JonBaillio

First post here so thanks for reading and helping.

94 Civic DX 1.5 ltr, automatic

Car has new thermostat and no leaks. Blown engine was replaced with used right before I bought it. It neither leaks coolant or oil. I bled the coolant system and fixed the temp gauge. Fan comes on but never shuts off.

Here is the strange part. Car will idle all day in park with the ambient air temp around 102 (North Texas Summer) with the AC on and will never overheat. I drive it and put it under load and it will not move above 25 percent on the temp gauge until I stop at a red light for more than a minute.

At that point it starts moving quickly to hot. I quickly turn the heater on to remove some of the excess heat and keep the temp down.

Again I am not loosing coolant so no head gasket issues. The only symptom other than getting really hot is that the upper radiator hose swells. I am curious to see if the radiator fan should cycle off because it is not.

Any direction would be helpful.

Jon

Ploeg8393

Is it actually getting hot or is it a gauge malfunction? I had this problem like this right after a swap. My temp gauge would always read high no matter what i did. I actually spent a lot of money trying to fix it. Problem was my transmission ground. I caused the meter to jump around and above normal.

Check those grounds.
Does the fan cycle on/off when you are idling?
Is the air extremely hot coming out of the vents?

I also think it may be some blockage since you stated the hose swell (thats what she said). Hose swell is normal but not excessive hose swell. There could be partial blockage in the radiator, engine, thermostat or somewhere else that allows enough coolant by to cool the car at idle but not when you are moving (engine rev = water pump increase). It could be acting like a thermostat but not opening up when you need it to. Know what i mean?

Open you radiator cap (when cold) and see if there is some degraded coolant in there. It will be brown in color and chunky.

If you are not afraid of getting dirty, remove your radiator and flush it out with the garden hose to make sure there is nothing in there. (cap on, garden hose int he upper radiator hose, plug the overflow, close the drain plug). If it has good flow you should be fine.

You can also do this to the engine but make sure you remove the thermostat first.

If all else fails, replace the thermostat. don't take someones word for it.

JonBaillio

thanks for the reply.

No, the fans do not cycle when idling. The Radiator fans simply stays on.
Temp gauge is working and the car has actually gotten hot enough to send coolant out the overflow.

I am pretty sure that the radiator it'self is clean but that may be a good call about flushing the block. Not exactly sure how to flush the block though, any ideas?

As far as the thermostat, I cam getting fluid cycled through the system so I am pretty certain that it working but is it possible that it could be installed backwards and causing a blockage?

Thanks
Jon

96DelSol

Turn the car on and inspect the lower hose, if its cool and the top hose is hot and swelling then look into your thermostat and do a full radiator flush...

JonBaillio

Thanks for the reply. I did a lot of research on here first and have done the upper hoes hot/ lower hose cold test but both are getting hot. but only the top on is swelling.

Again, is it possible to actually install the thermostat in backwards and cause a blockage?

Jon

Ploeg8393

Hmm, don't remember, its been a while since i changed one, but i guess anything is possible. And if it is backwards it would cause blockage.

To flush the block:

remove both hoses from the radiator
remove the hose from where the thermostat is
remove thermostat
replace hose near thermostat
insert garden hose into the upper radiator hose
turn on garden hose


Is the fan always on, even when the car is cold? Or does it turn on once, then never turn back off?

When the car is running and it is warm (normal temp) are both hoses pressurized (it will be hard to squeeze them)?

JonBaillio

Update:

Replaced upper radiator hose installed Prestone back flush kit. Also used their flush product per instructions. Radiator fluid was nasty and here is why: there was rust in the system.

My bet is that the used engine set for a long time without being drained and rust built up in the passages. So I'm sure that I got a lot out but not everything because when I put the new hose in and thermostat (figured all that sludge couldn't have been kind to it) there was still crud in the hose connections.

Fan would always stay on because someone had installed the jumper across the leads. Removed that and the radiator fan would kick in just after the system had warmed up.

All this to no avail though. Drove it around the block and it still tried to overheat. So I'm still confused. Any other idea guys?

I may end up taking it to the radiator shop and seeing if they have a better way to force all the rust and crud out of the cooling passages in the block and head. that is unless you guys have any other suggestions.

Thanks in advance.
Jon

lynxs1981

Have you checked the sensors in the head? If there was that much rust in the system, it could cause a host of problems, possibly a trashed water pump.

My advice, remove your thermostat for a bit and drive it. This will let the coolant move freely and help with rust removal. Then change the fluid and replace the thermostat.

Ploeg8393

if there is rust in the system there is rust in your headgasket. i would try to force the fluid the other way to move the rust out of the head gasket.

JonBaillio

After all my work it is still overheating.

So at this point I essentially have two options:

1. Have the Radiator cored out (chemical cleaning) with the whole system be professionally flushed. Flushing the block just uses water though as the shop does not use solvents or other chemicals. This will run me $175.00

2. Replace the radiator myself and pray that the block can be back flushed using the kit that I installed already. Local parts store has radiator for 90 bucks.

So which is better? If I go with option 2 is there a better than stock replacement that I can use? I don’t want to spend the money on the racing Radiator but simply something slightly better. Does the SI, Integra, or 1.6 liter automatics have larger radiators that bolt into place of mine?
As a reminder mine is a 94 1.6 auto coupe.

Again thanks for the help,
Jon

Ploeg8393

First you already have a dual core radiator since you have an automatice (cooland and transmission fluid both run through it). Well you should. Your radiator is sufficient for that car, no question about it.

DO NOT GO WITH OPTION 1. A NEW RADIATOR IS CHEAPER.

I bought a radiator at a junk yard for 50 bucks one time, work perfectly. If you find one at the junkyard that has fluid in it, it is probably in working condition. Make sure it has the connections for the tranny. Or buy a new one.

JonBaillio

Yeah, and I finally discovered that their is a small leak in the radiator somewhere.

I found that Rock Auto has one for about 60 bucks Shipped. I'll will most likely go that route and throw in an additional Trans cooler to to lighten the load on the radiator. Probably can do it all for around 100 bucks.

HondaPartsHero

I've bought a few from these guys, awesome fit, cheap prices

$40 OEM replacement (includes shipping)
http://cgi.ebay.com/ebaymotors/92-93...Q5fAccessories

$65 All Aluminum replacement (includes shipping)
http://cgi.ebay.com/ebaymotors/92-93...Q5fAccessories

JonBaillio

Thanks guys. I buy a lot of stuff from Ebay but I went with Rock Auto for the Radiator in this case. It is 64 bucks shipped two day. I will be installing a plate transmission cooler as well durring the install. Together this should reduce my temps and protect the transmission better.

Next will be be cap/rotor/plugs/wires. Funny thing is that I haven't had a car with a mecahnically driven distributor in so long I am having to dig deep to recall everything I need to know.

Thanks for the help guys. I'll take some pics of the install and post them up in a few days.


Jon

JonBaillio

So yesterday I got the new radiator in. I also upped for a tube and fin style additional transmission cooler installed inline.

Once I had the old radiator out I did another backflush because I could still see rust residue in the upper water inlet going into the block. Although the coolant had only been in there about a week it still had enough of an orange color to make me nervous.

After the install came the refill. I started with a bottle of SuperCool by Gunk products. Could have used Purple Ice or Watter wetter but went with this. Now here is the strange thing. I poured in about 3/4 of a gallon of coolant (not pre-mixed) expecting to add equal amount of water. Unfortunately that completely filled the radiator to the neck. My assumption is that the block was still full of clean water from the flush. So I ran the car to circulate fluid. It remained at the same level after turning on the heater to insure that it was flowing through the system.

Now the test drive. The car maintained a temp about 1/3 of the way up the gauge! I was so impressed with my self.

Later in the day I took for a highway drive and again it ran perfectly Until.....


I decided to flip a u-turn. I had to slow down fast and when I turned around the temp started to climb quickly to about to 3/4 and continued to climb until pulled over and shut it off.

The car wasn't boiling over and the fan was on. The system did what it should and quickly brought it back down.

So my thoughts are that this was an air bubble (I bled the system a couple of times) or too much anti-freeze and not enough water.

It was 103-108 outside yesterday when I drove it so that certainly doesn't help.

Wanted to post this rather long update. Thanks for reading and especially if you have some ideas.

Jon

JonBaillio

So as is typical in this sort of repair in this old of a car you fix one thing and it leads to another.

After all listed above it still wasn't cooling very well although when it got hot it was able correct that with just a few moments of idling. So I notice a drip that got bigger and bigger on the back side of the block. At the connection of the main coolant line where it comes out of the water pump there is a line that runs to the IACV. It was leaking at the clamp.

Seems like a simple fix but where the hose is connected you really have to struggle to get a clamp on there. I got a new clamp on only to see the corroded hose pop a hole just behind the new clamp. So in the end, I put a new hose on, cleaned the IACV as I removed it to make it easier to reconnect the hose, and all seems better.

Hopefully this will help someone else later on.

Jon