When does a diesel reach full operating temperature?
Submitted: Tuesday, Jul 11, 2006 at 10:41
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Brid from Cost Effective Maintenance
Reading thread 35643 made me wonder how long it takes to reach full operating temperature in a diesel. I've always used about 20 minutes as a yardstick to get everything fully stabilized to the normal operating conditions (whatever normal may be). Clearly this will vary enormously with engine size, and duty cycle. A chain saw will be fully stabilized quickly, while a 15,000HP ship engine might take a little longer. A fully loaded engine will reach a higher stabilized temperature than a lightly loaded one.
I remember doing some performance benchmarks on a Cat 789 rear dump at Ok Tedi
mine in PNG. Part of the work involved measuring haul cycle times. We did several cycles in succession from the start of shift (cold engine)...and about 15 mins run to the starting point. The haul times continued to improve over the first 3 cycles (about 12 mins each) then stabilize. So, I suppose optimum operating conditions were achieved in about 50 minutes for that engine.
As far as warming up before you drive off goes, I don't see a lot of benefit in long periods of idling to pre-warm the engine. I'm happy to get the oil up (while I put on the
seat belt) and drive gently for maybe 5 kms. All the running gear is still cold until you start driving anyway.
More recently I did some tests on some Cat 440HP engines powering
water pumps on a cotton property. The worker helping me idled the engines until he could feel the cylinders warm up and then open up the valves to pump
water, and load the engine up. About 5 minutes max probably. If they had them all running at the same time, there could have been 30-40 pumps running...and one bloke to start them all. About 8 engines per pump station, so it may have just worked out this way. Once the last engine is started the first can go to work. Not sure whether there is some compromise in this case, or not.
Be interested to hear others comments.
Regards
Brid
Reply By: robak (QLD) - Tuesday, Jul 11, 2006 at 10:50
Tuesday, Jul 11, 2006 at 10:50
When on long trips I notice that my engine runs best after it has driven for over 2 hours.
R.
AnswerID:
182906
Reply By: Kiwi Kia - Tuesday, Jul 11, 2006 at 11:59
Tuesday, Jul 11, 2006 at 11:59
Traveling on a sea going car ferry with a large multi engine diesel electric setup I find that they start the engines no more then 5 minutes before steaming out on full load.
If your oil pressure is up and the coolant is circulating (thermostats open) then it's fair enough to guess that temperatures are all 'normal' or 'optomised' or 'in the green' so why wait?
AnswerID:
182911
Reply By: Patrol22 - Tuesday, Jul 11, 2006 at 12:46
Tuesday, Jul 11, 2006 at 12:46
I usually don't go through a warm up cycle EXCEPT when it gets really cold....like it has been down here over the past couple of weeks going down to -7/-8C. To warm the engine I use the heat cycle (GU 2.8tdi) and to get the transmission oil turning over select N on the transfer case and select 4th on the gearbox. Does it work any better than driving off like Miss Daisy......f*&^#d if'n I know but it seems to work for me.
AnswerID:
182918
Reply By: Member - Jeff M (WA) - Tuesday, Jul 11, 2006 at 13:04
Tuesday, Jul 11, 2006 at 13:04
I used to warm up at idle, but have been shown the error in my ways off this site. However, I still let it run for about 30 seconds before I take off, but select reverse while I wait so that there is some load on the engine (auto) and so that the auto fluid get's a chance to get moving before I head off. (that is of course when it's quite cold) it it's not really cold I just start and drive off slow. I keep my rev's as best under 2k as I can until my mechanical guage hits about 70-80c (running temp is 90c).
I find that the warm up times can very dramatically depending on which route I take in the morning. ie suburbs or main road.
I also find that the factory temp guage is at half when my mechanical guage is only just leaving the bottom (60c) and it is still at half about 5 minutes of driving later when my mechanical guage hits 90c.
AnswerID:
182922
Follow Up By: Member - Roachie (SA) - Tuesday, Jul 11, 2006 at 15:35
Tuesday, Jul 11, 2006 at 15:35
Geez Jeff, you've just made my day....!!!!!
Quote: "(running temp is 90c)."
You may be aware that I've posted on here several (hundred) times about my Patrol's over-warming. However, it's "normal" running temp on the VDO gauge (top radiator hose) is around 83oC, so maybe she's not too bad after all. Of course, as I've said in the past, she does get up to 100oC and beyond if i start to ask too much of her and/or if the ambient temp is pretty high.
Cheers.
Roachie
FollowupID:
439417
Follow Up By: Member - Jeff M (WA) - Tuesday, Jul 11, 2006 at 15:46
Tuesday, Jul 11, 2006 at 15:46
Oh yeah, I was concerned about it too, but I was going
camping up at wedge with "the boys" many of which are diesel mechanics at Westrac (work on big cat machinery all day) and they recon that 90c is a pretty good operating temp for a diesel.
Mine will sit at 100c on a hot day while cruising at 110km/hr with a full load of
camping gear on board. Off road I'll get her up to about 105c before I back off and then I'll stop at let her cool her head (so to speak) at 110c. The factory temp guage does not move from half until 110c !!
FollowupID:
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Follow Up By: DEANO WA - Tuesday, Jul 11, 2006 at 22:15
Tuesday, Jul 11, 2006 at 22:15
hey all, i have it on GOOD authority that the patrol temp gauge (as stated above) doesn't have the same temperment as 'VDO' type gauges.
mine was reading just before the red line ,but was only 92c.
FollowupID:
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Follow Up By: Member - Roachie (SA) - Tuesday, Jul 11, 2006 at 22:27
Tuesday, Jul 11, 2006 at 22:27
G'day Deano,
Yep, I've reported about this on previous occasions on here.....
My Nissan gauge will hit the "normal" mark from cold start-up and the VDO gauge will barely be up to 50oC. The Nissan gauge will stay on that same position (which is just to the left of vertical), whilst the VDO gauge will show varying temps from 50oC up to about 107oC. At that point the Nissan gauge will start to rise rapidly from normal up to almost into the RED zone.......at which point the VDO gauge will show about 118oC.
I'm sure this is probably the same with all factory temperature gauges....... The manufacturers don't want the average driver to be concerned about temps varying all the time, so they fit a gauge which will show normal (without moving at all) even though the "real" temp is varying. That's why I have a little chuckle to myself when blokes say........ "I can drive my 'Nissan Landcruiser' all day at 45oC outside temp and the temp gauge just doesn't move at all". They seem to think the actual
water temp isn't varying all day either......they fail to understand that the gauge is simply calibrated in such a way that it doesn't move unless and until the temp gets REALLY HOT!!!!
Cheers
Roachie
FollowupID:
439544
Follow Up By: Richard Kovac - Wednesday, Jul 12, 2006 at 00:03
Wednesday, Jul 12, 2006 at 00:03
Hi Roachie
"I can drive my 'Nissan Landcruiser' all day at 45oC outside temp and the temp gauge just doesn't move at all".
Maybe that's because the standard gauge is reading
the block temp. ie the controlled temp. not the waste temp that you maybe reading.
this is why they put thermostats in the cooling system to maintain a constant temp
I've been there and tested many an engine for so called over heating to only fine it's incorrect reading of the gauge.
boiling temp of
water at sea level maybe 100 oC but that's not the same as coolant or
water under pressure,
I've said before that most new diesel engines are made to run at 105 oC to help them meet EU standards
-----
there is no harm meant to all readers in the above comments
Richard
FollowupID:
439579
Follow Up By: Member - Jeff M (WA) - Wednesday, Jul 12, 2006 at 10:19
Wednesday, Jul 12, 2006 at 10:19
LOL, Yeah I know what you mean Roachie, there is no convincing them either!!
Richard,
mine is measuring block temp as I bypassed my throttle body heater and used that hose for the guage (it comes straight out of
the block about half way along).
FollowupID:
439626
Reply By: cowpat - Tuesday, Jul 11, 2006 at 13:55
Tuesday, Jul 11, 2006 at 13:55
I've an LC100 std with a 4.2 N/A diesel. Seems to run best on the highway after about 1/2 hour. I don't concern myself with warmup apart from letting the oil pressure build up. Casper
AnswerID:
182929
Reply By: Member - Oldplodder (QLD) - Tuesday, Jul 11, 2006 at 15:01
Tuesday, Jul 11, 2006 at 15:01
With the 4wd, I usually like to see the
water temp gauge starting to move in the first 30 to 60 secs. The first 1k from
home is all downhill, so that helps.
Then drive gently for the next 3 to 5 k for the engine to warm up.
Gear box and drive train I think takes about another 15 minutes depending on the outside temp.
But larger engines are a different story. Was doing some engine installations for stationary alternators and also large power boats and they often have heaters in the
water jacket to keep the engine warm. They need to run at full power in less than 30 seconds,
well the alternators do, the power boat owners like to hop on board and be away, and they have the money to pay for the convenience :-). If you need power that quickly, maybe you should look at some sort of heating.
AnswerID:
182941
Reply By: cowpat - Tuesday, Jul 11, 2006 at 17:52
Tuesday, Jul 11, 2006 at 17:52
The fellow I had rebore my dirt bike engine seems quite experienced and said that the clearances specified by the piston manufacturers are unnecessarily large, and protect the engine against (ab)users who do not warm up the engine before running it hard on full throttle, or racers that need to go full-on from cold.
He prefers to
bore them out with minimal clearance but you *must*must*must* warm up the engine for 1-2 km or until you feel the cylinder is hot before hitting it hard or you risk seizing it (or other damage).
Might be that engines that are not expected to be warmed up much are designed differently from those that are. Casper
AnswerID:
182970
Reply By: Keith_A (Qld) - Tuesday, Jul 11, 2006 at 19:16
Tuesday, Jul 11, 2006 at 19:16
Good Question - Had to do an oil change on my 4.2 TD Diesel Patrol on Saturday.
Truck was cold - in the shed. Needed to warm it.
Idled it for aprox 5 minutes, then drove it 'around
the block' for 15 minutes.
Temp gauge showed just below normal (as usual).
Dropped the oil - only just warm. A long way from hot.
OK - it was a winters day, and I kept the revs down, but the oil was far from being hot.
For winter, I would guess it needs at least an hour................regards......Keith.
AnswerID:
182990
Follow Up By: Member - Roachie (SA) - Tuesday, Jul 11, 2006 at 22:34
Tuesday, Jul 11, 2006 at 22:34
Keith,
I've fitted a VDO temp gauge to my sump. It only starts @ 50oC and 100oC is about in the middle of the gauge. The close calibration marks go from 50 to 80; then the spacings are less
well defined. This suggests that between 50 and 80oC is the sort of temps which would be considered normal, whilst 100oC is starting to get a bit on the warm side. Around town the gauge never even gets started.
Even on a longish trip (say several hours), the gauge barely gets up to around 60oC. On a very hot day with no real load (like the trailer hangin' off the back), it'll get up to around 85oC. The hottest I've had it has been 100oC on New Years Eve, when it was a 45oC evening, and I was towing the camper trailer down to the
Murray River @ around 105oC with air con on and the
water temp was running @ around 118oC for a couple of hours.
Cheers
Roachie
FollowupID:
439549
Reply By: Member - Stephen M (NSW) - Tuesday, Jul 11, 2006 at 20:43
Tuesday, Jul 11, 2006 at 20:43
These winter mornings I think I can tell roughly by the heat that is coming from the heater. I can drive about 2 klms and I start to feel warmth coming from the heater vents.By the time I'v done 10k I'm cooking so for me I say that my hilux is pretty
well up to temp, even though the temp guage is still lower than say driving for about 1/2 hour by about 1 or 2 mil. I dont warm myn up in the mornings I just fire it up wait for the oil light to go out 3/4 seconds I'm gone, but I dont take myn over 1.5rpm on the tacho till I feel the heat or see the guage move. Never had any problems. My wifes a shocker in our commodore, always running late to work so, by the time the electric door on the garage goes up, its in, start,hit reverse while the oil still getting to the top, in drive gone, I reckon shes doing 60 with in 100m pisses me off, have told her if it blows up she's walking. Luckily both our cars are garaged and the garage has insulation in the roof and is definately alot warmer in there so maybe that helps, no washing ice of the windows for me. Regards Steve M
AnswerID:
183011
Reply By: Sarg - Tuesday, Jul 11, 2006 at 23:16
Tuesday, Jul 11, 2006 at 23:16
"I remember doing some performance benchmarks on a Cat 789 rear dump at Ok Tedi
mine in PNG. Part of the work involved measuring haul cycle times. We did several cycles in succession from the start of shift (cold engine)...and about 15 mins run to the starting point. The haul times continued to improve over the first 3 cycles (about 12 mins each) then stabilize. So, I suppose optimum operating conditions were achieved in about 50 minutes for that engine."
Probably not so much the engine taking time to warm up, but the 120 lt of transmission oil, 420 lt of diff oil, 130 lt of steering oil, 515 lt of hydraulic oil, 83 lt of final drive oil, (& the 212 lt of engine oil).
And some of the blokes here bitch about their service costs !!
AnswerID:
183068