Overheating 91 Accord LX

look for bubbles in the expansion bottle. if you have any, it's definitely head gasket. you'll see them at idle when the motor is at full working temperature. traditional symptoms of water in the oil are rare in hondas because of the wet cylinder liner configuration - any gas leaking from the cylinders can only go into the coolant unless the head is cracked.

regarding repair, are you planning on doing the work yourself? if so, the math works, but if you're having it done by a shop, examine the economics of simply replacing the engine with a used low mileage japanese import engine. head gasket repair takes hours and is very labor intensive. shops also routinely skim heads, which i personally don't approve of unless there's a definite head warping problem.

snipped-for-privacy@charter.net wrote in news:1172925865.592113.240130@

If the car begins to overheat when the engine is operating at elevated speeds, there is a problem with heat being shed.

What coolant are you using? I wonder if your block and/or rad is silted up and not allowing sufficient fluid flow.

How old is the radiator, and what brand is it? If you have an automatic, is the rad a dual-core or single-core?

It's a brand new radiator from Advance, the motor is low mileage by Honda standards (85,000). Since the fans don't come on with the A/C I'm leaning towards it being either : A) The fan timer ( I think I've found where it is in the car , but I'm not sure exactly) B)A wiring problem between the switch and the fan motor. C)Fan motor

But since neither of the fans are coming on with the A/C it's screaming to me that it's the timer.

P.S.: I swapped the power window relay with the Fan relay on the under- hood fuse box, and no change.

you're barking up the wrong tree dude. if the car overheats when you're on the freeway, it's /not/ the fans. freeway airflow vastly exceeds fan-induced airflow. especially this time of year.

check for gotchas like newspaper stuck to the a/c condenser, but mainly, look into the head gasket. you only need to over-heat the motor once [say a crack in the old radiator] and differential thermal expansion can break the seal. from that point on, it's going to leak slowly, which you won't notice, then faster, until you do notice. overheating at freeway speed is one of those symptoms.

Yeah, but still the fans not coming on with the A/C is another symptom towards it being a switch or relay.

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Are you keeping the reservoir filled to the -MAX- mark (per the manual)? It's one of the best ways to really figure out what's happening. If you don't keep enough coolant in the reservoir the temp sensors can end up high-n-dry when the thermostat opens and then the fan won't run when you come off the highway.

It's also a good way to tell if you're USING coolant, either to displace air or through leakage. That's why the manual tells you to make sure to fill the reservoir any time you change the coolant or have work performed on the system. It just makes sense to keep some reserve in the reservoir.

My coolant stays at max summer and winter, by itself. It's a 'peace of mind' kind of thing.

'Curly'

It is right smack dab between the Min and Max mark, it never runs any lower, or higher. I also ran it up to temp and turned the A/C on a little while ago and let it run for about 10 minutes. The temp never went up past half on the gauge (should be around 195 degrees). And neither of the fans came on. I unplugged the A switch (the one that controls the radiator fan) and checked it for continuity with my volt meter it showed a constant flow across the terminals of around 11.5 volts. Noting that the upper hose is hot, and the bottom hose is pressurized, this tells me that the water pump is flowing correctly, the thermostat is open, and the switch on the outlet housing has continuity. It's looking more and more like the timer is bad.

snipped-for-privacy@charter.net wrote in news: snipped-for-privacy@31g2000cwt.googlegroups.com:

This is NOT your problem. Fans are there to force airflow through the heat exchangers at IDLE. At speed they are neither used nor needed.

You have a problem with fluid flow through the cores or through the block. You should also verify the actual temperature with an infrared thermometer, just to be certain it isn't the gauge misleading you.

Did you use an OEM thermostat? Just because the upper hose gets hot doesn't mean the thermostat has opened, or has opened enough.

When the car is beginning to overheat, feel the rad all over with your hand. Is it equally hot all over, or are there cooler spots?

Another one I just tried was jumpering the connections across the harness that plugs into A switch. by theory, and advice, this should have made the fan come on. The fan did not start. I then used my handy old volt meter to check and I was getting 13.5 VDC across the harness which tells me the circuit is powered up. The relay is good, as I checked it by swapping it with the power window relay right next to it and the power windows still work. It's either got to be the timer, the motor, or the wiring.

snipped-for-privacy@charter.net wrote in news:1172943632.961090.180270 @z35g2000cwz.googlegroups.com:

This does not tell you the thermostat is open, or is/isn't open all the way.

Tegger, I used a Stant thermostat from Advance and installed it at the same time as the radiator about 3 weeks ago. The dealership said I was getting proper coolant flow through the block as they checked out the water pump under warranty. The reason I am suspicious about the radiator fans not coming on when the A/C is engaged is I have been told by several people that the fans should come on with the A/C.

ok, now we're getting there. use a honda thermostat. yes, the aftermarket "should" be ok, but it isn't. make sure it's fitted correctly too. right way up, right way out. forget the fans in your diagnostics. you'll need to fix them, but they're not the cause of the overheating.

How old is the radiator? You are stating the classic conditions for a plugged up unit...

JT

snipped-for-privacy@charter.net wrote in news: snipped-for-privacy@n33g2000cwc.googlegroups.com:

There ya go. Rip that sucker out and put in a proper dealer thermostat.

Bet your problem goes away.

Turns out it was a brand new junk thermostat from Advance auto parts. Installed correctly and everything. We used a buddy of mine's IR temp gauge and noticed that the temp was 195 on the engine side of the thermostat, and 120 on the hose side. BINGO!!! no coolant flow. Thanks for the input.

snipped-for-privacy@charter.net wrote in news:1172966925.365404.103140 @c51g2000cwc.googlegroups.com:

Ah, the joys of aftermarket parts!

Hope you learned a lesson here.

Though I have not had any overheating problems, I am going to get a couple of OEM thermostats for the next incursion into the cooling system. I'm convinced!

JT

I learned my lesson with my old Volvos, the first cars I had in a while that had temperature guages. Aftermarket thermostats, mostly Stants, were all over the place. Some were too hot, most too cold, and nearly all of them wandered up and down the temperature scale at will. The first time I used a genuine OEM thermostat it was like magic.

Mike

I don't get it. If it's so well known that aftermarket thermostats are crap (I had the same problem once, replaced the thermostat and the problem remained), isn't it time that they got sued? Car manufacturers with bad parts have to do recalls.