I have a kind of strange issue with my car. Its 2002 infiniti i35 with mileage of 183k

About 4 months ago I was driving and car overheated and big hose that goes to the radiator blew. I replaced it.

About 2 months ago I was in the parking lot with engine running, I saw that it was overheating. I shut the car off and after one hour the car was running with no issues.

Week ago I was driving and car overheated. I noticed that it was leaking coolant at fast rate under engine. I thought it was water pump leaking, but when I took it to mechanic, he said it was gasket at thermostat housing. He also recommended me taking the car to a specialist to see why its overheating as according to him, even though he replaced the gasket, problem is not fixed.

I know the fans are working, at least sometimes, radiator does look old, but not sure if its the issue. What do you guys think?

 

Hopefully he replaced the thermostat at the same time.

It's possible that the radiator is clogged. Look in the white plastic overflow reservoir and see if there's any mud in the bottom. Follow the small coolant line from the radiator cap to find the overflow reservoir. Be careful with the reservoir. It will be very brittle.

 

Blown hoses and leaking gaskets can also be a sign of a blown head gasket. The exhaust gases can escape into the cooling system and pressurize it causing the leaks and blown hose.

Try running it with the radiator cap off. DON"T OPEN IT WHEN IT'S HOT. It should run and rev up without spitting any water out. You may get a little overflow as the water heats and expands. If it's spewing water or has bubbles you're pressurizing it with exhaust gases. Let it run till it gets hot and kicks the fan on. This won't totally rule it out but if it's spewing you know there's a problem.

 

Start with the simple stuff first -- air in the cooling system, old coolant, bad rad cap, dead cooling fans. Next order would be radiator, thermostat. Last are the water pump & head gasket.

 

No, he just replaced gasket and actually did it for free

I guess I'll have have to check radiator level on daily basis until I figure out exact issue.

I'll start the car today with cap off and see how it goes.

 

When the top hose was blown, I replaced it and filled with new coolant, so I doubt its air or coolant. Speaking of bad rad cap, I did not notice any leaking over there.

Cooling fans are working, unless they are messed up and work only sometimes. But so far when I start the car, the fans turn on eventually.

 

If you do not have the a/c on, the radiator fans will not run all the time. They will cycle on and off. But if you turn the a/c on, the fans will run constantly. And both radiator fans always run at the same time. If you ever have only one fan running, that means the non-running fan is bad.

When you fill a radiator, it is quite possible to have air pockets trapped in the engine. You have to have the front of the car elevated about a foot and run the engine with the radiator cap off until the thermostat opens and allows coolant the circulate through the radiator.

 

Last time (yesterday) radiator was filled by mechanic.

I started the car with cap open, fan kicked in in about 15 minutes. Coolant was calm, no spewing, even when fans kicked in.

I guess I could do what Dennis mentioned as well.

I noticed that OEM thermostat cost like $20. Do you think I should replace it based on my symptoms? Or first make sure there is no air by lifting car upfront and having it running for 30 minutes?

 

It couldn't hurt. I've personally never had any issues burping the cooling system in a Maxima but it doesn't cost anything to try it.

How did the overflow tank look inside?

 

I looked at it, but didn't see any issues. Maybe mechanic drained overflow tank as well when he was fixing it.

For now I am caring gallon of water in my trunk for emergencies, but thinking that car can overheat at any given time is not good. I might replace thermostat just so I know for future that that part is good.

 

check to see if the coolant hose near the oil pan is leaking, sometimes they get old and swollen. I had an issue with mine where i took my car in for an oil change at precision tune, and they damaged the hose and all my coolant leaked out. Luckily i saw the temp guage moving up and shut the car off. They said they didnt touch the hose, but i know differently. They ended up replacing the hose and the coolant for free.

 

I just reread this thread and it seems like it hasn't overheated since the water leak was fixed right? If that's the case I don't see a problem. All of this is simply because your mechanic said it might not be fixed. If it's pissing a puddle that'll cause it to overheat. I can't think of what else the mechanic could be worried about.

I'd just drive it for a while and see. I'm not sure why the mechanic thinks it's going to overheat again but it doesn't seem to make sense.

 

I saw the puddle only on the day it overheated. And I had issues with the car overheating 4 months ago and 2 months ago. I never added coolant after it overheated 4 months ago, so I don't think it was leaking all time.

I think overheating caused gasket to be blown couple days ago. I don't see puddle or any leaks after gasket replacement and radiator water level appears to be the same.

I guess I'll just keep checking radiator level for now and monitor gauge levels of engine temperature very closely.

 

I also noticed this sound.

https://youtu.be/0Aucf8elv6M

You think its thermostat?

 

I don't know what that sound is, but it is not good. I can guarantee you that the thermostat is not making that noise. Thermostats do not make any noise - period.

 

Could be the belt tensioner or one of the accessories. Get a mechanics stethoscope and have a listen around the accessories by touching each one with it. These are a "must have" for anyone who wants to work on a car. Just be careful with it near the belt.
http://www.harborfreight.com/mechani...ope-69913.html

You could also pull the belt and run it to see if the noise goes away. That would narrow it down.

 

So today in the morning, I started the car, noticed that it got to normal temperature level pretty fast, but got to work with no issues. I work 10 minutes from home.

I went up to pick my lunch and the car started overheating. I immediately pulled over and confirmed that fans are running. Instead of picking up lunch, I remained in a restaurant for 30 minutes so that my car can cool down a little.

On the way back, in couple minutes car started overheating again, I was able to get to work, driving with no A/C, but gauge was at about 80-90% high.

So what do you guys think? I didn't see any leakage. I checked coolant level last time on Saturday morning and level was normal, the same as it was on the day I got it fixed (Wednesday).

Yesterday, after driving for about one hour, I saw that the gauge was in the middle instead of usual slightly below middle, but eventually it went down.

 

That noise you're hearing could be a failing water pump. It's pretty rare but these cars aren't getting any younger. If you remove the belt you'll have a much easier time narrowing down the sound.

If not the pump I'd be looking for a clogged radiator.

 

I see, which belt are you talking about? the one that turns alternator?

I ordered thermostat and will replace to be safe.

 

It happened again, on the way home car overheated. I parked it. Lots of coolant was missing, seems like same gasket is broken.

For 3 days straight I was checking coolant level and it remained topped. Not sure what happened in last 2 days, but now my car is disabled once again.

I am curious why the local mechanic referred me to some foreign car specialist to troubleshoot the problem. Could be that he didn't know how to replace the water pump.

But I think it is time to take it to more expensive mechanic and pay a big bill.

 

Are you sure all of the rubber hoses are ok? I'm not just talking about the upper and lower radiator hoses. Check the rubber hoses that run across the firewall then around driver side of motor where the change to metal then back to rubber. Check all of them make sure the rubber isn't swelling on them.

Next I would fill everything back up leave rad cap off jack front of car up. Turn the car on heat on high let it run. Look for bubbles to start bubbling by the rad cap. Let it run a while it won't blow in ur face as long as u leave cap off. As it bubbles and water/antifreeze gets sucked down keep topping the rad off. Leave it running a good say 15 min doing the above steps. If you notice the bubbles stop for a good while and the fluid is full turn car off put cap on. Eat some dinner after an hour come back check the level. If it's dropped top it off and make sure the over flow tank is filled to the right level.

As you're watching for bubbles also be looking for leaks. Feel the bottom side of hoses check for small leaks ect. A mechanic is probably going to bend you over to replace the water pump so try everything else first and leave that as a last resort.

 

Thanks for all your help.

My mechanic called today saying he is confused as well with the car.

On Sunday, it was overheating, I added gallon of water to the radiator. Then I took it to his shop (30 mins away). Today he called saying water level on the radiator was full. So apparently it didn't leak at all after I added gallon of water. But sometime before, it lost gallon of coolant.

He said he will lift the car and see if he will find there any issues. He also said that noise that was in the video is gone now.

 

Check the Infinity factory workshop manual. Follow the overheating diagnostics thoroughly.
Scan the TSBs too.
Use a volt meter and jump the fans, check the relay switch operation.

 

Could be a worn drive belt it says in the Max chart for overheating. Those things can wear down to under 120 lbs.

 

Ok but just so you know you may want to or have the mechanic do the steps I wrote out above in my last post. What happens is air-pockets get trapped in the system and sometimes it can make the car over heat or get hotter than normal. By lifting the wheels removing rad cap letting car run with heat on high you can see the air pockets bubble out of system. Just a suggestion.

 

Sure, I'll let him know. It's strange though that the radiator has been replaced with coolant 3 times already (through out these 4 months) and overheating was always the problem. But it worth a try.

 

That's because air is in the cooling system. He can replace the coolant 20 times it won't help. It shouldn't have been replaced each time. If you follow the steps I mentioned above this should remove any air pockets in the system

 

Has there ever been stop-leak in the cooling system? I worked on a Toyota once with similar symptoms. Someone had put stop-leak in it with the wrong type of coolant. It clogged some of the smaller passageways causing overheating.
It was hard to diagnose since it didn't make much sense. Replaced the radiator. inspected the pump etc....

 

You think this mechanic is shaking this guy down?

 

Yes because they should've already got to the bottom it within a few hours.

When they say coolant are they putting 50/50 in? The system takes over 2 gallons of 50/50. So if you flush the system with water fill radiator up with concentrate antifreeze because 1 gallon of water is in the block.

 

No, he brought it to the mechanic with this problem. The stop-leak idea is just a long shot. If it was the case it most likely would have been put in a while before.

I also wonder if the car was ever run with just water. I've seen other cars run on water for so long that the fins on the pump corroded off leaving just the shaft. With reduced circulation you'll have overheating. With overheating you'll boil out the water.

I don't think the car has a water leak. I think the car has a circulation issue that's causing it to oveheat and lose water. Probably through the expansion tank. The mechanic could put some UV dye in the coolant and drive it till it looses water again. That would at least give an idea of where it's coming out when it does lose water.

It's common for a diagnosis to take longer than a "few hours". I've seen it take days to figure out what's causing interment problems. It can take an hour or more for a car to cool enough to even spend any time under the hood.

His issue has nothing to do with the coolant mix or the belts.

 

Not sure if it will help in any way, but here are videos from overheating

 

Stop-a-leak would be excess foreign material.

It wouldn't really make a difference what's clogging it.

 

You're blowing gases back into the system.

Did you do a Block Test?
Is the Car Losing Rad Fluid?
I also see steam coming from the bottom of the motor?

Bubbles and Gas blowing back into the reservoir tank is not a good sign.

 

Just a quick update. My mechanic called saying he replaced pump and chain tensioner (I asked him to replace tensioner as well).

He said pump looked good, so it appears it was never an issue. But he said he found a leak under thermostat. He said it was where metal pipe goes into engine block. I am not sure how that connection is called though.

Let me know if you know what it is.

 

I googled it and I guess it's this one

 

any updates?

 

any updates???? i am having similar issues, hoping derrick can chime in ! my car is at mechanic shop now and will post progress.

Driving home from work friday on 65mph highway, notice a drop in rpms while feathering the gas pedal on highway (cruising in a cruise control manner), then buckling and more loss of rpms, look at temp gauge its at 100%, pull over after babying it 1/2 mile, coolant reseviour boiling over flowing, hang out 35 mins, resviour completely empty, get to a gas station 3 miles away and reseviour boiling again and temps 100 % in the 3 miles, buy antifreeze for what was boiled over, waited 35 mins again, filled up 1/4 of the antifreeze bottle to max in tank.

drove 3 miles again got to 100% temp, and boiling reseviour again, left car at friends house, filled up resviour w almost rest of antifreeze bottle, got it to the mechanic shop, but ti was %95 temp and just under boiling over (engine bay dry, but bubbliing to the brim in resivour tank)

at mechnic shop now. replaced radiator in 2014 with Koyo or whatever name, and do not believe i ever had to do thermostat, and replaced ECTS 12 months ago thanks to derrick helping me with a code (he suggested either thermostat or ECTS first, and it was ECTS that got rid of code at that time)

 

Part of your problems getting home stem from the fact that you apparently don't understand the purpose and use of the cooling overflow tank The key word is overflow, as in excess. So when you had the overheating problem, trying to refill the cooling system by adding coolant to the overflow/excess tank was the incorrect thing to do.

The cooling system needs more liquid than that little tank can hold. So you never added enough coolant to make a difference. Whenever you need to add coolant to the engine, you have to remove the radiator cap and add coolant that way. And you most likely have to wait more than 35 minutes before you remove the radiator cap on a car that is overheating because of the cooling system being pressurized which does not allow liquid to cool as fast.

As to why the engine overheated is anyone's guess. Since you do not work on the car yourself, you will have to wait and see what the mechanic finds. I just hope that you didn't do any damage like warp the head by driving the car as much as you did with the engine overheating.

 

ughhh... this all scares me..... =(