300k

On a 1997 Civic EX d16y5 have the issue where out of nowhere started boiling over but the temp gauge is not reading hot on the dash cluster. The temp gauge is barely at the half mark. Replaced thermostat, still the same, not reading hot but obviously over heating. Have been doing some research and in the morning I'll be taking off the radiator cap, and letting the system run 2 fan cycles and keep topping off radiator as the thermostat opens and air is expelled through the cap opening of the radiator.

According to a Honda Certified Master Technician and graduate of HONDA PACT, the d16 is a very efficient motor that can take between 20-30 min to reach operating temperature.

Ok, so I did some google searches and found posts similar to an issue i was having and the replies are mixed results and the forums didn't have a final fix.

So I reply, asking a question, hoping whoever has been on the thread would still be in touch and may be able to help whoever else out that has a similar problem and I'm getting bitched at like crazy. SAME CAR, ALMOST IDENTICAL MOTOR, SAME STYLE SYMPTOM which can be a magnitude of different fixes.

Why would you NOT want the post to just keep stacking up that way we don't have to search through 50 different threads to find solutions. EVERY thread has different suggestions and tips. It was nice to me to scroll through a few pages of a thread and see all the solutions people have come up with over the years, all for just a little bit different result or symptom.

Did I really steal someones post? Maybe thats what you were molesting me for over on the other forum?

There should be a huge banner on the top of the page that says "NotARaCist needs something to be mad about, please don't reply to threads!"

Or a banner in general that says "Don't reply to a thread or someone will start bitching."

If there's an Admin somewhere on here or a Moderator, I'm sorry, it won't happen again. When I search public domain and see posts about the same problem I'm having I didn't know I wasn't supposed to reply. From this point on, I'll start a new thread.

300k

OK Guys that actually OWN a Honda and not a Cavalier with a Vtec sticker and a set of Konigs:

Let the car run with the radiator cap off for about 40 minutes and the dang thing never read above the halfway mark on the temp gauge in the dash cluster! It was around 50F today. Fan never kicked on and didn't get any burping of coolant expelling from the radiator.

Got a call later on from my Honda Tech - He's very weary of Thermostats being defective. He tells me to take a temperature gun (I bought one of these from amazon for $12 to check engine parts to make sure they were cool enough to work on safely so I already had one) and point it at the upper and then lower radiator hose to check the temp of the hose. This is a great method to test your Thermostat without removing it again. I was advised to check the upper hose and the lower hose and they should be relatively close in temp. If the lower hose is significantly cooler (apprx 30 or more degrees cooler) than the upper hose, this is a for sure sign the Thermostat is not opening. To my luck as it warmed up, my lower hose read about 5 degrees less than the upper hose which he stated was to be expected. Now once the lower hose gets to around 205F the radiator fan should kick on.

Well at about 210F fan still hasn't kicked on so I shut the car off.

I was warned not to let it get above 215F. This indicates either a faulty Fan motor or a faulty switch. The next step here is to take a Digital Multi Meter and test continuity at the plug where the Radiator fan plugs in right in front of the overflow tank. If you have continuity then your switch is good and the fan is faulty. No continuity then the switch is faulty. (Don't forget to check the relay and fuse both in the box by the battery.)

I was told not to jump the connector on the Temp Switch plug at from the thermostat housing because you're jumping a hot to a ground and that can burn things up. (Which I had done yesterday and didn't work.) Turning on the A/C will NOT work to test the Radiator fan if the vehicle has it's own heat sync and fan for the A/C.

I won't be using a meter because I don't have one, but what I WILL do tomorrow is get a radiator with fan from the junk yard ($42) and they'll throw in the temp switch (don't forget a 24mm socket).

I'm going to replace the fan first since so many think jumping the fan will tell you if it works or not. Then I'll have an extra radiator and switch in my arsenal of spare parts. I'll post on here tomorrow and let you guys know what happens.

Hope this was informative, sure eliminated a LOT of guess work!!

rice a roni

iTrader: (1)

So your issue is that your temp gauge doesn't show hot, but your engine is over heating?

On your typical civic, the normal temp gauge needle only goes to the 9 o' clock position at operating temperature.

You're not sure if your fan works or if it is causing the overheating...does it overheat on the highway when you're driving it? If not, it is possible that your fan isnt working. The fan doesnt play a cooling part on the highway.

tony_2018

Pull temp sensor and test in hot water, follow fsm.
Pull thermostat and test in hot water, follow fsm.
pull thermo fan switch plug and jump it to see if the fan circuit is working properly, the fan should come on.

NotARaCist

iTrader: (1)

You do realize your **** attitude isn't going to get you very far, nor ingratiate yourself to people who can help you...right? There is a certain way things are expected to work around here. No two issues are the same, no matter how similar they might seem. If you find a related thread, try those solutions. If they don't help, then you make your own thread, and mention what you tried. This tells us what you have and haven't done, and also shows us that you've put in a modicum of effort.

Now that we have basic posting etiquette out of the way, unless you live in the great white north, whatever technician told you 20-30 minutes to reach operating temp was just trying to get rid of you. Outside of near or below freezing temperatures, the engine should warm up in 15 minutes of idle time, or 5-10 minutes of driving time. If it doesn't, your thermostat might be stuck open (or removed). Test your thermostat. First, visually inspect to make sure it isn't stuck open. If it is, replace it with a Honda OEM thermostat from your local dealer. Don't trust parts store ****. If it isn't, then suspend it in water, put a food thermometer in the water, and turn the stove on. The thermostat should pop open when the water temperature reaches the opening point, which IIRC is 195*F. Yes, this is the proper, FSM technique for testing the thermostat.

Your fan switch should activate the fan at ~210*F. Disconnect the fan switch, and jumper that connector. Does the fan come on when you do that?

While we're looking at things, your D16Y5 is not the original motor for your car. Is it a full HX swap, or just the block?

300k

Yes, my question with this is, the gauge reads cold upon first starting and then climbs to 9 o' clock after running. Normal operating temp. However, when the overflow tank is boiling and there's steam pouring from under the hood, the temp gauge never reads over 9 o' clock.

300k

Ok, so I found that the fan was not working. The fan from the junk yard is installed and engages right as it should. (The fan i replaced did not work AT ALL). Test drove about 30 miles, stopped and there's still steam pouring from the hood. Pop the hood and see the steam is emitting from the radiator area! The fan kicks on and blows the steam away, then when it goes off it starts steaming again, the fan comes back on to blow the steam way.

Even though I believed the thermostat (Honda OEM) was working by my temp gun test, I took it out and tested it in a pan of hot water on the stove, expands and collapses as it should.

What are your guys feelings about it still steaming?

300k

I do not know if this is full swap, everything under the hood looks complete and doesn't appear to have any variation from being stock. Since you're thinking it's possible this motor was replaced at some point in time, I'm now wondering if this cooling system issue is the reason why there's a different motor in this vehicle.

As far as the Honda Tech getting rid of me, this technician spent an hour on the phone with me during the entire warm up process and coolant system bleeding. He advised me to allow up to the 30-40 minutes and stayed on the phone walking me through different steps to narrow this down.

NotARaCist

iTrader: (1)

30-40 minute warm up times still aren't right, unless you're in sub-zero temperatures, like I said.

Steam off the radiator could be a few things. Is it still the original radiator with plastic end caps? It's not uncommon for those end tanks to spring leaks, and if the pressurized coolant is leaking out, that would create steam. Also, check to make sure your radiator hoses have proper hose clamps on them - same reason.

I'm not sure that the motor swap is directly related, but we can figure out if it's a full swap, or just a block swap, pretty easily. Remove your valve cover, and post a picture of the rocker arms. If they're roller rockers, it's a complete Y5 swap. If they're just normal rockers, it's a Y5 block with a Y8 head, which is essentially the same as a straight Y8.

300k

Thanks for this tip, I'm going to check this right away. Not sure if this is the original radiator however the end caps are bright red.

I'll definitely have to look into this. Are you aware of the differences in the Y8 and the Y5. Horsepower differences or economical focus?

NotARaCist

iTrader: (1)

The Y5 is VTEC-E, the Y8 is just normal VTEC. They both use the same head casting, but the Y5's head uses roller rockers to reduce valvetrain resistance to increase gas mileage. The cams are different as well. The CR between the motors is the same, 9.6:1. The Y5's ECU has other trickery to make it more fuel efficient, but the end goal is a slight loss in power in the Y5, with a slight gain in gas mileage. The blocks themselves are pretty much the same, the differences are in the head and ECU.

TomCat39

I disagree with this statement. Operating temperature is considered officially reached once the fan kicks on and it can be 30 minutes on a cool day (not cold) to get the first fan to kick on when burping the car.

I started my wife's car at 10pm in the basement which had an ambient temperature of about 60 degrees F. It was over 30 minutes even with some high idle rips of the throttle (near WOT) for the first fan to kick on. Only about another 5 minutes of idling for the second fan. I was then at 10:42pm.

It was 20 minute process with my car on a late spring, early summer day so ambient temps were even higher.

What his Honda Tech said is exactly the same thing as my factory train Honda Tech with 25 years experience relayed to me. On cold days it can take 40 plus minutes.

Do you have evidence of coolant anywhere. You could have a pin hole letting hot steam/coolant spray out. For me it was the plastic part of my rad the blew, acted similiar and didn't over heat.

Usually you can find evidence of white from the evaporated coolant somewhere in the engine bay.

tony_2018

i hoope you're not using straight water as coolant

eghatch9295

iTrader: (1)

bad radiator cap.

TomCat39

Also should note, not all temperature sending units are equal. The one on my wife's old head put the gauge much lower (maybe 1/3) at operating temp. The one that is on the head of the car now puts the temp gauge almost to the 9o'clock position, just barely less than half way (more like I'm accustomed to).

Once you once you get your fan working properly, you might think about swapping that sending unit. It does go to the head water jacket so coolant will come out when you pull it, and you will need to burp (bleed the air out of) the cooling system afterwords.

I didn't look it up on your 96+ car but I am pretty sure it's in the same area as the 92-95. Jacking up the car on the passenger side could help reduce the amount of coolant loss when you pull that one sensor/sending unit out.

Almost forgot.... The following thread should help you be able to identify your head so you can see what head you have on what block. The block stamp is straight forward while the head is based on casting stamp codes.

https://honda-tech.com/honda-civic-d...-here-3210150/

NotARaCist

iTrader: (1)

TomCat, as I already said, the casting codes between the Y5 and Y8 are the same. What's different is the internals.

TomCat39

My bad, never noticed that.

So yeah, the roller rockers vs tap rockers like you said previously.

spAdam

iTrader: (1)

That was my immediate thought. If the thing isn't holding pressure the coolant will be able to boil at a lower temperature and will bubble in the overflow tank. This is a serious condition as the boiling is happening near the cylinder walls and vapor won't cool the walls... It Can/will lead to detonation and damage if not taken care of.

The thing that's screaming at me though right now is the steam in the bay... Have you pressure tested the system for leaks?

300k

Appreciate the responses. As far as coolant goes, I'm using Honda brand coolant.

There is no evidence of a leak! I've checked everywhere you guys suggested. The fan IS coming on right at 9 o' clock on the gauge from a cold start up.

I'm seeing steam before the fan kicks on which is odd and the temp gauge is about 1/3 when I notice the steam. Temp gauge at 9 o' clock the fan kicks on and blows the steam away. The reservoir stopped boiling over but I'll check for bubbles and the steam is emitting from the center region of the radiator from the fan area. Like the radiator is getting too hot for too long before the fan knows it's time to give it a blow job.

I'll buy a radiator cap today. As far as the sending unit and fan control, it seems everything is on point because the temp gauge is indicating operating temp and the fan kicks on in synchrony. These are two separate circuits right?

Does anyone have numbers regarding tolerances so I can test the sensor plugs with a multi-meter? This type of test should tell me if the sensors are providing the correct amount of voltage or resistance for a proper reading. Does the temperature unit send a reading to the ECU and then from the ECU to the gauge? Or straight to the gauge. Where is the fan switch sending it's reading?

spAdam

iTrader: (1)

The gauge sender and the ecu sender are two separate sensors. The calibration curve for the one to the ecu is in the service manual. All in all you have three temp sensors if you include the fan switch.

There shouldn't be steam under any conditions.

Go to vatozone and get a radiator cap. While you're there, rent a pressure tester. It's free when you return it.

eghatch9295

iTrader: (1)

did i win?

spAdam

iTrader: (1)

I think OP pushed it off a bridge over the weekend. Problem solved.

tony_2018

80% sure but I'm waiting for the OP to do his tests.

300k

It's stated in my replies that I've tried everything suggested except the multi-meter because I don't know what the reading tolerances are.

A Honda tech suggested a Lisle Spill-free funnel to properly ad coolant and burp the system, I just had one arrive today from Amzaon. I work 70 hrs a week so I'm waiting until the weekend to get a radiator cap from Honda and the testing parameters from iN on the sensors.

I'll keep you guys posted