S-Prihadi

Gents,

1st, our engine is supposed to run hotter than older cars, in the name of thermal/combustion efficiency.
We have a heater at our thermostat housing to assist with such function. Not that the heater is to warm up the coolant, but the heater is to melt to wax of the thermostat, so that the thermostat can open earlier when needed,
or do not heat the wax so soon and use higher temperature wax.... to get our engine hotter an average 95C or do 105 to 108C when needed. Older cars commonly uses 86C opening thermostat.

Example of the working of the heater assisted thermostat on our M276 engine

You can see the MAP controlled thermostat ini action in my car : https://mbworld.org/forums/e-class-w...at-action.html


Have an eye opener here, for BMW, which at least the give the thermostat opening temperature, it is 108C !!! If by wax alone and no heater assist.








Now, what I want to discuss is about potential borderline performance of the coolant circulation pump at idling speed of 550-700 RPM.
At first I have always thought that it is 100% the doing of the MAP controlled thermostat, but when I was testing engine oils pressure and done many statonary revving till 108C and engine computer intervene and doesn't allow me to do
even max out soft limiter limit to 4,200 RPM anymore. Engine computer intervention has a DTC logged but not the engine check light level . Engine computer said ; RPM too fast

I then looked at the log file of the test and I am seeing potential borderline performance of the coolant circulation pump at idling speed of 550-700 RPM, if for my tropical location 30-34C
hot and high humidity.

Here is why I came to the conclusion above. Below is one of the log file.



From left to Zone A is high RPM stationary generating heat to the coolant.
Zone A to B is when even RPM reduced from 3,500 to 2,500 , the engine block heat started to creep to the coolant, hence 98C becomes 100C.
Zone B to C is 2,500 RPM slowing down and spending longer time at idling, coolant is absorbing more heat from session of Zone A and 100C becomes 104C.
It is easier to warm up the coolant by idling after doing 3,500ish RPM for a while, than while maintaining 3,500ish RPM.

C to D is how I cool the engine, by short-quick rev up, I get from 104C to 96C.
This reminds me of the older engine with Vicous coupling for its crankshaft powered fan.
Remember older engine like below :


In my younger days, if I see coolant temp hitting 90is C, depending on the engine, if vico-coupling type fan, I will do the short-quick rev up to get higher fan speed.
If engine uses full electric fan, I will turn off the HVAC and headlight ( if at nite ). Those days 85-87C is the norm but never 90ish C.


Unfortunately, M276 coolant flow path/gallery is not documented in its tech manual, only the M278 is shown.






Now comes the other information I have collected, in relation to the engine cooling system.
I have installed pressure sensor for engine coolant and for aftercooler coolant. These two are totally separate circuit, unlike M278 which if older model share the coolant recovery bottle for these 2 separate duties.
Later M278 model, MB added a small coolant recovery bottle for aftercooler, similar to M276 3.0 Turbo and there then them 2 circuits becomes totally separated, like M276 3.0 Turbo.

My current installation location for engine coolant pressure sensing is WRONG.
If I were to borrow M278 coolant circuit drawing, my current coolant pressure sensor is as below :



I am currently using option 1










I should have placed pressure sensor as closest as possible to the output of the mechanical coolant pump....but surely that is not possible.

What is visible from outside the engine are 2 coolant outputs at engine block and 1 input at coolant circulation pump

Thermostat housing is actually like a Y connector, it merges Bank 1 and Bank 2 coolant output from engine block/cylinder heads for the radiator hose ( radiator input ).



The best place for me to read coolant circulation pump pressure actually is this output 2.




If thermostat housing removed, these are the Bank 1 and Bank 2 coolant output leaving engine block/cylinder head. This applies to M276 3.5L non turbo too.








If seen on coolant circulation pump........one would think the pump itself has its own output visible from outside the engine, no Output 1 below is just providing a coolant path/gallery for Bank 1 and is not from the impeller




water pump = coolant circulation pump



See, B1 is not the impeller's output, it is the waterpump provided coolant path only for Bank 1 coolant output to join thermostat housing.

water pump = coolant circulation pump







Assuming I can benefit better coolant circulation volume* ( *pressure too, it is related ), my only way to do it is to reduce useless coolant flow to HVAC heater core.
Not total shutd down of flow but perhaps reduce it by 50% - 60% .

I was thingking to machine a plug with holes, the holes as the flow regulating component.
If I place the pressure sensor adapter at A ( below image ) the hose of engine block output 2 to the HVAC core, I can use the adapter pipe internal diameter to place my "plugs" there. B below is plastic pipe of output 2 meeting rubber hose.






Typical hose adapter for sensor is 2mm wider OD than the pipe ID so that hose can fit well without leak.



Using above sensor adapter size as example, I can make 2 washers of 21.5mm OD from stainless steel (SS). Washers center bore I can use 4mm SS bolt and nut to secure them at the very lip of the pipe 2 ends and washer will then never move.
The 2 washers I drill holes to allow coolant to flow, but at 40 - 50% flow only.
This way I get 3 benefits, 1st is the thermostat will then get higher coolant flow volume then current OPEN-100% flow to HVAC heater core.
2nd I do not waste my HVAC evaporator cooling power from heater core heat "contamination"
3rd, if restriction is created by my washers, the turbo coolant output/return then will have better flow towards coolant circulation pump because less competition from HVAC heater core output/return hose.

At the moment, M276 3.0 turbo the coolant flow from output 2 is as follows :
- Output 2 from rear of engine block to HVAC core
- HVAC cote to 1st tee, joined by 2 of turbocharger spent/return coolant lines
- and then to suction side of small 12V DC coolant circulation pump to keep car heater running in ECO engine off mode I think.
- output of 12V DC coolant circulation pump to a 2nd tee belonging to radiator output which is the the input for mechanical coolant circulation pump


This is the pressure of the engine coolant, at current installation location, it is basically almost useless . It was ONLY because the easiest location to work on.... LOL

Engine RPM is related to coolant pump spinning speed and pressure.



Below is to see how heat effect coolant pressure, but nothing to do with its mechanical coolant pump performance. I wonder, a 1.4BAR ( 20.3 psi ) coolant cap, when will it ever vent by over pressure ?




The aftercooler coolant c irculation pump is 12V DC , so it is not so speed variable like engine coolant mechanical one. I never yet measured this DC pump PWM signal, I think its a simple 2 speed at the most even though using PWM.
The install location is good, right after pump's output and MB has a Tee there already being plugged for probably other engine variant.









So the pressure reading accurately represents the performance of the DC pump and also when and if pressure rise due to very hot coolant temperature.








The intake air temperature is the one heating up the coolant. Ambient temp of this test is about 25C. At good car speed 100KM/H or more, the aftercooler can be only 12-14C hotter than ambient...impressive for its small size.









So, any suggestion to improve the engine's block coolant flow , other than what I plan to do.... will be great.

Many thanks

E55Greasemonkey

You're creating a solution that's looking for a problem that doesn't exist. "Don't fix it unless it's broken"

CaliBenzDriver

Programmable Thermostat:
This fancy 108C/230F thermostat is guaranteed to get some attention when any part of the heater circuit quits, temperature shoots up to above and beyon in headgasket territories ... lol
Honest preventive maintenance is king


Cool pump:
I guess if you want to improve coolant flow you need to upgrade the pump throughput.

The way you like high RPM to spin TT, 2-speed electrical pump in cool return line maybe your ticket.

Searching for an upgraded impeller serpentine pump maybe hardler than standard 12VDC pump, right ?

S-Prihadi

Well if car is in a region with 20C average ambient temperature in day time and driven calm, you are right, it is not a problem, but me in a daytime 30-34C ambient temperature and I drive it hard sometime.
The M276 3,0 Turbo cooling system itself is poor for hard driving.
It does not take a racer to drive my car, just me having agressive fun on this short 3.9KM track for 3 laps : https://en.wikipedia.org/wiki/Sentul...tional_Circuit
The engine will hit 120C and that's it, I have to slow down.




By end of 2nd lap lap at 32C ambient temperature, maximum throttle leaving corner 11 to enter corner 1 ( 3rd lap now ), by corner 4 the engine will hit 120C. So me have to do 1 cool down lap and then hit the rest area for 30 minutes.
My 1.6L 2010 Ford Fiesta cooling system does well under the same scenario, but the brake will fade by 2nd lap.
The E400 brakes are OK, won't fade but the brake pad get damaged by the time I done 3 times of such 3 laps.

The same with the standard damper I get, they are SACHS. They are dangerous at a mere 110MPH when switching lane fast. Not a maniac zig zag lane change, just a bit fast single event lane change.
My solution was simple, replaced it with comfy Bilstein B4 all 4, solved. B4 at the front and B6 at the rear is better though and that is the final set up.
Comfy like standard car but so much safer at high speed.

If you don't log your engine parameters like me, you have to rely on warning lights and hence "Don't fix it unless it's broken" is good for you because what you dont know , you dont worry.

Overheating for me that can mean a meltdown and a total loss.
The logs have helped me observe potential weakness or soon to be trouble brewing or find opportunity where I think I can make improvement.

I don't tune my engine, its bone stock. I don't like tuning it for more power using aftermarket system. I want it to last as long as it can.

CaliBenzDriver

yeahh...we want you to stay cool and not slow down on your favorite track loop.

S-Prihadi

Yes Cali, this kind of MAP thermostat worries me a great deal because if the heater failed while I drive engine hard, it is dangerous to have such high temperature wax.
This is not a fail safe system, this is FAIL & KILL for my hot climate.

On marine diesels I seen newbie operator/captain warp cylinder heads often from overheating. Plastic garbage at sea is our number 1 enemy for Jakarta based yachts.
Jakarta garbage thrown into river is insane !!!

Marine engines uses sea water as cooling power, not airflow like cars. So seawater cools down the 50/50 fresh water coolant circuit of engine, using heat exchanger. So double jacket system so to speak.
Even our exhaust manifold and turbocharger are all wet system, coolant inside circulating.

So each engine has 2 pumps, 1 is regular coolant circulation pump like our car engine and one extra is sea water pump using rubber impellers driven using one of the camshaft. No electric pump here.
I also installed pressure sensor at the sea water pump, because without it I can't detect seawater blockage from plastic garbage ahead of temperature rise.

If overheating occurs on a marine diesel from bad weather ( high engine load) and minor fouling of the heat exchanger ( barnacle can grow inside it ) or partial blockage of sea water pump inlet by plastic garbage,
the key is to not turn off the engine, but go to neutral gear and raise RPM to approx 1,000 ( this is a 2,300 max WOT engine ) and cooling power will increase while load is removed.
Newbie Captain who turn off his engine under the same scenario, usually get warped cylinder head.
Fresh water coolant circuit is slow to respond to actual engine thermal load. When an overheating engine is turned off the heat build up is massive and is still in progress, that is how the cylinder head get warped.

Marine engine has its own beauty for us learning about engine load. Car engine at the highway at zero gradient road, even doing WOT for gear change 1-2-3-4 and maintaining say 120MPH at 4th gear is easy load.
Marine engine on yachts are set at approx 75% load by propeller size + gearbox ratio, and estimated 3/4 wet load of fuel, water and people....in fair weather.
The engine load to marine engine at cruise speed is equal to a truck going to a never ending hill on a fix gradient equal to 75% engine load and do this for hours and hours non stop.
Easy analogy is load a 100kw generator to 75kw non stop.

In bad sea, each climbing up a wave is equal to extra gradient of a hill, this is where engine will suffer and more so if the original propeller load calculation are for top speed and not for bad weather.
Some Italian yachts are very bad for their propeller load calculation, they chase top speed and assumed light wet load of fuel, water and people. I call them marina to marina user profile, not open sea.
American sporfishing yachts are the better ones, they do their propeller load calculation very well due to the nature of use, long range with heavy fuel load and ready for bad weather.
The British yachts Sunseeker/Princess/Fairline propeller calculation are not bad, probably because they have North Sea and things can go wild there.

=============

I don't think I can find a higher power mechanical coolant circulation pump for the engine or bigger radiator but fit nice and sweet like OEM.
What i can do is, during thermostat OPEN state, is to make sure coolant majority flow to important areas and not wasteful one like HVAC heater core ( I am in the tropics ).
If the diversion of coolant flow to heater core let say represent 20% of total coolant flow of the circulation pump capability, me reducing that heater core volume to 10% would still be some advantage.

Let me try to draw M276 non turbo cooling circuit on the M278 drawing. Even M276 turbo circuit is very similar to M276 non turbo, so easier to view a non turbo M276.

CaliBenzDriver

Restricting your heater core circulation to a trickle makes complete sense in tropical weater.

What makes hardly any sense is heating the cavity next to A/C evap with 200F coolant without any flow control.

I remember reading the M276(/8?) coolant pump is purposely undersized to save fuel. It basically pumps next to nothing at low Rpm. An electric pump was added to help circulation plus serve the option of engine-off cabin heating.

Last week I saw Tasos talk about a lower temp thermostat for BMW for the same reason you mention: hot countries don't need to worsen heat stress. So these 190F programmable thermostats are available for some cars.
I bet the ECU temp sensor will get you a "low temp" code


Plan B:
Thermostat heater is programmable by an ECU PWM signal, right?
How about overwriting the default target temperature value for a base 190F ?

pierrejoliat

Surya, do you have heated washer fluid? I wonder if that's where that blocked "T" goes? Also, for cars with the "Rest" feature, wouldn't the thermostat need to be open to circulate coolant through the heater core?

S-Prihadi

Nope, lucky me no heater to washer. Aha, probably that is where/what the blocked T is for .... thank you Sir. EDIT : this Tee is at aftercooler coolant system, I think the Tee won't be for washer fluid.

The only fluid coolant based heater in my car is the HVAC core, nothing else.

S-Prihadi

If for circulation of hot coolant to HVAC heater core, but not for any assist to radiator cooling, I have that small 12V DC pump in my engine bay.
I think this pump only run when and if I choose heater and in ECO engine kill mode. As long as engine is running, the mechanical coolant circulation pump itself has enough flow and pressure to heat up and circulate coolant to
heater core of HVAC.

===========================

Cali wrote :
Plan B:
Thermostat heater is programmable by an ECU PWM signal, right?
How about overwriting the default target temperature value for a base 190F ?

ha ha ha I wish I have such ECM re-write skill. No cant do

==============

Cali wrote :
I remember reading the M276(/8?) coolant pump is purposely undersized to save fuel. It basically pumps next to nothing at low Rpm. An electric pump was added to help circulation plus serve the option of engine-off cabin heating.

Well, M278 has Y16/2 shut off valve at the rear of the engine block to stop any flow to heater core. So it can stop the flow and 100% use of the flow for radiator cooling.
Our HVAC systemn still have electric heater too at HVAC housing.

=================

Cali wrote :
Last week I saw Tasos talk about a lower temp thermostat for BMW for the same reason you mention: hot countries don't need to worsen heat stress. So these 190F programmable thermostats are available for some cars.
I bet the ECU temp sensor will get you a "low temp" code

Damn, that is such a beautiful news. I dont think we have anything like that for our M276. MB surely uses software only, easier for them...as long as the heater does not fail.

pierrejoliat

Hmm, I don't have a turbo, but I will look tomorrow where the hose comes from to the washer tank, I would think it might not be a good idea to put 160 F washer fluid on a 5 F windshield, also, I believe at some point we found out on this forum that different parts of the world got 2 maybe three sizes of radiators, wonder what the capacity of yours is?

S-Prihadi

Wow...MB is kinda crazy.

M276 3.5L non turbo or M276 3.0 turbo or even the higher power M278 and M157, its radiator item 10 is all same P/N A204 500 36 03...yikes !!!!
The only add-on for turbo engines is the aftercooler, that is all....item 40 or P/N A009 500 38 03











Item 250 below is the same as item 40 above, P/N A009 500 38 03

S-Prihadi

Pierre,

The washer fluid heater taps from channel to HVAC heater core. This is M276 3.5L non turbo

kajtek1

Man, you need to get a diesel.
My cars operate at 40C quite often, with 50 that happens from time to time and never overheat.
Manu fact at gentle highway driving most of them will stay at 78C with close to 40C outside.

S-Prihadi

You drive so kind to your engine K1 hence 40C ambient is no issue. But I guess maintaining 40MPH is not a problem where u drive yes. You win on the wind flow department.

MB Indonesia never dare to import their modern common rail diesel sedans.
Our fuel can't qualify for its Euro rating.
Euro4 fuel only available last year, which MB diesels are I think already Euro5 or higher even back 5+ years ago right ?

The funny part is this year, Toyota Indonesia have to get all buyers of their new cars of 2022 with diesels, to sign a liability release, where owners are only allowed to use Euro4 diesel, or else no warranty.
The Japanese giant seems to not be able to backward their technology too long.
We still have non Euro4 diesel. What quality ? I don't know, I think it is still Euro2 or worse.

My friends 112 footer yacht, 12V MTU 4000 series x 2 units. His common rail injectors only live to 2,000 hours in Indonesia, where in Europe with proper fuel, 4,000+ hours to 6,000 hours is not a problem.
US$75K for 24 injectors...OUCh !!!!
Yacht is based in Labuan Bajo, Eastern Indonesia, where Euro4 diesel fuel is almost non existent.

The marine diesel is never a Euro 4 unless you are at Java island bigger cities and request Euro4 and must buy minimum 5,000 liter by tanker truck and are for cars actually.
Elsewhere you get crappy one as marine diesel , but pay high price of Euro4.

pierrejoliat

Ahh, but what about line 40? I'm just asking, I wonder which way flow is ?

S-Prihadi

Yes, how dumb of me ....
Heater circuit always need 1 Input and 1 output.
So the line 110 is the input for washer fluid warmer and the line 40 is output. Line 40 is to the small 12V DC circulation pump belonging to engine coolant circuit, same as line 110.
So what's the Tee for on my 3.0 turbo aftercooler coolant circuit ? Still a mystery.

pierrejoliat

Not dumb at all, we are figuring this out together, all input is good! Maybe its plumbed different with a turbo?

S-Prihadi

The E400 cooling hoses for hvac heater core and turbo coolant merging at their return is not accurate in EPC. This is the price of a Pariah model.

Basically E400 3.0 turbo M276 ACTUAL cooling ( Turbos + HVAC heater Tee ) system does not exist in EPC, unless I use W207 EPC page and that W207 is a TURBOCHARGED M276 3.5 , yes the rare 3.5 turbo.


=================

Anyway, I have drawn the actual coolant schematic on E400 3.0 Turbo M276.




The sad thruth for me in the tropics is as follows :

01. Take a look at coolant line C, which is the result of A and B merging. Observe where does C goes to.

02. The only way any coolant can benefit the cooling power of the radiator is, it has to join line F or E (hot side) and travel to D (cold side ) via the small capillary tubes of the radiator.
E to D is the only zone any coolant can get its heat released. Line F is inside engine block, so out of the question. Only E is feasible.

03. Coolant line A and B is good for engine warm up period, before thermostat opens. When and if thermostat opens, A + B which becomes C, is injected to join coolant line D into coolant circ. pump gets no real
cooling from radiator, it gets cooling only from dilution of joining ( tee ) its hot self to a cooler coolant flow out of the radiator cool side D. This is a waste of radiator power for hot climate cars, which a few post ago I have showed that even
the high HP M157 is using the same radiator unit like M276 3.0 turbo or non turbo 3.5.

I do not know how much BTU of heat cooling a turbocharger is worth : https://www.garrettmotion.com/racing...or-your-turbo/
But I am sure its not small BTU quantity, because its basically almost like cooling an exhaust header/manifold of a 2 cylinders engine ( 2 turbos ).

So the summary is like this :
A - I lost not only coolant flow and pressure from the rear of the engine block into HVAC heater core which is line A, I also lost the opportunity that X liters perminute of those coolant never gets cooled down by the radiator.
B - The coolant lines into the 2 turbos which are from the rear of the engine block too ( special coolant output port for turbo ) which eventually becomes line B..... is the same story as above, wasted fluid path without radiator cooling power.
How much does A + B represent in BTU of cooling potential I lost ? Lets just use an easy 20%-25% as wasted.

So sad for me tropical country dude.

Can I do anything to improve, aside from what I been thingking to do initailly ?.... there is one more alternative.
Alternative is : if I can custom made a electric water solenoid/valve with 90- 95C triggered opening and make a special Tee at line E, I will divert the current injection into C and move it the new tee at E.

Damn, if only I did not throw the old hose years ago where C is injected, I could use that plastic Tee for experiment sake.


I am sure this hose which is radiator INPUT (E) is the same Internal Diameter as radiator OUTPUT hose (C).

S-Prihadi

To see how lame my cooling system is : 32C ambient temperature





First 3 lap it was my friend, he is taking his own sweet time.
Pit stop to change me as driver and the 2 lap + 1 cooling lap is mine and I will show below in a graph.




Highest speed at the straight , which is also where the start-finish line is at. The 1 lap marker above is the 2nd lap. After that cooling lap to the right. Very left of graph is 1st lap.






So basically within 2 laps or 8KM or 5 miles = 120C already and if I push it to 3rd lap, it will surely pass 120C.
Its like 5C accumulative each lap and the 2nd lap hence we can see 120C where 1st lap saw 115C at the end of the straight.

ninobrn99

Would an aux heat exchanger help like on the VW and BMWs?

S-Prihadi

It is very complex to add those mini radiators like BMW M cars get.
Anyway unless at the track, 120C coolant temp won't happen. 110C is as high as I seen on the road.
Maybe if I do towing it may be hotter ... but I will never tow anything heheheh.

Thanks for the suggestion.
I have accepted the fact my cooling system is not meant to be for very hard driving.