Cooling Systems -- Problems & Solutions (Radiator, Fan, etc)

olesalior · January 2010

Yeah, the level it heats to is the same as when there was no problem; I just was concerned that the lower hose didn't heat up; then again this radiator may also have a larger core, not sure. I guess I wont worry about it sense it's doing good lol.

imidazol97 · January 2010

If you are concerned about the flow rate, when the truck is not HOT but just warm take the radiator cap off and see if you can see the flow into the top of the radiator from the thermostat after the truck has idled to warm up the coolant again. It works best to have someone goose the throttle if you can't reach it yourself under the hood.

If you idled the truck outdoors and the ambient temp is cool or cold, the water through the radiator is probably being cooled and the lower hose is carrying cold water back. If you idled inside a garage, then the lower hose should get a little warm. Does that truck have a fixed fan that rotates all the time pulling air through the radiator? That would keep the radiator cooling even at idle unlike electric fans that wait for a high temp before phasing on.

drsin2000 · February 2010

never a problem, then suddenly the temp gauge goes all the way high.. I've had the thermastat replaced, and water pump but still the gauge fluctuates high, and the radiator won't hold water but there's no apparent leak under the car. I'm a female and totally lost on this situation. please help

srs_49 · February 2010

If you're losing coolant (but no leak) and the car is running hot, you may have lost the head gasket. This means that there may be a leak between the coolant passages of the engine and one of the cylinders or oil passages. Yes, it's bad.

Did you check your oil level? Is it normal, and is the color normal? If coolant gets into the oil pan, the oil level will be higher than expected and the color may be a putrid brown.

imidazol97 · February 2010

Are you filling the car with coolant mix at the radiator cap or is there a recovery tank? Be sure the radiator itself is getting filled.

Sr49 is right that you may have a head gasket leaking which is leaking. Shops should use a tester that sniffs the air above the water in the radiator and checks for hydrocarbons that come from burning the gasoline in the cylinders. Or there may be a test strip for that check.

Another problem is the radiator may not be letting water flow through it right. I do know a friend has a Firebird and he eventually connected the electric cooling fan to turn on at lower temperatures with an electronic box to help his stay cooler..

georgiaman · February 2010

Hi All:

I have a strange problem with my 1999 Nissan Sentra GXE Automatic. For the last 2 years or so, I have noticed that it occasionally leaks a small amount of coolant (approximately 1 oz) when parked overnight. I took it to the dealer and they ran the pressure test several times and did not find a leak. They said everything is fine. Recently, I took it to Midas and they did a pressure test and couldnt find a leak either, but I had the radiator replaced by them anyway. That did not stop the leak and now I am at a loss as to what to do.

I have noticed that the coolant leaks usually when the temperature overnight is below freezing. Also, it leaks when parked on level ground, and not when it is parked overnight on a slope.

There is no warning light on, or any sign of engine overheating. The car runs fine, and the dealer and other shops where I have had oil change and service never noticed any problem with the car.

Any ideas what it could be?

Thanks in Advance.

bolivar · February 2010

I think you've got a hose with a loose clamp. If you have screw clamps, tighten all of them up. If you've got spring clamps, consider replacing them with screw clamps. (Might not be an easy job.)

I've had several clamps do exactly as you describe. Leak when extremely cold.

georgiaman · February 2010

Thanks bolivar!

The clamps were tightened at the time I replaced the radiator a month ago, but that did not solve the problem.

srs_49 · February 2010

Put a piece of newspaper or cardboard under the car when you park it for the night, to try and narrow down th source of the leak.

Do you know for sure it's leaking from the radiator or a hose?

Like leaks in houses, these can be tough to find. The coolant can leak out one place, run along the engine in channels, etc, and drop on the ground in a location far removed from the original leak.

Mr_Shiftright · February 2010

I'd check the water pump

kiawah · February 2010

Coolant leaks typically could be (in no particular order):
- heater core inside car, typically you might smell antifreeze in cabin, passenger carpet wet, or windows fog up
- engine head gasket, allows coolant to leak into cylinder, get's burned up when car start and comes out as vapor out the exhaust. Can ruin cat converter, and of course water in engine is not good.
- water pump, could drip around shaft
- any and all hose connections, as previously mentioned
- radiator core, sometimes obvious, sometimes pin holes will drop so little that the air flow vaporizes and hard to find. Could also leak internal into transmission cooler section, disaster for transmission.
- cracked overflow container, or hose to the container.

georgiaman · February 2010

Thanks for your detailed reply!

From your list, I think I shall check the overflow container and the water pump first.

If it is a leaking water pump, approximately how much should it cost to replace?

fullerru · April 2010

Greetings friends

I've been having a slight problem with my 1998 toyota mark II - 1G-FE 1988cc engine.
Here it goes: whenever I pressure the car (drive real hard) or use the ac the temperature gauge rises and will continue to rise to even red zone if I dont ease up. When this happens the radiator loses no coolant nor does it boil, it just seem to be cool and normal and i never have to top it up...ever.
The radiator have been removed, flushed and rod out, cap has been changed, clutch for fan replaced and also the thermostat has been replaced but still the problem remains.
I am now suspecting that the problem is stemming from either a faulty coolant temperature sensor or temperature switch, however, i've looked for a temperature switch where I know they are normally located (at the exit or inlet goose-neck where the hoses are connected) but cant seem to locate it.
Can anyone offer some input on this problem or help me locate the temp. switch or temp. control unit on this car?????

Mr_Shiftright · April 2010

You mean, by "switch" the fan sensor as opposed to the gauge sensor?

If your fan turns on during this "overheat" then no sense chasing the fan switch/sensor or the relay.

I'm sorry but we don't see this engine in the USA, so I can't locate the part---unless you know of some older US model that might have used it.

rickysmyboy · April 2010

Hi everyone,

I hope someone can help me out. I have a 99 Chevy silverado, 5.3, 4 weel drive. Started overheating so flushed out radiator and changed thermostat. Next day, still over heating, replaced water pump and verified fans are working. STILL overheating, The BIG question, WHAT'S LEFT??? Any one know what steps I am missing? Any help would be great.

Thanks to ya all

imidazol97 · April 2010

Diagnosis:

How do you know it was overheating?
Is the temperature gauge reading high?
Is the coolant bubbling?
Is the engine actually above the permitted range?

Possible factors:

Temperature gauge reading wrong due to gauge or sensor bad?
Head gasket leaking?
Pressure cap not sealing and holding proper pressure allowing the engine to go above the boiling point of the pressurized coolant giving boiling?

Tests:

Infrared heat thermometer to see if thermostat area/upper radiator hose are actually above the 230 or so it might reach under pressure in a hot environment.
Check coolant with a test strip or sensor to see if hydrocarbons are in it from leaking head.
Clean pressure cap. Check pressure if a cap check device is available. Is upper hose becoming very solid because of pressure--that might indicate the cap is working. I do not recommend opening cap when car might be under pressure warm because of danger from coolant spewing out.

rickysmyboy · April 2010

Well, have pressure on upper hose, gauge is reading hot, no "Bubbling" in over flow to indicate overheating, replaced thermostat, water pump, chemically flushed radiator, put in fresh antifreeze, new radiator cap. Checking clutch fan to make sure it is working properly.
I read there is a sending sensor for this year? Is that correct?
Think the sensor could be bad since there are no other obvious indicators?

THANKS for any help

imidazol97 · April 2010

Is there a time or type of driving when it overheats? That might indicate inadequate flow through radiator.

Have you used a chemical test strip or the sniffer type sensor to check for hydrocarbons in coolant as a worse case possibility?

Has interior of lower hose collapsed restricting flow to water pump when it sucks the coolant through the hose?

rickysmyboy · April 2010

I am not familiar with that kind of testing. Actually called chevy shop and for $49.95 they can run diagnostic.
The "Worse case" possibility is what? I have exhausted my knowledge at this point. Granted, I am no mechanic either.

imidazol97 · April 2010

Shops use a tailpipe type sniffer that senses hydrocarbons coming from the coolant. That indicates a combustion leak into the coolant, typically a head gasket. There also are test strips that can be dipped into the coolant to sense hydrocarbs that I've heard mentioned on car repair programs on radio.

Radiator shops do a flow test on radiators to see if enough coolant can flow through the radiator.

If the lower radiator hose is somewhat soft after years, it might have the inner layer pulling away from the outer part and partially blocking the flow of coolant from the radiator.

rickysmyboy · April 2010

OK You have helped alot. Just 2 questions, How hard is it to change head gasket?
How can you test the lower hose for integraty?

Very thankful for your input

imidazol97 · April 2010

Feeling the hose is one technique. If uncertain, taking it off and looking at interior is best. By then it's cheap just to go ahead and replace it.

Does it overheat driving at speed along the highway or roads? Overheat sitting idling?

Head gasket requires careful diagnosis and checking pressure inside cylinder with compression tester to see if a particular cylinder doesn't maintain as high pressure as next one. It requires removing the intake manifold, valve covers, and then the head bolts. Head needs to be inspected for cracks, etc., that might cause leaking.

rickysmyboy · April 2010

Just went out and started truck for 2 minutes, let it get to operating range, no change in resistance on fan but let it run idle, not highway. It heats up at highway speeds, not on idle. Felt top and bottom hoses, top felt hot and bottom did not.
Suggestions on the "Cheaper" way to check for sure?

Mr_Shiftright · April 2010

Okay, if it heats up at speed but not at idle you have a coolant circulation problem, not an air circulation problem.

By the way, a chemical flush of the radiator is a pretty lame procedure---you could still have a clogged radiator.

imidazol97 · April 2010

Agree with shiftright. Now that you've said it's an overheat at higher speeds, it's back to the radiator and or lower radiator hose.

The cheapest is to take the radiator out yourself and take it to shop for proper cleaning.

rickysmyboy · April 2010

just ran it at speed for a few minutes (Actually went on highway for a few miles) The gauge never mooved but after coming back, I felt no resistance change in the fan, is that a correct way to see if the fan clutch is bad or going bad?

Any idea whats the best way to make sure radiator is not plugged? (No more LAME testings)
Thanks for your input.

Mr_Shiftright · April 2010

You'd have to pull it out and have it flow-tested.

Again, if you have high speed overheat, this is probably not a fan problem (air problem).

oldfarmer50 · May 2010

Ok let's see how smart you guys are.

1984 Corvette 5.7L with 100+K miles runs hot at lower speeds. Gets up to a 235 temp before radiator fan kicks on and cools things off. Runs normal at highway speeds.

Am I looking at a sticking thermostat or a defective fan switch or something major?

Mr_Shiftright · May 2010

If you overheat at lower speeds but not at higher speeds, you have an AIR circulation problem, not a coolant circulation problem.

bolivar · May 2010

Your car may be running correctly.

Does it hit 235 before fans with the AC off? Or is your AC dead and not running? The Cadillac referenced below will not let the AC turn on if the AC pressure is low or high.

In other words, for Cadillas Northstars, if you are running the car with the AC off, it is set to let the temp hit about 225 before it turns the fans on. That's just the way they programmed it.

If you have the AC working and on, the fans run all the time (above 195 or so??).

oldfarmer50 · May 2010

"...you have an AIR circulation problem..."

That's interesting. This is a car my son is considering so I have not driven it myself. I'm being told that for some reason the fan does not kick on until about 235 and then it does come on. The present owner say the AC does not operate as it needs some sort of valve. Not sure if one has anything to do with the other but any thoughts would be welcome.

I'm trying to let my son make his own decisions but the urge to "protect" him is still very strong even though he's 25.

oldfarmer50 · May 2010

"...Does it hit 235 before fans with the AC off?..."

Can't say for sure. As I just posted to Shifty, the owner says the AC does not operate. As I understand it, when driving in the city at slower speed the temp reaches 235 and the fan comes on and the car cools to "normal" whatever that is ( for most cars I've owned that would be around 195).

Remember, this is and OLD Corvette so I don't know if the computer in it is very fancy. That's why in my original post I was wondering if it could be so sort of mechanical switch which was the problem. If this is typical of all GM cars that would be fine. I just don't want my son to buy this and find out it's a money pit.

obyone · May 2010

With an '84 vette you might want to check the body out closely since the frame wasn't the best leading to a lot of flexing causing the fiberglass to crack. If I were looking to buy a used vette, I'd look at a C5 or newer as the C5 has hydroformed rails which means a much stiffer suspension and no creaks or body cracks. Just my opinion of course.

bolivar · May 2010

84 Corvette will be a money pit.

kiawah · May 2010

As was my '75.

oldfarmer50 · May 2010

Now you guys are scaring me.

Then again I would think any corvette could be expensive to repair.

The kid has got the hots for this car so the money pit thing may be a moot point. I'm just hoping it's a smaller pit.

Any other thoughts on the cooling issue? The owner suggested installing a manual fan turn-on switch but I was wondering if there might be some other way of fixing such a problem.

bolivar · May 2010

Repair the AC. The fans will probably then run all the time, as designed.

A Corvette is nothing but a top-of-the-line GM. It's a Chevy motor and transmission and Cadillac electronics.

Here is the life line of many Corvettes.
-The first owner babies it. Probably doesn't put many miles on it. It's the car 'he always wanted', or 'it's the 4/5/6 one he's owned'. After about 3/4 years the toy goes stale. Or, if he's a multi-owner, it's time to buy the new model. The car has excellent maintenance from this owner.
-The second owner always wanted a Corvette but never had enough money to buy a new one. He drives it a lot. He keeps it about 3/4 years and then a baby comes, so he has to get something more practical. Usually maintained pretty good. If some small stuff fails, it might not get repaired quickly, if at all.
-The following owners see the car as a 'hot rod', and treats it like one. Maintenance is slipped. If the car starts and gets down the road, all is good. A 'check engine' light is ignored. The AC doesn't work, just roll the window down. The dash display fails, and it's going to cost $1,000 to repair, just keep up with the other traffic for speedometer, and those other displays aren't actually needed.

This is an 85, right? 25 years old. Had about 6 previous owners, at a minimum? It's probably been 'hit' at least one time. It's going to be a money pit if you try to get everything working and keep it that way. If your son just wants it to 'get down the road', it might manage to do that.

P.S. I've owned 4.

oldfarmer50 · June 2010

"...Repair the AC..."

Now that sounds like a plan. If the fan and the AC are interconnected as you say that might be all it needs. Thanks.

As to the typical Corvette history all I can say is LOL. This one was supposedly owned by a doctor in Kingston NY from 1984 until around 2006 when the current owner, a guy in his 70's bought it. I ran a Carfax on it and it came back clean for accidents (at least back to 1996 when Carfax started). I get the impression that the current owner doesn't want to sell it but his wife doesn't want him putting any more money into it.

As I said, my kid has hot pants for it so my opinion isn't worth much. Thanks for the advice on the fan.

Mr_Shiftright · June 2010

Since the subject has come up, I would agree that a 1984 Corvette is not a good choice. It has CFI injection, which is not the best and hard to tune and fix right, and very difficult to modify.

IIRC, the '84 Vette had a thermostatically controlled fan that only worked UNDER 35 mph.

If he likes C4s, he'd be much better off shopping for a later 80s model. Better in every conceivable way.

oldfarmer50 · June 2010

"...better off shopping for a later 80's model..."

Too late, the 84' is now sitting in my driveway. At least he had a mechanic check it out and there seems to be no major mechanical problems.

So you are saying that the fan situation may be a thermostat switch problem? That was what I thought might be the problem.

I least we now have a couple of directions to go. Thank you all for your comments.

Mr_Shiftright · June 2010

Oh the '84 is good enough but if he has dreams of modifications on that CFI system or any future "collectibility" he can forget it. He'd best find himself someone who understands CFI injection, too.

Yeah the fan might be a thermostat switch. That's how it works.

burdawg · June 2010

Is that CFI fuel injection similiar to the Bosch mechanical system that was on my Mercedes 280?

Mr_Shiftright · June 2010

Methinks not. The Bosch system is a Tuned Port Injection, debuting in 1985. So that's called TPI, whereas CFI is the older cantankerous system designed by captives held deep in the GM prison system. :P

burdawg · June 2010

No, I meant the very early mechanical FI that was on the late 70's and early 80's cars. If you remember, they had fuel distributors with diaphragms built in to regulate the flow of fuel based on demand (some later ones had crude electrical controls also), but the flow was continuous to the cylinders. I can't remember the actual names, but things like "Bosch J Tronic" come to mind. I used to have a manual for them, but it's long gone. It was very helpful at the time though I remember. I seem to remember that it first appeared on the 280 sedans around 1975 or 1976, I'm not sure when on the V8's but probably about the same.

Mr_Shiftright · June 2010

Oh I see. Yeah, Bosch did a lot of licensing. Didn't the 1975 Cadillac Eldo use some form of Bosch FI? In any event, whatever GM did to the early C4 injection, it wasn't an improvement.

burdawg · June 2010

Now that I think about it, the name was Bosch CIS, for continuous injection system.

kathysierra · July 2010

We must take care of ac be it residential ac or car ac.
Air conditioning Florida is dedicated to provide air conditioning maintenance, ac repair and, air conditioning services at affordable price.

bolivar · July 2010

What's the price for a service call to northern Oklahoma?

nise188 · July 2010

Some guy told my husband to drop efferdent tablets into the radiator to clean. My radiator overflow tank and cap is getting a real fine silty build up that looks like clay. Engine runs great. Car has overheated twice. Once last summer. Once last winter, from freezing I am sure. When the winter overheating occurred, I pulled over, turned the car off, and "snap, crackle, pop." Then, I put anti-freeze/ coolant in it. Car still runs great. The car is a 1995 Cougar, with over 200,000 miles. Odometer quit at 178,000. It has used oil and water since I got it at about 160,000 miles. We live a mile down a dirt road. But, the car just keeps going and going. I drive it to work 5 days a week, 20 miles each way. Will efferdent work or harm?

kiawah · July 2010

Auto parts stores sell radiator cleaning solution, made for cleaning out the coolant system.

Cooling Systems -- Problems & Solutions (Radiator, Fan, etc)

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