Howdy, I have owned this car since new. Currently 177k on the motor. runs great, adjusted the valves at 100k. flush trans every 20k, oil every 3k. Timing belt, water pump done at 110k honda OEM parts, belt looked great. Anyways, the past week i noticed some fluctuations in the engine temp never over 200 but normally its rock steady, I run a scan gauge. Checked the overflow and it was full, didn't think much of it. Next day opened the cap and noticed the coolant was low. A few days prior if the car sat a few days i had a stumble at idle for 15-20 secs. In one swoop i decided to do the plugs, original dual platniums (i had cleaned them several times) radiator cap and original thermostat. That solved my rough idle and temp fluctuations. When i tested the thermostat it was stuck closed. Luckily we have had a decently cold winter in the north so no over heating. I added coolant the next day after i a drive to work to cycle the engine. Checked it the next few days with no change and let it go. Today, 5 days later i check it again and radiator was low. Overflow tank level hasn't moved. I thinking small head gasket leak. I put a pressure tester on the radiator and it very very slowly drifted down. I also set it to 10 psi and started engine, when i revved it i could get it go up i psi.

Anyways, only thing else that comes to mind is a heater core leak, any additional input would be appreciated.

 

How much fluid have you lost? You are either leaking or burning it. The passenger floor area would be wet if you have lost a considerable amount from the heater core.

Good luck with the search. I had a coolant leak in my Integra about 2 months ago. Turned out to be the hose going from the block to the hater core was split. Makes sense as the car didn't lose coolant until it warmed up and I turned the heat on. Thankfully it never overheated according to the gauge as it was like 10º F each day.

 

Look ever so carefully around the overflow reservoir. My guess is that the radiator is filling the reservoir ever so slowly and the excess is going out the drain tube. Check for white deposits around that drain tube of the reservoir. Head gaskets are all too common on these Hondas and yours is, quite frankly, overdue. A buddy at work has discovered that his went bad and that there was no overheating on the gauge. The guess is that the air pocket didn't get hot enough to run the gauge up.

Good eye catching yours and tracking it diligently.

Ed Fisher
Dallas, Tx

 

While fingers crossed, I pulled the head in the evening over several days last week. If the gasket was bad, it was very very minor. Which relates closely to issue. I would only lose coolant after my 25 mile drive to work on the highway. On slow city driving I wasn't getting any loss. I checked the head at work with an indicator and it was under the .004 spec. So I stoned it and top of the deck. Getting it all back together was as much as a challange with all the random hidden connectors. I will also say, f pulling the intake seperate. I just pulled the head with it attached. Then replaced the gasket off the car. I also ordered the exhaust studs and Bolts with oem gasket kit. Worked great, had 3 studs strip nuts so I had to weld them to get them free. After a few heat cycles I think I'm good, system has burped and levels is holding.

 

Nice job. I did the same on my 1994 and had another head gasket problem a year later. It turns out that Honda had upgraded the head gaskets but the local dealer sold me an old one. That didn't bode well for my dealer parts guy trust. I educated them and this list so hopefully no one has to re-learn that one.

Thanks for getting back to the list. Sometimes people don't do the follow-up.

PS- I had to label all of my connectors. Advanced years makes my memory fuzzy it would seem....

Ed
Dallas, Tx