long steep hills

[djelica]

Hi everyone,

Just some questions on driving behaviour when it comes to long steep climbs (like the Coquihalla or Kootenay Pass).

I know that most will recommend a pyrometer gauge, but I have not installed one and really wonder if the location at the egr blanking plate is indicative of real temperatures at the turbo. Is it possible that people are being lulled into a sense of safety when real temps may be different where it really matters?

Anyway, the real questions are what do you do when you see elevated temps and what conditions are most likely to create temperature problems? Long steep hills is obvious, but are there other conditions (such as strong headwinds) that may cause overheating for the L400? Anyone experience high temps in other situations?

And what driving modification is best when in a long steep hill situation?

When on Kootenay pass I try to keep my engine revs, momentum and speed up, but this is not always possible with other (slower) drivers on the road.

There is a point on the highway (each way) where the grade is steepest towards the end and this is where you can feel that the machine start to struggle to maintain its rpms. At this point I will take off the OD and settle in for driving the remaining distance to the top at about 3000 rpm (at just under 90kph). There is plenty of throttle left and I imagine I could be doing over 100kph in the 3500 rpm range (but feel no need to as 90 kph is fine with me).

But what is best for the machine and keeping everything cool?

What does your pyrometer tell you in this situation?

Finally does anyone have a pyro just pre or post turbo that could verify that a pyro at the blanking plate is providing an accurate picture for temps at the turbo?

Thanks in advance for any input on this.

Darren

[jessef]

Is it possible that people are being lulled into a sense of safety when real temps may be different where it really matters?

Temp gauge and pyro represent to completely different temps. One is coolant and one is exhaust gas. Exhaust gas is a more precise and direct temp measurement for engine heat.

Anyway, the real questions are what do you do when you see elevated temps and what conditions are most likely to create temperature problems? Long steep hills is obvious, but are there other conditions (such as strong headwinds) that may cause overheating for the L400? Anyone experience high temps in other situations?

Just long steep hills. The 4M40 in the L400 can sustain 130-140km/hr against a headwind barrelling down the I-5 without breaking a sweat and still maintain safe EGT's.

And what driving modification is best when in a long steep hill situation?

Back off the throttle. Modification of the downward pressure that is exerted by your foot on the gas pedal.

There is a point on the highway (each way) where the grade is steepest towards the end and this is where you can feel that the machine start to struggle to maintain its rpms. At this point I will take off the OD and settle in for driving the remaining distance to the top at about 3000 rpm (at just under 90kph). There is plenty of throttle left and I imagine I could be doing over 100kph in the 3500 rpm range (but feel no need to as 90 kph is fine with me).

That is the best thing to do. Keep the RPM's up close to 3000 and again, back off the throttle. There is no way to tell how much you need unless you have a gauge (pyro/EGT) to tell you.

But what is best for the machine and keeping everything cool?

What does your pyrometer tell you in this situation?

A well maintained cooling system (if it hasn't been done since it's arrival in Japan, get it done, otherwise run the very high risk of cracking the head).

Pyro just tells you what the EGT's are.

Finally does anyone have a pyro just pre or post turbo that could verify that a pyro at the blanking plate is providing an accurate picture for temps at the turbo?

The most accurate reading you can get is threading a hole and inserting the probe directly into the exhaust manifold. Because this is not the simplest/cost effective solution (you may have to remove the turbo to get the metal shavings out), most people put the probe either in a bung in the EGR location on the exhaust manifold (pre-turbo) or close to the flange on the exhaust pipe (post turbo/dump pipe).

The readings you get post/pre turbo are close enough to dictate how you drive up steep hills/towing, etc...

Better to have a pyro than no pyro a wise man once said.

[psilosin]

I know that most will recommend a pyrometer gauge, but I have not installed one and really wonder if the location at the egr blanking plate is indicative of real temperatures at the turbo. Is it possible that people are being lulled into a sense of safety when real temps may be different where it really matters?

Think you have the purpose of the pyrometer/EGT gauge mixed up a bit. The turbo itself is irrelevant to the use of an EGT gauge. You don't actually care what the temperature is at the turbo...you are looking for the most accurate measure of the combustion temperature INSIDE the engine.

Some people install their EGT gauge right after the turbo, not because it is better but because it can be an easier install (compared to drilling & taping a port into teh exhaust manifold if you didn't have a handy dandy easy to reach EGR blank right there on the exhaust manifold just waiting to be used). Installing teh EGT probe at the EGR blanking plate is a far superior location as it is that much closer to the combustion process thus giving a more accurate reading. Measured EGT temps in an after turbo installation can be a few hundred degrees below what the actual EGT temperature is inside the engine.

It is so easy and convienient to install an EGT pyro probe in the EGR blanking plate location on an L400 that I cannot think of any reason to install it anywhere else. As a contrasting example on my other vehicle (Hilux Surf) the EGR blank spot pretty much requires 23 jointed arms to reach so installing after the turbo instead is pretty tempting even if not as accurate...

[davidwwc]

Jfarseng wrote:
Just long steep hills. The 4M40 in the L400 can sustain 130-140km/hr against a headwind barrelling down the I-5 without breaking a sweat and still maintain safe EGT's.

Hi, Jfarseng,

Is this a stock l400 you are talking about? How steep is the hill ? Right now I am trying to fix my L400's steep hill speed. this post will add further knowlege for me to know the potential of the L400.

Thanks,
DC

[jessef]

stock proper working L400 can do 130km/hr on a straight highway

steep hill is relative to the place/how fast you are going/driver/conditions,etc...

[djelica]

Hey thanks for those fast answers. I have a far better understanding now.

cheers, Darren

[pajerry]

I will stress the importance of getting your cooling system flushed or replaced as I was cruising westbound on the #3 last weekend fully loaded 4 of us and gear, pyro reading max 850f at EGR blank while climbing at 3KRPM , and my stock coolant guage started moving upwards right before the crest of the pass.. Pulled over, revs at 1200, heat on full hot went down in a minute.

I will now be buying an after market coolant temp guage and new radiator


Whats the best/easiest coolant temp sensor location on an L400. Im hoping I can just replace the stock sensor or something?

THanks

[Rising Sun Auto Import]

I will stress the importance of getting your cooling system flushed or replaced as I was cruising westbound on the #3 last weekend fully loaded 4 of us and gear, pyro reading max 850f at EGR blank while climbing at 3KRPM , and my stock coolant guage started moving upwards right before the crest of the pass.. Pulled over, revs at 1200, heat on full hot went down in a minute.

I will now be buying an after market coolant temp guage and new radiator


Whats the best/easiest coolant temp sensor location on an L400. Im hoping I can just replace the stock sensor or something?

THanks

IMO, to keep your cooling system regularly ( 2 year or 50,000km ) is the key to make engine healthy.
Stock 2 pin sensor, thermostat, water pump, coolant replacement and hoses replacement need to be checked as long as your radiator is okay.

Steven

[Profister]

IMO, to keep your cooling system regularly ( 2 year or 50,000km ) is the key to make engine healthy.

What do you mean?

[nxski]

I think he means the things listed below that should be replaced that often.

[Profister]

Well, the recommended action for what is listed is even more confusing...

[pajerry]

Does anyone agree that those should be swapped every 50K? Coolant and a flush maybe while checking hoses maybe, but seems excessive no?

Anybody know if Japanoid even flushes the system while they service it? I forget what they said about that. I've never checked it myself besides topping it up the past two years.


Is it at all normal to see the stock guage move? Not to red, just another 1/8th or 1/4 past normal point?

[Rising Sun Auto Import]

Does anyone agree that those should be swapped every 50K? Coolant and a flush maybe while checking hoses maybe, but seems excessive no?

Anybody know if Japanoid even flushes the system while they service it? I forget what they said about that. I've never checked it myself besides topping it up the past two years.


Is it at all normal to see the stock guage move? Not to red, just another 1/8th or 1/4 past normal point?

Most engine failure comes from broken radiator and hoses caused by bad coolant circulation, accumulated corrosion.
Same as human body.
The frequent service you get, the more clean head your vehicle has, shiny......
I know Toyota dealer selling good extended coolant ( very expensive though ).
Shop usually recommend to take care of cooling system.

Exact half point for the pajero, so yours seems to be not normal.
Replace 2 pin sensor ( I would free-rent it for you to test ), and see what's next.

Steven

[nxski]

It's completely normal for the temp gauge to fluctuate a bit. I'll keep running it at half for a little while but if it stays up there or goes higher pull over. If the engine overheats you don't want to shut it off or you risk cracking your head.

[pajerry]

Yeah, it has happened once before and the second I noticed it more than the half mark I pulled over and let it idle at 1200rpm or so with the heaters on until it cools down. Im still looking to put in an aftermarket guage if anyone knows the best/easiest placement for this?

looks like the factory guage works fine as is, although I'd rather have the peace of mind. I figured as long as the pyro wasn't reading 1000deg or more I'd be fine, I was wrong..

I'll probably replace the rad and hoses by next year unless it does it again. Its not often I have four people, a roof box, and a rear rack packed to the max while pinning it at 3000rpm for more than a few minutes.. although it is a little disappointing.