Coolant Bubbling (boiling?) Through Reservoir

[whh333]

I have a 1993 SC300 with high mileage (140,000) and I am losing coolant, about a pint or less every 100 miles. Engine seems to run fine, no oil loss, smooth, gas mileage OK, comes up to operating temperature seemingly as it should, temperature stays normal and stable through hot and cold conditions. Radiator that came on car was leaking, so I purchased a new radiator through radiators.com. Radiator they sent has an additional sensor hole in base by the drain petcock that I had to plug with a pipe plug. Coolant is 50% Havoline extended life.

I have been trying to track down where coolant is being lost for weeks--no detectable coolant smell in exhaust, no leaks I can find anywhere. Coolant smell in engine bay when hood is opened. Finally discovered that there are bubbles coming from radiator to coolant reservoir. When I turn on cabin heater, they subside temporarily. Somehow, it seems coolant is boiling off.

Car allegedly had new timing belt and water pump replaced about 5,000 miles ago. I am not confident that the mechanic that did this was qualified.

I have an infrared thermometer and get readings of about 160F from fins on radiator. Measuring 210F in water bypass outlet in water pump area.

I bought a new radiator cap to rule this out and it had no effect. Also, I tried to get an 1993 SC400 cap but it would not fit.

Any ideas on how to diagnose would be appreciated.

I will post this same message on the general maintenance board.

Thanks!!!!!

Bill Harrison

[JPI]

Your vehicle is overheating. DON'T DRIVE IT ANYMORE. Call your mechanic and ask him how did he top off the coolant? On the V8 you will need to top the coolant on the thrrotle body. When there is an air pocket in the coolant it will destroy your engine. Where are you located?

JPI

[whh333]

I am in Lower Alabama, Fairhope, AL. I have an SC300 not a 400. I thought the instructions were to fill, run engine 5 minutes, then top off. I could be wrong, I do not have the instructions. I am not running the car, it is sitting until I solve this one, but how is this not showing up on the temperature gauge? The car had been badly misrepresented by the seller, but the temp gauge needle is always one needle width above the tick just below the halfway point on the gauge.

I will recheck the instructions--I have factory manuals.

Thanks for the help.

Bill Harrison

[mktbully]

if your temp needle is working properly and you do not see it going to the H or see steam come out then you're not over heating.

you probably have an air pocket some where and it's slowing purging the air out.

also do yourself a HUGE favor and get rid of that extended life crap...aka Dexcool. dexcool has been KNOWN to kill many GM cars and engines. also had a friend that used dexcool and he had to constantly refill the coolant because it would just dissappear. also in many of the GM cases the coolant system developed an air pocket and the dexcool sludged up.

just stay w/ prestone green coolant (yellow bottle). mix in 50% distilled water and change it once a yr or etc.

if you want to get fancy..toyota makes a pink coolant that's pretty good. i believe honda also has their blend of silca free coolant.

[SKperformance]

if your temp needle is working properly and you do not see it going to the H or see steam come out then you're not over heating.

you probably have an air pocket some where and it's slowing purging the air out.

also do yourself a HUGE favor and get rid of that extended life crap...aka Dexcool. dexcool has been KNOWN to kill many GM cars and engines. also had a friend that used dexcool and he had to constantly refill the coolant because it would just dissappear. also in many of the GM cases the coolant system developed an air pocket and the dexcool sludged up.

just stay w/ prestone green coolant (yellow bottle). mix in 50% distilled water and change it once a yr or etc.

if you want to get fancy..toyota makes a pink coolant that's pretty good. i believe honda also has their blend of silca free coolant.

that has to be the stupidest thing to say

since when are any of us toyota engineers

make your own decsion

you can listen to the guy who thinks he is an engineer but can't fix the missing leak

or the people who made the car

everybody is a critic

[AWJ]

SK - that is really inappropriate. I'm very disappointed in that statement.

mktbully is correct in his statements. Regardless of what the real problem is here. I doubt anyone can fix any problem with any thing over the internet. Unless they can hook up to the problem via the internet. This is an advice forum. You can agree, you can disagree, but show respect - what is stupid about anything that was said here?

[joedoc]

It seems to me that a slow coolant leak combined with bubbles in the coolant raises some concern about the head gasket. did you mention the appearance of the oil?

[SKperformance]

just stay w/ prestone green coolant :whistles:

[mktbully]

just stay w/ prestone green coolant :whistles:

well the prestone is just a personal favorite..use any brand you want...(notice i put in etc. in my statement).

but the dexcool is known to kill engines, that was my point. i can careless what coolant you run. i don't drive it you do.

besides that what is wrong w/ prestone? why not show me something i did wrong instead of calling names?

i don't disrespect you on here...i would assume you can do the same.

[whh333]

I appreciate any ideas I cannot get and take responsibility for whatever I agree or disagree with, so there is no bad input as far as I am concerned.

I will be emptying out the cooling system before this is over, so the green coolant will be going back in the system.

There is no oil in the water or water in the oil. I do not mind changing the head gasket myself, I am just not wanting to jump into it, take the head off, and have to say "Well it's not the head gasket!". Several years ago, I woke up after an appendectomy to hear the doctor say "Well, your appendix was totally normal when I removed it!"

Had a brain storm and did another test this morning. Opened the radiator cap, started the engine, and bubbles started in about a minute. For what it is worth, the bubbles are big blobby bubbles, not little ones, and they do not seem to have steam in them, just air. I guess if they traveled far enough, they could have started as steam and cooled down, but it would seem it they cooled down from steam bubbles, they would not be bubbles any more. Bubblology.

This weekend, I will pull the spark plugs and do a compression test. I am trying to find a radiator pressure tester, and will do this with the plugs still out in case I am getting leaks into any of the cylinders.

Many, many thanks for all the input.

Bill Harrison

[AWJ]

Good luck Bill. Feel free to empty the system for piece of mind; but I'm confident you will find it is a air lock towards the heater core. Try running it with the heater on full blast. Keep an eye on that temp gauge just to make sure you are not over heating. Top it off. You are losing coolant as the air is slowly displaced by the coolant. It isn't really going anywhere but where it is supposed to. If you do drain it, follow the procedure in the fsm. Run the car before draining with the heater full blast and shut the car off with the heater on full blast. Then drain it. Refill it in the same condition. Drive it around and make sure no overheat or leaks. Top off as needed. Most likely, no big deal.

I've had this happen on a couple of different vehicles. The car doesn't overheat, there is no leak, but the fluid is gone. Eventually, it will be topped. Don't pull the head. It's aiight. Bubblology. I like it.

[K9crew]

Any ideas on how to diagnose would be appreciated.

Bill,

You could purchase a cooling system leak detector kit. You add a special dye into the coolant and then use a black light to find the source of the leak. I have no idea how much those kits cost but you'd probably find the leak very quickly. I'm sure there are low and high end kits to suit most budgets. I know you mentioned replacing the radiator cap but have you considered having the cooling system pressure tested?

Good luck!

:)

[SKperformance]

a common problem of sc's is the heater control valve leaking at the firewall

it is intermittent and can let air in the system as well as a disapearing coolant problem

look for the old thread to see the pics of where to look and how to fix

the reason i mentioned that changing to green is bad is because it is not made for the car

it is not compatible with the seals hoses or other metals

more than just it seems ok so i will use it problem.

GM cars are crap i have one ,had one and worked for them

they have problems no matter what thanks to there great engineering

so don;t blame the dex-cool for an engine just being a lump of.....

using the wrong coolant can cause lots of problems the least of it being a new engine

[mktbully]

a common problem of sc's is the heater control valve leaking at the firewall

it is intermittent and can let air in the system as well as a disapearing coolant problem

look for the old thread to see the pics of where to look and how to fix

the reason i mentioned that changing to green is bad is because it is not made for the car

it is not compatible with the seals hoses or other metals

more than just it seems ok so i will use it problem.

GM cars are crap i have one ,had one and worked for them

they have problems no matter what thanks to there great engineering

so don;t blame the dex-cool for an engine just being a lump of.....

using the wrong coolant can cause lots of problems the least of it being a new engine

so what coolant is made for the car? because i did mention the toyota pink coolant in my post...is that it? or is there another coolant that i didn't mention?

so i guess everyone is wrong when they blame the coolant clumping up and causing sludge? how about the cars before they started using dexcool? they seem to be running ok.

[SKperformance]

dexcool is the coolant made for the engine the orange stuff

the pink stuff is prestones new global antifreeze compatible with either type and mix

find a lexus with coolant clumping and sludge in the coolant using dexcool

then make an assumption the coolant is bad

you won;t

and who is everyone?

and cars running the regular green where designed for it

i have the green in my civic it works great as are millions of other cars

and dex in my lex and gm

not a clump ever

when a lack of maintance or other problems come into play anything can happen especiallly if the coolant is contaminated with bad water or ther worng coolant

if dex was so bad you think toyota would still use it?

[whh333]

Some progress, I think!!!! Using suggestions from posts, I topped up system as much as possible, tried to burp air out of upper hose, crammed as much coolant into system as I could, then bypassed the heater control valve on the firewall by replacing it with a 90 degree copper pipe fitting.

Drove about 80 miles, which would have shown a drop of at least a few inches in the reservoir tank before, and there was no detectable loss of coolant!!!

I still had the bubbles in the reservoir tank, though.

Either the coolant has been working air out of the system and is about out, or the heater control valve was sucking coolant into the vacuum system and into the intake manifold. I had checked it for external leaks several times before, and could not find any.

The bubbles will need to be tracked down.

With luck, I will be able to get a radiator pressure tester in a few days, and I will have access to a vacuum tester tomorrow to check the vacuum circuit on the heater control valve.

Thanks for the new ideas, because I was stuck checking the same things repeatedly with no results. I am optomistic that the problem can be figured out with some more work.

Bill Harrison

[mktbully]

dexcool is the coolant made for the engine the orange stuff

the pink stuff is prestones new global antifreeze compatible with either type and mix

find a lexus with coolant clumping and sludge in the coolant using dexcool

then make an assumption the coolant is bad

you won;t

and who is everyone?

and cars running the regular green where designed for it

i have the green in my civic it works great as are millions of other cars

and dex in my lex and gm

not a clump ever

when a lack of maintance or other problems come into play anything can happen especiallly if the coolant is contaminated with bad water or ther worng coolant

if dex was so bad you think toyota would still use it?

right..dexcool is the orange stuff.

toyota makes their own coolant - red/pink in color...it's not called dexcool.

lexus and toyota use their red/pink toyota coolant....silica free/low silica. no clumping or sludge build up.

so you use the orange coolant in your lex?

lack of mainteance...i believe the GM dexcool is an extended drain coolant..no? people had problems of coolant around 30K...do a google search.

dexcool is not used in toyotas...they use their Toyota red/pink coolant...i don't think it's called dexcool.

i think you're getting the GM dexcool coolant and the toyota red/pink extended drain coolant mixed up.

what are you arguing over? all i said is not to use dexcool (orange coolant) in the cars (lex) because it's known to clump up in GM cars...do you want to RISK that in your car? i agree i made the mistake of mentioning prestone but i was just referring to the fact that the dexcool should be changed out. you want to argue against that? look on the internet on the number of complaints on dexcool coolant. are you going to say that all these GM cars have problems due to their poor GM design? what about all those GM cars that used green coolant before they changed...they still run fine..are you saying GM still made bad coolant systems back then?

[SKperformance]

your getting yourself lost in asking a question with a question

i buy the toyota coolant from a toyota parts desk,that and only that

the green you understand why

gm engineering is what it is

crappy at the best

take a drive in a new escalade

my firend has one it has more deficencies or manufacturing than i can belive

but i am now spoiled by toyota over engineering or what seems to be

like the infamous 95 and onward defective fuel sending units that gm blames all gas companies for fouling it and making there cars give the wrong readings

or the 10 plus recall issues that almost every car has

btw i am not arguing just stating points and trying to answer you questions

[AWJ]

Bill,

I think you've got it friend. If coolant was going into the vacuum - you'd be sucking it through the intake I believe. That would smoke like a mutha. I say, hook it all back up and keep an eye on level. Fill if/when it drops. Try to keep it at 50/50 mix though. As long as you don't overheat or smoke. No worries mate. Best of luck.

Toyota anit freeze fluid = very good

GM = maybe not so hot

I thought they were the same too at one point. Shame on me.

Can't we all just get along.

;)

Hey take it easy on GM and Caddie... people gotta buy those things. That's my meal ticket.

I say they're great cars. but i won't buy one

[TWINTURBO619]

I have a 1993 SC300 with high mileage (140,000) and I am losing coolant, about a pint or less every 100 miles. Engine seems to run fine, no oil loss, smooth, gas mileage OK, comes up to operating temperature seemingly as it should, temperature stays normal and stable through hot and cold conditions. Radiator that came on car was leaking, so I purchased a new radiator through radiators.com. Radiator they sent has an additional sensor hole in base by the drain petcock that I had to plug with a pipe plug. Coolant is 50% Havoline extended life.

I have been trying to track down where coolant is being lost for weeks--no detectable coolant smell in exhaust, no leaks I can find anywhere. Coolant smell in engine bay when hood is opened. Finally discovered that there are bubbles coming from radiator to coolant reservoir. When I turn on cabin heater, they subside temporarily. Somehow, it seems coolant is boiling off.

Car allegedly had new timing belt and water pump replaced about 5,000 miles ago. I am not confident that the mechanic that did this was qualified.

I have an infrared thermometer and get readings of about 160F from fins on radiator. Measuring 210F in water bypass outlet in water pump area.

I bought a new radiator cap to rule this out and it had no effect. Also, I tried to get an 1993 SC400 cap but it would not fit.

Any ideas on how to diagnose would be appreciated.

I will post this same message on the general maintenance board.

Thanks!!!!!

Bill Harrison

i know i'm late on this post and probably everyone already helped you out with this problem, but i couldn't help add that the radiator you got from radiators.com is actually a GS300/IS300 radiator because of the sensor. my car has that sensor but not too familiar with the sc300 setup. as for the boiling, you probably have a pinhole air leak which is hard too find... that or a fine crack somewhere. hope this helps any.

[mktbully]

your getting yourself lost in asking a question with a question

i buy the toyota coolant from a toyota parts desk,that and only that

the green you understand why

gm engineering is what it is

crappy at the best

take a drive in a new escalade

my firend has one it has more deficencies or manufacturing than i can belive

but i am now spoiled by toyota over engineering or what seems to be

like the infamous 95 and onward defective fuel sending units that gm blames all gas companies for fouling it and making there cars give the wrong readings

or the 10 plus recall issues that almost every car has

btw i am not arguing just stating points and trying to answer you questions

Toyota OEM coolant is this color:

mixed w/ water it's pink..some say it's reddish. is that what you buy?

[SKperformance]

mine even mixed doesn't look pink,it is deep red

but i haven't bought any new stock of coolant from the toyota parts desk in a while maybe they reformulated it but i haven;t seen it

[mktbully]

mine even mixed doesn't look pink,it is deep red

but i haven't bought any new stock of coolant from the toyota parts desk in a while maybe they reformulated it but i haven;t seen it

so we both agree this red/pink toyota coolant is what to use in the SC?

[SKperformance]

sure

which ever colour it happens to be in your area from the toyota parts desk

maybe the pink if for hot climates only

[whh333]

Hello again, it's me, the one with the trouble of the bubbling reservoir. I did not solve the problem over the past week, because I still have bubbles. I have bypassed the heater valve, bypassed the throttle body, and drained the Extended Life antifreeze and replaced with water, all to no avail. Also, removed the thermostat and confirmed it is operating in boiling water, and had already changed the radiator cap.

Still no smell of antifreeze in the exhaust, no oil in the water, no water in the oil. I have a veteran mechanic friend who confirms no smell of antifreeze in the exhaust and agrees to hold off pulling the head gasket until some conclusions can be drawn.

The only think left other than the head gasket is the Exhaust Gas Recirculation circuit. I would like to bypass this or test it before pulling the head gasket.

The strange thing about this problem is that I can drive the car to operating temperature, it will develop a slight miss at idle, and I can make the engine smooth out perfectly by twisting the radiator cap and relieving the coolant pressure. When the radiator cap is removed, exhaust gas comes out.

Any ideas on how to check out to determine whether the EGR is causing this would be appreciated. After that gets eliminated, the head gasket or the engine as a whole gets changed.

Still waiting on the radiator pressure tester to get here and I am confident it will show a leakdown, but finding the source is something I have not been able to do for weeks.

Regarding the question about the alternate radiator, I do not have a reference of having a working SC300 radiator to compare to because the car had a leaking radiator when I bought it, though a pre-buy at the Orlando Lexus dealership did not reveal this.

When all this is finished, Toyota anti-freeze will go back in the car.

Thanks again for all the help and ideas.

Bill Harrison