Warm up, cool down... among other things.

SlimTim

Active Member
Hi all,

Haven't been on the forum much lately. I've been out using my new collie on some, mostly moderate to easy, tracks as I'm a full beginner. I've got a couple of questions I hope you lovely people could help me with.
  • How long do you think we should be warming up our 4-bys?
  • How long should we cool them down to avoid turbo heat soak?
  • What exactly is turbo heat soak?
  • What other problems could be encountered from not letting your car cool down?
  • Whats the best way to clean your engine bay?
Thanks in advance.
Tim.
 

Marck

Well-Known Member
Any engine should be at full operating temp before you work it hard. For me that's probably 15 mins after coolant temp reaches opperating temp.

The following is what I have picked up over the years but not sure how much of it is true it just seems logical to me.

As for cool down I think it depends on how hard you have been working. Turbos work at very high rpm and temps so you are trying to give the cooling system time to draw heat away. From what I understand is if you shut down when everything is very hot and things cool at different rates you stress components. If you can remove the heat in an even and controlled manner this problem is reduced. The other thing is with oil cooled turbos is that if the oil stops pumping and the turbo is at 600 degrees the oil in the turbo will get hotter than it should

The other thing I have been told is if you shut down rapidly (stall) after a hard run you get a preasure wave in the intake and when this oscillates it can violently stall the turbo and damage it. This was on petrol sports cars but it may transfer to Diesel engines if it's true.

I'm interested in what people who know what they are talking about have to say.
 

Batts88

Well-Known Member
If you have a manual in the glove box it may say something about warming up the donk.

Not 100% sure about cool down but I think I read on another forum that if you have a pyrometer a guide is to wait till it's below 160 deg celcius before shutting down anyway that's what I've been doing with my patrol. Also when I had a 1986 Toyota sahara factory turbo I remember reading in the manual that if driving at 60 k's or less no cool down is required but mine had a turbo timer which made things easier.
 

Collie14

Active Member
I think in the manual it says about 2 mins or something for warm up, I would say not to be pushing your rig hard until it's at operating temperature.
As for cool down I put a turbo timer in mine, makes life easy, if I've been driving around town I pretty much hit the stop button right away, driving on freeways for a small amount of time it's 2 mins, pulling off the freeway to fuel up is 3 mins and offroad and long highway driving is 5 mins. That's what I do, I sleep easy at night doing that.
 

80lover96gxl

Moderator
I use to be engine operating temp before moving off till a wise man once said to me, that's all well and good to have engine temps good but all other components like gearbox, t case, diffs and brakes are still cold. Now days i let it run for a few mins then move off and just cruise until temps come up, that way all components are at operating temps around the same time.

For cool down , a couple streets before home i just back it off and pretty much idle into the driveway, give it 30sec and shut it down. Hwy to stop normally 2-3 mins.
 

Aaron Schubert

Moderator
The most damage is done to an engine in its warm up period. Those who start their vehicles and let them idle before driving off are not doing any favours; you should get in and drive away, just take it gently until your engine temperature is in the normal range.

Every turbo is different, with some of the newer ones not needing any cool down period. Essentially though, when you've been working the vehicle hard (soft, sandy tracks, up hill climbs or on the bitumen at over 80km/h) give it a minute or so just idling before you turn it off. If its really been working hard, 2 - 5 minutes.

An EGT gauge would do you wonders; you can see how the engine is going. I watch mine until the temperature drops to around 190 degrees at the dump pipe, and then turn it off.

In terms of cleaning your engine bay, again very dependant on your vehicle. Old diesels like mine can pretty well be pressure washed without an issue. I tend to use a hose that's on a light spray and hose it off (obviously avoid as much of the electrics as possible). Before hosing it off I use the CT18 truck wash; mix it around 5:1 and spray it on. Let it dry, and then hose it all off about 15 minutes later. Magic stuff.

Aaron
 

Swaggie

Moderator
Regardless of how I drive I always allow a minute or so for the turbo to Kool down, not that I drive mine hard at all anyway, That's my turbo timer lol
 

SlimTim

Active Member
Thanks so much for the replies and info.

Seems like the best option is to just give it a minute or two both on cool down and warm up, a little longer if I've been pushing it.
 

hiluxdriver

Well-Known Member
I heard different to Aaron. You can start your car and drive away once oil pressure is up, though not advised to flog it until all temps are up the normal operating temps. The first couple of engine cycles before oil pressure is up is where the damage is done - from what I've heard. I also heard that you don't really need a cool down period if you haven't been excessively working the engine. Driving home from work is not excessive, soft sand and towing is excessive. But I suppose you do what you feel is best for your car.

I'm sure Muc will be along shortly to prove everyone wrong though :)
 

cookie64

4x4 Earth Contributer
In my previous TD 4wd's I had a Turbo Timer, when I bought a new 4wd some years ago I was informed that they couldn't install one as they are illegal. I called BS but then found that it is in fact illegal to leave your car running with no one in the vehicle - here in SA not sure about other states so in fact I guess you could cop it if you have one.

I typically start the 4wd and let it run for about 30 seconds while I put my seatbelt on and my phone on charge, if I have been working the turbo hard then I typically drive easy to where we are stopping for lunch or wherever and then turn off - common sense really.

cheers
 

vk1dx

Well-Known Member
Heat up: I drive almost immediately but always gently until the motor warms up.
Cool down: Unless the motor has been working hard then I just turn it off. If worked hard - about a minute or so before turning it off..
Cleaning the engine bay: I spray with a whole can of degreaser (I think it was supercheap stuff) , let it sit for a few minutes and then rinse it thoroughly with the hose. Taking care to only gently spray the electronics and fuse boxes.

Can't answer the other q's.

Phil
 

oldlux

Well-Known Member
FWIW I usually start ute and drive off gently, stop and open gate, drive through, close gate and then nurse it for the first couple of roundabouts. I have about 4 Ks before hitting the freeway by which time it has reached operating temperature. I try not to flog it too hard anyway. As for cool down if arriving home it is the gate thing again and my driveway is 160 M long so it is all good by the time I am up at the house so switch off. If I'm stopping for fuel on the highway I let it idle until EGT gets down to around 200-220 deg before switching off.
As Phil says, degreaser and hose off but don't do it while stinking hot, let it cool down for a while first.
 

Aaron Schubert

Moderator
I heard different to Aaron. You can start your car and drive away once oil pressure is up, though not advised to flog it until all temps are up the normal operating temps. The first couple of engine cycles before oil pressure is up is where the damage is done - from what I've heard. I also heard that you don't really need a cool down period if you haven't been excessively working the engine. Driving home from work is not excessive, soft sand and towing is excessive. But I suppose you do what you feel is best for your car.

I'm sure Muc will be along shortly to prove everyone wrong though :)

Righto, I should clarify. I agree with what you've said regarding oil pressure. I was implying starting your vehicle and letting it idle for more than a minute before driving off is not a good idea, nor necessary. I've seen people let their vehicle run cold for 10 - 20 minutes before driving off. That is not good for an engine. By all means give it up to a minute before you drive off, but no need for more.

Aaron
 

SlimTim

Active Member
Thanks again guys.

I think I'm doing what most people seem to do. I usually get in, let it run for a minute or so, then take it easy for the first bit.

Re the engine bay cleaning. Is a little splashed mud going to cause any real problems? I'm too freaked about killing the electrics. It's a 2015 collie. When you say "go easy on the electricts" I open the bonett, there's electronic stuff everywhere.

Thanks again.
 

Aaron Schubert

Moderator
Thanks again guys.

I think I'm doing what most people seem to do. I usually get in, let it run for a minute or so, then take it easy for the first bit.

Re the engine bay cleaning. Is a little splashed mud going to cause any real problems? I'm too freaked about killing the electrics. It's a 2015 collie. When you say "go easy on the electricts" I open the bonett, there's electronic stuff everywhere.

Thanks again.

The mud won't matter. I meant don't spray jets of water into any connections etc. A light spray will be fine

Aaron
 

vk1dx

Well-Known Member
Re the engine bay cleaning. Is a little splashed mud going to cause any real problems? I'm too freaked about killing the electrics. It's a 2015 collie. When you say "go easy on the electricts" I open the bonett, there's electronic stuff everywhere.

Thanks again.
I don't like mud sitting on the engine and being baked on by the heat of the motor. I get it off as soon as I could. As Peter Brock proved with the red 186 holden motor - taking the red paint off helped with cooling. Hence I get rid of the mud. Doug Chivas told me about it as well.

I use a strong water jet to hose anything non electronic. I spray the fuse box and batteries, alternator and starter with a gentler spray. Well that is the aim. I NEVER put a strong jet on the fuse box area. Maybe that is a little clearer.

The fuse box and other "protected" wiring etc all resides in the passenger side front corner of the engine bay, right next to the front crank battery. That is what I call the "electronic stuff". Basically the rest get a real thorough hose, with a few exemptions.

Phil

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