for bringing that to my attention. I have the pins facing towards the front of the coach. Can you take a look at the attached photos.

Post 19 below gives you what you need. It looks like you have it right. Trust me, If there is a way to install something backwards, i will find it.

[BUB1988]

We have a CAT 3126E in a 2003 DP. Our regulators open at 195 on my scangaugeD.
Normal operating when the CAC and radiator is clean is under 200. Small grades, headwinds, etc goes up to 205.. We just came off a trip to Cody, Yellowstone, and Glacier and we had to stop 6 times getting up and around Buffalo.

[Bigd9]

Why did you have to stop 6 times?
What were the temperatures?
When you say clean CAC and radiator, what do you mean? How do you know they are clean?
Water pump. Have you checked the belt to see if it it is tight?

[Skip426]

Originally Posted by BUB1988

We have a CAT 3126E in a 2003 DP. Our regulators open at 195 on my scangaugeD.
Normal operating when the CAC and radiator is clean is under 200. Small grades, headwinds, etc goes up to 205.. We just came off a trip to Cody, Yellowstone, and Glacier and we had to stop 6 times getting up and around Buffalo.

Under some conditions , if only one of the two regulators is operating the engine will cool ; under load , both regulators need to be fully operational to allow enough flow to the radiator to keep the temperature down.

As Bigd9 says you need to be sure the rad and CAC are as clean as possible as the first step when looking at engine overheating problems.

[BUB1988]

Bigd9
Why did you have to stop 6 times?
What were the temperatures?
When you say clean CAC and radiator, what do you mean? How do you know they are clean?
Water pump. Have you checked the belt to see if it it is tight?


We had to stop 6 times due to high temp warnings. The warnings start at 218/220 and then at 224 engine protect came on as we were pulling over.
I did clean the CAC and Radiator (Simple Green Extreme) before we left Florida as an annual thing I do. We did have them cleaned again after Cody which did help for quite a while.
We did have the water pump belt checked when we had the CAC and Radiator cleaned and the belt was okay.

UPDATE:: Once back in Florida I started investigating what could be the issue. I took a blue towel and did a quick swipe of the CAC and it came back very gummed up again. I thought that the slobber tube light be the issue, but it was already at the edge of the rock guard. Looking for something else I found that the oil dipstick tube was missing a clamp which I replaced. I also noticed that the dipstick was really loose in the tube when locked down. It seemed that it might be missing a rubber spacer or gasket like the oil filler has. I fabricated one today so we will see if that was the culprit. The whole side of the radiator and framing had a coating of grime from the oil.

SKIP426::
I have changed out the regulators last year when I replaced the coolant.

We're going on a trip next week (FL to NC) so we should see what happens. I've placed some towels in a few areas around the dipstick tube and oil filler area so I can easily tell if oil is still coming out of the area??

[Bigd9]

I have seen pictures of CAC and radiators from coaches where the owners swore up and down they cleaned them yearly. The problem is you can't see the dirt that is between the two radiators.

I carefully cut a rectangle hole in the fan shroud and I used a endoscope to look at the area between mine. Another way is to cut the hole and insert a small light down between the two radiators. You should see the light from outside through the fins. Have someone move the light around and make sure all of the area is clean.

Double check the water pump belt again. It is a small V belt, not the larger flat serpentine belt, and you can see it from below. Mine looked good, but it was as loose as a goose, as they say. Its not easy to adjust.

[doorguy]

I had the exact same problem in CO doing the same route. Just going up a slight grade would raise the temp to the mid range on the gauge which I wasn't comfortable with. I replaced the "temp regulators" there and still had the issue. Called my guy at Sacramento Truck Center (FL shop) and he said check you water pump v-belt tension. If you can spin the pulley by hand it is too loose. I did and I could spin it with 2 fingers. I retightened the belt and it solved the entire problem.

[BUB1988]

UPDATE!!
We took a trip from Tampa, FL to Fayetteville, NC and back.
Temp stayed below 204 for the whole trip and pretty much below 200.. Not much of a grade anywhere on the trip, but even if flat Florida it was getting up towards 209 before making the changes I made. Changes were stopped oil leaking from dipstick and pressure cleaned CAC and radiator. I had already checked the belt tension in a previous stop in Montana.

[doorguy]

Look down below for the V-belt pulley that runs the waterpump. If you can turn it with your hand, it is too loose which will cause slippage.