G430 Overheating

emcclariion · July 1, 2015

All,

I am pulling my hair out with this, I have had my GS430 for 3 years and it has a issue which I cannot resolve.

When the outside temp hits about 25c, I have over heating issues with the aircon on, I never let it go anywhere near the red, I just turn off the aircon.

I have drained the Radiator, burped it with the heating on so the cooling should be ok, but it still gets hot.

The fans kick in, but they seem to not go into turbo mode then just stick at one speed, I am sure this is fine as the GS430 doesn't not have different speeds.

One final point the aircon could do with a re-gas as it does take it time to cool and the aircon rad is missing loads of the vertical fins, so it is not perfect and the service area has reduced, but it should not cause overheat.

HELP!!!! the heat is killing me

Steve · July 1, 2015

I recon its either the fan is not enough or has a fault.

Maybe take it to a aircon specialist to see if it is that

CustomIce · July 1, 2015

Have you checked the thermostat? Might not be opening fully and could cause decreased circulation only noticeable when on "full load"

Worth a check.

Steve · July 1, 2015

Guy has a good point.

emcclariion · July 1, 2015

that was my next move, can you get them from any parts firm, they are not lexus only?

ColinBarber · July 1, 2015

euro car parts have a third party stat listed for £10.56.

ColinBarber · July 1, 2015

The fans kick in, but they seem to not go into turbo mode then just stick at one speed, I am sure this is fine as the GS430 doesn't not have different speeds.

The fans are dual speed. When the AC is engaged the fans will operate at a low speed. If the AC refrigerant pressure goes over a certain limit, or the coolant temperature goes over 90 deg, then the fans will operate at full speed.

You should disconnect the wiring to the coolant temperature switch on the back of the radiator to test the fans - they should operate at full speed.

emcclariion · July 2, 2015

Update:

As you know it was HOT yesterday, did not even bother with A/C as I know it would cause issues, anyway in traffic the car was ok fans keeping under 100C ODB11 reader, but as I moved off after 20mins in traffic I started to creep over 100c, I needed to do my normal lift and coast in neutral to control the temp, got home waited for it cool, checked coolant all good, gave it a burp no air, the rad is holding pressure.

So it can only 2 things, dodgy water pump, unlikely as the water is circulating, ok could have lost loads of fins, but once again unlikely, so it can only be the thermostat, I have ordered a new one, hope it gets here soon.

Mihanicos · July 5, 2015

Whenever you drain the coolant for any reason, you should bleed the system so no air is left in.

Some manufacturers have a drain plug and others do not.

Remove the radiator cap with the engine cold and check that the thermostat opens, the hose from the engine cylinder head to the radiator gets hot.

Rev the engine a little and you should see the water circulating. Indication that the water pump is ok.

Now, with the heating fully on and the radiator cap removed, you must find the heater hoses and squeeze the heater intake hose first and then the heater outlet hose.

As you squeeze, observe the water level in the radiator rise. with the heater fan on high, feel the air temperature coming out of the heater.

When really hot, the system has been bled and there is no air in the coolant.

Never mind about the water overflowing due to expansion as the temperature rises.

Hope this is the cause of your overheating.

Another reason that causes overheating are worn piston rings but with this engine is highly unlikely.

Always start from the inexpensive and simple causes and leave the expensive solutions last.

Good luck.

emcclariion · July 6, 2015

Hi thanks for the comments, another update.

Changed the thermostat, the old one was not in good shape, thought I had sorted it, it will now sit in park and you can run the aircon and it will be ok, before it would over heat with in 5 to 10mins when hot. but once I started to drive round town under load with little air, it started climbing again, but the climb was not as harsh, I thought I had some air in it, so spent a lot of time burping it, there was some air not much.

so I took the rad top clips of and parted the rad from the Aircon condenser, well we seemed to have a great deal of green stuff and as I looked closer it looked blocked, it seems the Aircon condenser has been breaking spilling all the little bits of Alloy in to the rad, I have cleaned a lot of it out, but it has damaged the fins, but on the plus point it did not overheat after that.

So I will need a new Rad, the problem is you cannot get GS430 one, I have heard a LS 400 one fits can anyone confirm???

Steve · July 6, 2015

have you considered having it refurbished? I had one done once and was an excellent job

emcclariion · July 6, 2015

I would, but my car is a daily, it would need to be off the road, there is a couple of second had ones on eBay and they look much better than mine, but would rather have a new one.

steve2006 · July 6, 2015

I would, but my car is a daily, it would need to be off the road, there is a couple of second had ones on Ebay and they look much better than mine, but would rather have a new one.

I have a good spare one off a late LS400, you are welcome to pop over to me and see if it would fit and take it FOC , send me a PM if interested.

emcclariion · July 7, 2015

Thanks Steve you are a good man, I have been searching and it seems the rad will fit, well the mounting points and main feeds, but it seems the LS400 does have a filler cap different and I am not sure how the reservoir will fit.

let me do some more research and I will get back to you.

Cougar · July 7, 2015

Not sure if this is relevant to your case but I've before that over heating would occur only when the A/C was on and it was down to the A/C condenser radiator being blocked. This caused the AC gas to heat up and not cool, the fans kicked in and blew hot air through the rad and not cooling the engine - the opposite of what it should do! Just a thought

emcclariion · July 8, 2015

Cougar, that was my first thoughts when I first started having the issue, but I would say with many of the fins missing there is less surface area, so it would get hotter, but with the vents there would be more hot air going into the rad.

Going to change my rad as I think the cooling system is under performing, the change of thermostat has helped a lot.

.

GS Taxi · November 23, 2015

Hiya mate. Did you ever manage to get a radiator for your GS430? I have a crack in the plastic header of mine and I have tried to get one for months.

I bit the bullet and got one from the US (very cheap) but when it arrived unfortunately it was identical in every way except for one small outlet was missing. The one that goes from the expansion tank to the radiator which connects with an L-shaped pipe. When I checked the US version of GS430 it seems that they have a different expansion tank to our UK counterparts.

I was considering trying to tap into the header using some sort of nozzle but it would have to be able to take the high pressure and I'm not certain how to do that.

Any joy yet?

Cheers,

Will.

emcclariion · November 23, 2015

Yes I got the Denzo rad with the same issue, just made a adapter which took the over flow into the top of the expansion tank....it been great not issues.

GS Taxi · November 23, 2015

Fantastic. Would you be good enough to take a picture of it when you get chance and post it here please?

I'd like to see how you've done it so I can get my motor back on the road. I've got another car so there's no rush at all mate. It would also be of great help to others because I'm sure (with these cars now being 15 years old or so) that radiator issues will start to surface soon. Mine has done well lasting 15 years to be honest!

Only if you get time.

Many thanks

Will.

emcclariion · November 23, 2015

Right there are two methods, but work is the same.

Yanks cars don't have a pressurised expansion tank, so you can just leave the expansion top pipe not connected its that simple, or like me I took the over flow pipe from the expansion tank cut a small section off and managed to find a pipe which was thick enough to fit the expansion top pipe and thin enough for the rad over flow pipe and just joined them, then removed the inner seal on the radiator cap so water would flow out of the rad overflow, but would still hold pressure.

don't worry about pressure, these radiators don't let the engine get any hotter the 82 degrees

GS Taxi · November 23, 2015

That's brilliant mate. I'll do that. Simple enough really.

Thanks for your help. I'm sure others will find this useful in time to come. :)

Will.

CustomIce · December 14, 2015

Out of interest (please correct me if i am wrong) but you mention after a while dropping to N and coasting. Now i thought it was a really bad thing to do to coast an auto? Thought it damaged the box somehow?

dave1 · December 16, 2015

Only way it could really damage box would be when you try putting it back into gear. Coasting in N is not a good idea at all anyway.

royoftherovers · December 16, 2015

Only way it could really damage box would be when you try putting it back into gear. Coasting in N is not a good idea at all anyway.

And I believe it to be contrary to the Highway Code! So do not do it.

Regards

John

emcclariion · December 17, 2015

Coasting in modern Auto Boxs is not a issue, as long as the engine is running and you are not thrashing the engine when you enable drive.

you need the engine running to make sure the gearbox has oil, modern boxes know what speed you are going and what you reves are using ie WOT, so they will engauge the correct gear, if you are reving the engine the engaugment will be harsh....which may cause problems with the drive train.

saying that I would not recomend doing it unless you have to, needing to cool the engine down.