Hey all, New to the forum, really struggling to solve an issue and hoping to find some tips and tricks.

So I have a 1993 Accord LX with the F22A1 and 4 speed automatic trans with 390k miles that I just recently took ownership on.

It's been overheating since I got it, with the symptoms being it overheating going up hills or sitting in traffic, heater on full blast would help lower the water temperature gauge.

With that, I went down the list of diagnosing what it could be, I found that the cooling fans were not switching on at a certain temp, but would turn on with AC on or with a jumper installed into the fan switch connector, verifying fan functionality. I purchased an oem honda cooling fan switch/thermo switch. Since the car was older I decided to just throw parts at it thinking it would at least help with the next 400k more miles so at this point I have changed each of the 4 related sensors found from the thermostat housing, under the distributor, and on the neck coming out of front of the engine for the fans to turn on with the car off. I also thought a really thorough flush was in order so I used distilled water to flush the system 5 different times...I will say, the fans were operating per normal with the last of the 5 flushes, that's when I felt comfortable to drain and refill with the honda coolant, thinking it was solved, put in the coolant and call it good. I put in the coolant, the issue is still present.

At this point I use a website service called justanswer to ask a honda mechanic for more tips. That mechanic and I follow a pattern of thought that leads us to believe the water pump simply isn't moving enough water to sufficiently trigger the thermostat and cooling fan mechanisms. So I change the water pump and timing belt. Same issue.

In summary, 1993 accord AT trans accord 400k miles, overheating sitting in my driveway allowing it to warm up for the coolant bleeding process with the fans never turning on, 4 honda oem sensors, honda oem thermostat, water pump/timing belt, and the radiator hoses are all new parts, still getting persistent overheating with no fan engagement or lower hose heat/pressure.

Additional FYI -
I use the bleeding funnel for the radiator to ensure the system is fully bled
The distributor above the sensors was leaking oil directly onto the connectors and their wiring, I changed the distributor to alleviate that.
I also found wire damage from the hot oil leaking onto the connectors, I ordered replacement pig tails (the necessary connectors with loose wire flying to install into your current set up) and installed those to replace damaged insulation on the wires at the connectors for the thermo switch, ect switch, and temp gauge sens.

I'm struggling to find the right way to verify what it should be, the only part I haven't ordered to just throw at it in hopes of help is the radiator fan control module found under the driver side dash.

 

Honestly quite a few things you haven't looked into yet. What is the condition of the radiator itself? Any rust inside or signs of the cooling channels etc being blocked up?

Do you have any signs of any engine issues? Namely, any indication that your headgasket might be failing? Might be worth a compression test just to rule it out. It is quite easy to do on these engines using the spark plug holes etc.

 

Pull the rad cap off and watch for bubbling, that would show a failing headgasket, could do a compression test too.. could replace the thermostat itself because it may have become stuck closed. Grab the hoses after it has warmed up and feel how hot they are in comparison. If one is fairly cold and one is still very hot, most likely it is stuck closed. Make sure you install with the jiggle pin at the 12 o'clock position if you do replace it.

 

Thank you for responding, in regards to the radiator itself. No signs of rust outside, or in the coolant before the initial flush, and no indication of brown fluid after 5 flushes. I used a garden hose on the first flush to get an idea of how much flow was going through, the radiator would allow the water to flow through the draincock without overflowing out of the top of the radiator. However, the fins on the front look to be like they could be 50% worn? just used, some slightly bent and what not.

In regards to head gasket, the engine runs really well, literally no smoke on start up, although, in all of my coolant flushes, I found some oil rising at the top of the recycle containers, and during my tests right now with water in my spillless funnel, there gets to be a slight film of oily substance that rests on the top inside the funnel. I can totally do a compression test, just need to get the right vacuum gauge. I've tried to use the head gasket checking system where you put a little resevoir of blue fluid into the radiator cap hole and try to suck in just fumes to see if the fluid stays blue or turns yellow but in the two times I've done it, I can't stop sucking up fluid.

 

Not sure where you are located, but when I lived in the US a decade ago, the parts shops would loan you a compression tester for free. The usual common stores.

Is that still the case? If so, can't hurt to compression test and see where you get. A leakdown test is better but much less common, so I woul always start with whatever is free.

I think you said you changed the thermostat right? That is usually my first thought whenever these engines overheat.

Re the radiator it probably is ok to be honest, especially if you didn't find any internal rust. You would have seen rust at the water pump anyway when changing it.

 

The engine does not need to be, nor should be, on when bleeding the cooling system.
Not sure what that means.

The way you bleed the cooling system on 90-02 F series engined Accords.
Look on the backside of the thermostat housing.

You will find a bleeder nipple.
Crack it open.
I prefer to add a foot long piece of clear tubing to the nipple.
Rotate the heater control to full hot to fully open the heater valve.
Start filling the system.
The bleeder screw should be left open, you will see bubbles and should only close it when you have a solid stream of coolant coming out of the bleeder nipple.
Close it.
Continue to fill radiator til full.
Also remove over flow, clean it out as best you can, reinstall and fill to the appropriate level with coolant.

WIth that done. Close the cooling system and start the engine.

Need more reading go to;
https://techauto.tripod.com/overheating.html