Bad thermostat on LX470? (1 Viewer)

[jbyrd78]

In March of 2021, my OEM radiator took a dump. I ended up installing a new KOYO radiator, and OEM lower & upper radiator hoses/clamps, along with a new OEM thermostat in my 2004 LX470 that currently has around 236,200 miles on the ODO.
I have only put around 17,000 miles on the new radiator and I haven't had any issues until this last month when theweather started getting cold.
I have started noticing that when I start the car to warm it up that it leaks small amounts of coolant, until the vehicle has warmed up.
At first I thought the leak was at the upper hose right where it goes into the top of the radiator. Upon further inspection, the coolant is coming out the very top of the header/tank right where it meets the fins under where the upper hose goes into the radiator.
Like I mentioned, this only happens when the vehicle is cold, and then it stops once the system has warmed up. I have been monitoring my temperature thru my ODB II & Torque app and it is reading normal.
Is there any other troubleshooting that you guy's would recommend to find the actual issue or is this a classic case of a bad thermostat?

 

[Bisho]

In March of 2001, my OEM radiator took a dump. I ended up installing a new KOYO radiator, and OEM lower & upper radiator hoses/clamps, along with a new OEM thermostat in my 2004 LX470 that currently has around 236,200 miles on the ODO.
I have only put around 17,000 miles on the new radiator and I haven't had any issues until this last month when theweather started getting cold.
I have started noticing that when I start the car to warm it up that it leaks small amounts of coolant, until the vehicle has warmed up.
At first I thought the leak was at the upper hose right where it goes into the top of the radiator. Upon further inspection, the coolant is coming out the very top of the header/tank right where it meets the fins under where the upper hose goes into the radiator.
Like I mentioned, this only happens when the vehicle is cold, and then it stops once the system has warmed up. I have been monitoring my temperature thru my ODB II & Torque app and it is reading normal.
Is there any other troubleshooting that you guy's would recommend to find the actual issue or is this a classic case of a bad thermostat?

I'm not sure how your connecting a radiator leak to the thermostat. Sounds to me that you need a new radiator, unfortunately. It sounds like its leaking until it warms up and expands, closing the leak.

 

[vipergrhd]

^^^ I agree with him, get another radiator. Get a new Toyota cap.

 

[nissanh]

As a last resort, using a channel lock try compressing the aluminum tabs that keeps the upper tank and the core together.

I once took the upper tank completely off the radiator in my car, cleaned the surface, applied FIPG and sealed everything back again and drove about 7 years.

 

[2001LC]

If ECT normal, thermostat has little or nothing to do with leaky radiator. Especially if just leaking when engine cold, during warm up..

"Replaced w/KOYO in 2004"
So 20 years old If not typo, or 10 year if meant 2014. Still a bit aged at 10 year. Not stating year LC or LX470 manufactured, makes difficult to aid OP.

"At first I thought the leak was at the upper hose right where it goes into the top of the radiator. Upon further inspection, the coolant is coming out the very top of the header/tank right where it meets the fins under where the upper hose goes into the radiator"
I'll assume "header/tank". is where radiators plastic top, seals (mates) to aluminum body of radiator. The plastic top cracking, is number one leak point. But we can get leaks at the seal between plastic top or bottom and body of radiator. Typically cracking plastic, happens on old radiators. Radiator plastic ages fastest, and cracks. When not kept submerge in Toyota coolant at all times. So many, fail to properly check coolant level, under the radiator cap. They run low for years, by just watching reservoirs' level thinking okay. Also it's important to flush coolant evert 2 years. Old coolant is hard on coolant system in many ways. Still cools but damaging.

"have been monitoring my temperature thru my ODB II & Torque app and it is reading normal."
Failed to state what actually ECT he's reading thru OBD. Just called normal. If 98-02 w/condenser fan, that would be 184F to 187F.

Number reason plastic prematurely ages, in OEM (T-rad). Is:
1) air in coolant system
2) not flushing timely
3) ECT running hot.
Or Combination of above!
Top radiator while cold and pressurize to ~17 PSI. Watch for weeps, leak, drips.


note: A stuck radiator cap, can blow a radiators plastic and cause leaks everywhere, when ECT normal of running hot. Leaks gets worst when hot, rather than slows.

 

[Rhetoric]

The Koyo is the issue. At some point last winter on my 07, I believe after installing a new Toyota rad cap, my Koyo leaked at that same spot you mention. I haven’t seen it continue to leak, but it could in fact be a very slow weep. My ECT runs between 192 - 196F. With very rare moments of 198-202 even in 110F weather.

I have a T.Rad in the garage ready to go in this spring so I can rid myself of aftermarket junk.

 

[2001LC]

The Koyo is the issue. At some point last winter on my 07, I believe after installing a new Toyota rad cap, my Koyo leaked at that same spot you mention. I haven’t seen it continue to leak, but it could in fact be a very slow weep. My ECT runs between 192 - 196F. With very rare moments of 198-202 even in 110F weather.

I have a T.Rad in the garage ready to go in this spring so I can rid myself of aftermarket junk.

Although Koyo probably is an okay aftermarket radiator. OEM is best IMHO!

Your ECT looks good, normal for 07.

One of the issues I run into, doing anything that bring coolant system to spec pressure. Which replacing a weak cap with OEM spec, result in increase pressure. It brings out the weak points and we get leaks.

With new OEM rad, I always:
Wash radiators (oil cooler and condenser), clear/clean fins.
Flush including open & drain block drains. I also blow out system. I avoid flushing with water, unless I must. In the 04-up with use Toyota SLL (pink)
Replace cap (New Cap is included with OEM rad)
Replace thermostat & seal (OEM)
Replace upper & lower rad hoses. Which includes repairing and pitted aluminum goose necks.
Make sure reservoir clean, filled and its hose straight to bottom and hose & cap clear of obstruction.
Bleed air from system! By topping each morning before sunup, 8 hours after warmup with vehicle park front end high overnight. Repeating until no air under cap, is important

Thereafter periodically:
Monitor ECT.
Check level.
Wash all 3 radiators fins, keeping fins clear/clean as needed.
Inspect belt, tensioner, fan clutch and fan bracket.

 

[jbyrd78]

Guy's, thanks for your posts and advice. I started this thread Monday before I went out to run errands Well, I started feeling like total crap as Monday went on. Now I am down and sick, hence while I've been "non-existent." Hopefully I will be feeling better in the next couple of days and I'll reply back

 

[2001LC]

Guy's, thanks for your posts and advice. I started this thread Monday before I went out to run errands Well, I started feeling like total crap as Monday went on. Now I am down and sick, hence while I've been "non-existent." Hopefully I will be feeling better in the next couple of days and I'll reply back

Hope you feel better soon.
I see you correct typo. From 2001 to 2021 replaced rad. So only 3 years old.

 

[jbyrd78]

Hope you feel better soon.
I see you correct typo. From 2001 to 2021 replaced rad. So only 3 years old.

Thank you, much appreciated! The aches, pains, and sore throat are gone. Now I just need to ditch this cough.

Yeah that 2001 to 2021 was a typo error, that I caught when I read your first post. The radiator only made it 3yrs, and around 17,000 miles. Never had an issue until this leak started. Now she is in the garage until the weather warms up and I can finally working on her.

 

[jbyrd78]

I'm not sure how your connecting a radiator leak to the thermostat. Sounds to me that you need a new radiator, unfortunately. It sounds like its leaking until it warms up and expands, closing the leak.

I actually had that thought in my mind as well. I just kinda wanted someone else to say it before I accepted it. Thank you

^^^ I agree with him, get another radiator. Get a new Toyota cap.

I actually installed a new Toyota, when I replaced the radiator and hoses. Thanks for reminding me.

As a last resort, using a channel lock try compressing the aluminum tabs that keeps the upper tank and the core together.

I once took the upper tank completely off the radiator in my car, cleaned the surface, applied FIPG and sealed everything back again and drove about 7 years.

Do you by chance have a link to a video showing how to do this?

If ECT normal, thermostat has little or nothing to do with leaky radiator. Especially if just leaking when engine cold, during warm up..

"Replaced w/KOYO in 2004"
So 20 years old If not typo, or 10 year if meant 2014. Still a bit aged at 10 year. Not stating year LC or LX470 manufactured, makes difficult to aid OP.

"At first I thought the leak was at the upper hose right where it goes into the top of the radiator. Upon further inspection, the coolant is coming out the very top of the header/tank right where it meets the fins under where the upper hose goes into the radiator"
I'll assume "header/tank". is where radiators plastic top, seals (mates) to aluminum body of radiator. The plastic top cracking, is number one leak point. But we can get leaks at the seal between plastic top or bottom and body of radiator. Typically cracking plastic, happens on old radiators. Radiator plastic ages fastest, and cracks. When not kept submerge in Toyota coolant at all times. So many, fail to properly check coolant level, under the radiator cap. They run low for years, by just watching reservoirs' level thinking okay. Also it's important to flush coolant evert 2 years. Old coolant is hard on coolant system in many ways. Still cools but damaging.

"have been monitoring my temperature thru my ODB II & Torque app and it is reading normal."
Failed to state what actually ECT he's reading thru OBD. Just called normal. If 98-02 w/condenser fan, that would be 184F to 187F.

Number reason plastic prematurely ages, in OEM (T-rad). Is:
1) air in coolant system
2) not flushing timely
3) ECT running hot.
Or Combination of above!
Top radiator while cold and pressurize to ~17 PSI. Watch for weeps, leak, drips.


note: A stuck radiator cap, can blow a radiators plastic and cause leaks everywhere, when ECT normal of running hot. Leaks gets worst when hot, rather than slows.

I'll be the first to admit, I didn't use Mr T's fruit punch. I went the Prestone Asian Red route b/c they guaranteed it for 150,000 miles, and all the ingredients on the back matched Toyota red. You live and learn.

The Koyo is the issue. At some point last winter on my 07, I believe after installing a new Toyota rad cap, my Koyo leaked at that same spot you mention. I haven’t seen it continue to leak, but it could in fact be a very slow weep. My ECT runs between 192 - 196F. With very rare moments of 198-202 even in 110F weather.

I have a T.Rad in the garage ready to go in this spring so I can rid myself of aftermarket junk.

Sounds like it's a KOYO issue. I'm wondering if I should reach out to them see what happens.

Although Koyo probably is an okay aftermarket radiator. OEM is best IMHO!

So the OEM is still top notch? Just asking b/c when I was looking to replace the original OEM, the KOYO radiator was highly recommended.

 

[2001LC]

I've never had any issue with OEM (T-rad) radiator. They save labor as come with foam, fitment perfect and presumable built to Toyota standard.

 

[jbyrd78]

I've never had any issue with OEM (T-rad) radiator. They save labor as come with foam, fitment perfect and presumable built to Toyota standard.

Finally got around to ordering the parts in the screenshot from my local dealership which is Ed Martin Toyota in Noblesville, IN. I'm also going to pickup 5 gallons of Mr. T's 50/50 SLL Coolant : 00272-SLLC2.
Eric's crew in the parts shop have always treated me right when I buy parts from them, so it's all good.
Hopefully this OEM radiator shows up with the foam and radiator cap. I only say that b/c when I was pricing everything, Toyotapartsdeal was showing radiator caps and thermostats as out of stock. Luckily the current thermostat only has low mileage on it, so I'm not going to stress it.
The parts will be here tomorrow, so I'm hoping to bust this job out before I go back to work next Wednesday.

 

[2001LC]

T-rad (Toyota) come with all foam and a t-rad cap. But I find the t-rad caps fitment a bit loose. If any leakage accrues. Either pinch tabs, to tighten. Or replace with Toyota cap.

 

[jbyrd78]

T-rad (Toyota) come with all foam and a t-rad cap. But I find the t-rad caps fitment a bit loose. If any leakage accrues. Either pinch tabs, to tighten. Or replace with Toyota cap.

I currently have a Toyota cap on there right now. I bought it when I installed the KOYO radiator. Do you think it would be safe to use it, until I am available to find another brand new Toyota cap, or would it be a gamble?