Overheating

I've got a 93 Civic LX with the stock D15B7. I've recently been noticing that if the engine runs for 15 mins or so it starts, to overheat. It's only noticeable when the car is at lower speeds (45 and below). When I get on the interstate and travel at higher speeds, the engine cools off and my temp stays right around normal but as soon as I slow down or stop it starts to go up again. I though that maybe it was due to low fluids or a bad thermostat. I changed the thermostat and filled up the coolant. Same problem still. I've checked the fuse for the radiator fan and it's good to go. The fan kicks on. I checked for a leak and I haven't noticed any fluid leaking from the radiator or hoses. I have noticed that there seems to be an oil leak around the crank seal on the side where the timing belt is. I go through oil kind of quick but I'm not burning it. When I top off my oil it doesn't overheat as much (temp is still well above normal but not as bad). When I start cold without my radiator cap on you can see the fluid move while the engine is running. Revving around 3 g's from idle will cause the fluid level to jump up and almost overflow. If I missed anything, I'll try to answer as quickly as possible. I'm on here almost 24 hrs a day. Thanks for taking the time to help.

I think you have a fan problem. Setting in the driveway make sure the fan comes on when it starts to overheat. Just for a backup you can use the A/C... YES the A/C..lol Hondas have a secondary cooling fan for the engine when you turn it on. Fan probs are usually an issue with the relays under in the enigine bay. Also make sure to check all your fuses too.

EDIT!!! --bahhh -- I need read better. Ok hmm... I take it you bled the system good and all? Has there been any smoke when you start the car or during warm up?

No smoke or anything unusual, just the overheating like I described.

head gasket, water pump, air bubble in system. I would try to bleed the system (radiator cap off, let it warm at idle, and then rev it a little). If it still does it, I'd do a compression test to check if the HG is bad. If that's fine I'd say it's likely to be your water pump (just a guess though). :dunno:

When was the last time you change your coolant?

What is your mixture ratio?

It has less than 500 miles on it since I changed the thermostat and coolant. The mixture is 50-50.

Sounds like the fluid is not moving fast enough to cool down the engine when it's just idling after it's been driven. I am guessing there might be a restriction in the radiator (some rows of the fins are clog?) orr the water pump is not doing it's job properly, when did you last change the water pump?

I've owned the car for about 9 months and I haven't changed it. There's no telling when it was last changed but that was next on my list. While I'm there I'm going to fix the seal on the crank to keep the oil from leaking. Hopefully that will fix it.

have u checked the relay switch to the fan. that was my problem when i had my d16z6

...I've checked the fuse for the radiator fan and it's good to go. The fan kicks on. ...

Been there, done that.

I say it probably is either your water pump or the radiator. If the fluid inside your radiator is and was nice an clean prior to your refilling, then probably it is your water pump. How many miles does the car have on? It might be a good time for water pump/timing belt job.

One thing that is interesting is that you have fluid circulating when the car is cold. Technically coolant should not recirculate when the car is cold and the thermostat is closed. Interesting...

I've got about 180,000. It's definatly time to change the belt.

Please let us know what happens after you replace the crank seal, water pump and timing belt, so we might able to use this info for future reference.

It's gonna be a week or two, I don't have the money for all of it yet. Does anyone know a good write up for replacing the crank seal? Also, I decided to go do some prowling and the other day. My car has been sitting for almost a month and a half. I cranked it up and let it run until it got to normal temp. When it didi I took off the radiator cap and my coolant was low by about two quarts. I know when I parked it that it was full. I decided I would look for a leak. I didn't notice any cracked hoses or any cracks in the radiator. I'm going to replace the hoses while I'm at it. The only thing I did notice was a spot on the tranny side of the valve cover where it looks like it's leaking oil. I hadn't noticed it before. It's really small. I'll definatly let you guys know when I replace everything though.

UPDATE: I haven't had any money to do anything yet but the car is on blocks and I'm having trouble breaking the bolt on the crank pulley. It's still gonna be a few weeks untill I get it finished. Any help on the crank pulley would be appriciated. I've already broken a socket trying. I'm about ready to try an impact wrench.

An impact wrench will be your best bet. Other than that, try a pipe on the end of your rachet to get more torque.

i have a b18b1 in my civic and when i was changing my timing belt i had to use an impact gun on the highest settings, those bolts are really on there, good luck, and i would replace your radiator. thats what it sounds like to be personal, you can get a good one in the junk yard for 20-30 bucks.:smokin:

Does anyone know of a full front radiator that fills the space for the ac condensor?

UPDATE: I finally pulled the crank pulley, timing belt and water pump. The pump appears to be ok because it was holding back a good bit of fluid without leaking but the gasket is in need of replacement. The head appears to be leaking oil all around. I will pull the head tonight and let you know what shows up.

UPDATE: Well the head gasket was shot. There doesn't appear to be any signs of warpage. The mating surface for the head will need to be cleaned for sure. So far there doesn't seem to be any problem with the valves or the cam. They look to be in pretty good condition for having 180,000 miles on them. I'm going to have the head checked for excess warping this week, hopefully it's ok.

Would there be any advantages to swapping the pistons to the ones from a D16Y7, lower or higher compression, more hp ect?

I've got a valve seal leaking so I'm going to go ahead an replace the valves and springs with titanium counterparts. Does anyone have recommendations for those. While I have the head ripped apart I'm going to port and polish.

Total of two valves leaking and finding stronger replacements that aren't custom made is almost impossible. COMPCAMS is the only place I can find any for the D15B7. I'm positive that a combination of the leaky valves and the headgasket were the culprit for the overheating. Now all I need to do is get all my new parts together and do the rebuild. I'm waiting for some parts to come in and the time to do it. I'll let you know how it goes.

you shouldn't have to replace the valves unless they are bent. All you need to do is to clean them off with the wire wheel and re-grind the valve seats.

Don't forget to test the valve springs, most likely your exhaust side are the ones that failed. If I recall right I think both sides have the same specs, you can swap the intake side springs to the exhaust side and just get new intake springs.

I don't recommand you to replace a larger radiator unless you know what you are doing, cause you might need to change your thermostat. Not to metion if your engine is running too cool your will have "limp home" problem.

About the port and polish, you will just need to polish the passages, no need to port it. Porting the D16Z6 head for NA will make the engine run worst (I have done this and checked it with the air flow tester, it actually will cost you more gas and lower HP) unless you are doing a force induction.

That's all I can come up for not in a short moment, but it should get you back on track with better performance. Good luck.