tiffaj

I recently bypassed the heater in my 1997 Maxima after the core developed a leak. A month or so later the car suddenly started overheating without losing coolant. I had a new thermostat installed with no improvement. Thinking that the problem must be caused by air trapped in the cooling system I tried to bleed the air using a spill-free funnel while running the engine. Running the engine for about 10 to 15 minutes after the thermostat opened resulted in a lot of air bubbles being released, but after about 15 minutes air started belching out at such a great rate that coolant continued being sprayed all over the engine housing and I had to turn the engine off. I've since tried the same procedure again with the same result, and unfortunately the car still overheats. I assume that the coolant is starting to boil when the belching starts. The other thing I've noticed is that the level of coolant rises substantially in the spill-free funnel after the thermostat opens (I would have expected it to fall). Does this suggest that the overheating is caused by an obstruction in the cooling system. Any help you can give me will be greatly appreciated since I've completely run out of ideas.

Quickywd01

iTrader: (16)

Did you have the heater on full blast while doing this? Do you rad fans work?

tiffaj

Yes the radiator fans do work. they come on about the same time the thermostat opens and they seem to stay on continuously after that until the car is turned off.

I have bypassed the heater by disconnecting the hoses at the firewall and connecting one hose to the other via a U bend.

Quickywd01

iTrader: (16)

I hope your headgasket hasn't blown up. Check the oil for coolant.

tiffaj

No, there's no sign of coolant in the oil or oil in the coolant, and the engine seems to run well.

Trini Boom

iTrader: (5)

No coolant in oil leads me to believe its only two things:
1. Still lots of air in the cooling system
2. Water pump degrading.

Quickywd01

iTrader: (16)

One guy pulled out his water pump and all the blades were rusted off. Whatever hose water he put in there must've had a lot of minerals in it.

tiffaj

No coolant in oil leads me to believe its only two things:
1. Still lots of air in the cooling system
2. Water pump degrading.

When I squeeze the top radiator hose and accelerate the engine I can feel a surge of coolant inside the hose. I understand that this indicates that the water pump is working.

I've tried to bleed the air out so many times already without success, but I guess I'll keep trying unless anyone can offer any other suggestions.

asand1

iTrader: (1)

Water and oil don't always cross contaminate. Combustion gasses can push into the coolant passage while running with no other symptoms. Have the cooling system tested for carbon monoxide (block tester).

CMax03

iTrader: (3)

bypass the core for now and test it for any further problems

Quickywd01

iTrader: (16)

Blown headgasket. Combustion gasses are blowing into the coolant and causing it to bubble and once the thermostat opens it lets the gasses come out like crazy. Just my guess. Good luck.

tiffaj

Thanks, this explanation certainly explains the symptoms. Is there an easy (cheap) way to confirm that it is the head gasket? Asand1 recommended testing for carbon monoxide in the coolant with a block tester. I don't know what this is or where I could get it done but given the age and value of the car I don't want to end up spending more than the car is worth.

asand1

iTrader: (1)

Its a quick test any shop should have. Check you tube for explanation.

The Wizard

iTrader: (43)

The cheapest option is to buy the test fluid for $12 and rent the block tester from Autozone for free.

Napa has the block tester and fluid sold as a kit for $35.

There's Amazon too..a bit pricey but offers the double chamber for the most "accurate results" according to the manufacturer

FanaticalKilla

That UVIEW tester is the exact same as the Bluepoint tester I used at work. The Detroit Diesel engine was pregnant, eh I mean the head gasket was toast lol They work awesome.

CMax03

iTrader: (3)

Are your coolant hoses swelling with air pressure?

DennisMik

iTrader: (2)

Maybe the radiator is plugging up and not allowing enough circulation. Try reverse flushing it.

Here are the photos of the corroded water pump that Quickywd01 talked about back in post # 7. Scary!

You gotta scroll down to post # 31 for the photos.

http://forums.maxima.org/5th-generat...-speeding.html

Quickywd01

iTrader: (16)

Good points to be taken into consideration.

tiffaj

Thanks to everyone for your help. This definitely seems to be the way to go. If it confirms that the head gasket has blown as it likely will, is anyone able to comment on the use of "Steel Seal" as an alternative to replacing the gasket?

tiffaj

No, not at all

The Wizard

iTrader: (43)

I'll spare you the details, but no, I do not recommend using "Steel Seal" or any other similar product on the market.

clint240sx

iTrader: (2)

Silly question, but if replacing the water pump, is the chain needed to replace as well, I know that they last a very long time (most cars do their timing belt when they change it)

JvG

A timing belt and water pump change out should happen at the same time. No need to change both out on the Maxima.

dwapenyi

iTrader: (3)

Ummm

To clarify, Maximas from 1995 onwards have a timing chain, and, assuming good maintenance like regular oil changes, will last for the life of the motor.

When changing the water pump, also replace the timing chain tensioner, not the whole chain.

max-nutcase

Never on a maxima, but if u do not intend to put cash into it, its worth a try...ive seen steel seal work quite a few times on cars, and few of them are still on the road with 3 plus yrs and 45k miles since steel seal...but i wouldnt use it if you have cash to fix and wanna drive it 5 more yrs

clint240sx

iTrader: (2)

Thank you sir, that's exactly the help I was looking for. Appreciate it
I knew we had a chain, but only heard info about them outlasting the engine
Never did that kind of maintenance before on mine

captchaos

I have a similar issue.

I had a leak a few months ago. I fixed the leak.

The past couple of weeks I needed the heat. Heat would work sometimes and other times just blew cold air. Yesterday morning I try to start car and it would not start. It also made a loud nasty sound as the car turned over. It would not start. I opened the rad cap and put as much 50/50 in as I could. It was only a few cups. For the past few months I only had water in the cooling system. When I had the leak I was going through gallons of water every week.

Now 2 nights ago, leading into yesterday morning, it was the coldest day of the season. It seemed like the water in the cooling system froze. FINALLY the car started... no loud nasty sound, and everything seemed fine. It seemed like a small miracle.

I went to drive the car today for the 1st time since all of this and it overheated pretty fast - only drove about 5 miles. I pulled over and let it cool, started again, drove a little more, let it cool, and also took the radiator cap off (too soon.) When I did this the fluid blew out of the radiator cap like a fierce volcano. I let car cool and left the radiator cap OFF. I let car sit for about 20 minutes and then I drove home. Leaving the cap off seemed to work best. I got her home (about 5 miles) but as I was coming down home stretch the needle was getting very high again.

It appeared leaving the cap off helped a bit. I don't think I would have been able to get her home as fast if I didn't.

I have a serious problem.

Any suggestions???

The Wizard

iTrader: (43)

Captain Chaos,
First, confirm that your fans are working. Both fans will kick on when the coolant temp reaches 203 degrees. They will cycle off after about 15 seconds when the temp gets below 203 degrees.

Secondly, park on a steep incline, remove radiator cap, and burp the system of any air. Make sure your heater is on too, and on full blast on high temp heat. Rev the engine to 1500rpms for a few minutes and see if you see air bubbles in the radiator.

Third, feel the upper and lower radiator hoses once the car is nice and warm. If only the upper is hot, then either you have a bad thermostat and/or a bad radiator cap.

asand1

iTrader: (1)

Frozen water, bad noises, and overheating sounds like you FUBARed the water pump.

captchaos

Ok I parked on slight incline in driveway, started car with Rad cap off, and let her idle. I added water cause I know I lost some last night. The water was bubbling in my large funnel and leaking out as well at Rad cap (did not have leak proof funnel.)

The Rad fan did coem on.
The needele did not go past halfway but I kept adding water.
After a good 10 minutes I felt both Rad hoses.
The top was warm/hot to touch. I could squeeze it and feel fluid running through it.
The bottom was cool/cold to touch and nothing was going on.

based on your analysis I should replace the Rad cap and Thermostat for starters?

How does a Rad cap go bad?

DennisMik

iTrader: (2)

A radiator cap has a spring in it to allow coolant to escape if the pressure in the cooling system increases too much, which is about 15 psi. This spring can wear out from being used/compressed too often.

In a car that doesn't have any problems, the spring is compressed and allows coolant out when the car is started and the engine warms up. When the engine is turned off and the engine cools off, the spring is compressed again to allow coolant back into the engine.

The maintaining of pressure in the cooling system is not as critical as many people believe. Should you develop a leak or small hole in a hose while you are driving, remove the radiator cap to eliminate the pressure that forces the coolant out through the leak. Make sure the radiator is full and you can drive quite a distance like this before you would need to add water again.

But back to your problem. If the lower radiator hose doesn't get hot, either the thermostat is not opening or the radiator is plugged up. This would not be the radiator cap. You can try reverse flushing the radiator first and see if crud comes out. I would take the radiator out of the car, but I suppose you could do it in the car, but it would be more difficult and probably pretty messy. This is cheap, no parts needed.

CS_AR

I try to only use Nissan OEM thermostats and radiator caps. The dealers usually keep those in stock. Those are two OEM engine cooling items that can keep you from losing an engine.

I've also used Stant radiator caps without issue on one of my other cars with a cast iron block.

captchaos

Months ago I had a leak and "fixed" it by putting Bar's Leaks in the radiator. Do you think this could have contributed to the overheating problem? I know I'm going to catch some not so nice words because I did that.

It was a pinhole leak between the engine and windshield - very hard to see let alone get to and I did not have anyone to do the work for a decent price at the time. I took a chance and it worked BUT now I have this overheating issue.

The car ran perfect for a few months though.

Fakie J Farkerton

iTrader: (51)

Bars stop leak should only be used at shady used car dealerships.

Your heater core is probably toast too.

captchaos

DENNISMIK: I took both hoses off the radiator and flushed the radiator with clean water. There doesn't seem to be any clogs in the radiator or the hoses.

I just bought an OEM Thermostat from Courtesy Nissan.

I guess this is the next step?

The Wizard

iTrader: (43)

I agree that the primary role of a radiator cap is to pressurize the system, but it can also cause overheating issues if malfunctioning and/or has leaks.

Just last week I fixed an overheat issue on a 95 Maxima, where the upper hose was hot and the lower was cool. I instantly thought thermostat but did my diagnostic prior to replacing parts. The issue with that Maxima was a combination of air in the system and a radiator cap that wouldn't hold pressure (I have a Stant radiator cap tester and cooling system tester). Even after I got all the air of the system, it didn't overheat anymore, but the temperature would hover at 205 degrees at idle and the low fans would stay on forever. It wasn't until after I replaced the radiator cap, did the cooling system behave as it should and the low fans would cycle on and off as they should. After careful examination, I believe the cap was letting air into the system through the top, contributing to the problems.

asand1

iTrader: (1)

No water flow would be another indication that the impeller is bent straight or sheared from the shaft.

captchaos

Ok here's where I'm at... I've burped the system for a good 20 minutes. I filled radiator while idling, on incline, with heat on full blast. If I drive with Rad Cap on she will overheat after only driving a few miles. If I fill and drive with Rad cap Off I can drive for several miles before the needle starts getting high. I then pull over, let her cool down a few minutes, and refill with water. I can then drive a few more miles (cap still off.)

Symptoms/things I'm going to do:

* I removed both radiator hoses and flushed Radiator with water. There was no clog in the radiator.
* WHILE BURPING SYSTEM THE Upper RAD hose is hot - lower RAD hose is cool
* Just got thermostat from Courtesy Nissan. I'm going to have my buddy put in next weekend.
* I want to blow out the heater core but I'm not sure where those hoses are. My buddy will know I'm sure.
* I'm going to buy a new OEM Rad Cap just to play it safe

So at this point I assume the problem can be:
* Bad Thermostat and/pr bad Rad Cap
* Clogged Heater Core
* Bad Water pump

THOUGHTS?

Fakie J Farkerton

iTrader: (51)

Radiator cap is my guess.

Don't be afraid to give it a couple revs while idling at an incline. Might force some trapped air out.

The Wizard

iTrader: (43)

I would do the cap first since it's the cheapest and easiest. Then replace the thermostat.

If you care to diagnose the thermostat, you can pull the thermostat and throw it into a pot of water and heat it on your stove. At 180 degrees, it should open. All you need is a cheap $5 thermometer for this test.