• We’re currently investigating an issue related to the forum theme and styling that is impacting page layout and visual formatting. The problem has been identified, and we are actively working on a resolution. There is no impact to user data or functionality, this is strictly a front-end display issue. We’ll post an update once the fix has been deployed. Thanks for your patience while we get this sorted.

can't find bleeder for coolant, can I just open the radiator cap and run the car to ?

Are you low on fluid from a leak? Otherwise I find it extremely unlikely that coolant (or more specifically the water pump) is causing the rough idle. You didn't mention if you've changed the plugs or wires.
 
I'm pretty sure coolant has nothing to do with your cars idle... its is there to cool the engine other than that it doesn't affect how the engine idles. Might have a vacuum leak or a plugged air/fuel filter etc. Bad plugs or wires.. it can be a number of things even a dirty throttle body. A quick google search shows a number of fixes/causes http://www.google.com/search?hl=en&...gh+idle&btnG=Google+Search&aq=f&aqi=&aql=&oq= http://www.preludeonline.com/f91/how-clean-iac-valve-smoothes-out-rough-idle-110161/ IAC valve is a very common problem
 
Last edited:
I had a 96 prelude si with the same issue. I traced it to a broken vacuum hose. Collant doesn't make any sense.

However, you can run the engine with the cap off, I did it several times on several cars. Some fluid will spill out though. Never open the cap when the coolant is hot though.
 
If it's got electronic ignition the PCM monitors the engine temp and will bring the idle up a little bit (300-500 rpm above normal) until the engine is warm. If there's a problem with the coolant temperature sensor it can affect the idle. I don't know if a '93 prelude is that sophisticated though.
 
On some cars, the air bypass is heated by coolant to close it. Air bubbles in the system might cause high idle but it won't cause rough idle. On my old Mazda the check was: touch the valve's coolant lines. if it burns you, there isn't any coolant flow issues.

Of course a Mazda <> Honda so your luck will vary.
 
jlee said:
Low coolant level will cause a two/three step idle in an MR2 (at least a Mk1). Don't ask me why, but it does.
Click to expand...

There is a sealed clock spring on the back side of the idle control valve shaft that is piped into the coolant bypass, presumeably to bias the idle control depending on coolant temp. Might have something to do with it.
 
on a prelude, one of their engines has a coolant line going to the throttle body that can cause weird idles. But i think this is on a H22a motor, an Si is more like a F23 series motor.



If you want to take care of all the air bubbles, just start off with a cold engine, remove the radiator cap and start up the car as it warms up, the radator will overfill slowly but it will boil out MOST of the air pockets if there are some as it warms up..

Ive done thing on a couple of cars. Make sure your overflow bottle is full and run it without the cap for about 20-30 minutes and I never had an issue with air pockets in my coolant.
 
93 si an H23a. It's my haul random stuff car so I haven't really cared to check it out. Idle is just wild, it'll jump from 700rpms to 3000rpms for about 50 minutes untill it warms up. It's very weird, I'll run the car for an hour and it hasn't even reached normal operating temp. something is not right with the cooling. I've checked the IAVC and I can't find any leaks in any hoses which was my first guess.
 
holden j caufield said:
93 si an H23a. It's my haul random stuff car so I haven't really cared to check it out. Idle is just wild, it'll jump from 700rpms to 3000rpms for about 50 minutes untill it warms up. It's very weird, I'll run the car for an hour and it hasn't even reached normal operating temp. something is not right with the cooling. I've checked the IAVC and I can't find any leaks in any hoses which was my first guess.
Click to expand...

Thermostat maybe?
 
You must log in or register to reply here.
Back
Top