RX1999 129Kmiles
Pump and Timing Belt last replaced (10/2006 at 40K) - by first owner shows on sticker and online Lexus Record

Notice steam comes out of the hood. Outside temp is 39F, with my AC set at 74F.
No engine warning light, engine temp looks normal from the panel. Steam comes on and off.

Back home and start inspection, coolant reservoir is empty.
passenger side,
- Upper Coolant Hose is dry. End to end
- Coolant Reservoir hose is dry. ENd to End
driver side,
- see the wet area as in the photo (radiator). also that pipe on the right side, A/C ?
- removing the under engine cover - cover is wet - driver side.
- Lower COolant hose is dry.

Fuse box, swap FAN1 and Fan2 (tan color) relay. Where is Fan#3 (I see the relay, but which fan ?)
start the engine, and I turn ON the heater to max.
Radiator fan turns ON for a while, after a few moments it turns OFF, then after a while ON again, then OFF.... Maybe the temp outside is very cold, not enough to make it steady ON. I could not see the steam or the leak.

I notice by this time the reservoir automatically fill to low side marker (from the empty)

I'll continue tomorrow as it is getting dark outside. Wipe and dry-off tomorrow.

Any advice based on the location of the wet area where I should look at ? thanks.

-Mike

 

top off radiator and reservour. with radiator cap off and preferably with a coolant bucket on it. turn car on and let engine get to operating temp and burp the coolant system. then pressure test coolant system and inspect for leaks.

 

Last time I loaned a tool from AutoZone, I was unable to connect it to my SC. The adapters would let me test the radiator cap but I could not hook it to the radiator.

To test a leak I would fill with tap water or distilled water and I think you need not run the engine. The thermostat has a pass through hole so you do not get the the flow, but the pressure get distributed.

Typical place the radiator leaks (assuming no projectile punctured the mesh) is the top and bottom. Lexus/Toyota uses plastic shell. That develops a crack and if you raise the radiator up about 3" you can see the hidden portion. Physical deformity is a dead give away.

Please do not exceed the pressure marked on the radiator cap during test. Although it is recommended to replace the hoses at about 10yrs, I have not bothered to replace them or the clamps.

Salim

 

Thanks Salim and kornpeef. I will try to borrow tomorrow at AdvancaAutoparts or Autozone.

I forgot to mention that upon driving the car, I smell bad from inside the car for couple minutes...
I google it, and some mention about the heater core.

I'll start with pressure test tomorrow.

Thanks,
-Mike

 

When did smell after you turn the heater on? If so heater core.

 

The photos kind of indicate leakage from radiator. Look on Rock Auto.com for a great price on replacement.

 

bad smell might be heater core. do you have any wet spots on the carpet under the dash.

 

+1, that's what i'm thinking too.

But, that doesn't mean the heater core isn't also leaking...although there's no evidence of that here.

 

update,

Inspect before I started, looking from the top of radiator down, there is a coolant leak just on top of the lower radiator tank cowl (only on the driver side).

Borrowed Pressure test coolant system from AutoZone. It is Motorad, none of the adapter works for my RX (radiator cap diameter is 14mm) so I drove to Advance AUto which they lend my the Power Build wherein #8 adaptor works fine. WIth engine Off, I pump ~12.8psi (88Kpa per my cap). Inspect radiator area, nothing that drastically flash out... I could not see the source of leakage.

Inside, I remove the glovebox, floor carpet is dry. the pipe near the air mix servo is dry. I do not go further inside as I do not know which is the Heater Core.

Pressure holds at about ~12.

Place the radiator cap cover, and start the engine. steam is observed on the radiator drive side... continue it until the engine temp is middle. steam.

Looking on the manual, removing the radiator requires to remove the condenser...
Also requires to discharge the refrigerant, I could not see the step to discharge the refrigerant... how to discharge the refrigerant ?

Can I try first the Bars leak ? until the radiator arrives

Thanks,
Mike

 

. how long did you let the pressure tester sit for? pump it up and let it sit for 10-15 min and see if it drops. double check that radiator cap and see if the gasket is in tact.

 

I sit it there for an hour. I was inspecting leak from top, and bottom. Then I go inside removing the glovebox.to inspect the carpet, It just drop barely to 12psi.

I decided to use the RX with NO A/C Heater going to autozone and advance auto to return the pressure test system using the RX. Is it about 20 miles. I open the hood again, looking from top down to radiator lower tank side. It is dry, I know it not dry (maybe 20ml coolant leak in there) before I leave. Weird.

I will check the radiator cap gasket.

I will not use the A/C Heater tonight going to the mall. And turn the A/C Heater tomorrow, to make further observation.

THanks-Mike

 

i would not use the Bars leak, unless an absolute emergency and that you have no alternative transportation. Any of those temporary band-aids often cause clogs elsewhere.

If you still have the pressure tester, you can also add in some UV dye to help track the leak.
Hopefully your problem is as simple as a bad rad cap that isn't holding pressure.

 

My 99 RX300 has a slow leak at something called a 'water seal plate'. It is in a miserable spot in the engine.
I haven't gotten around to fixing it yet. Just add coolant occasionally.

 

I believe if you are ingenious you should be able to sneek radiator past condenser, I just changed my radiator on the RX400h and it could be done without removing the condenser. You had to raise the condenser up about two inches to get to the bottom screws on the radiator. Had to remove front latch point from infront of condenser. Find some documentation for the old RX300 and see what they say, the Haynes manual may have the procedure. edit: just found my Haynes book says on the old RX300 you have to remove condenser....sorry....

 

If you take the radiator out, you will gain access for the plate

Service manual states that the condenser has to removed too. Buy o-rings
Salim