Hey guys, I have a 1994 Accord 4dr that just came in to my shop. I'm a street rod and custom bike shop, not a Honda shop. Its a friend of mine and I'm just trying to help the guy out, and I could use some advice. He brought it in for constant overheating problems. has a new radiator,cap and fan assembly done a few weeks ago at another shop. Now it has the problem, hence the reason he brought it to my shop and not that guy again.
I have drained the coolant, replaced the thermostat and seal, refilled the coolant, bled the system at the relief screw on the thermostat housing, topped up coolant fully, let car heat up and cycle through, topped up again and put cap on. The idle-air control valve is rolling the idle up and down, so I tapped on it with a ratchet to possibly free something up. Still doing it. That's where I left it at the end of the day. Still overheating also.
Another issue is that the Radiator fan won't come on when the car is running, but kicks on when you turn the ignition off...Just wondering where to start looking to solve that little problem as well. Not making a dime on this deal guys, just hoping I can get some help fixing a down on his luck Honda owner. Thanks for any help guys!!

 

Do you have an IFR thermo? At ~196 thermo switch a closes at that and the fans should come on.

My thought, thermo switch a (green plug on/near t-stat) is bad. You can pull the plug, jump the two wires with a paperclip or something, turn the key to on and see if BOTH fans come on.

The idle "loop"....humm, thinking you might still have air in the system. Did you bleed with the heat set to max? Next pull and clean the IACV and might as well do the FITV.

 

I will give that a try in the morning. I was thinking I still might have an air pocket somewhere... As last resort for the IACV issue, could it simply be unplugged to stop the up and down idle? That valve is just there to regulate throttle at start-up until the engine temp is up, right?

 

The IACV is used all the time....Idle air control valve. So if you turn on the ac, it is in play....I could go on but I bet you get the idea.

Now the FITV...fast idle thermo valve is suppose to only be used when the car is cold....choke for a fuel injected honda. Once the engine is warm (normal op temp) it is out of the picture. Unless leaking air and the IACV is trying to adjust for it being bad.

Try the bleeding again. IMO, remove the rad cap, open the bleeder, set the heat to max. Let it sit a few minutes....you're not getting paid for this. SLOWLY add coolant until it is coming out the bleeder as a "pretty good" flow.

Close bleeder. Put the rad cap back on - ONLY to the FIRST CLICK (warning). You do not want the cap to build pressure in the system..just holding the fluid in. Start the car and let it run, keeping an eye on the temp gauge. If the gauge goes too high shut the car off...too high would be around ~3/4 on the gauge for this gen.

It could take ~20 minutes for the fans to cycle....this is where the IFR temp reader would be nice...or more depending on the temps/air flow in the shop....btw turn the blower motor off.

If the fans cycle. Shut the car off and top of the rad and overflow. Should be done?

If the fans do not cycle....again, I'm with thermo a being bad.

Let us know what you find.

EDIT: Forgot. BOTH fans should come on....if only one does there is an issue with the other. If only one comes on, let us know which did not come on (drivers/pass).

 

Ok, I jumped the plug for the fan switch by the thermostat and the fan does work. I'm taking that as the switch is bad. Bled the system again, temp seems stable but the idle is still jumping up and down...

 

Remove the IACV and FITV and clean both and reinstall, should (if they are both still working properly) help the issue. You may or may not have to adjust the base idle afterwards using the procedure by jimblake found here:

https://www.hondaaccordforum.com/for...e-speed-38734/

 

I was going to suggest the base idle & firefighter beat me to it.

 

All possible thanks to your great DIY write-up Jim

 

I hate splitting hairs but we all have to do it.

You say "fan", I read this as one.......BOTH FANS should have come on.