lothian

2000 Honda Accord
J30A1 3.0L USDM SOHC VTEC V6 200hp; 4-Speed Automatic
~119k miles

I completed a timing belt replacement job (all three belts & both pulleys, TB auto-tensioner, water pump & front eng. mount--all Honda parts). I quadruple-checked timing marks before and after TB removal and replacement, and I manually turned over the engine a dozen times to seat the belt, check for interference, and TDC at all pulleys--absolutely no problems there. Once finished, I topped off the coolant. Then I started the engine...

- Cold engine turns over fine, but idles high at ~1700 (per scanner; engine temp is 61°). After ~5 secs the engine surges cyclically between ~1600 to ~1700;
- I can hold idle steady with the throttle or by shifting into gear, although load idle remains high;
- I held idle at ~2500 for ~5 min, then drove it around my neighborhood for ~2 miles (~10 mins @ <30mph);
- I drove it through each gear: idle is steady (though high) thru 2,3,4, but engine surges in first gear;
- Surging resumes after I shift to park (or neutral); engine temp levels at 174°;
- There is no check engine light, and no codes on the scanner;
- I found no obvious vacuum leaks or loose electrical connections;

I have not purged the coolant system of air per procedure because I simply cannot locate the bleeder valve on this engine, even with shop manual and flashlight in hand!

I followed the procedure in the shop manual, and noted my progress on paper as I worked. I found no loose vacuum lines in the vicinity, nor any loose electrical connectors... yet could I have possibly missed something, or pulled something loose? Could replacing a TB induce the idle surge with no codes? ...or is this merely coincidental, unrelated problem.

wagon97

I would bleed it anyway. Just might take longer to get all bubbles out. Do you have One of the funnels made for bleeding? Hopefully someone will address were bleeder is but I believe I have read some models do not have one. This would be an easy start to your problem and hopefully fix.

lothian

I suspect the air in the coolant also. Problem is, I don't know how to bleed it effectively AND my engine may be one of those without a coolant bleeder valve.

It seems there should be no connection between doing a timing belt (TB) job and experiencing subsequent idle problems--the two systems are on opposites of the engine!

The connection is... coolant! A significant quantity of coolant drains when the water pump is removed during a TB job. The highest point in the coolant system on this vehicle is... pause for effect... the IAC valve (IACV) under the throttle body! Air replaces the coolant in the IACV (which uses coolant temp to actuate), which causes the surging--well.. technically, it's the ECM causing the surging due to incorrect information from the sensor in the IACV due to lack of coolant.

Interestingly, I'm not getting a P0505 code so I don't suspect a bad IACV. However, I do see the possibility that the IACV is either clogged or suffering an air lock within its coolant chamber. Risk of latter is probably why the service manual recommends purging air from the coolant as part of the TB installation!

Page 10-10 of the "98-00 Accord Service Manual, V6 Supplement" shows the location of a coolant "drain bolt" on the block. Fine. What I need an illustration of the location of a coolant bleeder valve on this engine, which intuition suggests should be near the top of the block...to purge air, not drain out coolant.





98-00 Accord Service Manual, V6 Supplement"; p.10-10

wagon97

Not sure about your car and bleeder valve location. I have a 97 4cyl. But in general you opened up your system and introduced air which should be purged out. I would purge air before looking at more complicated repairs. It should have been purged anyway. Even though you did not use a bleeder valve you could just bleed system anyway. Here is a link showing a Honda being purged. Your car might have some differences but in general should apply. Like I said I am not familiar with your year car. Good Luck

lothian

The thing is, a J30A1 3.0L V6 VTEC (my engine) doesn't have a coolant bleeder valve, which explains why there's no such procedure in the 98-00 Accord Service Manual--perhaps the engineers designed some integral method to get the air out. I simply topped off the radiator w/coolant and ran the engine at ~2000rpm for ~5mins and added more as necessary. Still the engine idle surges (hunts, pulses, etc...).

I'm not getting a P0505 code, so I don't suspect a bad IACV. However, I do recognize the possibility that the IACV is either clogged or suffering an air lock within its coolant chamber. And given the fact that the thing is 1) a 15yo part that's 2) never been serviced and 3) sat for a week drained of coolant (while I waited for the TB parts to arrive), it isn't beyond reason that my gremlin may reside within.

Soooo... with some difficulty (Philips head screws? ...really Honda engineers?) I removed the IACV from beneath the throttle body and found mild carbon yuckiness; it soaks in carb cleaner as I write this. I'll re-attach after I confirm the valve portion can move freely (it doesn't presently, from what I can feel). If that doesn't work, I'll pick up a new OEM IACV and install it. Why not an aftermarket IACV? I've read elsewhere that the Honda ECM doesn't play well with aftermarket IACVs, and the OEM part is a measly $160.

19Accord97

The illustration you provided me looks to be the bleeder valve as it looks the exact same as my bleeder valve in my 97.

I don't know why there would be a drain bolt on a motor when draining coolant is done by opening the valve on the bottom of the radiator.

lothian

'Bleeder valves' and 'drain valves' look the same because they're the same type of device; location distinguishes their name and function. A coolant bleeder valve (such on your '97, and on some 4-cyl Honda engines) is 1) located relatively high on the block and 2) serves to purge air from the closed coolant system. A coolant drain valve (such as that on my '00 v6 VTEC) is 1) located relatively low on the block (Honda refers to is as a "drain bolt"--see image) and 2) serves as complement to the radiator petcock valve to more effectively release coolant from the system. Anywho...

My engine doesn't have a coolant bleeder valve. This is likely the reason I find no "air purge procedure" in the 98-00 Accord Service Manual--perhaps the engineers designed some integral method to get the air out. I simply topped off the radiator w/coolant and ran the engine at ~2000rpm for ~5mins and added more as necessary, which seems adequate for this engine. Oh... and in doing so, I also performed the "Idle Re-learn Procedure" by default. ...so I got that goin' for me ...which is nice.

In any case, I fixed my idle problem. I replaced the IACV (Honda p/n:16022-P8A-A03; ~$163 from 'hondapartsnow.com' as of 01/15) after the cleaned-up original 15yo part did not fix the idle problem. I'm still incredulous. (...there's just no pleasing some people.)

For those of you experiencing idle hunting, check that IACV!

moapys

Cross-post from other threads; if you choose to cheap-out and get a 3rd-party IACV, versus OEM (not judging...gambling isn't for everyone)...: Suggest that you buy TWO; get them from two varied sources - say AutoZone AND Advance - if you MUST save half your cash. You may get one that works fine, or you might get a bad one. Should you have two on hand, you can quickly cross-check, and put the odds back in your favor. As they say; "ask me know I know"