CAT C7 Cold Blooded engine

pameridan04 · 08-08-2011, 08:33 PM

Hi guys:

How long do you let your DP coach warm up? I have made the mistake of starting the engine and pulling out after just a minute or two after it hits bag pressure. My engine will buck and smoke like crazy until it warms up.

If I let it warm up for about 6 or 7 minutes no problem.

It's a hard habit to break.

How long does your DP take to warm up? I was just on a 1650 mile trip. My engine temp gauge never even hits the half way mark. Usually between 1/4 and 1/2 when it is running. Is that normal? I have a CAT C7 350 turbo.

Regards... Jim P.

Mr_D · 08-08-2011, 08:38 PM

Cummins says to start, let pressure build and drive reasonably till up to temp. No need for long idle times when starting out nor stopping. Just going down an off ramp slowing down is enough cool off time.
Sounds to me like some sensor is not working correctly on your CAT

MaverickBBD · 08-08-2011, 10:26 PM

So anybody remember the flash point of diesel fuel? I don't care if it is T.C.T. or P.M. but suspect it has to be P.M. to get an accurate reading at that temperature. So to get to approx. 200 degrees F from compression, there is no question why the H.E.U.I. has to inject the fuel at that pressure. I like to get it to at least 90* F before starting. That means I preheat even at fifty. Hope that helps.

Gary D · 08-09-2011, 09:08 AM

After having the radiator steam cleaned the gauge now reads below the halfway mark. Suggest that you monitor engine temp on the computer monitor. The temperature now runs between 196-200F. Before cleaning the engine would heat up when climbing long grades. No problem with temperature now.

1ciderdog · 08-09-2011, 07:23 PM

Jim P.
I do not have to warm up the Cat C-7 330 HP diesel much more than getting the air pressure up or just a couple of minutes. I don't push it while it is still cool but I do drive it without any of the problems you describe. Perhaps it is time for a new fuel filter and/or air filter. I have both a needle type and a digital temp gauge and normal temp is above 190 degrees on the digital and the needle is below the halfway mark on the analog (?) gauge. Temp goes up on hills in hot weather.
Safe Travels
Bob

pameridan04 · 08-09-2011, 08:19 PM

Hi Guys:

Well I had a oil change and new air filter installed last fall and a fuel filter about 5K miles ago.

I also sometimes have hesitation when I step on the gas before the rig is all the way warmed up. Can my gas jets or something need cleaning?

Don't know, looking for answers???

Regards Jim P.

Pusherman · 08-11-2011, 05:42 PM

Might be time for a new thermostat in the radiator as well. Manufacuturers suggest this replacement every several years. Cheap insurance.

cbeierl · 08-11-2011, 08:13 PM

Make that a pair of thermostats (I think CAT calls them regulators).

pameridan04 · 08-11-2011, 08:53 PM

Hi guys:

Is it easy to change the thermostats or regulators or do I have to have a diesel mechanic do it?

I think you may have hit on something, with the extra time it takes to warm up, and the engine always running cool.

Thanks for the recomendation.

cbeierl · 08-12-2011, 07:35 AM

Here's where they're located (faint red circle in upper center):

RCtime · 08-12-2011, 02:09 PM

I changed my thermostats a few months ago. They are under the red circle in the above picture.
Drain off a gallon of fluid, then remove the housing. Two thermostats. Hardest part is removing any baked on old gasket material. Do not scrape the surface with anything that will mar or scratch.
Fill the housing with antifreeze, drop in the thermostats and reinstall the top housing.
refill radiator,Test for leaks.
Now when I drive I can see the temperature gauge rise and then fall slightly when the thermostats open, then settle in their normal operating range.

pameridan04 · 08-12-2011, 09:05 PM

Hi Guys:

Thank you very much. I will have my buddy who is a mechanice give me a hand.

You have been very helpful.

Regards Jim P.

wagonmaster2 · 08-13-2011, 08:01 PM

Quote:

Originally Posted by RCtime

I changed my thermostats a few months ago. They are under the red circle in the above picture.
Drain off a gallon of fluid, then remove the housing. Two thermostats. Hardest part is removing any baked on old gasket material. Do not scrape the surface with anything that will mar or scratch.
Fill the housing with antifreeze, drop in the thermostats and reinstall the top housing.
refill radiator,Test for leaks.
Now when I drive I can see the temperature gauge rise and then fall slightly when the thermostats open, then settle in their normal operating range.

RC, what temperature thermostats did you use? I replaced mine a couple years ago and Cat said to use 190 degrees, which was what was in it originally but at 192-194 the engine now runs hotter than it used to even with several radiator cleanings, new coolant, and have checked to be sure the water pump belt is tight, so on my next change I'm considering using 180 degree ones. Course one of the old ones I replaced had come apart and was neither fully closing nor openings but I like the temps it ran then, usually around 175-185 degrees, and it did take about 10 miles for it to reach that temp. Now it reaches 192 practically before the tranny can even get to 6th gear.

Wagonmaster2
2004 Meridian 36G

RCtime · 08-13-2011, 08:41 PM

Wagonmaster

I really dont know what degree of STATS I used. I called Quinn Caterpiller, locally with my ser.# and they supplied me with the thermostats for my engine.
I can say this, DEPENDING on the outside weather conditions, usually I can see a fluctuation on my temperature gauge within 3-4 mile of slow driving.
Now mind you I start up, idle up air pressure, hook up the toad etc. I just dont blow and go

stuhly · 08-13-2011, 09:42 PM

Most diesel engines run best at 190 - 200. I wouldnt go to 180 stats myself. All of our otr trucks used 190.

jimmccreary · 08-16-2011, 08:27 PM

Jim P.
I have a C7 330 DP. When my engine overheated, I changed both thermostats, but that changed nothing about overheating. Then, following this forum I cleaned the radiator and the overheating problem went away. My temp gauge reads exactly the same as yours. It stays right at a position between 1/4 and 1/2 of the scale. When I go down a long hill, the temperature will actually cool down briefly. On a long pull the temp can move up to about 1/2 scale. Then I keep RPM at 2000 and keep speed down. My conclusion is that there is nothing wrong with your rig or your thermostats. Your rig is running normally. Nothing wrong with preemptive maintenance though.
When air pressure release sounds and jacks are up, I drive. At this time the temp is still on cold.
hope this helps.
jim & debbie, 04 Journey 34h

pameridan04 · 10-16-2011, 03:13 PM

Hi Guys:

Just an update. I took my coach to a Freightliner dealer. I couldn,t stand the LONG warm up and the bucking when I tried to pull out with my engine temp at 125 or even 130 degrees after 15 minutes of warm up.

Long story short, I had them put it on a Dyno. Yep two thermostats or regulators later, adjust the valves, (just hitting 30k miles), flush and refill radiator, new software upgrade, change primary fuel filter. Runs GREAT now, BUT my wallet is $1,000.00 RVBUCKS lighter.

The price we pay for diesels.

It's not over yet. Before beddie bye for the winter I took the coach up to my dealer to install new HWH springs I bought and to winterize it. Not to mention my LP water heater will not ignite anymore. More RVbucks are gonna go out.

On my last trip to Bethpage, I tried to sneak through a regular toll lane with my coach and smacked the blue pole before we got on the bridge. No major damage, but mirror needs a paint touch up.

I am still working 50 plus hrs a week, never enough hours in the day.

Regards PAM04

RCtime · 10-16-2011, 05:57 PM

OK you did good, just relax now and when Spring time comes hit the road.
Its all behind you you, and looking forward to the next adventures is priceless.