overheating/radiator mystery problem

[Chucks]

first of all this forum is a life saver, its helped me on more than one occassion!

i own a 90 lexus es250 w/ a jmd engine, swapped approx 1.5 years ago i believe.

anyways a while back i noticed while driving that my temp. gauge was just a little bit higher than normal so when i got home i let the engine cool down before checking the radiator. when i did the reservoir tank was empty and the radiator was not full and of course i refilled both with radiator fluid/water.

i checked my oil level as well just to make sure my engine wasn't running dry causing the temp to rise and it was perfectly fine.

so i've been keeping an eye on it these past couple days each time after driving the reservoir tank gets just a little lower and/or the radiator fluid level gets just a little bit lower to where i the fluid isn't visible when you take the cap off.

there are NO apparent/obvious radiator/hose leaks or cracks. theres never a pool of fluid underneath my car. since i religiously check my radiator/reservoir and keep them filled my running temp. is normal but i really don't plan on doing this for the entire life of the car. i would GREATLY appreciate any insight/advice/info/etc. on this problem. thanks in advance.

[Dave's]

You could put white paper or newspaper under the whole engine compartment and let it run for a while (maybe rev it a bit now and then) and check for leaks. You could have it pressure tested. If nothing obvious then you probably have a bad head gasket. This can allow coolant to mix with oil or go out the exhaust. If in the oil it turns milky and out the exhaust you should see somewhat white 'smoke'. Maybe only when revving at first. (Some white smoke when first started is normal.) Good luck.

[Kingdom934]

Another sign of a BHG is a milky/milk shake color under the oil cap.

Sounds odd for it to be getting low.

[fredk]

does it skip when you start it up from an overnite sit?

[monito]

check ALL the cooling lines. I too have coolant leak, and for me, it's coming from one of the 2 hoses that connects the EGR and the throttle body.

Also, look for hairline cracks on the radiator

[Dave's]

Oh yeah, check your carpet. Could be your heater core.

[Chucks]

wow, thank you for all the responses it is genuinely appreciated.

to answer each thing at a time, no it does not skip or stall on the start

i will try the newspaper trick to see if anything comes up that i may have missed.

is there anyway i can check for "milky" oil without actually having to drain the oil? i will defintiely look on the oil cap to see but as for something a little more in depth any suggestions?

i will re-check the hoses just to be thorough

lastly, i have no idea what the heater core is

[Dave's]

Just pulling the dipstick will usually show oil that is not normal. Usually appears to have somewhat "milky" droplets. (Try mixing a little oil with a few drops of coolant sometime.)

Heater core: Can't speak for every vehicle out there but typically there should be two hoses running to the passenger side firewall. Inside, behind and/or below the glovebox is a plastic box, (plenum) which contains a small radiator (heater core). When vent controls are set to heat the air flows past, or thru, this core and heats the air being blown into the compartment. Some vehicles have a valve in the supply hose which cuts off flow when heat is not required but unless it cuts off both lines the system is under pressure and if there's a leak.... Anyway, if the heater core develops a leak you usually find your carpet wet. Try pressing white paper towels hard into the front carpet. Shouldn't pick up any moisture. If coolant-colored, suspect heater core, otherwise it may be an A/C drain tube problem. Another tip of a leaking heater core is a film on windshield when blowing air on it with defrost. Hope this helps.

[white90dx]

Try replacing the radiator cap too. I know it sounds stupid, but that could be causing this too... If the coolant boils to easily, it can steam out without you really noticing as you drive down the road. This has happened to my Camry before.

-Charlie

[Chucks]

so i know i've said this before but let me say thank you again for all the responses, it is appreciated greatly!!

so i think i found the source of my problem, after careful inspection i found a very fine hairline crack on top of my radiator. this would explain fluid loss and overheating of course. so rather than try to weld or seal i'm just going to replace it with a new one as well as new hoses and a new cap just for the hell of it.

my question is i'm hoping that the radiator crack is the SOURCE of my problem and not a part of a bigger puzzle. looking at my oil and oil cap i didn't notice any milky/soapy appearance nor did i notice any radiator fluid present in the oil, so i would hope to negate the potential risk of a faulty head gasket. if anyone has any opinions/advice/etc. i would of course appreciate it!

[white90dx]

Originally Posted by Chucks

so i know i've said this before but let me say thank you again for all the responses, it is appreciated greatly!!

so i think i found the source of my problem, after careful inspection i found a very fine hairline crack on top of my radiator. this would explain fluid loss and overheating of course. so rather than try to weld or seal i'm just going to replace it with a new one as well as new hoses and a new cap just for the hell of it.

my question is i'm hoping that the radiator crack is the SOURCE of my problem and not a part of a bigger puzzle. looking at my oil and oil cap i didn't notice any milky/soapy appearance nor did i notice any radiator fluid present in the oil, so i would hope to negate the potential risk of a faulty head gasket. if anyone has any opinions/advice/etc. i would of course appreciate it!

Cracks in the plastic end tanks of the radiator are normal for old cars. Unless it was catastrophic, it is not a sign of any deeper problems.

Watch for excessive bubbles in the coolant while "burping" the cooling system after replacing the radiator, just in case.

-Charlie

[Kep]

You can find all metal radiators on the market. I am not fond of the plastic capped ones. I suggest that you get an all metal one. Remember the automatic transmission fluid lines to the bottom and have a supply of fluid to replace any that you loose (probably less than a cup or two).

Kep

[Chucks]

you guys are right there with me definitely going w/ the all metal radiator. thanks for the heads up on the tranny fluid lines and thanks again to everyone who left a comment it is always appreciated! thanks, let you know how things go or if any other further questions come up