Engine running hot?

But high in that temperature range. Any ideas on how to fix this? I have replaced the thermostat, upper radiator hose, engine coolant temp sensor, cooling fan relay, and the temp sensor that is mounted to the radiator and it is still running hot. I have jumped a wire from the battery to the fan and the fan turns on. My coolant level appears to be fine (the coolant is at the proper levels in the reserve tank when hot and cold and when I remove the radiator cap the coolant is filled tot he top.) The only things I can think of that I have left to check are the radiator itself, the water pump, temp sending unit, and the lower radiator hose.

This issue mainly presents itself when driving around town. On the highway the temperature remains constant. In stop and go traffic it runs hot and when my cooling fan does kick on it is only when the temperature is about to go outside the normal range. It will also fluctuate while driving around town, it will be hot for a while and then suddenly drop in temperature. Any ideas or recommendations on how I should proceed.

Inside car not under hood after driving it, no leak inside and guage is not running hot. What could be wrong? Compession check. Good?

Just cuz you did a compression check, doesn't mean that all the cooling system checks out ok. Check your hoses going into and out of the heater core. Check the size of the hoses to the inlet and outlit of the core. I ran into the same problem with my 92 taurus and the hoses were 2 sizes too big so antifreeze was leaking into the box(not on the floorboards).

1995 Taurus, 3.0L, 123,000 miles -

Thought the car was running fine until I went to get an emissions test. They told me NOx levels too high. The "internet" says that means engine running "hot".

Talked to my dad and he says it could be a number of things. I ruled out most based on how the car was running. The only issue I had was that I had to add coolant a few weeks ago - but I didn't check it when I bought the car in Feb so I chalked it up to normal usage.

I ruled out the thermostat because the temp guage on car was always stable on the cool side of the guage. Until today, when I let the car run in the garage for a few minutes while listening to a song. I watched the temp guage climb above the halfway point and I figure it would have continued to climb if I didn't shut off the car.

Checked the coolant level just in case and it was a little lower - it was noticeable but still above the minumum level. Now I am worried I have a bigger problem. Is this a thermostat issue or something worse? How do I get the engine temp down?

Thanks

Thanks for the reply. Not really sure since I usually run the fan on MAX - the highest setting. Its tough to hear the engine even with the radio off with all the "white noise". In SW Texas near the gulf so not only hot but amazingly humid this time of year so a/c runs full out. I will check when I leave work.

I did have a problem recently, when the a/c was on the car would stall when idling. It would run at 900rpms and then when the engine fan started, rpms would bounce up and down between 1100 rpms and 500 rpms as the fan started and stopped until it went below 500rpms and then stalled. It usually took a couple of cycles when engine was cold, when engine hot it would stall immediately.

I changed oil/filters and I cleaned the idle air control valve (thanks to the tech help on this site) and it solved the problem. Car does have a small oil leak (1/2 qt every 1500 miles) from the oil pan that needs to be fixed. The car runs fine otherwise.

Does that help?

On my ride home, it is 15 miles - the temp climbed most of the way up the guage about 12 miles into the drive. I turned off the a/c and the temp fell to the midpoint and stayed there.

With the car idling and the a/c off, the fan was off. When I turned the a/c on - the fan started almost immediately. I am assuming that is good?

OH NO. Plugged fins! Is it contagious? :Mrgreen:

Thank you, I will read the post and take the appropriate action. Would my plugged radiator fins cause the high NOx levels (my registration expired and I need to pass the test to renew).

Thank you. Thank you

Since I don't have a shop I trust, I will rent a compressor this weekend and let you know how it goes.

Since it is an airflow issue, would a larger MAF help or not mess with it because of the PCM (I'll admit it, the extra HP would be fun).

Thanks again for the help, it saved me from a lot of work I couldn't afford.

Ok, I guess I will take it to a shop. Can I print this thread out and give it to them?

(Sorry for the length on this one) Went to OReilly's and got an air filter, oil filter, that oil filter wrench thingy, a hydrometer, 5 quarts of 10w30 high mileage oil. I asked for a fuel line and they gave me a rubber one. I knew that wasn't what I needed so I told them I needed a different one to make your tool and they just stared at me like I was nuts.

So I went to Home Depot and got a $5 blow gun 1/8", 10ft of 1/4" copper refrigerator line ($7) and a 1/4" to 1/8" compressor coupler ($1.50). Used a small hack saw to cut a 2ft line, put the coupler on one end, used a hammer and pliers on the other, cut a small opening on the end I closed and screwed the coupler into the blow gun - and viola. A fin cleaning tool. (I should have used teflon tape on the connectors because there was some air leakage, but not much).

Had to try it out, so I went back and rented a compressor 6.0scfm at 90psi ($20 for 4 hrs). Did what you said and it blew a whole lot of garbage out of the radiator (I didn't forget the compressor). Kept doing it until I couldn't see any more dust and stuff flying out - took about an hour. When I was done I could look through the condenser and radiator and see light and the fan on the other side.

Hopefully that worked. Tested anti-freeze (never done that before) - good to -40 freezing and 228 boiling point- thats good. Changed air filter, never did that before, took about a minute.

Went to change the oil and I couldn't get the drain plug off - I think the last guy used an impact wrench so I guess I will just have to take that to a quick change place and tell them not to do that again (unless you have a trick to get it off).

Hopefully, this is all I need. I have an appointement for Monday so I will bring my tool in and have them use their air to clean the radiator and put it on the computer to see if their are any other issues. Hopefully, it runs fine and can pass now. I will let you know. Thanks for the help.

By the way. Working on the car almost as fun as working on computers.

1993 Taurus Radiator cooling Fan not coming on. By passed switches and fan works, Radiator fan control relay replaced, main fuse is good. What else controls fan operation?

Got on the highway for 10 miles, then drove around the neighborhood for 10 minutes at about 25-30 mph, then let the car idle in the driveway for 10 mins - engine seems to be mighty happy, no temp creep. I will update after she gets in the shop.

Almost the whole time. I turned it off once for about a mile. Seemed like the car was driving a little rough and I wanted to see if it was the a/c causing it - more like I was a bit uneven on the gas when driving it in 2nd gear. Otherwise it was on all the time.

Had to cancel appointment due to lack of funds. Since the house fire things have been tight (lost everything. Including cars). Here is where I am at now. Took to Autozone to read codes - there were none. Car appears to be running cooler, but I failed emissions again and all tests were much higher. Started thinking catalytic converter issue.

Car rides fine - but when you drive at a constant speed it will randomly hesitate or lurch a little - it is almost imperceptible unless you are looking for it - but it is there. It accelerates fine and there is no smoke from the exhaust. Estimated MPG at 20.8 with the A/C on and all highway driving.

When I parked the car today I heard a sizzling sound from a drip on the manifold. Opened the hood and spit on it and it boiled immediately, it was really really hot. I could now smell antifreeze burning on the engine and a small wet spot on the ground underneath the overflow. It isn't there when everything cools so it seems to happen with the engine running. Temp guage in car at 50% when car is hot.

There is a hose between the overflow and the radiator cap and runs below this small black metal thing that looks like a small oil filter that has what appears to be a sensor underneath it. That is the hose that gets moist and feels soft. Will repair the hose. Could this be a vacuum leak? Thermostat? Timing? Should I still drive the car?

No codes yet. BUT. I still need to pass emissions. So I took the car to a shop. They said immediately it was the Cat Converter ($1200 quote). Can't afford that. Took to another shop - they said the same thing ($1000 quote).

What makes this site great is that us mechanically challenged can bounce the issue off a mechanic and get a much less "profit-motivated" answer. That is what happened with my compressor. Every mechanic told me it was the compressor when it really was low on oil and the idle air control valve.

So even though I didn't get my answer here, I will post what I did. My uncle bounced this off his mechanic and he told me: The rising and then falling temp was probably the thermostat ($12 to replace). The NOx could be carbon build-up and a vacuum leak. The spotting of coolant was probably a loose hose connection from the radiator. If not those then it probably is the cat converter or the small leak in the oil pan.

Yes, the hose from just below the radiator cap to the overflow was loose. Tightened up the connection and used a zip tie thingy to secure and no more leak. I replaced the thermostat and no more running up of the temp guage. I used this Seafoam stuff (mechanic recommended it) put directly into the throttle body to clean the engine. Blew black smoke everywhere (it was quite impressive). Checked vacuum hoses on the manifold and from idle air control to vacuum pump (I learned to read the vacuum diagram - it should be under your hood somewhere or you can get it at Autozone's website). There were four or five hoses that were pretty stiff and cracking. Replaced them all.

Car temp doesn't run up anymore. It is pretty consistent at 25-30% up guage. The little hesistation is almost gone - but I am sure that is just a vacuum hose issue so I will check them all. Once I replace them all, I will take to emission testing center and try once again - I have a much better feeling about it now. I will update if I pass.

Emissions tests improved, but still failed NOx levels. No engine light so no codes yet. I can't keep paying the $40 to have it tested and my registration expires next month. Car runs good so I guess I only have three things to do - start changing out sensors, replace the catalytic converter or sell the thing.

If I have no codes, are there sensors I should start with (like the oxygen sensor). I saw an universal cat. Converter, can I use them or shoud I use OEM. How hard are they to change? Will a cleaner work? Finally, are there valves or sensors I need to change with the cat. Converter?

If it is too much money I guess I can sell the thing and look for old Bronco (pre-'83 so I don't need emissions).

What would make my car run hot. I have changed the thermostat.