Lwerewolf

gs450h - normal inverter "2" temperature range?

Recommended Posts

Hello,

I was driving with hybridassistant on as of late to keep an eye on the engine temperature (had a suspect tiny headgasket leak, so far according to pressure testing & watching the cleaned "dip" area with a boroscope + a few days of generally stupidly hard accelerations & harsh driving... nothing to worry about - spilled coolant dip in the valley during inverter bleeding in the past), and I noticed that the "inv. 2" temperature sensor (which I'm guessing is the IGBTs for MG2) was hitting 140c+ on sustained "hard" (100kw+) accelerations.

First thought - air lock in the inverter cooling loop, so I bled it according to the service instructions (and tinkered a bit with a vacuum pump). The radiator appears to be fine, the inverter pump works (turbulence + it pumps through hoses attached to the bleed ports), the electric fans both turn on. The current daytime outside temperatures are ~32 celsius, so that might be something.

At any rate, went testing today, and the inverter generally stays below 90 except when accelerating hard at low speeds in second gear, until MG2 comes to revs. 0-140kph doesn't see temps higher than 90 or so (if they ever peak that high, usually they float around 78 during acceleration), 65-140kph can see up to 134 (probably momentarily higher due to OBD2 readout periods), generally only on an uphill and generally only in the range of, say... 65-100kph. Night time testing with 15deg. ambient leads to a max of 110 or so, same highway, same conditions. Steady 150kph (GPS speed) cruise = inv. 1 temperatures ~90, inv. 2 sub-60, even on uphills, so I'm not really worried about normal day-to-day driving conditions.

Now the bleeding did improve things, but I still find a 134+ celsius worst-case (full throtttle, high gear & low revs mg2, uphill slope) to be worrying.

One last note - it's a LHD car, so the inverter cooling loop is slightly different due to the relocated inverter - there's an additional bleed port right next to it. I'm starting to wonder if that's why I mostly read about LHD cars blowing inverters >_<

At any rate, does anybody have an idea if the temperatures that I'm looking at are ok?

Cheers!

Share this post


Link to post
Share on other sites

Hi,

From the data of the engine active test, the coolant temperature range is between -40C and 140C. Normal range is between 80C and 105C after warm up.

A note about the temperature sensor states that if the displayed temperature is 140C, then the sensor is short circuited. If it displays -40C, then it is open circuited. It may be worth checking the sensor although from your description it seems to be ok. Sometimes a short circuit occurs at higher temperatures than normal. 

Another point to consider which is critical, is the radiator cap, and if it opens at a lower than specified pressure, this leads to coolant boiling at a lower temperature. If this happens, then the rate of heat rejected through the radiator is reduced proportionally. Hence a rise in the coolant temperature.

I would suggest that you check the inverter cap and make sure it is within specifications. [ Range : 15 Kpa to 44Kpa ] Minimum 12 Kpa. If it opens at a lower pressure, replace the radiator cap. Check that its vacuum valve is not stuck and free to move.

Also make certain that everything is clean a free from any rust deposits. The coolant should changed initially at 100, 000 miles or 10 years of life whichever comes first.

I hope the foregoing will be of help to you. 

Chris.

 

Share this post


Link to post
Share on other sites

Coolant replacement is at 100,000 miles irrespective of time, please accept my apologies for my mistake.

Make sure that you have no leaks at all because this would reduce the system operating pressure and this in turn would lower the boiling point of the coolant. Once the coolant boils within the system, more coolant will be released from the radiator cap leading to less mass of coolant which in turn raises its temperature causing further boiling. At standard atmospheric pressure pure water boils at 100C.

Chris.

Share this post


Link to post
Share on other sites

Hi Chris,

Coolant temps >65c. for the inverter don't appear to be considered normal, at least according to everything that I've read. The inverter temperatures spike, but they are measured at the IGBTs, and electronics can put out ridiculous amounts of heat in a short time frame 🙂

No leaks found while presure testing. The cap appears to hold pressure, having attached a vacuum/pressure pump to the inverter-side bleed port I can force the cap to hold ~0.3 bar and it also draws fluid from the expansion tank without holding vacuum... on the other hand, I'm wondering if it might be drawing air from the expansion tank line - it's quite a long line, and given that the inverter coolant doesn't get hot at all... maybe it doesn't expand enough to "bleed" that line. I've been attaching it with the expansion tank high above in the air, I should've pushed fluid to the expansion tank by attaching the pressure pump to the inverter bleed port and forcing coolant through it.

I'm waiting for a replacement cap to arrive regardless - preventative maintenance can't hurt, and it's probably the original one 🙂

Coolant is pretty much fresh - I did blow an inverter about a year ago when I got the car... let's say that some maintenance hadn't been done properly and I wasn't quite aware of it at the time.

At any rate, tested today again and... 27deg. ambient, high gear, 65KPH acceleration - inv temp 2 goes to 125 almost immediately and then stays there until about 110kph or so. Uphill or level doesn't matter. Low gear acceleration in the same speed range doesn't see inverter temperatures higher than 100, and only for a split second - usually it peaks to 90 for one reading (1/4sec refresh intervals or so) and then holds 75 to 80. I'm not surprised that the temperatures are higher in the "high gear" scenario, but I'm wondering if they are supposed to go that high (hitting thermal throttling) on a properly functioning cooling system (and other components, of course).

Share this post


Link to post
Share on other sites

Hi,

I agree, inverters do generate a lot of heat instantly and the coolant should be able to absorb it.

Upon further reflection, may be the coolant is not circulating fast enough to remove the heat from the inverters. At the same time, the engine and the inverters share the same cooling system, and if the engine has developed gas blow by from the combustion chambers due to piston wear, this would contribute to more heat added to the coolant.  Gas blow by is more intense under hard and severe acceleration. You can check this by removing the engine oil filler cap momentarily and see if there are any gases coming out. Engine oil consumption is another indication. Beware of oil coming out usually from a nearby camshaft.  However, this heat  from gas blow by should not cause an immediate coolant temperature rise as that due to inverter heat generation.

Whenever the cooling system is opened for any repairs, replacements, you must make sure the heater is fully on and bleed the air from the heater radiator by squeezing the flow hose into the heater radiator while the engine is running, with the engine thermostat open and the radiator cap off. As you squeeze the hose the coolant level in the radiator should fluctuate. keep doing so until the coolant level changes to the slightest squeeze on the heater hose.  Any trapped air in the heater radiator will compromise the coolant flow and this will hinder efficient coolant flow.

Another point to consider is the water pump impeller being worn out, a very remote possibility but I have seen some cases totally unbelievable.

As long as the expansion tank has coolant in it,  any air in the tube from the radiator to it should bleed out. The volume of the coolant when it expands is more than the internal volume of the tube from the radiator to the expansion tank.

Check the water temperature sensor by immersing it in water and reading its resistance.

At 20C, the resistance between its terminals should be 2.32 to 2.59 K Ohms.

At 80C "         "                  "                "                  "         310 to 326      Ohms.

Replace the sensor if the readings are not within specified range.

Chris.

 

 

 

Share this post


Link to post
Share on other sites

They don't share the same cooling system - the expansion tank is the same on the 3GS, but the pressurized part (i.e. the actual cooling loop) isn't... Getting combustion gasses from the engine in the inverter coolant loop is highly unlikely.

Engine-wise - no oil consumption, no antifreeze consumption, can't hit 100deg. on the engine (OBD2 monitor) to save my life - 95c at 60kph on a 7km long uphill requiring 50kw to maintain speed, that was from yesterday, highway accelerations to stupid speeds can't get more than that either... it doesn't really see coolant temps higher than 87 in daily driving scenarios.

Share this post


Link to post
Share on other sites

I have been doing some research on the Internet about Inverter applications for cars. Researchgate.net and Freescale have  some papers on high temperature electronics, such as Insulated Gate BipolarTransistor  [ IGBT ] modules for electric and hybrid vehicles. 

As far as I could make, IGBT are used in conjunction with other semiconductors and the operating temperature limit of their circuits is 150C mainly due to solder considerations. Research is going on to improve the operating temperatures.

Share this post


Link to post
Share on other sites

Well, here's some food for thought...

The following applies for the 3rd gen GS, 4th gen hybrids use 3.266 diffs across the board.

JDM & USDM gs450h's have a 3.769 final drive diff - the exact same unit that the GS350 (& Mark X 133).

EUDM (& General) gs450h's have a 3.266 final drive diff, the exact same unit that the IS220D uses.

This explains the shift point & shift speed discrepancies that I've noticed in acceleration & track day videos, and since the rest of the drivetrain is the same (engine, transmission, driveshaft, inverter)... it might just be a simple case of the EU version being overgeared for full throttle below certain speeds.

I'm looking into diff options, it'll probably be a gs350 diff with an eventual LSD upgrade.

Share this post


Link to post
Share on other sites

The GS450H has a LSD as standard equipment. This I would think would be a direct fit to the GS350 diff.

John.

Share this post


Link to post
Share on other sites
2 hours ago, Britprius said:

The GS450H has a LSD as standard equipment. This I would think would be a direct fit to the GS350 diff.

John.

Where are you getting this information from?

These are the torsen cassettes:

IS-F: https://www.toyodiy.com/parts/xref?s=41301-53050&mE=on

IS-F, RC-F, GS-F, ls460 f-sport, gs200t f-sport: https://www.toyodiy.com/parts/xref?s=41301-53051&mE=on

gt86 & 1st gen IS: https://www.toyodiy.com/parts/xref?s=41301-53020 &mE=on

 

And now the gs450h cassette:

https://www.toyodiy.com/parts/xref?s=41301-50030&mE=on

https://www.toyodiy.com/parts/xref?s=41301-50031&mE=on

Inside view (from a uzs190 gs430, same cassette as shown on toyodiy):

https://www.drive2.com/l/533520976021815931/ - the thing being given a certain rude hand gesture, halfway through the article 😄

50031 seems to be a revision of the same basic part, looked up images of it just in case... same open diff.

At any rate, the gs430 diff does seem to fit (not my car & not my video):

 

Share this post


Link to post
Share on other sites

The 3gen UK GS450H definitely has a LSD as standard equipment.

John.

Share this post


Link to post
Share on other sites
On 10/19/2019 at 8:53 PM, Britprius said:

The 3gen UK GS450H definitely has a LSD as standard equipment.

John.

https://www.lexusy.pl/LS430/ncf/ncf260e/m_02_0061.pdf

https://st.club-lexus(blocked word)/files/m_dr_0006_142634.pdf

Most likely something like this. If it was a clutch pack or a helical, we would've known for sure 😉

At any rate, found out about these guys:

https://www.facebook.com/valracing1/

I've seen several mentions of them doing custom diffs according to measurements, so that's an option for now... unless I find a leftover quaife (discontinued years ago) or decide to go for a clutch pack (probably a death wish on a daily for icy mountain roads, even if it's 1-way... not that a torsen isn't dangerous).

On a sidenote, talk about derailing the topic... sorry 😕

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Club Hybrid Poll

  • 292 Hybrid Reliability

    1. 1. If you were to consider buying a Hybrid model over 5 years old, would you be worried about the reliability of the Hybrid system?


      • Not really as Hybrid systems are always reliable
      • Not if it had a Manufacturers Warranty on the Hybrid system
      • I would not buy a Hybrid model over 5 years old