Running hot

[tlava]

Somethings I still haven't resolved--after the engine runs about a minute, the fluid in the radiator begins to rise and will overflow if I don't tighten down cap--is this normal, since the radiator I guess pressurizes? does it suggest an overfilled radiator?

Also, one morning, I noticed the hoses were sucked in, after about a 1.5 hr drive on highways, etc the day before; on opening the radiator cap and releasing the vacuum, the hoses popped back into position. Driving about a half hr on mountain roads the other day, this didn't happen, so it seems inconsistent, or maybe only happens after extended driving?

Though I haven't highway tested yet, driving 50--65 on mountain roads (depending on hills, curves, etc), the temp gauge stays below the half mark; when i pulled into a parking lot after about 15 mins. of this sort of driving, the temp gauge rose to just a bit over half, but then began to drop, and stayed just a bit below as I let it idle about 5 mins.

does all this seem normal? should I still have it checked out for possible fan clutch (though new) of block or thermostat issues?

thanks!

[Maineah]

I was able to remove the temp sensor--the thing looks so basic, hard to believe it would go bad; I'm wondering if maybe someone had put the wrong one in? maybe meant for the 4 cyl rather than the 6? could that cause a too hot reading?

I will replace it, and see what happens...

should the threads be treated? I use Harvey Seal thread compound on LP and plumbing fittings--good up to 6,000 psi on gas fittings, and up to +400 F, so should work well in this application...I swear by this stuff--never use teflon tape...

Should be put in dry it needs a good ground to work properly.

[90toydolphin]

I've never heard of over filling a radiator. when it cools the water will collapse in volume and should be pulling in water from the reserve tank. when it heats and expands it flow into the reserve tank. you should never drive around with the radiator cap loose or off, the water will expand and flow out of the radiator and can actually boil because the pressure is released. the water when heated will create pressure which keeps the water from actually boiling. water under pressure requires a higher temp to boil and turn into gas.

[tlava]

Ok--thanks for that--so after running a 30-secs to maybe one minute, it would be normal for the water to start to rise and perhaps overflow? I assume from what you are saying that as the system pressurizes, it pushes up the spring on the cap and lets water into the tank, under normal running conditions, and not just if it pressurizes too much (if that is possible due to a blockage or something)?

[Davidadro]

Have you replaced your radiator?

[tlava]

I've replaced the radiator, fan clutch, thermostat (not sure what temp, probably 180-90), and now the coolant sensor...

[Davidadro]

Wow? Could be deposit a plugged water jacket(s) in the block? I'm a bit puzzled. If you haven’t tried to, or had your cooling system flushed, maybe that would be prudent? It seems you have done the things one does for the problems you are incurring. I had mentioned the water pump, but if you’re getting flow, I can’t see that being an issue.

I know the EGR system uses coolant somehow to maintain a proper exhaust temp, but I'm not sure if it has a valve that could restrict the coolant flow or if the gasket being bad could allow pressure and temperature changes to enter ones cooling system? Anyone have ideas on that scenario? Sorry I’m not much more help here, and hope all goes well, and it gets completely resolved for you.

[tlava]

thanks--

I do notice less coolant in the reserve tank this morning than yesterday--it was cooler overnight, if that matters...

[Davidadro]

Head Gasket? If the head gasket is bad, it will cause you to lose some coolant, and allow compression and temprature into the cooling system. just a thought if have not had checked.

[waiter]

Water density changes pretty significantly with temperature. from 25 deg C to 85 Deg C water expands about 4%,

That water needs to go somewhere (your overflow tank). Then the reverse happens when it cools down. Waters gets small when it cools, at least until it gets to about 3 deg C, then it starts to expand again.

Heres a chart that shows water density vs temperature. Remember, the more dense it is, the less volume it will occupy.

Water Density Chart

John Mc

88 Dolphin 4 Auto

[90toydolphin]

this may take doing several times. before you start the truck remove the radiator cap. if it is not full to the top fill it to the top and replace the cap. start the truck and allow it to heat to running temp, middle of the gauge then shut off. do not remove the radiator cap again until checking it the next time. make note of where the level is on your overflow. do it again the next day or after lots of hours to totally cool. check level in radiator and if not full top it off again and run again until warm and wait again to check level again the next day. again check level in overflow. eventually you should have a full radiator when cold. at that point make sure you over flow is full to the cold mark on it. should be a hot and cold mark on the over flow tank. the cold would be the lower mark on the tank. if the hoses are calapsed when it is cold and don't expand when the radiator cap is removed you might try to manually squez them to make them round before topping off the tank. if the engine and radiator is full the hoses shouldn't be able to calapse when it cools. as the engine cools it should pull water in from the overflow keeping the system totally full and hoses expanded. if your overflow tank isn't working properly, that is allowing in water when it warms and letting water back into the engine when it cools you could have a problem with the radiator cap. there are arrows on the radiator cap, make sure it is pointing to the hose that goes to the overflow tank. maybe got a wrong cap along the way???? shot in the dark on that one. after changing the radiator on one of my trucks, not a toyota, it took quite awhile to get what i assumed was trapped air out of the engine and truly full of water, several days if not a week. once it is truly full you should never have to remove the radiator cap, just add fluid to the over flow as needed. because of the way my overflow is designed it allows some evaporation so fluid is need occassionally.

[tlava]

Ok--this is all helpful. My reserve tank though has a "Min" and "Max"--so it the "Min" = "cold"?

[stamar]

You know what just occurred to me?

Getting an external transmission cooler must bring the radiator temperature down because hot transmission fluid isnt coming through the bottom of the radiator anymore.

this lowers overall system temperature.

How much I have no idea at all maybe someone can tell me.

[tlava]

Yes--thanks--I do have a tranny cooler....I'm can't remember if it bypasses the radiator, or just adds an extra cooling option--I'll have to look at the lines again..

[waiter]

Tlava - I would say, unless you can physically locate the transmission cooler out side of the radiators normal airflow, (i.e not in front of the radiator) then your best option is the tranny cooler that's part of the radiator. (fluid-to-fluid cooler is a lot more efficient than fluid-to-air).

Normally the tranny fluid goes thru the radiator, then thru an air cooler mounted in front of the radiator. This is a good option.

John

[90toydolphin]

min level of overflow is the ideal level when cold. if it's a little high when it expands it may be released with the overflow tube coming out of the over flow tank. the negative of having it over flow this way is the polution concern and danger to animals, i understand cats in particular, that seem to like to drink it. supposedly sweet, i haven't tried it ).

[tlava]

Yes I believe the tranny is cooled both by the radiator and secondarily by the tranny cooler--I believe both sets of hoses were still connected... but I wonder if when I had the new radiator put in, that was still the case? If I crawl under I should be able to tell?

[tlava]

Hi All--

Had this to 3 mechanics, at least--none of them can find anything wrong. Got on

the freeway the other day after knocking around on mountain roads for about an

hr., and sure enough, once I got it up to 70 on the freeway, the temp started

climbing and didn't stop--almost like not having a fan at all; when it got to

the H, I pulled off--the reserve tank filled up and was boiling and bubbling

like a witch's cauldron...I lost a little bit of the steaming coolant out the

overflow hose. Vexingly, when I first opened the hood, I could turn the fan

fairly easily. After letting the RV sit for about 10 mins to cool off, the fan

actually tightened up--almost like extreme delayed reaction or as if it is

working in reverse, or as if something--too much wind through the radiator?--I

don't know--is keeping the fan from kicking in. In any case, once the temp

dropped down a bit below the H, I started on the road again, and the engine

began to cool down; I kept the speed at 65 and under. Things seemed OK till I

got off the freeway and into stop and go traffic--the temp started to climb

again, which it normally does not do. I parked a few minutes later, opened the

hood, and noticed the hoses were collapsed. I started it again, since the fan

had tightened up, and it began to cool down well despite collapsed hoses.

This has me mystified. Could it be the that i have a slight head gasket leak on

the exhaust side, and hydrocarbons are getting into the coolant and superheating

it? Is it just a problem with the fan (which, as mentioned previously, is new)?

I assume the t-stat is not the problem,since the water is plenty hot (i.e.,

water has to be circulating, but for some reason getting/staying tooo hot)

I hasted to add that there are no detectable power issues, no white smoke which

might indicate coolant burning off in the exhaust, and no water in the oil

Again, I'm puzzled--and the problem even seems even worse now since the last

mechanic replaced the new t-stat with another new one of the same temp rating

(170) and put on a new radiator cap to replace the already new cap claiming that

it wasn't building up enough pressure--seems like plenty of pressure to me....

Does anyone know a mechanic in the area who might be able to figure this out?

The vehicle is currently in Binghamton, NY...

[waiter]

Replace the fan clutch, or buy one of those metal blocks that bypasses the clutch.

I'm basing this on your statement that when you pulled over and stopped, the fan turned freely.

JOhn Mc

88 Dolphin 4 Auto

[Totem]

is just the fan new or the fan clutch/fan assembly new? unless blades broken just the fan part wouldn't matter. the hoses are collapsed because of the steam and vacuum.

the clutch on the fan drive will "tighten" or loosen depending on the bi-metal thermo position which is directly determined by heat. It should spin more freely when cool and be tight when hot; hence being driven by the motor more to cool. When cold the clutch will be tight again due to fluid viscosity change.

right now if this were my problem and I had stumped mechs I would be thinking the following:

1.) bad fan clutch

2.) severe air bubbles in system (radiator, motor etc)

3.) severe blockage

(but would be leaning on 2 or 3 at this point)

you have a cooling issue. Its radiator, clutch, thermostat or blockage related. alas its a nasty one because the low hanging fruits have been checked. hopefully you didn't get a bad part on the clutch. Possible but improbable.

I second the making a fixed (always engaged clutch at this point also) or putting in a wrecker one to eliminate 1 from the equation.

My advice at this point would be to flush system of all coolant, and replace along with maybe trying to locate another clutch out of a junkyard to ensure correct part. "new" clutches from china can be junk. I'd take a tried and true Toyota clutch out of a junk car any day before a new one. (trust me we make them). My gut though tells me air bubble or blockage.

One time I had my Celica GTS coolant replaced by the oil change guys and had this EXACT same problem. I had to bleed the system. When the vehicle would overheat; I would pull over and let it cool down to where I could open up the radiator to add coolant full and then also fill the reservoir to correct line at cold. yes this was a pain. yes this took time and yes it took whole jug of freeze. but; it worked. no more overheat. I'm sure you have done this but if not give that a try; otherwise you are basically looking at a tear down to find the blockage.

[waiter]

Totem, this vehicle he's talking about is a nissan toyhouse. but your same advice would apply.

John Mc 88

Dolphin 4 Auto

[tlava]

a " tear down" means also replacing the head gasket?

so when replacing coolant, check each morning when cold, before starting engine, and if low, top off? it was full prior to this last incident (couldn't fit any more coolant in), though it was at the "min" level when cold in the reserve tank.

So what about the idea of hydrocarbons superheating the fluid? not accurate? can I rule out a head gasket issue?

[tlava]

Oh--also--can you explain metal block thing? what is that--what do I ask for at a parts store--, where do I get one, how attached, etc....

[tlava]

should also add that I added some White Shehperd gasket seal at one point, suspecting a HG leak, but have driven since without an overheat issue...but could this stuff cause a blockage? it is not a fiber-type sealer, and product claims will not...

[waiter]

STOP - In the very early entries, you mentioned that you replaced the radiator, fan clutch, and thermostat. Why did you do this???

John Mc

88 Dolphin 4 Auto

[Totem]

yikes, i wouldnt have added anything unless there was a missing coolant situation. Is there? Does the coolant keep disapearing? is it in the oil?

If the coolant is blowing by then you should be able to smell it in the exhaust....

[tlava]

Well, I replaced all that stuff because various folks suggested those might be the problems--all replaced most likely unnecessarily.

There is no evidence of moisture in oil or coolant in exhaust that I can detect, but in case of a small seepage just beginning in the head gasket, allowing gasses to maybe get into coolant, I put the White Shepherd stuff in...

now I'm wondering if I should try a system flush and another White Shepherd treatment, since I had to do the first one in two installments, not having drained out enough coolant to get th whole bottle in

[Totem]

coolant additives are snake oil; you could just as easily use black pepper from dinner table to plug a pin hole leak... you aren't leaking though; you are not cooling. coolant is failing to circulate and so the coolant that is present in the jackets is super heating and exploding into reservoir. Air bubbles can cause lack of flow;

or

blockages such as radiator "quick fix" that previous owners have put in there may have made their way into the motor...

or

mixing incorrect coolants in the same radiator can have unintended chemical sludge reactions that plug engine.

You have eliminated the thermostat (where sludges can stick) from the picture.

Time to crack the motor open.

if you still have your old fan drive, you could drill a hole through it and run a bolt through it so its locked. this will save the trouble of metal block to fan mount.

[waiter]

I don't like the symptoms you described for the fan, i.e it spins freely when you popped the hood. The other part about this is that you said it starts getting harder to turn as the engine cools off. seems like this is all backwards.

ANYWAY - if your heating issue was like this before you replaced all this stuff, Statistically, that would mean you had a defective original, and the replacement was defective. Possible,

Did this always do this (if you know)????

John Mc

88 Dolphin 4 Auto

[tlava]

Well, it's a new radiator, so no previous stuff; I have, as I say, myself added White Shepherd (though that is a non-particulate sealer) and have mixed different brands of coolant--does that matter?--i.e., after the t-stat was replaced, and the shop added whatever coolant they added (they also say they added something to the coolant for some reason--can't remember what), I topped of reserve with a diff brand.

Do I have the "crack the motor" for a blockage? won't a coolant system/ block flush take care of that?

the fan, to clarify, doesn't spin like a pinwheel, but didn't seem snug, either--pretty easy to move and I could get probably a revolution or two out of it with a middling push--as contrasted to a blade or two when it is engaged...

on a 3k trip from Or to FL, it got hot once, just outside of SL, but was OK the rest of that trip (I replaced the radiator cap then); as I say, i just had the radiator cap replaced a second time... that was the mechanic's decision, since he said it wasn't building pressure, which I still don't exactly understand...

[waiter]

Did it always do this?? or was there a time that it was OK??

JOhn Mc

88 Dolphin 4 Auto

[Totem]

So you have mixed coolant brands and possibly types... yikes. could make a jelly like smuckers in there as a result.

would a flush remove the jelly? maybe, maybe not.

The fan spinning as mentioned will change.

As mentioned before, a fan drive has ATF in it. When fluid is cold its thicker; so unless the fan drive evacuated it just might have fluid in it still after shut down; this would make seem tight when cold. if shut down while "on" the ATF is thick and when the car is started this is why your fan may be stuck on sometimes till it heats enough to reach viscosity that can evacuate... a little more heat and the bi metal will open the other way and the fluid will be pushed centrifugally back into play in the drives jaws.

Make no mistake when it heats up it gets thinner, but will be spinning until the centripetal force spins it out; at that point its not psinning hardly at all and the fan is VERY easy to turn by hand; had you shut the motor down at that second... So you really cannot determine if a fan drive is functioning correctly just based on whether or not its spinning freely at shutdown. you would need to know where you are in the bi metal valve being open or not process and whether or not the fluid is in the reservoir or in the drive teeth... A better way to tell is to actually LISTEN for the fan.

Trust me you will KNOW when the fan comes on. makes a WHOOOSHING sound that many mistake while driving as a transmission failing to kick issue etc, but nope, that's your trusty fan drive on "on".

So to paraphrase; the situation that seems "backwards" to waiter might just be nominal operation. and that is why "On/Off" fan drives can be frustrating to trouble shoot.

Generally as mentioned if its coming on I say its legit and working. The fan will always be spinning and making air to some degree, but when heated up it will really track with the motor RPM and make noticeable airflow. :-)

[tlava]

Ok, so where am I... maybe fan is OK; this leaves poss of a blockage--but if the fluid is not circulating, why would it be so hot? and the other poss. could be hydrocarbon gasses seeping into the fluid and superheating it?

this is the first I heard about not being able to use diff brands of anti freeze---this is really the case? seems like this information should be printed on the jugs, in that case....

I did also read the MOPAR is a better brand to get because it includes a small amt;. of sodium silicate to help seal leaks?

[waiter]

You still didn't say if this problem has always existed or not.

John mc

88 Dolphin 4 Auto

[Maineah]

Combustion gases will not heat the water but it will introduce air/gas that do not work well as a coolant. So far every suggestion in the book has been suggested your fan clutch probably will spin free when you stop, the bimetallic strip has to be heated by air flow, once it cools a bit the fluid inside the fan assembly gets thicker and it becomes harder to turn that's normal. It was suggested that the fan should roar when it is engaged and it should then move a lot of air. You really need to find out if there is any hydrocarbons in the cooling system this is some thing you can not do at home unless you have a gas analyzer. Pretty much every thing points to head gaskets. Leaking head gaskets don’t necessarily mean you’ll find water in the oil or oil in the coolant excessive pressure, loss of water, overheating yes.