How long is engine warm-up?

Topic: How long is engine warm-up? (Read 1542 times) previous topic - next topic

How long is engine warm-up?

June 02, 2021, 09:38:08 am

Two times now I have had this happen to me. Start the coach in the morning, let it idle a few minutes, air pressure up to 120, pull out of the campsite and when I try to accelerate onto the main road or even out of the campground, I have no power. Had to get up a short little hill yesterday still in the campground and came to almost a complete stop before the top. Yes it was cold overnight each time this happens, but how long must I warm up before attempting to get rolling? I don't like to upset the neighbors by idling for 15 minutes in my campsite before rolling out. 1998 U295, Cummins C8.3.

Re: How long is engine warm-up?

Reply #1 – June 02, 2021, 09:59:55 am

In my humble opinion there is something else causing that slow start. The experts will tell. I have had that issue and only time had slow responce was due to leaks in CAC, after I fixed them it was like a new engine.
JohnH

Re: How long is engine warm-up?

Reply #2 – June 02, 2021, 10:12:35 am

As soon as I have 80 psi air, I leave a campground or where ever we are. Campers hate the noise and smoke diesels make at altitude when it's cold. I don't max rpm for a couple of minutes until temps are up. At the fire dept, as soon as the oil pressure moved in about a second, it was pedal to the metal out to fuel cutoff. It never seemed to hurt the Detroits.

Perhaps you are getting air in the fuel system overnight. Fuel solenoid sticking? Throttle linkage? Have someone push the pedal to the floor while you are watching the injection pump. Check intercooler for cracks, hoses, etc. How much boost do you get normally?

Pierce

Re: How long is engine warm-up?

Reply #3 – June 02, 2021, 11:09:43 am

Quote from: Pierce & Gaylie Stewart – June 02, 2021, 10:12:35 am

Campers hate the noise and smoke diesels make at altitude when it's cold.

This is a great thing to point out and something that used to frustrate the hell out of me when I was living in a 5th wheel. Most campers (myself included back then) don't understand that we have to sit there running our engines in the morning. When I do it now, I watch my air pressure gauges like a hawk and shut it down as soon as possible if I have more packing up to do.

Dan, you're going to get more informed responses than I have to offer but perhaps a fuel pressure/filter issue? That's at least low hanging fruit to check

Re: How long is engine warm-up?

Reply #4 – June 02, 2021, 11:14:53 am

The answer to "how long do I need to idle before driving off" is IT DEPENDS.

If you will be driving at low speeds getting out of the CG and then city streets, as soon as your air pressure is up (dryer purges) you are good to go. Wait until the coolant temperature rises before going to WOT.

If you are parked at a freeway entrance where you have to push hard, wait until coolant temperature is pretty close to operating temperature.

And, for faster warm up, after a minute or so, increase idle speed to around 1,100 RPM.

Re: How long is engine warm-up?

Reply #5 – June 02, 2021, 11:38:29 am

Engine warm up will have nothing to do with the loss of power you are experiencing.
As Pierce stated.... fire trucks are out the door as soon as they have sufficient air pressure. They can't waste the time it would take to "warm up" their diesels.

Re: How long is engine warm-up?

Reply #6 – June 02, 2021, 11:40:45 am

I ask that very question from the top dog at Cummins Atlantic , years ago and his reply was--" when your oil pressure was up , drive off at moderate speeds " and it was awaste of ------to idle a cold cummins engine and expect it to heat up .

Brad Metzger

Re: How long is engine warm-up?

Reply #7 – June 02, 2021, 11:49:48 am

I go as soon as I have air pressure. I want to get the engine up to operating
temperature as soon as I can. When I had the Monaco with the 8.3 it would
seem a little gutless for the first block when it was freezing out but would
still go. You may have a problem with something else. Do you have a King
throttle control.

Re: How long is engine warm-up?

Reply #8 – June 02, 2021, 11:59:33 am

Quote from: FourTravelers – June 02, 2021, 11:38:29 am

Engine warm up will have nothing to do with the loss of power you are experiencing.
As Pierce stated.... fire trucks are out the door as soon as they have sufficient air pressure. They can't waste the time it would take to "warm up" their diesels.

No block heaters either. On my last visit, I did notice that some new apparatus have block heaters with a pull disconnect.

No, when we got a call, our job was to get the the scene asap without hitting anyone. Drownings were the worst.

Pierce

Re: How long is engine warm-up?

Reply #9 – June 02, 2021, 12:35:17 pm

Those of us with air throttles must wait until we have at least 70-80 psi before the accelerator pedal will work. I have a 115V air compressor hard mounted in our coach. When we are in a camp ground with close neighbors I use the air compressor to bring the air system up to about 100 psi before we unplug from shore power. That way when I start the engine we already have sufficient pressure for throttle, brakes, and the suspension "ride height" adjustment. I let the air dryer purge one time (to be sure it is going to work) then we're ready to roll.

Re: How long is engine warm-up?

Reply #10 – June 02, 2021, 06:10:03 pm

It could be a lazy fuel shut off solenoid. See my current post on broke down in Albuquerque. My coach usually does just fine after warming up to full air pressure. I try not to idle more than that in a campsite. Also 36' with C8.3.

Re: How long is engine warm-up?

Reply #11 – June 02, 2021, 08:31:07 pm

If you have the Racor water/fuel separator. The unit has 5-6 Rubber O rings and a plastic bowl. Any one of which can leak air into the system and take a few minutes to clear out .

Re: How long is engine warm-up?

Reply #12 – June 02, 2021, 10:12:19 pm

Quote from: Brad Metzger – June 02, 2021, 11:40:45 am

I ask that very question from the top dog at Cummins Atlantic , years ago and his reply was--" when your oil pressure was up , drive off at moderate speeds " and it was awaste of ------to idle a cold cummins engine and expect it to heat up . Brad Metzger

This is what I was instructed to do also. Pistons increase in temperature prior to the rest of the engine. Start, establish oil pressure, proceed with reduced power till fully warmed up to minimum engine temperature. Cold weather will increase time.
Scott

Re: How long is engine warm-up?

Reply #13 – June 02, 2021, 10:14:39 pm

Caterpillar people don't have to worry, throttle only works after engine warms a bit. It is gradual. Computer does it.

I had that happen the 1st time out. Staying in altitude with 15 degree temps. Took off from rest stop, onto freeway down hill, only to find when I hit level ground, I had little throttle.

Now that I know, no problem

Chris

Re: How long is engine warm-up?

Reply #14 – June 02, 2021, 10:15:09 pm

If we've been sitting in one spot long enough for the air pressure to drop we'll start up the day before we leave to build air.
Usually when most everyone is away from the campground, doing whatever it is they do, so not many are bothered.
Some frown on this for the short idle but it works for us, especially if it's cold out.
Short idle to build pressure, put a little heat in the engine block (if cold out good time to turn on block heater).
Next morning, start and ease out slowly and as quietly as possible with a DD.

That's the crowded campground scenario, just us, totally different rollout procedure.

Re: How long is engine warm-up?

Reply #15 – June 02, 2021, 10:18:01 pm

Quote from: Brad Metzger – June 02, 2021, 11:40:45 am

I ask that very question from the top dog at Cummins Atlantic , years ago and his reply was--" when your oil pressure was up , drive off at moderate speeds " and it was awaste of ------to idle a cold cummins engine and expect it to heat up . Brad Metzger

Re: How long is engine warm-up?

Reply #16 – June 02, 2021, 10:19:05 pm

Quote

pull out of the campsite and when I try to accelerate onto the main road or even out of the campground, I have no power.

I am with oldguy regarding the King Control throttle. This exact same thing has happened to me several times. Takeoff from the campground and no power. Has always fixed itself though.
jor

* had inadvertently posted this comment in an unrelated thread.

Re: How long is engine warm-up?

Reply #17 – June 03, 2021, 03:19:53 am

Last trip, The night before we departed I turned on the Aqua Hot engine pre-heat. Got up in the AM and finished packing up. Just before I unplugged from shore power. I hooked up an air hose with two male ends and ran a 5 Gal compressor to air up the coach. When we were ready to go. It was just a matter of firing up, Checking that oil pressure had built up and drove off to hook up the toad.

Of course the toad is the spanner in the works for a quick minimum idle getaway unless one is in a pull through. So you will idle some with a back in site and hooking up a toad. But it will at least be away from others if you pre-heat the engine (when cold) and pressurize the tanks with a compressor.

Re: How long is engine warm-up?

Reply #18 – June 03, 2021, 07:30:09 am

FYI
If using an aux air compressor need to make sure you have a good air dryer on it. Putting wet air into the coach air system is not a wise thing to do.

Re: How long is engine warm-up?

Reply #19 – June 03, 2021, 07:45:26 am

Quote from: Phranko – June 02, 2021, 10:15:09 pm

If we've been sitting in one spot long enough for the air pressure to drop we'll start up the day before we leave to build air.

I would suggest that this is not particularly good for the engine. Running it the night before just to build air pressure will leave condensation in the engine and exhaust system.

That is why it is recommended to only start the engine (when exercising the coach) if you can drive at least 25 highway miles-- long enough to rid the engine of any moisture.

Again, this is "best practices", and occasionally just running the engine for a short time is unlikely to do long-term damage.

Re: How long is engine warm-up?

Reply #20 – June 03, 2021, 09:01:58 am

Quote from: Dan & Annie – June 02, 2021, 09:38:08 am

Yes it was cold overnight each time this happens, but how long must I warm up before attempting to get rolling? I don't like to upset the neighbors by idling for 15 minutes in my campsite before rolling out. 1998 U295, Cummins C8.3.

We must remember that our primary propulsion is at its heart a heat engine. A machine to extract useful work from heat. Diesel engines compress air to create the heat necessary from combustion. A full charge of cold fresh air with every cycle. You aren't going to receive full engine power output until everything is up to operating temperature.

Really big engines have external heaters to either warm the engine and oil before starting or keep everything warm for immediate full power operation.

Re: How long is engine warm-up?

Reply #21 – June 03, 2021, 09:25:48 am

With temps as low as 30's I've always let my diesels run long enough to thin the oil a bit. Some oil journals are small and I want bearings from top to bottom well lubed before any load.. I don't like extended idle anymore than the next owner/driver but in the 70's thru the 90's it was typical to leave in a truck on Sunday and only shut it off before Friday to check the oil.. I started buying Thermo king gen sets for cab air and heat and that allowed for sleep and wait time engine shut down.. We put a million miles often on the motors that were never shut down. Still I don't see the use of wearing on an engine when it's not moving me down the road.. I've had drivers leave one sit and idle for 2 hrs in 60 deg weather while they sit in a truck stop telling war stories.. That never put a driver on my good side because it proves he has no concern over my fuel cost or my engine wear.. If drivers were in better supply it would get you fired on my job but the shortage makes one have to put up with things you wouldn't normally tolerate.

Re: How long is engine warm-up?

Reply #22 – June 03, 2021, 12:09:37 pm

In all my years on the FD we never allowed the engines to warm up before responding to a call, had to go now, 100% throttle. This was with all diesels. Engines. Ladder Trucks, Squads, Rescues. Didn't matter. In 24 years I never personally saw any adverse effects to any of these engines. Seemed remarkable to me with my mechanical experience. Just saying.... Jim.

Re: How long is engine warm-up?

Reply #23 – June 03, 2021, 12:37:58 pm

It is a matter of PRIORITIES.

For emergency vehicles SPEED of departure is far more important than shortening engine life. And there are very few fire trucks with high mileage.

Those are not necessarily the same priorities for RV owners. Neither is right or wrong, just different.

And for our use you could also debate "best practices" vs "what I got away with". They ARE different.

Re: How long is engine warm-up?

Reply #24 – June 03, 2021, 02:11:36 pm

The B50 for the Electronic M11 engine is 800,000 miles until an in-frame refresh. Our coach engines are classified as being under rather lite duty service conditions. It is highly unlikely that any idling a coach does (which is minuscule idling compared to class 8 trucks) would ever lower that 800,000 mile figure anywhere close to the miles a coach will see in it's life time.

The idling warming up issue (at least to me) is more about good campground manners than worrying about whether that rebuild will happen at 600,000 as opposed to 800,000 miles.

Affiliate Notice