Topics that apply to all 92-95 civics
By EJ1ITR
#354427 Hi everyone. I need some advice. I have a 95 civic with an B18cR swap. I am running the stock civic radiator.

Recently my car started to overheat. Upon some investigation I discovered that the coolant was overflowing out of the reservoir tank and emptying the radiator until it was too low on coolant and the engine would overheat.

I thought that it was the head gasket leaking and letting combustion gases into the coolant. Note that the engine runs fine and there is no smoke. Compression test shows 270 psi in each cylinder.

I tested for exhaust gas in the coolant today with a block tester and it came back negative. I tried it three times and the fluid never changed color. While doing the test however, I noticed some small black pieces of rubber floating in the radiator. I picked them out and this is what I got: http://grab.by/Iq8u

I am thinking that they are from the bottom of the radiator cap but I am not sure because I never payed attention to the bottom of the cap before; I dont know what it is supposed to look like. Can someone confirm this for me?

Also I noticed that revving up the engine caused the coolant to rise. It lowered again when the radiator fan kicked on which I thought was weird. Is this just the thermal expansion of the fluid? Im talking about around .5" difference.

My problem might just be the radiator cap which will be awesome if so. The head gasket is only about 2 years old and I really don't want to install a new one again. It is OEM in case you were wondering.

Thanks in advance!
By MG6
#354430 take a photo of your rad cap.

as for the overflowing coolant. did you change your T-Stat? If not, might be time to change this out.

Also, water pump? Did you change this out yet and what is your last time it was changed?
By EJ1ITR
#354431 Thanks for helping out.

Here is the pic of the cap: http://imgur.com/VFVXga3

I went to pep boys and bought a new one which has 2 layers of black "disks" on the bottom which is missing on mine. I forgot to take a pic of it.

I installed it and so far it doesn't seem to be overflowing anymore. I will find out for sure when I drive it on my 50 mile commute to work tomorrow. If it does fix it, the next thing I am going to do is flush my cooling system.

As for the thermostat, its around 2 years old and is the next on the list to change if the cap doesn't fix it. The car only overheats when it gets too low on coolant; if it was the thermostat, wouldn't it overheat regardless?

The water pump is new, installed earlier this year, along with a timing belt and cam seals.
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By suspendedHatch
#354432 Yeah, the cap wore out and wasn't holding pressure, then the system boiled and pushed coolant out the overflow. Replace the cap, flush the system, refill with 50/50.

The best way to flush is to remove the thermostat (might as well replace it) and remove one of the heater hoses. Get some milk jugs to catch the coolant that will spill out even though you've drained the radiator. Once everything is drained, blast the hose directly into the heater and radiator. The heater core gets gooey and doesn't get flushed properly if you just go from the radiator. There's also a bolt on the block next to the exhaust manifold but that may or may not be overkill, depending on the severity of your OCD.