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I am troubleshooting my G.F.’s 99 Honda Civic 1.6L. It idles rough when it reaches Normal Op. Temp. I started with tune up. Then went on to check pcv valve…good. I started bleeding the coolant system as you showed me in your video, by the way excellent info. and no rigging in all your videos, when it reached temp.and the thermo. opened the coolant recirculated as it should, it kept letting out small bubbles and smells like burnt exhaust……BLOWN HEAD GASKET????? I am gonna get an adapter for my pressure tester today to be sure. Wouldn’t that for sure be the reason for rough idle at normal op. temp., because the heat expands the crack and allows exhaust fumes into the coolant system. It runs fine when on the throttle, So it must be small, and no steam out the tail pipe. No water in oil. This would also confuse the IAC valve right? Also, how serious? I have changed plenty of head gaskets in the past but they were major. Will it progressively get worst? She told me the mechanic she used on her last vehicle used something in the coolant,I’m thinking Bars Stop Leak or something like it, Isn’t that just like using duct tape on a radiator hose- might or might not work, It will reoccur. Suggestions? I probably already know what you guys on here will say, which is what I was taught, Change the HEAD GASKET!!!! Thanks for any input
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The method I use and have the best success with is to bring each cylinder to TDC and pressurize each cylinder at a time with shop air pressure. 175 to 190 psi. If you use the adapter from your compression gauge make sure the Schrader valve is removed from the end of the hose.
Have the rad cap removed and fill the rad to the top. (before pressurizing) If the level raises or you see bubbles you just found your combustion leak. It might take several minutes for this to happen so be patient.
I was gonna use a radiator pressure tester, pump it up to the lbs listed on the cap, listen, then pull plugs etc… The compression tester totally slipped my mind, And I don’t have to get an adapter to fit the small *ss neck on these Honda radiators. My shop compressor is set to 125 psi. Do you think that is enough? Or should I turn it up? The only confusing part of the equation is every time I Have checked the coolant level it has never moved….. Always full!!!! No Overheating. I checked the plugs and all four looked the same, WHITE. Which means Lean on fuel Right? One more note…. The exhaust system is rusting pretty bad and we live in Eastern NC no salt on the roads. Just the occasional beach trip. The muffler is almost separated from the flange which does point to allot of condensation in the exhaust. Right?
Do a block test, if it passes than you have nothing to worry about. At my shop we don’t even bother with blowing air in the cyl. normally you only do that (leak down) when you have a compression issue. Do it when cold all the way to operating temp. The hotter the better. it will boil at operating temp. with the cap off, so be aware of that to avoid getting hot coolant all over you.
Update….. I started the car again at air temperature. Opened the heater core valve,had the AC on max, and opened the radiator cap. Revved the car up to what felt like 3000 rpm and held it until the thermostat opened and both coolant fans came on and thats when the eruption starts. Right as the thermo. opens the bubbles start out small, like less than 1/16″ DIA,and then less than say 5 secs later they get pretty big, about 1/4″-3/8th” in DIA. The stench that comes out is awful,it smells exactly like exhaust fumes and antifreeze mixed,as I mentioned before I have changed quite a few head gaskets before, and the coolant looks like brown/green/white and very agitated. I shut the engine down. Got the #1 Piston to TDC, pulled the plug and screwed a compression tester male end into the head. As I mentioned before my comp. is only rated to 125psi, pressurized it and it held. I did the same for each cylinder. I do understand that the compression is up around 200psi or so, maybe more under fire and load right? Not positive on exact compression? I also know that as the coolant heats to 185 or 195, based on thermostat, things start to expand. Not confident that 125 psi was enough,and since my coolant system pressure tester is for the standard size rad. neck, I used an old pressure reg. intended for gases etc.. put a standard valve stem-3/8 THREADED fitting on one end and used the gas nipple with flange nut. Took the fl. nut off. Had a gauge on it. Adjusted it to 16 psi output. Pulled one of the hoses right behind thermo.housing off attached it to my new toy. I then used a 3″ piece of heater hose with a plug in one end and attached it to the nipple after housing. the other end of the hose went to the head or the intake cant recall. Pumped the system to 16 psi. The cap released a little water then stopped. The gauge stayed at 16 psi. No leaks. I turned it up to 18 psi in case the gauge was off, no leaks, pressure held. The engine was cold since I came up with this spur of the moment. I’ll try again tomorrow warm. All my other experiences the blown gasket was bad enough the cylinder filled up or the pressure went down dramatically. In those cases I used my pump to rad. neck tool…….. No coolant in oil, No loss of coolant, only rough idle at normal op. temp. When you hold the throttle 50% and let right off the engine almost completely dies. This will not beat me. Any suggestions. Could the IAC be letting in a little air into the system causing all these problems???? Or intake? Also the thermo housing is attached to the lower rad hose, I am new to hondas, but I thought the lower hose went to water pump, upper hose to thermo. when the thermo opens the coolant in eng flows to top of radiator. I will go over all this again tomorrow evening THNX……
It can be a lot of different things as far as the idle issues. You’re are making this WAY too difficult. DO A BLOCK TEST. That is what your next step needs to be. Point blank period. More will come after depending if that test passes or fails. Keep us posted.
Sorry just saw your post. It is also known as a combustion leak test. I will post a video, you can rent this tool at any parts store, or buy one for about $40. When you do this the most important thing is 1. not to suck coolant up into the tube and 2. make sure the chemical used is new, and sealed otherwise it will give you a false reading. Remove some of the fluid out of the radiator or expansion tank to avoid this. The tester used in this he’s doing using vacuum. Normal testers with have a squeeze ball you put on top of the tube and just squeeze it so it will pull air through the fluid.
Well just watched your video 6:30 am here. About to head off to my “JOB”,would rather play with engines and oil and grease all day, but oh well, I have seen squeeze ball tester before but never used one. I understand the principles. I guess the crack or whatever is so small it is not causing the coolant to boil into the reservoir and cause coolant loss, by the way the reservoir is cracked so if coolant does go in there the system can’t draw it back in during recirc. cycle. I will go by one of the many great parts stores after work and get one or the other. Have you ever seen an issue as mine where the coolant is not leaving the system but is definitely not right. The problem started with rough idle after warm up 6 months ago and has progressively got worst. To the point she parked and said please fix it. She has said numerous times the engine has never over-heated. And in my experiences with combustion gases in coolant system the temp would climb and climb then release or keep climbing to the point of OH ****! SHUT ER DOWN! This must be so small at this point the cap is relieving the air but not losing coolant. Thanks again….. I’ll repost this evening
Back at this evening. Thought I would start over with beginning tonight.Only got a couple hrs. to work on it.. Ran the engine around 3000rpm I think… Does it have to be exactly 3000rpm, because I haven’t checked to see if I am getting it that high, no TACH in car,I do have engine analyzer I can hook up if so. Small bubbles started coming up, the thermostat and fan kicked on, noticed condenser fan wasn’t running. I forgot to turn on the A/C. I let off the throttle and it went to normal idle, very smooth. I got in the car and set it to MAX A/C. I revved to about half throttle. and the temp. gauge rose a little higher than usual. When the thermostat opened it went down very slightly.I let off the throttle and it almost cut-off. I remembered a bad IAC valve causes this,and the thermostat could be sticking slightly. Shut it down. I waited for it to cool down. I pulled the IAC valve and checked the ohms. According to Hayne’s book,with the rotary valve type,I put negative of my multimeter on center terminal and the positive on either of the other two both should read 16-28 ohms, NOPE, barely 2 ohms. That is the idle issue when the engine gets warmed up and the A/C is wide open. It is supposed to compensate for extra loads on the engine at normal op.temp. while idling right? It is one big VACUUM LEAK! There’s # 1,2,and 3 on ERIC the CAR GUY’S video about Honda Idle Issues. Check for air in the coolant system, check for vacuum leaks, and IAC,which also is a big vacuum leak by itself. I am gonna get a new thermostat and maybe the one on there now is faulty and allowing the water to boil over just barely, so little that the coolant doesn’t leave the system.I’m also gonna get a new radiator cap. Thanx again for the help.
Again, a block test will put most of your questions to rest. That needs to be done. No point in doing anything else yet. If you have a bad head this has to be addressed first.
I am going to change the timing belt, tensioner and change the water pump as well, so I will do the the block test before I get into the timing area of the engine.You are correct, I am this invested in it. If I am going to have the front of the engine apart, I don’t want to have to tear it back down again later if I find out that a cracked head/blown head gasket was the,or,part of the problem. I’m sure you gave the name of that Blue Stuff in your video,but can you refresh my memory please? Thanks again for all the help. This is a very good forum, I am glad I found. I feel I could ask about any type vehicle,and get good,informative help that would not lead me astray…. More to come later..
Sounds like you’re making progress. BTW I’ve written extensively about Honda idle issues here.
http://www.ericthecarguy.com/faq/solving-automotive-idle-problems
I’d address any mechanical issues first such as the suspected head gasket issue. I’ve written about that and show the block test in a video in this article.
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
Good luck and keep us posted.
You can buy the block test kit at NAPA for about $25. I think some stores rent them out, but none in my area do. See if a local shop has it available for a small fee to replace their solution you use.
Update.. Can’t do the test till Friday. I pulled the thermostat,throttle body,and pulled the plastic reservoir to check it for a leak yesterday evening. I removed the IAC valve, It was definitely full of carbon build up, as was the throttle body and the inside of the intake manifold. I removed the butterfly and the throttle spring.Cleaned everything well with CRC T.B. and INT. Manifold Spray. There was factory grease behind the linkage that the throttle cable ties into, so I added new before I reassembled it. The throttle body operates a lot better now.Cleaned the IAC valve mechanical parts, I didn’t want to mess with any of the electrical parts.The reservoir didn’t have any leaks except the cap seal. I put the thermostat in a pot of water and heated it up on the stove. When my temp. probe reached 185 the thermo. was barely even opening. In fact, the water started boiling before the thermo. even fully opened. I did notice the thermo. was definitely original equipment. With 170,000 miles is that possible, or did the first owner or owners have the dealer service it, I don’t know. Gonna do another thermo. test just for the heck of it. Definitely gonna buy an O.E. thermostat that’s for sure! A few questions that I have……………………………………………………………………………….Should I try to clean the inside of the int. manifold or remove it and clean it thoroughly, which means —Do I remove the injectors and clean them as well since I am this far into it? Every thing I clean should make the engine run better and longer right? What temp. should a thermostat start opening if it is say a 185 deg.,exactly 185 or a little before, and how fast? Now that I cleaned the IAC is that gonna make the ohms right,I haven’t checked that yet. Finally, Does it matter if the reservoir cap is sealed well? Thanks again!!!!!!!!
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