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Engine temperature gage goes up and down.

05-23-2005, 03:38 PM
Hey I have a question/concern here. When Im driving my 91 honda civic hatch it runs fine. There are a few problems I am having with it though. Number one is when I am driving it in any speed but 80 the engine thermometer goes up and down consistantley. No matter if Im changing speeds or anything like that, I can go a constant speed and its changing. Also my second concern is I have a high idle. I have already tried cleaning the IACV with carb cleaner real good, and that worked for about 2 days but then it came back. Would that fail a state inspection? I live in Ohio and need to get car inspected in 6 days along with getting a new exhaust on cause it has a whole in pipe and Im sure it wont pass alone with that. Well any help will be greatly appreciated thanks!

05-23-2005, 03:51 PM
Check your throttle cable. Make sure it's not wedged in place. You can turn the idle down with the idle screw if you need to. Also, if your temp keeps fluctating, I'd say you need to check your connection on the guage or thermostat itself. Don't want to overheat...

05-23-2005, 04:03 PM
My temp was doing that for a while. I kept thinking there was just air in the system (which could be the cause, it just wasnt mine) my problem was the thermostat. does yours get a little hot while cruising sometimes, then go down to normal when you pound the gas?

05-23-2005, 05:19 PM
Hopefully this doesnt sound stupid, but where is the throttle cable and the idle screw located? Yes it will get hot when traveling on the freeway doing normal speeds of around 70-75, but I dont notice it dropping when I hit the gas. It just goes up and down whenever really but when Im doing 80 it seems to stay in the middle.

05-24-2005, 07:22 AM
You should definitely check for air in the line. There is a little breather bolt that you can loosen while the car is running right in the front near the distributor just above the upper radiator hose. When it starts to bubble a bit, tighten it back up. Do a search on here though cuz I forget if you should turn your heat on high or whatever during this process. If that doesn't work, might want to get a new thermostat.

As for the throttle cable and idle screw. You really shouldn't have to mess with it unless it's already been messed with. I'm not familiar with the dpfi as much as the mpfi... if you have the mpfi or si model, the throttle cable runs horizontally to the throttle body and runs just behind the fuel rail. On the dpfi set up I think it's longer, goes vertically to the front of the car and loops around or whatever. Anyway, I noticed when I had a high idle (didn't mess with it cuz cam and fan stays on all the time) I noticed it was pretty high in the winter in cold starts, and the reason was because when my engine was replaced the throttle cable was wedged against the engine bay wall with no slack. I gave it slack and adjusted the idle screw as needed. GL

05-24-2005, 11:39 AM
yeah i had that same issue, but when i figured it out after replacing the heater core, the thermostat, and radiator i got really pissed because it was the most simple thing in the world, this might not be the issue for you, and it probably isn't, but it might be...did you check if your coolant resevoir has a hose going into the resevoir itself, mine didn't and it would go fine for a while and then it world go up and down in heat randomly, i put a new hose in there and it works great now, it's worth a look before you go spending the kind of money and time i spent when you can spend it tuning out your ride.

05-24-2005, 04:20 PM
Watch for headgasket problems now. ;)

05-26-2005, 04:41 PM
Yes there is a hose from the resevoir to the radiator. Should that be completley full? Still cannot find the idle screw, anywhere. Will this mess with me trying to pass the state inspections?

05-27-2005, 08:59 PM
well something weird happend today. The same thing was happening with the needle going up and down on the temp gauge. But when I got off the freeway then drove about 5 miles off freeway, I came to a stop sign, then my engine light came on, and smoke was coming out under the hood, and big clouds of white smoke form tail pipe. I had to park the car at work as that was my destination and I was there. When I got off work I had a guy take a look at it that was a mechanic at chevy dealer for like 20 years. He said the oil looked ok (no milkyness to it). So I went from work to the nearest gas station and poured water in the rad and the resevoir. At first the needle went up to high but I think that had to do with it just getting all in the system, cause the coolant looked pretty low as it is. So after stopping after another 10 or so miles I put more water in and put in a few quarts of oil, that was low too. Now after running for about 20 miles it has been fine. No jumping in temp gauges, and no smoke anywhere.

Any suggestions?? Sorry the rambling.

EF You
05-27-2005, 09:13 PM
sounds to me like you have either a crack in the head, a crack in the block, or a crack in the throttle body or Idle Speed Control motor. the first two mean your engine is shot, the last two give you a little hope.

heres what you do, start the car with the radiator cap off. if the radiator starts bubbling a lot of air out of it, you have a crack in either the head or the block, and engine compression is leaking into the coolant system. another way to confirm this is if your upper radiator hose tries to swell up, or by doing a compression test. another really good way is to pressurize each cylinder with air using a compression tester threaded fitting and any air line for air tools. do each one for a few seconds with the radiator cap off. if its cracked anywhere internally, it will bubble steadily from the radiator.

now, if you are lucky, which you probably arent, its just a small coolant passage in the intake system. look around the intake manifold and you will see a bunch of small black coolant hoses. they feed coolant into passages in the throttle body, ISC, and valve cover breather tube. this is supposed to keep the incoming air warmer for cold climates, or some other almost useless BS. sometimes the internal passages in those things crack, and cause coolant to suck into the intake. what you need to try is to bypass all of them. take the one that goes to the valve cover breather from the intake manifold and disconnect it. do the same for the throttle body ones and ISC ones. now, you should have an open fitting on the intake manifold and on the black pipe under the intake manifold (the one that connects the thermostat housing to the water pump) you need to connect a hose from one open fitting directly to the other. this bypasses all the intake coolant passages, but leaves very little chance for those other fittings to leak. if you just block them off, they might leak under pressure, but if you connect them to each other, they can still flow.

try that first, and if the car still blows whites smoke, start looking for another engine.

05-27-2005, 09:34 PM
My money goes on a futre headgasket failure. Happened to me, and my friends DX under the same conditions.

Good reason to upgrade. ;)

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