Maxima Spec-R

Well I hate to start a whole new thread for this, but after searching and searching for the past few days, I really haven't found any other threads just like it.

The problem I have is that my maxima is still overheating after changing the water pump, thermostat and radiator cap. The heater blows cold air at 85 degrees on the highest fan setting and the fans run faster than I've ever heard them spin before. I tried bleeding the system this morning and all I got was a lot of steam coming out of the radiator fill hole. The upper hose was very hot and the lower was cold at the bottom and hotter at the top closer to the thermostat. A couple days ago I took the radiator out of the car and ran hose water through it. It seemed to flow just fine in both directions. None of the hoses are collapsing as far as I can see.

So, after reading all of that, does anyone have any ideas on what could be causing the problem? Is there any way a radiator could seem like it flows water fine with hose water but have restricted flow of the coolant/water when in the car? Possibly because of being pressurized? I also thought about the heater core, but wouldn't both radiator hoses still get hot if the clog was back there?

I've seen a couple threads ending in successful fixes of similar problems by replacing the radiator, but I don't feel like throwing more money at the problem unless I have the support of strangers on the internet

Thanks for your insight


******FIXED******

Problem turned out to be a clogged up radiator (jayeyeMax, I knew I had a feeling you were right). A Mishimoto was used as a replacement and damn is it nice. Great to look at, about 3 times wider than the stock radiator and (almost) a direct swap install.






Right out of the box. Great looking radiator







I immediately noticed the HUGE difference in size between the stock radiator. Its about the same dimensions, but the OE radiator core only takes up about 1/3 the usable space where the Mishi uses all of it







I used the opportunity to replace all the t bolt clamps that I hate with stainless worm clamps. Even pressure and look much better







Heres how it looks after the install





So, earlier I said "almost" a direct swap for the Mishimoto. That's because it does have some hangups during the install. The first thing you'll notice is that the fans dont fit right. The two lower posts that hold the fans at the base don't allow room for the fans to fit completely flush with the radiator itself. This is where most people have broken the screws or even the fan shroud itself. Just tighten to the point where they're not gonna come loose and be done with it. There will be about a half an inch gap at the top between the radiator and fans, but it wont hurt anything or shift around while driving. The other thing that's been mentioned before is that the cap hits the bottom of the hood. It does, but just barely. Enough in my case where I could still close the hood, but it felt like it was pressing down on the very front edge of the rad cap. I just took a hammer (as deloa84 suggested) and hit it lightly till it made a shallow dent for the cap to fit into. Other than that, the radiator is a great fit. Hose inlet and outlet holes are sized perfectly for the stock hoses and even with the fans on, theres still plenty of clearance between the header. Lastly, CHECK YOUR DRAIN VALVE before filling with coolant. Luckily, I decided to check mine not trusting Mishimoto to have it tightened all the way, and sure enough, it wasn't.

Thanks again to all of you that posted in here to help me solve this problem. In the end, I replaced just about all of my cooling system, but at least now I know that all those parts are brand new and that I saved about $1000 in labor charges doing it myself.

jayeyeMax

its the radiator restricting flow, i had this same problem where my car would overheat after i changed the thermostat and waterpump i was very pissed it still overheated so i just bought a radiator and it fixed the problem.

njmaxseltd

iTrader: (19)

This is alarming. Does the steam constantly come out or were you able to successfully top the system off? If your constantly getting air into the cooling system, one can conclude you "may" have a blown head gasket.

surban1

iTrader: (17)

from what you report, i'd pull the thermostat and put it into a pot of water and then bring them to a boil to confirm that it's opening properly before i'd replace radiator.

Maxima Spec-R

I've got a good feeling that you're right about that. Did you ever flush out your old radiator before replacing it?

It seems unlikely to me that it could be a BHG. Not that I disagree with what you're saying, but the steam is constant and the radiator never bubbles over like I heard it typically does with the blown gasket and its never been low on coolant/water. It also runs absolutely fine performance wise and I don't smell coolant in the exhaust. At least I really hope its not the head gasket

That's a good idea. I've read that new thermostats can be defective out of the box so I should have done that before putting it on. Though I will say that the original stat looked almost brand new and I shouldn't have even replaced it in the first place. I've only had my max for 1 year and about 10,000 of its 200,000 total miles so it's hard to say exactly what work its had done in the past.

Thank you all for your responses

Edit - I should also include the fact that after I shut the engine down, I heard a gurgling coming from the radiator. I'm not sure if thats helpful but it sounded almost like air escaping the system. Problem still persists and the level of the coolant has not changed.

DBear

I don't mean to be insulting, and I don't even know if it's possible to do it wrong on this car, but are you sure the thermostat is in right side up?

Maxima Spec-R

I don't take that as an insult at all. Even technicians that work on cars all day as their profession have the occasional mistake like that, and I'm just some DIY shade tree mechanic with a lot to learn still. I'm boiling the old thermostat as I write this to see if it opens and if it doesn't, I'll pull the new thermostat off the car and inspect the way I installed it and then boil it too. Theres a serious chance it could be a faulty oreilly auto thermostat that I installed. The thermostat itself is held on in a one way housing with three bolts in a triangle shape. I'm not sure it can be installed wrong, but I'll definitely look it over. Better to take a half hour inspecting work thats already been done than spending a hundred dollars trying to replace something that may not be broken.

DennisMik

iTrader: (2)

Something that has been discussed here on the org is that some non-nissan thermostats don't open as much as the Nissan one. They open at the correct temperature, just not enough, which restricts coolant flow.

It sounds like the cooling system isn't full. But if you have a circulation problem, I can see why. If you are going to take the thermostat out of the car, try running the car without any thermostat in it and see what happens.

Maxima Spec-R

Alright, I just boiled the old thermostat. It opened up like it should. The amount it opened however seemed very small. Does anyone know how far the valve is supposed to move? Its possible the water cooled before it opened fully (dumped boiling water into coffee can rather than boiling in pot on stove, thought itd be easier to see the valve in still water) but in about a minutes time it only opened roughly a couple mm from the closed position. It also shut immediately after pulling it out of the water. If it's not opening completely, theres a chance the oreilly stat isn't opening at all so it still overheats. If it is opening completely, then a stuck closed stat wasn't the problem to begin with and I have to think its the radiator.

Maxima Spec-R

Thats another good idea Dennis. I know you were trying to help me before in the "noobie question" thread. Thanks for following up on that here. That goes along perfectly with what I just found out about the OE stat. If it isn't opening as much as it should and the oreilly stat (Murray brand to be specific) isn't designed to open far enough, then it makes sense that nothing would improve

phatboislim

iTrader: (27)

um...did you bleed/air the system?

Maxima Spec-R

I've tried a few different times. I keep getting steam. How important is raising the front end? I tried squeezing the hoses and revving the engine a bit, but just more steam. If I had access to a floor jack right now I'd lift the front end up and try again. From what I read earlier, it can be done either way, its just faster with the front in the air. I let it idle with the cap off for about 20 minutes this morning while squeezing hoses every 5 minutes or so.

phatboislim

iTrader: (27)

yea i believe so, try jacking the car in the air...i dont know where the bleeder valve is on the VQs or even if it has one. when i replaced my radiator i didnt have to do this, i just left the top off and it bubbled/aired itself out

asand1

iTrader: (1)

If the radiator tube towards the middle (where air flow is the greatest) are plugged, you could overheat while still having some flow.

ShocknAwe

iTrader: (3)

When you bleed it you must turn the heat on as well and jacking it up at an angle does help too

Maxima Spec-R

From what I've read, the VG has a bleed valve but the VQ doesn't. I did a coolant flush a year ago when I first bought my car and just made sure I poured in the new stuff slowly to let out trapped air. I'll see if I can get a jack or at least park the car on an incline somewhere.

There is a group of the tubing that I just noticed is all bent inward from debris hitting it. The tubes are surprisingly weak and easy to bend. The area of the damage is about a 3 inch diameter on the passenger side middle of the radiator. Think thats enough to be a probable cause? More tubes on the inside may very well be clogged.

I made sure to turn the heat and fans on all the way. I need to go out and find an incline to park on somewhere.

ShocknAwe

iTrader: (3)

well really that is not necessary. I don't do that. So the level in both the rad and the overflow tank are where they are supposed to be? I mean you filled the rad up to the top and did the same to the tank up to mid way between min and max? As I started reading I assumed it was a faulty auto parts store thermo. They fail from the get go or about 3mnths down the road. Do yourself a favor and get an OEM Nissan. I have never bought a auto parts store thermo but the Nissan comes with the metal bracket with the neck as well. DO the auto store thermos just come with the thermo itself and you have to remove the existing thermo and replace with the new on the original stock neck?

Maxima Spec-R

I filled the radiator up until I could see water pooling just above the top tubing on the inside. Then the tank I filled until about just under the maximum line in case I overfilled the radiator. I know what you mean about OEM. The pump I bought was OEM as well as the rad cap. I shouldn't have gotten a stat from oreillys but at the time I was sure it'd be a cheap and simple fix. It was the first thing I replaced. The auto store one came with the whole assembly, housing and all. It was a direct swap with the bolts and hose. After looking at the old housing it looks like the thermostat is held on with one directional screw heads (?) that have grips for turning it clockwise and then counter clockwise to unscrew them the screwdriver just slips out of the grooves. Its not stripped, it actually was designed that way for some reason. I might have to get creative to remove it.

ShocknAwe

iTrader: (3)

hmmm well if your level was low you would see the level on the overflow tank drop more than usual when the car is up to temp and running. My guess is a bad thermo. It could open but simply not open enough. They really do fail I would say 1 out of every 2 sold. THey are about the same as auto store starters. They simply don't last

Maxima Spec-R

I just remembered why I dismissed the idea of a faulty thermostat earlier. Wouldn't the lower hose be hot since it flows all the way till it reaches the stat? Or would the hot coolant stay in the radiator since the cold coolant already in the lower hose cant go anywhere?

Edit - I just need to go pull the thermostat out of the housing and find out for myself. I'll be back when I have the results.

Maxima Spec-R

Just tested the thermostat. I pulled the whole thermostat out of the housing, swapped the housing with the new oreilly stat that was on there and drove the car with no thermostat valve. Still overheating

I have more information on it now though. After this last test drive I popped the hood and felt the hoses and radiator. The upper hose, top of the radiator itself, cap and hose going to the reservoir are all very hot. The body of the radiator and lower hose are about the same temperature as the outside air. They feel almost cold in comparison. I'm not entirely sure what a radiator looks like internally, but doesn't that seem like almost certainly a clog somewhere in the top of it? If anything, it'd have to be a partial clog since I already ran hose water through it. I guess a partial clog, or multiple small clogs could be enough to have that effect.

maxgtr2000

iTrader: (29)

I replaced a thermostat on my van that has a VG in it. First time I did it i put the stat in wrong. Corrected it and filled everything and it still ran hot. There is probably some air somewhere in the system. I let it idle for awhile and kept putting in water until it wouldn't take, the temps came down but the fan still would stay on. After a few drives I kept putting fluid in the overflow bottle to the fill line, that ended up taking care of the problem which was air in the system. You should turn the heat on while it is idling because the heater core is part of the system, if there is air in there the only way it will move on is with the heat activated.

Maxima Spec-R

Do you know if it even reaches the heater core if the air feels cold with the heater turned up all the way? I'll try again before I flat out buy a radiator.

DennisMik

iTrader: (2)

Since you have driven the car without the thermostat and still have the problem, this info is in the "nice to know" category.

The thermostat doesn't open a whole lot. This is from the FSM:

Valve opening temperature - 180°F
Valve lift - more than 0.339 in @ 203°F
check if valve closes at 9°F below valve opening temperature.

Maxima Spec-R

Thats good to know. Yeah, I did those in reverse order. I wasn't planning on pulling the new thermostat originally but decided that it'd be a good idea.

At this point I guess I'd like to be a little more certain its the radiator before I buy one. I just asked importrp about pricing on a koyo to my area. I'm sure buying OEM would just be ridiculous. Courtesy parts priced one out at around $360. If I could I'd just buy a mishimoto which I'd like to have anyway, but funds are a little low after spending $200 on other replacement parts.

Thanks again everyone for your recommendations. I'll attempt another air bleeding and if that doesn't work, I'll invest in a new radiator.

Any other advice or success stories from radiator replacements?

DennisMik

iTrader: (2)

You are down to 2 possibilities for your problem - the radiator and the water pump. The radiator is the easier item to replace. I suppose there are places that can test the radiator to see if it is plugged, but it probably costs at least half the price of a new radiator. I've had 3 maximas and 3 koyo radiators and don't have any complaints with them. They do just fine in our 110 degree summer days. I hope you are getting the pricing for the Koyo in the group deals forum.

Here is some more "nice to know" info. Water always flows through the heater core. There is no valve to turn it on and off. Inside the car, heat is regulated by directing the air through the heater core or around it. So when you are filling the cooling system, turning the heat up in the car doesn't accomplish anything except getting greasy fingerprints on the heater control panel.

Here is a diagram of the water flow pattern in the cooling system.

Maxima Spec-R

Thanks for the heads up. I did see the group deal so I'm thinking it'll be around $120 shipped...unless the $106 included that. Glad to hear the koyos are a good buy.

Just recently I read about a water control valve. Its some kind of secondary thermostat supposedly? Anyone ever heard of those failing? The one I heard of was being replaced on a 2000 max.

asand1

iTrader: (1)

The radiator needs to be filled to the bottom of the cap. You way to much air in the system still, and this is why you keep making steam.
What other symptoms are house having? Is the engine actually getting too hot?

Maxima Spec-R

That's a tough one for me to answer. The car has never shut off while I'm driving (I dont drive it far on test runs though) and it feels hotter than normal under the hood, but not super hot. The most important details I can think of are lower hose being cold, the heater not blowing hot air, and radiator fans working on what seems like overdrive at all times. Well that, and the things I've already done. Is steam more likely air in the line, or trapped water in the radiator evaporating because it cant get through?

DennisMik

iTrader: (2)

Steam is water that got too hot and boiled. If an engine is working correctly, this will not happen as the water pump circulates the water though the radiator where it will get cooled to keep it from boiling. If the coolant level gets too low, then the water pump can't push the water to and through the radiator for proper cooling and the water will boil. It creates a downhill effect. Not enough water circulation and the water boils. Steam pressure builds up and the radiator cap lets the steam out. Steam is water in a vaporized form. When that steam escapes, you now have less water in the radiator. Viscous cycle.

If the engine has truly overheated the water till it boils, the steam is routed to the plastic overflow tank by the passenger fender. The steam will cool and condense back into water and fill up that tank. Is this happening?

If the engine is full with coolant, the lower radiator hose will be hot when the thermostat opens and allows coolant to flow through the radiator. If the lower hose doesn't get hot, you don't have any water flow. 3 reasons for no water flow - low coolant level, plugged radiator or bad water pump.

Sometimes it may be necessary to raise the front end of the car up when you fill the radiator, but when you first fill the radiator/engine with coolant, you should start the engine and let it warm up and get the thermostat to open. You do this with the radiator cap off. When the thermostat opens, any air that is trapped in the engine will now get pushed to the radiator and it will gurgle out of the radiator since the cap is off. This process will push some of the coolant out as the air is pushed out. But after the air escapes, if you look into the radiator, it will appear empty. Add coolant as needed and you should see the coolant flowing in the radiator. And like Asand1 said, fill the radiator all the way up to the bottom of the radiator cap. Also make sure the overflow tank is filled.

You don't have a water control valve in your engine. That was an experiment that didn't accomplish anything and was only used in the 2000 and 2001 year models.

Maxima Spec-R

Thanks for the very thorough information. I'll give filling it up and burping the air out one more go, but if that fails I might just end up going over to oreilly auto and buying a radiator for $120. I know koyos are probably more trustworthy and cheaper, but then I'd also have to wait till it got here next week to install it.

asand1

iTrader: (1)

Engines regularly get hot enough to boil coolant. The cap is designed to hold pressure, thereby raising the boiling point. Until you put the cap on it will keep steaming.
Fill it to the bottom of the overflow tube, cap it and fill the overflow to the high mark. As it heats and cools over the next couple days it will release trapped air into the overflow and draw coolant back in when it cools.

Trini Boom

iTrader: (5)

Just recently had this problem. You need to drain your radiator and look inside to inspect for sludge clogging the fins. If there is any sign of sludge, you have some work cut out for you. You need to do a complete flush but it may be a bit late if the sludge been there for a while. Had to replace both heater core and radiator after reverse flush from dealer was unsuccessful in removing sludge.

maxgtr2000

iTrader: (29)

Some vehicles have heater core control valves, apparently ours do not, that is probably why most instructions would be to leaving it running with the heat on. I had to replace a radiator awhile back and got an ebay one for about $80 shipped, I've had it for a few years now, no issues.

Maxima Spec-R

Yeah I've been thinking about a few things since I last posted on here. I'm debating right now if I want to buy a mishimoto replacement since I've been wanting to buy one anyway. It's a little sooner than I'd planned, but why waste $100 getting one and investing in a mishi just a couple months later? It just depends on the price quote I get from JMAuto. If its under a certain amount I'll go for it. If not I'll just stick with a koyo from ImportRP.

Thanks to all who've been offering advice and suggestions on here. I'll be sure to update this when I install the new radiator. I don't want to sound like I'm not trying hard enough to bleed the system, I will try a time or two more while my radiators in the mail. I just feel like at this point if it was air, it'd be out by now. A 15 year old radiator would probably be close to the end of its usable life anyway.

1trucavalier

For future reference. To remove air from a VQ. turn on car with radiatior cap off let warm up to opp temp (cap still off), constant rev engine slightly (low rpm just enough that the coolant flows through the whole car but not bubble all out the radiatior), You will need a 2nd person to slightly pour as your rev. pour while rev, check for bubbles, pour while rev.

cashoit

Agree with Trini.

Test the radiator. Water should flow into the filler neck or upper hose and out the lower hose

user name001

Correct me if im wrong,

arent the 4th gens practically the same as the 5th gen? i have a fifth gen, a good way to bleed the cooling system of air is remove your CTS (coolant temp. Sensor) and fill. when coolant comes flowing out i put the CTS back in, run it till its warm, top off and close the rad cap.

might wanna try that.

Maxima Spec-R

New radiator is on the way. I'll be really careful about pouring in the water/coolant mixture nice and slow when I fill it up. Bought myself a Mishimoto from JMAuto here on the org. They seem like good people, but I've have a few problems with them. I was supposed to get free two day shipping with my purchase but apparently was given wrong information and the sale ended the day before. Still got a pretty good price for the radiator itself and the shipping was free, it's just taking its time getting here. I should have it here by tomorrow or Thursday and then I'll come back and hopefully end this thread by saying it fixed the problem and then describing how good the Mishimoto looks sitting in my engine bay.

ShocknAwe

iTrader: (3)

Its a pretty rad and not gonna lie, I went for it for both looks and function. Never will the cooling required by the car exceed the capabilities of the Mish. BE CAREFUL PUTTING THE SCREWS ON FOR THE FANS!!! The screws break off extremely easy and most likely you wont be able to get it flush like you want