Engine temp up and down WTF

[supramad77]

Guys i have been having some problems with my motor the last couple of weeks. It has been dumping water out periodicly and the temperature guage is going up and down like mad. There does not seem to be any blockages in the rad. Am i looking at BHG?
The car runs pretty good but is a little rough when cold.
Yesterday the temp guage was right up flashing and then the next second it was normal and stayed like that for the rest of the drive. WTF
Help Please.

[Moorman]

Last weekend I was seeing the same. Fan clutch was only *sometimes* engaging, so it'd start to heat up, then the fan would spin up and temps would shoot back to normal. This would repeat randomly. Replace that fan clutch & I bet you'll be back to normal.

[Dangerous Ken]

Pat,

To find out for sure it's not a BHG, get a test kit for BHGs.
Snap on has a good one here in the states for around $30?

Ok, the rad is flushed and 'probably' not clogged.
There's still all those passages that carry coolant to and from the engine.
This summer I had an overheating problem (it blinked on me too) and it turned out to be a split suicide hose (so instead of coolant flowing to the engine, it slowly exited under the intake). A hint to a blown coolant hose is the smell of coolant to me, but since you just use water, that may not work for you.
A week later, one of the hoses that go from the engine to the heater valve blew on me dumping yet another fill of toyota red.

Of note is I ran a draino crystals solution through the rad And engine.
Well, the 23 year old coolant hoses needed replacing anyway and the draino solution was probably the straw that broke the camels back. But once the hoses were replaced, the temp returned to the 1/2 mark, even in 100 degree weather at 80mph.

Ken

[BillyM]

Wah woah woah guys... easy shit first.

Upand down temperature is usually caused by a sticky thermostat. 3 bolts, $15, 5min
If your radiator cap is older than a couple of years, replace it too.

Do that first, then come back if it keeps it up.

--BillyM

[ma71supraturbo]

While youre replacing that thermostat and radiator cap, check ALL of the radiator hoses. If any are bulging or show any crustation near the clamps replace them. A leak (even a small one) will give BHG-like symptoms as it introduces air into the system...

[AJ]

Make sure you get a Toyota OEM cap and thermostat.

[supramad77]

How long do thermostats last . I can remember replacing mine prolly in the last four years.
The rad cap was on the car when i got it.



Wah woah woah guys... easy shit first.

Upand down temperature is usually caused by a sticky thermostat. 3 bolts, $15, 5min
If your radiator cap is older than a couple of years, replace it too.

Do that first, then come back if it keeps it up.

--BillyM

[BillyM]

....too many variables to say Pat. I've gotten bad aftermarket ones out of the box, and then again, I've had original ones only replaced 20 years later in some of my cars. All I know is that they are cheap, easy to replace, and can cause the exact thing you are referring to.

One thing I forgot to mention, get ahold of a system pressure tester. It will have a pump, gauge, and hose running to a standard radiator cap. Pump it up to about 20psi and let it sit for an hour. If you get drips under your car, and or the pressure goes down, you have leaks that you need to get taken care of. ...but still swap that thermostat and cap with factory parts.

One other thing that can introduce air into your system and make you lose coolant, pop the lid of your overflow tank, make sure the rubber gasket under the lid is in good condition. Once it starts getting thin, it is worth cutting out a piece of rubber and replacing it. If it doesn't seal, the system wont draw antifreeze back in as it cycles hot and cold every time you drive it.

--BillyM

[supramad77]

I removed the thermostat and ran the car for a couple of days with no problems. However i tested the thermostat in boiling water and it is working. It is still quite shiny as it was not all that old.
So it is back in to see what happens.
BTW i have flushed out the rad flush and the water looked like it had oil in there. I am not sure if it was the rad flush making it look oily or it is indeed oil from the engine.

[Moorman]

Wah woah woah guys... easy shit first.


--BillyM

Yes, fan clutch, easy shit. ;)

[TSupraman85]

Last weekend I was seeing the same. Fan clutch was only *sometimes* engaging, so it'd start to heat up, then the fan would spin up and temps would shoot back to normal. This would repeat randomly. Replace that fan clutch & I bet you'll be back to normal.
I was about to type fan clutch!Give it a spin if it spins more than two turns freely it's bad!

[BillyM]

Hey... F you guys! Hahah.

I already won, he tested it, eat a bag of ass!

Give this two spins *points to crotch* ...bitches.

--BillyM

[Junkie]

Guy's,read his other thread and then reread this one.Rusty/oily water,temps are fine w/o the t-stat,tested t-stat and it works.Flushed system and coolant still funky..............drive it a couple more days,I'll bet it gets worse.
Get a rad tester for checking exhaust gasses in the cooling system.To pull a Billy,I'll paypal ya $25 US if I'm wrong "1/2 my cost for tester :p cause youll have enough left to test all you friends cars"

[BillyM]

...haha, then you and all your friends can tell ladies you've been "tested".

Junk, layin down the Fuck-you-Money.

If I were less unemployed, I'd jump in just for the sake of arguement.

--billyM

[Junkie]

No F-U $$$ just 30 years of working on cars,tells me to start with that test,as it involve no wrench turning,and confirms yay or nay BHG/Cracked head.

[BillyM]

...well of my few years around here, I realized that folks have this grand ability to exaggerate the idea of BHG in these cars (it must carry over from the piggies...) and 9 out of 10 "oh my god, I think I blew my head gasket" threads end with "oh... bad radiator/cap/thermo/air in the system". (I even made this mistake once, in my early days... *sigh*)

I'm all about testing though, much better to catch it now if anything's going to happen. The sooner you know, the sooner you can pick a time to fix it up. ...be more descriptive on what you saw in the coolant. Just a sheen on top when you emptied it, or little globs of it?

..and Junk, that was so tossing down Fuck-you-Money.
"Oh, our opinions differ?"
*SLAM* "Money's down, Fuck-you!"

I've been doing it for years on here, never lost a cent, yet, hahah.

Be good guys,
--BillyM

[supramad77]

It was just a sheen like you see on the road after a car has droped some oil and it has rained on it.
I drove it yesterday for about five miles the temp gauge went up for a second then dropped to normal and was fine the rest of the time. I guess time will tell.






...well of my few years around here, I realized that folks have this grand ability to exaggerate the idea of BHG in these cars (it must carry over from the piggies...) and 9 out of 10 "oh my god, I think I blew my head gasket" threads end with "oh... bad radiator/cap/thermo/air in the system". (I even made this mistake once, in my early days... *sigh*)

I'm all about testing though, much better to catch it now if anything's going to happen. The sooner you know, the sooner you can pick a time to fix it up. ...be more descriptive on what you saw in the coolant. Just a sheen on top when you emptied it, or little globs of it?

..and Junk, that was so tossing down Fuck-you-Money.
"Oh, our opinions differ?"
*SLAM* "Money's down, Fuck-you!"

I've been doing it for years on here, never lost a cent, yet, hahah.

Be good guys,
--BillyM

[CarFreek]

Get a rad tester for checking exhaust gasses in the cooling system.To pull a Billy,I'll paypal ya $25 US if I'm wrong "1/2 my cost for tester :p cause youll have enough left to test all you friends cars"
The Junkster knows-I rolled into his driveway bout 18 months ago w/ weird over heat prob-I was positive it was head gasket-whipped out the tester-no gas in system-WTF-Ended up being two completely different things-#1-Half plugged radiator-Got one from Nix99 cheep-pressure tested in front of me :) -#2 issue, found a week or two later, was timing was out 170 or so-Rotor was cracked and walking around on shaft-good thing he didnt lay out f you money on my hood!

[Junkie]

I'm all about testing,when possible,before swapping parts.......that's why I make the bank and am gainfully employed .... so :new_mofug Billy.....there I said it.

Every swinging Dick on this forum should own that tester,or go in with a buddy on one. "no offence to the ladies :p "Refill bottles of the test fluid are cheep,good thing,as it does age after being opened,and will turn color in the main bottle.I check the bottle every few months for this reason,replace it just because,once a year.

Unlike the old "bubble" tester,the blue fluid turning green or yellow removes all doubt,if it stays blue,then it's time to test parts.........Hmmmm,I own a rad cap testerand radiator pressure tester.I have a hose bib that flows more water than ANY water pump,so I can flow test a Rad also.


Now,go back..........T-stat tests in water,so we know it opens at temp.Car w/t-stat will go above normal,then finaly drop.The only reason I know of for this issue,is some sort of air/gas bubble keeping the fluid from reaching the t-stat.When the gauge does finaly drop,you have had one of two things happen.The air/gas has superheated enough to open the t-stat,or enough pressure has built up enough,to get the NOW superheated water to the t-stat.So,in retrospec....he is either sucking air into the system thru a hose,gasket,seal,etc.Or has BHG.
That leaves 2 tests,pressure test the cooling system,or Above mention BHG test.

[TSupraman85]

Or instead of ivesting in that just go by a shop or even a inspection station thats been around for a while and put the 5 gas over your radiator fill with the car runnig if you have bhg you'll most likely get hcs.Wow!Were all so smart,the fan was a good guess,seeing that I didn't read the other thread!

[82MKIILtype]

Well not to fan the flames here but ... what about a cracked head?

Unlike BHGs, cracked heads are definatly a problem with 5Ms. I know personally as I was victum to almost the identicial symtoms you are getting now plus a few others to boot. (mine was realy bad.... 3 cylinders cracked)

These heads are known to crack between the two valves and the spark plug hole. Usually it's due to extreme overheating ... but you never know.

because it's affecting your cooling system, Exhaust gas/coolant tester will still show you have a problem.


Just for $hits a giggles, pull out your spark plugs and with a very bright light ... inspect the plug seating surface of the head for hairline cracks. They might be easier to see when the engine is hot. Also, any trace of moisture/steam under the rubber plug cap is a sure sign. Mine got so bad I had a small perculator spitting tiny drops coolant out the spark plug cap breather every couple of seconds when my engine was running.

Pay perticularly attention to #3 and #4 cylinders.

Get this fixed ... I'm dying to know what the problem is... :hahano: