The_Honda_Guy

Hey guys, getting ready to do some service on the car.

My plans were to replace the thermostat, gasket, flush the cooling system, replace the radiator cap, check the heating system, and check that the cooling fans and gauge work properly. What brands do you guys use for these parts and is there anything else I'm missing?

94hatchling

Honestly, unless you just really want to, if the thermostat is working properly, then leave it be. Dont fix what isnt broken.

Typically for a coolant service, i just do a drain and fill...

As for parts, I always like going with OEM. Majestic Honda is your friend when it comes to these parts.

The_Honda_Guy

That's the thing, the thermostat isn't working properly. If I let the car sit and run it'll warm up, but as soon as you start driving it the car will stay relatively cold. I'm sure the thermostat is probably stuck open, so that's the reason for going through everything. I'm pretty sure it's still the original thermostat.

I figured I should stick with OEM on most of the parts. I know that the aftermarket thermostats typically cause problems with getting stuck more often than the OEM ones. Also, I looked around at the aftermarket radiator caps and all of them are 1.3 kg/cm2 compared to the 1.1 kg/cm2 stock cap. This is a daily driver, so there's no point in putting extra pressure on the cooling system to try and raise the boiling point and risk causing leaks. For coolant I was going to go with the Prestone long life coolant since I've had good luck with it in the past and using their radiator flush too.

Any other ideas?

civicsi940

Majestic Honda FTW! i do agree

ChevelleSSLS6

no hose? lol...

...coolant hoses if they're 5yrs/100k miles.

EG8AI

i agree with the oem part--get everything oem honda. thermostat is a cheap fix. if you haven't swapped it out before, might as well swap it now since you're gonna remove the hoses and flush the coolant. upper and lower hoses as mentioned in the above post

while you're ordering, pick up some coolant at the dealership, unless you rather get some from your local autoparts store. don't get the 50/50.. just mix it yourself cause you'll be buying 2 gallons for the price of one--diluted water is preferred if you are **** like me .

i don't know how much you know, but it's just basic stuff. oh.. don't forget to turn your heater control to max before doing all this.. you needa flush the coolant in the heater core also.

The_Honda_Guy

Yea, I guess I might as well replace the hoses too while I'm at it. I was thinking of getting some of the red Samco hoses, but wasn't sure how well they would hold up compared to the OEM ones. I know there's lots of people who use them on their cars, so I figure they can't be all that bad.

94hatchling

SAMCO hoses surpass OEM hoses. You are speaking of it being a DD only, so there is no need in the extra expense for SAMCO versus OEM... just my .02 cents

The_Honda_Guy

Yea, I knew they were good hoses. I see that Samco makes the upper and lower hoses but do they make the heater ones too? Is there maybe another company to go with for the other 3 hoses? I usually like to splurge a little bit when it's worth the small extra money. I might as well replace the upper and lower radiator hoses as well as the 3 heater hoses and get them all out of the way. Also, I'll be switching to the screw type hose clamps instead of the squeeze type ones since the screw type ones don't come loose over time.

I'll for sure stick with the OEM temperature and style thermostat so that it doesn't cause problems. I've seen too many of the aftermarket ones fail and since this is a daily driver I don't want the thermostat to open at an earlier temperature than stock so that the vehicle maintains good heat during the winter. Also, the OEM gaskets have always been the best in my book compared to a lot of the aftermarket. Same kinda goes for the cap. No reason to go for the 1.3 bar aftermarket thermostats and increase the pressure on the system to try and raise the boiling point, not to mention it just puts that much more stress on the system that wasn't designed for 1.3 bar.

Is the OEM coolant anything special anyways? I don't think Honda would even carry the original green stuff anymore since it hasn't been in use for years. I know this car takes the standard 3 year/50,000 mile coolant and not the long life 5 year/100,000 mile coolant. Nice thing is that the Prestone Long-Life (yellow jug) is compatible with the green and can replace it, yet it has the qualities of a long-life coolant.

So my list so far is:

Honda OEM thermostat
Honda OEM thermostat gasket
Honda OEM radiator cap
Prestone Radiator Flush
Prestone Long-Life coolant (50/50 mix)

honda.lioness

--Nothing wrong with changing a thermostat pre-emptively on a car this old. It minimizes the risk of being on the road and having the thermostat fail. Heckuva lot of blown head gaskets out there, and a failed thermostat puts an engine that much closer.

--Make sure you buy a new gasket for the engine block drain bolt. Also, the shop manual says to use liquid gasket on the engine drain bolt's threads. Permatex Ultra Grey gasket maker is what I use.

--When you are purging the system of air, be aware that it may take 40 minutes to an hour for the rad fan to come on twice.

--OEM Coolant is frequently strongly recommended because other coolants are said to destroy the water pump bearings. OTOH, I and I know a few others swear by the orange Havoline brand. I have used it in my 91 Civic for five years now. I have been changing it every two years but am switching to three years for the next cycle. It is possible Prestone has improved its formula, but I personally would not roll the dice on anything other than the Havoline orange or the OEM coolant. The Havoline orange is available pre-mixed and also undiluted. Undiluted is much cheaper. Use only distilled water when mixing.

The_Honda_Guy

I was thinking about the drain bolt before. I noticed it when I was going to do my girlfriend's cooling system service on her 97 DX. Problem is that when I tried to turn it it didn't want to come off very easily. I decided that instead of trying to get it off and possibly snapping it off in the block that I would just leave it and try to get all of the flushing water out myself. That's the only thing that sucks with a car this old is that you run the risk of breaking things like that off, especially if they've never been removed before. If I was able to get it out, I'd use my Hondabond HT, which is essentially Permatex Ultra Grey.

I hear ya about purging the system. Thankfully the D15 has a bleeder valve on the upper radiator hose, but honestly, the cap is the highest point in the system and it should be bled from there.

I think the reason that they say other coolants will destroy the pump bearings is because they're talking about using a long-life coolant (Dexcool, Mopar Long-Life coolant, etc.) when you need to use a standard (green) coolant. I've used the cheapest regular green coolant in tons of vehicles at work and haven't had problems yet. I do know for a fact that if you put green coolant in a long-life cooling system and vice-versa that it will destroy things. A lot of the time it will corrode the cooling system components badly and can ruin the entire engine, radiator, heater core, etc. In my 87 RX-7 I used the Prestone Long-Life coolant as well as using it in my 90 Probe GT and didn't have problems with it. It's also in the girlfriend's 97 DX and seems to be doing an amazing job of keeping a very steady temperature.

The_Honda_Guy

I was thinking about the drain bolt before. I noticed it when I was going to do my girlfriend's cooling system service on her 97 DX. Problem is that when I tried to turn it it didn't want to come off very easily. I decided that instead of trying to get it off and possibly snapping it off in the block that I would just leave it and try to get all of the flushing water out myself. That's the only thing that sucks with a car this old is that you run the risk of breaking things like that off, especially if they've never been removed before. If I was able to get it out, I'd use my Hondabond HT, which is essentially Permatex Ultra Grey.

I hear ya about purging the system. Thankfully the D15 has a bleeder valve on the upper radiator hose, but honestly, the cap is the highest point in the system and it should be bled from there.

I think the reason that they say other coolants will destroy the pump bearings is because they're talking about using a long-life coolant (Dexcool, Mopar Long-Life coolant, etc.) when you need to use a standard (green) coolant. I've used the cheapest regular green coolant in tons of vehicles at work and haven't had problems yet. I do know for a fact that if you put green coolant in a long-life cooling system and vice-versa that it will destroy things. A lot of the time it will corrode the cooling system components badly and can ruin the entire engine, radiator, heater core, etc. In my 87 RX-7 I used the Prestone Long-Life coolant as well as using it in my 90 Probe GT and didn't have problems with it. It's also in the girlfriend's 97 DX and seems to be doing an amazing job of keeping a very steady temperature.

b18cKoupe

Im doing my 94 civic this week, just went to the dealer and got thermostat and gasket and 2 gallons of the oem coolant. That coolant was tough to buy, then I get home and realize its 50/50 and I need 2 more gallons. bastards. Also had to order the drain plug washer.

Im doing all this because the thermostat is stuck closed...I think...the car overheats and the radiator and cap barely gets warm so Im hoping thats the problem. It due anyway haven't done it in about 2 years. Im leaving everything else though, all the hoses look good.

The_Honda_Guy

I'll stop by the dealership and check out the OEM coolant and see what's in it and what it's recommended for before buying it. You should only need 2 gallons of coolant, not 4. Usually the Civic's cooling system can hold like 1.6 gallons I believe. Let me know if you can get the drain plug loose without breaking it. lol

I checked around about the radiator hoses. It looks like Samco makes a kit for my 94 EX but it's only the upper and lower hoses. There's a few other off-brand companies that make silicone hoses for the heater hoses and the IACV hoses too. For anyone looking for a new radiator, holy ****, hit up the deal on eBay with the Mishimoto radiator, hose kit, and fan. It was on there for like 280 bucks shipped. That's a pretty awesome price. IIRC Mishimoto makes some nice OEM replacement parts (cap was 1.1 bar, silicone hoses, stock fan temp). I will probably check out the condition of my radiator and if it is deteriorating may jump on this kit. Besides Samco, who else makes a nice set of hoses?

AK94GSR

mishimoto makes hoses at a good price

honda.lioness

I see the drain bolt and its washer are the same part for all 88-08 Civics. It is on the aft side of the engine for the 96-00 Civics, which I gather is the problem. It is on the front on earlier Civics. FWIW, on my 93 and 91 Civics, I take off the exhaust shield and use a 19 mm, 3/8-inch drive deep socket with extension and 1.5 foot breaker bar to free this bolt. Since getting the right tools, it has not been a problem to loosen. I prefer to free it and drain from it, because I think doing so gets out more of the old coolant and grit that has accumulated.

I was holding off on recommending the Hondabond because it is not as explicit in its labeling about using it for cooling part sealing points. But I expect you're right; it will be fine. I bought my first tube of Hondabond just last week (for an oil pan job) from a Honda motorcycle dealer, at half the price that the Honda car dealer wanted.

It is true many Hondas now do not have a bleeder valve and the instructions say you just bleed through the radiator cap hole, which allegedly (and it seems by inspection) for these Hondas is the high point. I am not so sure the bleeder valve does not have advantages though. I figure it gets the first big pocket of air out quicker, hence first one fills until coolant runs from it in a solid, non-bubbly stream. Then the car is run with the rad cap loose or off for the final bleed. So I continue to use the bleeder valve.

It is not the cooling system that is long life; it is various makes of coolant. The typical American manufacturer's car does not have the aluminum yada parts that Hondas have. I believe using Prestone green caused an early failure of my 91 Civic's water pump c. 2000. The Havoline orange Dexcool, for one, notes that it is suited for certain engines, Hondas among them. From reading of many reports of problems with standard green coolant, I would never advise its use in a Honda, at least not one that a person planned on keeping for more than a year. Saving money by not using Honda OEM coolant is fine, but use the Havoline orange Dexcool. It is proven, AFAIC. The green coolants are not.

b18cKoupe

The Helms says for a full refill of rad and block its 3.6 gallons for the d16z6. Im gonna doublecheck tomorrow before I buy 2 more gallons of that stuff though, and just a heads up my dealer didnt have the drain bolt washers in stock so you might wanna call ahead and order them or get em from majestic.

EDIT: just checked, I read the conversion wrong. it is .96 gallons for the d16z6. (from helm manual) For entire system including overflow.

The_Honda_Guy

Yea, the drain plug on the back of the block can be a PITA to get to on the 96-00 D16's. The reason I didn't try to remove it on the girlfriend's car is because I didn't want to run the risk of snapping it off in the block since it's never been removed before. If I were to snap it off in the block I'd be pretty well screwed. Figured it wasn't worth the risk.

Like I said, I'll stop in at the dealership tomorrow and see what I can figure out with the coolant. I'm wondering if Honda sells a cooling system flush chemical also. Dexcool is made for GM vehicles. It is along the same lines as the Mopar long-life coolant, but is not exactly the same. Also, if you've ever worked on a Kia, their coolant is a forest green color. Volkwagen's is a really light orange color. Certain cars need specific coolant. You cannot use Dexcool in a non-Dexcool GM vehicle, it will destroy the cooling system components. I've seen the effects of using a regular (green) coolant in a long-life coolant system and it's not pretty. That's the reason you don't want to use a coolant that wasn't designed to be used in that system.

One thing I'm looking at is this:

http://cgi.ebay.com/ebaymotors/MISHI...Q5fAccessories

That's an auction for a Mishimotor aluminum radiator, Mishimoto slim radiator fan, and Mishimotor silicone radiator hose kit. Definitely not bad for the price.

One other thing I'm looking at:

http://cgi.ebay.com/ebaymotors/SAMCO...Q5fAccessories

That's the Samco hoses for the D15/D16.

After doing some more searching it looks like for the D15/D16 they only make the upper and lower radiator hoses aftermarket silicone ones. There's a few other cars that have the full heater hoses and such, but not for the D15/D16. I checked Samco's website and Mishimoto's website and they just have the 2 hose kit. Does anyone know if there's any manufacturers that make the other hoses or will I just have to get new OEM ones?

honda.lioness

If you think your gf's Honda's cooling system is really filthy, you can fill it with water, run several minutes, then empty. Observe what comes out. Repeat until the water comes out pretty clean.

The label says it is suitable for many makes. Naturally also read each car's owner's manual. From 1992 on, Civic manuals say the following or similar:

"Always use Genuine Honda antifreeze/coolant. If it is not available, you may use another major-brand non-silicate coolant as a temporary replacement. Make sure it is a high-quality coolant recommended for aluminum engines. However, continued use of any non-Honda coolant can result in corrosion, causing the cooling system to malfunction or fail. Have the cooling system flushed and refilled with Honda antifreeze/ coolant as soon as possible."

The 91 and earlier Civic owner's manuals say to use only "a Honda RECOMMENDED antifreeze/coolant." It is not clear if the engine materials yada design changed from 91 to 92 or Honda found too many folks were experimenting with non-OEM coolant and having problems. I would bet on the latter.

In any event, for the anecdotal database, I can say a few others and I (who frequent one of the Usenet Honda groups) have been using the orange Havoline Dexcool for years without cooling system problems. The one time I had an early water pump failure was years ago when I was using a non-OEM green antifreeze.

OTOH, for a car not my own, I would definitely use the Honda OEM antifreeze. Just saying. Your mileage and extent of risk taking may differ.

The_Honda_Guy

Went to the dealership today and picked up 2 gallons of coolant and a thermostat and gasket. After talking to the parts department there they said the same thing about using the OEM coolant. They said that the regular green coolant had borates and silicates in it that would damage the coolant system in Hondas if used for prolonged periods of time. The Honda long-life Type 2 coolant should work out great. They said that's what they used in all their Honda vehicles that came through the shop. I think I got it for like 12 or 13 bucks a gallon, not a bad deal. Also, you can't beat it's awesome blue color! :D The thermostat cost me a little more, 20 bucks for it and the gasket, but it's worth the extra money.

I also picked up a jug of Prestone super radiator flush at Wal-Mart for like 3 bucks a bottle. I asked at the Honda dealership and they said that Honda themselves do not make a coolant flush chemical, only the coolant. I've always liked the BG products but did not want to spend 20ish or more dollars for the two bottle kit where I was only going to use the flush chemical.

I went ahead and flushed the system with the bad thermostat in it until I got all the old coolant out with a hose, then ran it for a while until the car warmed back up. I added in my coolant flush chemical, let it run, flushed it out with the hose again, let it run, then flushed all the chemical and junk out with the hose, then opened the petcock and let all the water drain out of the system (or most of it anyways). While the car ran I made sure to empty the reservoir and clean it out with some of the flush chemical to make it all nice and clean. After that I changed the thermostat and sure enough, it and the thermostat housing were corroded to hell. I cleaned the housing up with some emery cloth and removed all the build-up, then inserted the thermostat and gasket back in properly (pin facing upwards and aligned with the notch in the housing). I then used my handy spill-proof funnel and started filling the radiator, then let the car run until the new thermostat opened up while letting the coolant bleed through the funnel and bleeder valve. After bleeding it all out and filling the reservoir I was good to go. Perfect heat now, temp gauge needle stays slightly until the small thermometer picture on the gauge, and no surging idle or air in the system. Also, while reading through the Haynes manual, they do not mention using the drain plug in the block, just the petcock at the bottom of the radiator for performing service. Also, their flush method is the same as the one I use. I don't think I'm going to risk removing the drain plug from my car or my girlfriend's car, especially since I'm not sure what I'd do if it did snap off in the block...

I figured for now I would just get the flush and thermostat done so that I could get the cooling system cleaned up and flushed out and have heat (it's winter in Iowa right now) and in a month or so order my new radiator, hoses, and radiator cap. As I said before I'm really debating going with the Mishimoto radiator, fan, and hose package for 325 bucks. To me that's one insane deal considering the Samco hoses alone were over 100 dollars. Also, a new radiator cap from Honda was going to run me 15 dollars at least, and an aftermarket no-name radiator would run at least 150. At least with the Mishimoto I'd be getting quality, performance parts. Also, the nice thing is if I went turbo down the road I wouldn't need a new radiator, fan, or hoses to go with the turbo setup.

My list of parts:

Honda OEM Type 2 anti-freeze/coolant
Prestone Super Radiator Flush
Honda OEM thermostat
Honda OEM thermostat gasket
Mishimoto aluminum half-radiator
Mishimoto 1.1 bar radiator cap
Mishimoto silicone upper and lower radiator hoses
Mishimoto radiator fan
Honda OEM heater hoses
Honda OEM IACV coolant hoses
Honda OEM radiator petcock gasket

So now my couple questions. Is there any other flush chemicals you guys have used? Any companies that make the heater hoses or IACV hoses for the EG? Any other items I could replace/upgrade on the cooling system?

JDMh22eg9

all oem honda we all love it so use it. its more but you get what you pay for

honda.lioness

I would just add that radiators for Hondas are the one item it is way okay to go aftermarket on. The OEM rads for many years are made of some sort of plastic prone to cracking. My 91 Civic is on its second radiator (the dealer broke the first one while fixing, poorly, something else). Rarely do I read a complaint on aftermarket radiators for Hondas. I know no one who says to go OEM on radiators.

The OEM coolant, while expensive, is supposed to last five years or longer, if memory serves, so that is one advantage. Plus one sleeps at night.

JDMh22eg9

i didn't mean the rad. but i didn't say so you guys didn't know haha im running a dc2 gsr full size in my h22 eg9.

b18cKoupe

just did my 94 ex civic yesterday. New thermostat and flush and refill.


The car took exactly 1 gallon of the honda coolant. Just as a heads up, it took almost an hour for the fan to come on twice while bleeding. Everything seems good though, idle is back to normal on cold starts, car warms up and maintains temp like it should. Also I recommend draining both the rad and block. 2/3 of the fluid on mine came out of the block, so if you really wanna flush you have to drain the block, also make sure you buy a new washer for the bolt and put some thread sealant on before reinstalling. And obviously check all hoses and replace as necessary. Its cheaper and easier now than later. It'd be a shame to waste that obscenely priced honda coolant.

honda.lioness

A few years ago I measured what I got out of my 91 Civic's radiator and block (and hoses and heater?). From just the petcock beneath the radiator, 0.99 gallon came out. When I removed the engine drain bolt, 0.25 more gallons came out the block. I think my owner's manual's specs section actually assumes the drain bolt is not removed, since it says 1.08 gallons is needed for a coolant change, whereas the overall coolant capacity (= radiator, hoses, and engine) is said to be 1.35 gallon. The reservoir holds 0.11 gallon, so the numbers add up pretty accurately.