help the old crippled man again please. 1993 civic d15b7 had a blown head gasket. did valve job & buttoned it up. started up very easily. fast idle 1200 rpms & timing advanced as well. reached operating temp and no reduction in rpms or timing. cooling fan came on shut off in about 25 seconds. about 2 minutes later the same. and then the same again. dash temp gauge reads ok but feels too hot to me. shut engine down. did ECU self diagnostic. check engine light comes on and stays on. cleared codes ran engine for a minute. still high rpms and timing. shut it down. did ECU self diagnostic...check engine light comes on, stays on. what gives? timing belt off a tooth? ECU now a boat anchor? please your best suggestions. ask me questions. what did I do wrong this time? intake manifold had oil and grit from blown head gasket. cleaned it out after removing all that might be hurt by solvent. maybe eacv or iac gummed up,didn't take them apart. should I? help

 

You need the code of course. Try running the engine until the CEL comes on, then put the jumper in without turning the key off. It should change from steady on to blinking codes. If the "BACK UP" fuse under the hood is blown, the ECU will not remember a code after you turn the key off.

The cooling system needs to be purged of air carefully. Air in the system can cause false readings from the ECT sensor, leading the ECU to think the engine is cold whan it is not, and increase idle. There should be a bolt similar to a brake bleeder on the fitting on the head for the top radiator hose. Set up with the car parked on level ground, engine COLD, and heater slider on full hot. Remove radiator cap and open that bolt. Pour coolant into the radiator until it is full and coolant comes out the bolt. Close the bolt. Start the engine with the cap off and watch the radiator to make sure it stays full, add coolant as needed. (If bubbles and / or coolant blast out when you rev the engine, head gasket is likely leaking, not good). When the engine warms up, radiator should start to overflow, put the cap on at that point and continue to full warm up. The recovery tank should be about half full. Then shut down and allow to cool and check in the radiator again.

Normal operating temperature of a Civic engine is 185 - 190 F, which is way too hot to touch. You can't judge engine temperature that way.

 

Thanks mk378. I'm trying to be cautious. I didn't touch the engine to determine engine temp. The heat hitting my body seemed much greater than I've experienced many times in the past. The first time I started the engine it ran for about 25-30 mins. The cel did not come on. I was very fearful of blowing another head gasket. That's when I shut it down. I then jumpered the ecu diag. term. I the turned on the ign. switch. The cel lit up but did not bliik. (big service manual says that means no codes stored) When I turned the ign. switch off the cel also turned off. I then checked the backup fuse and reset the ecu memory. I started the engine and ran it for about a minute to hopefully store codes. I shut the engine off and repeated the code retrieval process. Same as before. Cel came on but did not blink. All that I just said may have been clear in my first posting. Just making sure I didn't mis-state the facts. The upper radiator hose-to-head fitting is cast for the air bleed bolt. Unfortunately the bolt hole dead-ends. It never got threaded at the factory. The upper radiator hose angles up about 2-3 inches to top of radiator. I did jack car up 4-5 inches to increase likelyhood of air purge and filled the radiator per your advise. I have not cranked engine yet. If your advise is still the same, please post back that it is. I'll do what you suggest right away. Thanks for your patience and time.

 

I bit the bullet. Started the engine. It had a slight miss on a cylinder for a few seconds. Then ran smooth. 27 minutes later the cooling fan came on. But only for 15 seconds. About a minute later the fan came on again... for about 15 seconds. I was really uneasy. The engine started to run a little eratically. I looked at the dash, no cel lit. I disconnected the ecav electrical plug. The ldle dropped to almost normal. I plugged it back in. The idle increased to the previous level. I crawled in the car and jumpered the ecu test plug. The cel blinked code 14. Probably because I unplugged it.

 

OK so it can read codes then. You should make sure the back-up circuit is operational. It is common to blow that fuse under the hood when swapping out the radio because the radio is also powered by it.

Now that it's been through another warm-up cycle, check that the radiator has stayed completely full. If it has it would be OK to put in gear and go around the block a few times on a test drive.

Fan should cycle on and off for relatively short times when you sit idling. The fan is controlled by the temperature of the water leaving the radiator, not the engine block. Once the fan has run a little there is a radiator full of relatively cool water to work from.

With EACV unplugged, the idle should drop so much that it barely stays running. Air leaks anywhere into the intake will increase idle speed. Apply carb cleaner around the intake manifold to head gasket and see if it gets sucked in because the gasket is leaking. Also test the throttle body gasket that way.

 

If I remember correctly when bleeding the coolant system Honda recommends leaving the cap off the radiator for at least three fan cycles from cold. I went through a hectic issue one summer in Downtown Las Vegas with an air in cooling system problem.

 

I will check for intake leaks as you suggested. Maybe I'll get lucky. Maybe something stupid simple is wrong. Maybe because the head was shaved, the intake man. bracket is holding the intake rear up causing the ports to be angled a little too much to seal properly. Hah! Fat chance of that huh? Or maybe the 2 head-to-block alignment dowels are too long due to shortened head height and preventing the head from sealing against the gasket enough. Couldn't be! Wrong symptoms for those 'left field' things.

I really think too much and too deeply.
This engine experiencd a blown head gasket. I took it apart and put it togeather again over a 2 month period. (We cripples move slow) It should perform as well as before, which was pretty good even with a head gasket dying. 1) Either the gasket blowing caused a lot of supporting part damage
2) Some parts just coincidentilly died at the same time
3) The machine shop didn't properly rework the head.
4) I'm at fault. I didn't reassemble/adjust the engine components properly
5) Maybe some combination of all the above.

I've filled the cooling system with the front of the car jacked up to facilitate air purging. Driven it around the block. Let it cool, topped-off the coolant. Ran the engine more with the car jacked up. The coolant level is remaining constant. Could there still be air bubbles? Yes. With the engine hot and the EACV unplugged the idle is still at 1100 rpm's. EACV plugged in
about 1300 rpm's. I pulled off the air intake to have access to inside of throttle body. When engine is cold there is high suction at fast idle valve port and EACV port. When engine is hot low suction at fast idle valve port and high suction at EACV port. When engine is hot and EACV unplugged, if EACV port is blocked engine shuts off. I have not tried to adjust the idle screw. The idle seems way too high for that. I did not clean out the idle screw circuit when I cleaned parts. Could the circuit be blocked by oily debris just like the rest of the inside of the intake manifold was? Is the fast idle vavle bad because of low suction when hot? Is EACV bad because the engine dies if throttle port is plugged? Shouldn't the idle screw circuit keep the engine running? Is the oxy sensor confusing the poor ECU? Is ECU in 'back up mode' because its fried? I did install a new H.D. radiator, a new thermostat, and a new radiator cap. I'm going to the junk yard Saturday to look for a EACV, a fast idle valve, and a ECU. But its probably just air still trapped in the system. I still wonder why after all the years of draining and flushing the system I never had a problem with air bubbles. BUT, I also never had a major head gasket failure, right? Please continue to have patience with me. I'll consider any and all advise offered. The old days were sooooo stupidly simplistic!

 

It's 3:04 pm. going out to check for intake leaks. Wish me luck that the carb cleaner don't ignite from the plug wires. I'll stay online and post the results. Back in a while.

 

Fast idle valve is supposed to be open only for cold starts, so yours is working. Of course you should also check that the throttle plate closes fully when the gas pedal is not pressed. Dirt in the idle screw circuit would cause it to slow down. If you block all 3 ports (FITV, IACV, and idle screw) the engine should stall out, if it doesn't, there's air leaking in somewhere else. Are all the vacuum hoses back on the manifold (brake booster, PCV, canister bleed, etc)?

To make sure the intake to head gasket makes up properly, you want to loosen all the bolts on both ends of the manifold brace, then tighten the stud nuts to the head, then secure the brace.

 

Last things first.
I did install the intake by the steps you outlined.
All the vacuum hoses and fittings were tagged and videoed for ease of
re-assembly.