Peculiar high engine temp scenario...98 LX470 (2 Viewers)

[abuck99]

For replacement foam, I installed this closed cell neoprene (Chloroprene) foam strip. Oil & coolant resistant, rated to -50C (-58F) to +150C (300F) Holding up well for 30 mo so far.
Amazon product ASIN B07H5DDWCL

 

[Leandro]

I put one of these to replace the foam when replaced the radiator

https://www.lowes.com/pd/Frost-King-17-ft-x-3-8-in-Grey-Vinyl-Foam-Window-Weatherstrip/3223867

Can't remember the size. It has sort of memory foam texture, it seals great.

 

[Eyo]

Hello all, I’m new here and a proud owner of a 1999 LC100. For the past 2 years during the summer I experience the same temperature increase with speed that as been described by Geanes. So fare I couldn’t find the problem. When ambient is over 105F and I drive over 60Mph as the speed increasing so as the water temperature. At 75Mph it reaches 205F and if I try to go faster it will go higher. Read out from OBD2.
In this thread I didn’t see if Geanes have found the solution, or anyone else…? I have no check engine, everything always looked after and changed in time or ahead of time. Fans working. The radiator is aftermarket though. But to change it to OEM is really costly, so with monitoring and controlling I can handle the situation, but it would be better if I could drive without gluing my eyes on the OBD2 temp. The gauge in the dash is steady, below half as normal.

 

[2001LC]

Hello all, I’m new here and a proud owner of a 1999 LC100. For the past 2 years during the summer I experience the same temperature increase with speed that as been described by Geanes. So fare I couldn’t find the problem. When ambient is over 105F and I drive over 60Mph as the speed increasing so as the water temperature. At 75Mph it reaches 205F and if I try to go faster it will go higher. Read out from OBD2.
In this thread I didn’t see if Geanes have found the solution, or anyone else…? I have no check engine, everything always looked after and changed in time or ahead of time. Fans working. The radiator is aftermarket though. But to change it to OEM is really costly, so with monitoring and controlling I can handle the situation, but it would be better if I could drive without gluing my eyes on the OBD2 temp. The gauge in the dash is steady, below half as normal.

List what you have done to make sure all of coolant system is to factory spec!

 

[nissanh]

List what you have done to make sure all of coolant system is to factory spec!

Use an IR thermometer: I did this check when outside temp is at 37C (with AC on) : Upper hose outlet located on the engine is at 94 C, lower hose inter at the thermostat housing 80 C. Do you see a difference as this much btween upper and lower?

Also, how old is your radiator, have you inspected it, both outside and inside the fins where water/coolant is channeled? I have Denso (not OEM) radiator. Check for any trapped bugs/grass/debris between the AC condenser and radiator. When I first got my LC (used), I was able to remove about 1/2 plastic/shopping bag full of stuff that was trapped between the two.

 

[Eyo]

All this temperature issue actually started when I replaced my leaky radiator to a new aftermarket one. I have used aftermarket radiators in other cars, like Nissan R50 without any issue, but still it could be the reason. The temperatures at the thermostat and the hose are around 60 and 75C, but these are temperatures when I already stopped obviously and by than my coolant read out temperature is also below 90C.
I bought a new temperature sensor, which I will replace soon and I will see if anything changes. But I'm also starting to give up on this and have to realize that the last thing to do is to install a known radiator or OEM
Thanks for the input!

 

[Fairgame]

Sounds like thermostat and start there,

 

[2001LC]

When I replace radiators. I also replace:

1. Radiator cap (Toyota)
2. Thermostat and Seal (Toyota)
3. Upper and lower radiator hoses (Toyota)
4. Heater Tees (if old) (Toyota)
5. Coolant. 98-03 LL "red" 100%, mixed 50/50 with distilled water. 04-up SLL (pink) premixed. (Toyota)
6. I also replace top and side foam. Many do not, but it does help direct air flow through radiator.

I also check:

1. Reservoir for proper operation. Hose must be straight and drop easily to the bottom. It's hoses and cap must be free of obstruction.
2. Fan clutch (fluid clutch) for proper operation. Which includes fan bracket operation.
3. All vacuum lines.
4. Air filter.
5. Fuel trims.

Additionally, what is missed by many shops, is proper topping of coolant. "We must get all air out of system":

1. First; the Toyota thermostat, most be installed correctly with jiggle valve at top. If not the coolant system will not bleed off air properly.
2. Second; we must check that coolant is to top of radiator, by removing cap after engine cools down for 8 hours. This needs to be done in the early morning before sun heats the air. It is best if vehicle sits overnight parked, with front end higher than rear. That wat, high point of coolant system is radiator cap. If coolant not all they to top, we fill and repeat after next 8 hour cool down.

 

[Eyo]

Thanks again for the input. All mentioned components are new and some are replaced twice already because of the doubt raised by the issue. Bleeding done as well with an attached funnel and checked several time.
I'm attaching some pictures of the read outs so you can see the temp relation to speed. All readings are pictured after at leas a 5 minutes constant driving at that speed to make sure of temperature accuracy.

 

[2001LC]

Thanks again for the input. All mentioned components are new and some are replaced twice already because of the doubt raised by the issue. Bleeding done as well with an attached funnel and checked several time.
I'm attaching some pictures of the read outs so you can see the temp relation to speed. All readings are pictured after at leas a 5 minutes constant driving at that speed to make sure of temperature accuracy.

View attachment 3454613

View attachment 3454614

View attachment 3454615

Why did you replace Radiator?

Since issue started with new aftermarket radiator, I'd start there and anything touch or replaced at that time. 98% chance it's not something else fail at same time. Exception, overheating do to coolant loss from cracked radiator. If this the case, and I knew all else "as it should be". I'd be looking at heads and head gaskets!

As for aftermarket radiator, it likely okay. But still; Whenever we use non OEM parts, we go down a rabbit hole. Obstructed or Restricted flow or rad cap release at too high a pressure, are first few things that come to mind.

Obstruction in coolant flow, are mostly from contaminates in system. Which can include plastic from busted heater tee or excessive FIPG used on water inlet. This can be hard to detect. They can also be from faulty (sticky) thermostat, reducing flow.

If coolant system all new OEM parts installed properly, coolant (Toy LL red mixed 50/50 w/D water or equivalent), no air in system and no obstruction in coolant system (in front of radiator, radiator fins clog, coolant flow passages within system). It then points to engine issues.

Fuel trims can give us clues:
Fuel mixture lean (to much air in mixture), which can be from vacuum leak or fuel starvation. Causes, cylinder head temp to increase.

I'd run logs of Fuel Trims (long and short both banks) while cruising on HWY at the various speeds/RPM, as you did above. I do this on level stretch of HWY, holding speed & RPM steady during during various ranges. It's when we're running engine with same "load", we're most interested in FT. We do not want to see, any change in throttle position or angle of road (load on engine), which will change FT. Typically I'll see about+3% LTFT (long term fuel trim). Which means engine currently running slightly lean, so ECM richen mixture to get baseline near 0%. LTFT is the new baseline EMC is setting to get STFT near 0%. If LTFT over 5% we start looking for why. Fuel trims gives us clues to a number of parts and systems.


Next look at head gasket.


You show U.A.E. as region you're driving in. Is this a stock (not built rig), USA configuration (EVAP, CATs, electric brake booster motor, LHD, etc..) or something different. Anything we should know to help you?

 

[Eyo]

I don't even want to think about head gasket But there would be indication of water level loss or water mix with oil and evaporation on the oil fill cap. However I was also thinking about the flow across the cooler if not due to contamination, but a poorly designed or manufactured aftermarket cooler issue. I have replaced the original as it started to leak slightly and red or pink discoloration started to show up on the cooler fins.