Page 1 of 2 12 LastLast
Results 1 to 10 of 20

Thread: How warm is too warm. How cool is too cool?

  1. #1
    Join Date
    Mar 2008
    Location
    Kilmore, VIC
    Posts
    848
    Total Downloaded
    0

    How warm is too warm. How cool is too cool?

    368DT engine (3.6), towing a 2.1t dual-axle full size/height caravan (18') with the aero of a billboard... @90km/hr highway. EGRs fully removed and EGR cooling system by-passed with water pipe and hose (Ø16mm) - ie. no EGR thermostat. Engine thermostat replaced (genuine) as a 10year maintenance item. 31.5" BFGs, otherwise pretty stock.

    So... here's some data to ponder. From Rovacom VCiQ datalogs.

    Towing. Level ground. 5th gear locked, easy cruising, 1900rpm. ~20deg ambient temp. Temps stabilised.
    Coolant - 95
    Engine Oil – 104
    Fuel – 89

    Towing. Undulating ground (Heathcote to Whycheproof, VIC). 4/5/6th gear, 1500-2500rpm. Generally maintaining 90km/hr but allowing it to drop back to about 80 on the steeper sections. ~25-30deg ambient temp. Temps dynamic.
    Coolant – 91-110 (any sort of uphill would cause the temps to start to rise and only drop back once the load came off)
    Engine Oil – 99-120
    Fuel – 82-113

    Non-towing highway running - 100-110km/hr. 6th gear locked. ~20deg ambient temp. Temps reasonably stable.
    Coolant – 75-81
    Engine Oil – 76-78
    Fuel – 55-67

    Non-towing highway running - 100-110km/hr. 6th gear locked. ~5deg ambient temp. Temps reasonably stable.
    Coolant – 53-65 (drops coming downhill, increases going uphill)
    Engine Oil – 59-64
    Fuel – 32-46

    Are those towing numbers too hot? As much as the 'van is a bit of a brick, the terrain wasn't overly steep or challenging (just rolling hills really), nor were the outside temps high. Not sure how it'll go in high-summer punching through the Snowy Mountains... I have to say I'm a bit concerned.
    I think the non-towing numbers in cool ambients are way too cool and am looking to put a blanking plug in the EGR bypass with an 1/8" air-bleed hole as I suspect I'm getting a large amount of engine thermostat bypass through this circuit, causing over-cooling. Engine warms up to ~50-60deg in the first 10 mins but then struggles to get much warmer after that under light load and highway airflow. It can take 20mins or more to get to 80 deg in stop/start urban running. Temperature profile isn't a quick warm-up and then thermostatic control (sharp rise and then cycling) but rather a slow climb with cycling only due to load and airflow - as if the engine thermostat is doing little or nothing.

    If I didn't trust the new engine thermostat I'd say the symptoms match having a thermostat that is jammed about half open (which I've experienced more than once in various cars). Overcooling in the cold weather with excessive bypass and then not flowing enough to deal with higher temperatures and/or loading.

    What are others seeing? Am I tilting at windmills or are there areas of concern here?
    Attached Images Attached Images
    DiscoClax
    '94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
    '08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID

  2. #2
    Join Date
    Sep 2012
    Location
    Adelaide Hills
    Posts
    13,298
    Total Downloaded
    0
    from my l320.
    non towing coolant looks a little cool.

    i dont have a heavy caravan so i cant help there

  3. #3
    Join Date
    Mar 2008
    Location
    Kilmore, VIC
    Posts
    848
    Total Downloaded
    0
    Another trace added here. This is the averaged data for this week running in to work in 5-10 deg ambient temps - non-towing, coolant temps shown only. The elevation profile is also shown - you can see where I do the downhill bit and the temps drop significantly before clawing their way back up... First half (roughly) is highway and the rest is urban. Top of scale is the theoretical thermostat opening point (ie. 88 deg)

    Temps 2.jpg
    DiscoClax
    '94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
    '08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID

  4. #4
    Join Date
    Jun 2014
    Location
    Dubbo
    Posts
    545
    Total Downloaded
    0
    Yep, clamp off that coolant bypass and go for a run. Im not a betting man but I think your temps would stabilise. Remember that EGR valves also control the flow of coolant through the EGR cooler. EGR traditionally only operates once the engine is up to operating temp.
    With the EGR bypassed you've got a constant and unregulated bypass flow. I.e. during warmup coolant is flowing through the bypass instead of warming up in the engine.
    During high operating temps, even with the thermostat wide open, hot coolant will still flow through the unregulated bypass straight back into the pump suction.

  5. #5
    Join Date
    Mar 2008
    Location
    Kilmore, VIC
    Posts
    848
    Total Downloaded
    0
    Thanks Beery. I must admit I haven't had a good look at the coolant flow schematics to work out what goes where and how I've affected it. It's a bit weird having someone else mod my car. I'm used to doing it all myself and knowing what's what for better or worse. My Indy said their experience is that the EGR thermostat is always half open so they thought it'd be OK to just bypass it at full flow, but they haven't done a TDV8 before. If the cooler has reasonable restriction to flow that would regulate it and minimise the effect. Equally if the EGR then dumps back to the inlet side of the pump it'll cause both the over cooling and then running toasty under load if suddenly opened right up... Starting to make sense now. Hopefully the weather is a bit better tomorrow and I'll have a poke around to understand it better.
    DiscoClax
    '94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
    '08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID

  6. #6
    Join Date
    Apr 2016
    Location
    Melbourne
    Posts
    4,203
    Total Downloaded
    0
    Can't help re TDV8 specific experience, but overcooling isn't necessarily due to a jammed thermostat.
    Of course you won't know until you physically check it, but I get that with my Tdi now.

    I'm putting it down to an excessively eager thermostat design, or build.

    I started with a waxtstat as the Tdi came.
    Had a bit of an issue with heating up with A/C on(I don't to at all).
    Heating issue was only under load, and in a Tdi, that means just about any incline, big or small!

    Got a tridon thermostat(actually got two), one 82, and one 88 degrees.
    I tested them both along with the waxstat. Waxstat was marked 88 the two Tridons actually marked 180(82C) and 190(88C)).

    With the waxtstat in place, I used to see regular 86-88 degree temps, and with the 1Gauge logging, steady graph between 86-89.
    Any uphill, and 92-95 was normal.

    Now with the Tridon 190(ie. 88°C thermostat fitted), temp range has changed dramatically doing the same driving.
    Normal steady range is 83-ish on a mild day, up to a reasonable 35 ambient day(no AC).... wouldn't make much difference.

    AC on, and this is where I'd hit issues.

    My point is that with the new Tridon stat, the characteristics have totally changed. Reaction time majorly quicker, and a lot earlier.
    Even tho it's an 88°C(being 190F) stat, it starts to open earlier albeit slowly, where the Waxstat version stayed put till the high 80's(technically using my IR thermometer, in the low 90's)

    Now in the Tdi, I see this same effect. This the case irrespective of temps between roughly 15-ish and high 30's, only above that did I see coolant temps in the high 80's low 90's with no AC on.

    Now that we have much cooler weather tho, below 15, I rarely see coolant temps in the mid to high 70's .. 74 a steady regular temp.
    So to me it appears that the thermostat may be jammed half open, but in reality it's simply it's reaction characteristic that I observed in the jar/pot when testing.
    it starts to open at a much earlier temp .. very small barely noticeable opening in the valve ... but still there.
    And it makes no difference if I'm in heavy traffic or running at 90-100 k/h .. I see mid 70's and maybe high 70's, 78 being max now with sub 15C ambient weather.

    This has been my new norm now for two winters and coming up to the 3rd in a few weeks.
    At first I thought it jammed open(a few months) from new .. pulled it, wasted time and coolant doing so.

    So, what I do now is that over winter I remove my fan(simple 30 sec job). Simply not needed, hasn't been since I installed the Tridon. Chuck it in the back of the car .. just in case I encounter higher teen ambients and above either via weather variance here at home, or if I'm traveling into such. I think it was close to 20C ambient where I'm stuck in traffic, coolant would rise up into the low 90's without the fan installed.

    ps. I'm looking into removing the viscous and installing an electric fan.. saves the 30 sec of removing fan!

    The one thing that strikes me odd in your figures is the fuel temp under load on the undulating section. 113 seems a bit high, but I have zero experience with your vehicle.
    D2 TD5 is my only experience with fuel temps, and never seen that .. have to be honest never looked to see if it goes that high in any conditions.
    Will have to get brother to do some logging on his D2.
    But it makes sense .. if coolant is high, fuel temp is cooled by coolant, so higher coolant temp .. higher fuel temp too.

    The other thing I've notice in my logs on my Tdi is that engine oil temps also depend on coolant temp, but I've never seen higher oil temps compared to coolant temps .. except on the cool down cycle. I expect oil has a longer latency between temp changes, so I'd expect to see coolant drop quicker than oil temps.
    But your logs show that oil temp seems to exceed coolant temps regularly. Maybe due to the TDV8 being a higher stressed design ie. higher specific output .. really don't know nothing about them.

    I've seen my Tdi engine oil max out in the high 90's, but then the coolant was over 110 C by comparison. Point being oil temp is almost always lower than coolant.

    FWIW: the trucks at work both Scania and MAN their oil temps are almost always in the 100's too. No info re coolant temps other than unmarked or rough estimate gauges. Oil temp via dash readout is usually 100 or more. loaded or unloaded.
    So thinking that modern engines are designed to hold higher oil temps, hence the need for more modern oil specs, and how many modern engines specify sythnetics as standard.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  7. #7
    Join Date
    Jan 1970
    Location
    NSW SW Slopes
    Posts
    11,475
    Total Downloaded
    0
    The 3.6 has a thermostat arrangement that only sends coolant through the radiator as needed to keep the coolant within the desired temperature range.

    When the thermostat was replaced, what if anything was done with the EGR coolant thermostat in the same housing? If it has been removed or is sticking or broken then the cooling system won't operate properly.
    Attached Files Attached Files
    MY12 RRV 4.4 TDV8 AB, +LLAMS, +e-diff, +ACC stop/go. Produce LLAMS for LR/RR, Jeep GC/Dodge Ram
    VK2HFG and APRS W1 digi

  8. #8
    Join Date
    May 2003
    Location
    On The Road
    Posts
    29,829
    Total Downloaded
    0
    Quote Originally Posted by Graeme View Post
    The 3.6 has a thermostat arrangement that only sends coolant through the radiator as needed to keep the coolant within the desired temperature range.
    This is the famous (infamous?) LR blending technique,, AFAIK all modern LR's use this.. unless tampered with.







    I wouldnt be comfortable with coolant temps over a 100 for any duration, yes maybe its a diesel and yes, maybe its newer and maybe , well maybe a lot of other excuses,, but 110 is still 110,, and that 110 heats up everything else,, and makes everything work harder, all the fluids, all the coolers, all the underbonnet components cop it.
    "How long since you've visited The Good Oil?"

    '93 V8 Rossi
    '97 to '07. sold.
    '01 V8 D2
    '06 to 10. written off.
    '03 4.6 V8 HSE D2a with Tornado ECM
    '10 to '21
    '16.5 RRS SDV8
    '21 to Infinity and Beyond!


    1988 Isuzu Bus. V10 15L NA Diesel
    Home is where you park it..

    [IMG][/IMG]

  9. #9
    Join Date
    Jan 1970
    Location
    NSW far north coast
    Posts
    17,279
    Total Downloaded
    0
    Quote Originally Posted by AK83 View Post

    FWIW: the trucks at work both Scania and MAN their oil temps are almost always in the 100's too. No info re coolant temps other than unmarked or rough estimate gauges. Oil temp via dash readout is usually 100 or more. loaded or unloaded.
    So thinking that modern engines are designed to hold higher oil temps, hence the need for more modern oil specs, and how many modern engines specify sythnetics as standard.
    This ^

    Way back when I was buggering around playing with oils on the dyno a good mate had done the same a few years before.
    Back then (80's) the race oils of choice were BP Corse or Castrol R.
    BP Corse was a highly additised, full mineral oil.
    Mark is a very good, switched on engineer (ex JRA, now works for a major truck manufacturer) and he found Corse 30 (an SAE30 oil, ie not a multigrade, so no viscosity index improves) fell over above 105°.
    Bellow that it was viscosity stable.

    I destroyed one engine with total coolant loss when using an ester based syn.
    One piston melted from detonation, all the lead in the bearings melted out, the rods were blue, the web's in the cast iron block cracked, but the engine still ran, the crank rotated, there was only a partial seizure when the piston melted!
    I don't think it would've survived those three laps of Eastern Ck with no coolant and a straight mineral oil. How warm is too warm. How cool is too cool?

  10. #10
    Join Date
    Mar 2008
    Location
    Kilmore, VIC
    Posts
    848
    Total Downloaded
    0
    Hmmmm, some good info above. I tried to get a look at where the changes have been made under the intake but it's near impossible to see anything in there, even with mirrors and a torch. I'll have to ask the Indy for details. I've printed off some good schematics and pictures of the circuits and I'll get him to walk me through what was changed and how. From there I can then start to work out what to do to fix it.

    I came across this in the workshop manual...
    The ECM monitors the fuel temperature constantly. If the fuel temperature exceeds 85°Celsius (185°F), the ECM invokes an
    engine 'derate' strategy. This reduces the amount of fuel delivered to the injectors in order to allow the fuel to cool. When this
    occurs, the driver may notice a loss of performance.

    If you refer to my towing trace you'll see for that hour and a half of data logging the fuel temps sat nearly always above 85 deg C and regularly went up above 100-110 deg. So there must have been some significant derating going on, you'd think. I didn't notice anything at the time but having a combined weight over 5t does tend to dampen the enthusiasm of the engine slightly anyway. I thought that the fuel cooler circuit was stand-alone and used its own air-fluid cooler in front of the radiator pack and its own thermostat and temp control. So why would the fuel be running so hot? Or am I missing something?
    DiscoClax
    '94 D1 3dr Aegean Blue - 300ci stroker RV8, 4HP24 & Compushift, usual bar-work, various APT gear, 235/85 M/Ts, 3deg arms, Detroit lockers, $$$$, etc.
    '08 RRS TDV8 Rimini Red - 285/60R18 Falken AT3Ws, Rock slider-steps, APT full under-protection, Mitch Hitch, Tradesman rack, Traxide DBS, Gap IID

Page 1 of 2 12 LastLast

Tags for this Thread

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Search AULRO.com ONLY!
Search All the Web!