Update[October 21, 2018]: fixed some of the problems, which revealed new ones. Edited the post to show the fixes and marked those problems as resolved. Thanks to everyone for all of the help so far.

Update [November 12, 2018]: fixed most of the problems; just have a leaky exhaust manifold now.


Hi everyone, I have a 1999 Accord LX with the 4-cylinder F23A engine and the four-speed automatic transmission. I replaced the old engine, the USDM F23A4, with the JDM F23A myself using the Honda factory service manual. The replacement was necessary because the F23A4 had a cracked block, which allowed the oil and coolant to mix.


TL; DR of vehicle history: The engine overheated, then I found oil and coolant mixing in the radiator. I went to a shop to get it diagnosed and repaired. The mechanic said it was a blown head gasket, and he would get the head resurfaced and replace the head gasket. That only made the issue worse; coolant would disappear at an alarming rate instead of slowly getting sipped away like before. A visit to a Honda dealership said it was a cracked block. I gave up on the issue until a few months ago. While removing the old engine, I saw liquid gasket liberally applied throughout the old engine, including where the spark plug gaskets on the valve cover should be.


Currently, after the replacement, I still have a few problems as outlined below and I do not know why they are occurring -- I would appreciate any pointers. There are potential causes I will check on this weekend listed as well, so I would like to know which ones are the most likely. Further down, there is a complete timeline of my engine replacement process. I have also included pictures or short videos to explain my issues more easily. I will take and upload more images if necessary.


Problems:

1. Exhaust leak between the exhaust manifold to J-pipe interface; broke one of the three stud bolts halfway. Visible in the
   video linked to above at 0:10" target="_blank">video linked to above at 0:10
   .
   
2. One bolt broke off on the power steering pump; can see power steering fluid leak out lightly (just enough to fill in the gap; does not drip or flow anywhere). Visible in the
   video linked above at 0:12" target="_blank">video linked above at 0:12
   , orhere as a still image.
   

Fixed problems:

1. Lots of white smoke coming out of the exhaust at idleFixed![October 21, 2018] Fixed coolant going into combustion chamber, not much white smoke anymore. The IACV was loose, letting coolant into the intake and therefore into the combustion chamber.
   
2. Surging engine speed when constant throttle is applied with a delayed reaction time to throttle input; white smoke would come out of the exhaust in pulses (Tried cleaning the IACV; did not solve the issue). Similar to this 1998 Accord on YouTube (not my video).Fixed![October 21, 2018] Had the TPS and MAP sensor connectors switched, so switching them back to their rightful places fixed it.The TPS sensor clip is blue and goes on the back of the intake manifold chamber (? is this the right term?), on the sensor placed directly opposite the round thing the throttle cables are connected to. The MAP sensor clip is gray and goes to the sensor on top of the intake manifold chamber.
   
3. After cleaning the IACV, there’s
   a new whooshing sound" target="_blank">a new whooshing sound
   coming from the engine bay somewhereSomewhat fixed![October 21, 2018] Same fix as Problem #1 above.
   
4. There is some liquid leaking out from the exhaust manifold to J-pipe interface, does not feel oily and does not dry quickly (→ coolant? I can’t tell). This is shown in the
   video linked to above at 0:19" target="_blank">video linked to above at 0:19
   , orhere as a still image.Fixed![October 21, 2018] Same fix as Problem #1 above.
   
5. Sometimes, once the engine reaches idle speed it would shake badly (rocking back and forth about 7-10 degrees)Fixed![October 21, 2018] Same fix as Problem #1 above.
   
6. I tried to put the transmission in drive and go for a test drive, but the engine simply stalled. This was at the first test start, and I have not tried to drive it since due to the other issues listed above.Fixed for now?[October 21, 2018] After switching the TPS and MAP sensor connectors back to the correct places, I can drive at least 10 mph now (haven't tried anything faster because coolant is currently leaking everywhere from somewhere close to the IACV)
   
7. There is a huge coolant leak from somewhere behind or under the intake manifold chamber and IACV. I can't pinpoint where it is exactly, but
   here's a video of the coolant leaking" target="_blank">here's a video of the coolant leaking
   . I tried the soap bubble method on the IACV coolant hoses, but my visibility of the area is poor so it didn't help. I have also taken(bad) pictures of the aftermath of all the leaking. Some potential causes I have thought of:
   1. IACV hoses have holes/cracks and are leaking
      
   2. IACV gasket is worn out and leaks
      
   3. Thislittle metal plate attached to the throttle body that connects to a coolant hose is leaking. It iscircled in this diagram. It's pretty hard to get to for tightening if I want to leave the throttle body installed.
      
   4. Side issue: since the leak occurs in bursts and sounds choppy as shown in the video, do I have air bubbles in my coolant system somewhere?
      
8. [NEW] Checked IACV hoses, replaced IACV gasket, still dumping coolant, and now have fault codes P0304 (current; cylinder 4 misfire), P0505 (pending; idle control system), P1399 (pending; random misfire) along with
   some awful screeching sounds" target="_blank">some awful screeching sounds
   . ? ? ? ? ? Fixed both Problem #7 and #8 by removing the IACV, replacing the IACV gasket and 2 coolant hoses, reinstalling the IACV, clearing all fault codes, and starting the engine again. Not sure which "solution" fixed what.
   

Timeline (really long, probably not necessary to read because I've summarized what I think is important above):

May 2018:

1. Bought used F23A engine from HMotorsOnline (HMO) with approx. 46,000 miles (not too sure on that); has a non-ULEV-compliant intake manifold, distributor(? Why? Forum posts on honda-tech say they’re the same), exhaust manifold (no AFR(?) sensor hole), valve cover(? looks the same underneath → did not install original ULEV valve cover; used the valve cover that came with the F23A)
   

June 2018:

1. Engine arrived; started removal of original F23A4 engine
   
2. Broke a bolt on the exhaust J-pipe (front pipe? The pipe from the exhaust manifold to the catalytic converter underneath the front seats) during removal, only 1 bolt remaining to hold that pipe on to the exhaust manifold; definitely has a little exhaust leak
   
3. Removal complete; swapped old automatic transmission onto new engine
   
4. Installed new parts as suggested by HMO:
   1. New timing belt, water pump, camshaft seal, valve cover seal, water pump seals
      
   2. New spark plugs,spark plug cables (did I connect them correctly?), spark plug seals on the valve cover
      
   3. New oil filter
      
5. Forgot to install balance shaft pulley bracket thing from some Honda TSB
   
6. Swapped ULEV parts between original F23A4 and new F23A while cleaning parts as needed (original F23A4 had a cracked block and as such had coolant and oil mixing everywhere); parts swapped:
   1. F23A4 intake manifold, intake chamber, throttle body (as one package)
      1. Noticed that the F23A intake manifold was missing some hoses, but as an entire package it seemed to be complete and wouldn’t affect anything; should I have not swapped it out?
         
   2. F23A4 coolant intake and exhaust tip things (F23A from HMO didn’t have the thermostat installed)
      
   3. F23A4 exhaust manifold with AFR sensor
      
   4. Soldered new connector for wiring harness for some connector on the back of the engine; not sure what it’s for but the connector was destroyed before; connects to a sensor on the firewall side of the head. (Old one here)
      
7. Wet sanded with high-grit sandpaper to get old intake and exhaust gasket material off; it was just stuck on
   

July 2018:

1. Found out CV boot was torn; replaced that
   
2. Installed engine with new engine coolant hoses and old heater core coolant hoses
   
3. Extracted old gas (sat in the car for at least 10 months now); got a few gallons of new gas into the car
   
4. Put in new oil (Mobil 5W-30?), coolant (Honda Type 2(?) pre-diluted coolant), and Honda automatic transmission fluid (ATF-Z1?)
   
5. Jump started car and got first start; lots of white smoke came out; left car running for a few minutes before trying to drive off to get some gas
   
6. Engine stalled
   
7. Checked engine bay; found leaking gasoline near the injectors
   
8. Ordered new injector gaskets on both the intake manifold side and the fuel rail side
   
9. Made sure pressurized fuel line from the fuel pump to the fuel rail was torqued correctly; confirmed no leaks from that part
   
10. Installed new injector gaskets
    

August 2018:

1. Thought it could have been incorrect battery or alternator wiring causing the erratic idle; confirmed correct voltage and polarity for both the alternator and battery while engine is running at both the battery terminals and the alternator terminals (~14 V; don’t remember exactly; not much fluctuation within the few minutes I monitored the voltage); kept transmission in park
   
2. Charged battery at a local automotive parts store
   
3. Started car; lots of white smoke at idle; sound from engine bay is loud and rattly (assuming from loose exhaust manifold - J-pipe interface; there’s probably a gap of about a millimeter between them on one side)
   
4. Getting on the gas just a bit would maintain constant engine speed at approximately 1500 RPM; white smoke would stop coming out of the exhaust
   
5. Getting on the gas any more than that would have the engine speed wildly fluctuating in a weird way; in chronological order:
   1. Step on gas and hold constant physical throttle position
      
   2. Nothing happens for a bit
      
   3. Engine speed spikes to 3000-4000 RPM
      
   4. Falls back down to idle
      
   5. Spikes back up to 3000-4000 RPM
      
   6. Falls to idle
      
   7. Repeat this cycle indefinitely,
      kind of like this" target="_blank">kind of like this
      1. (Already looked at the comments, and cleaning the IACV doesn’t help as explained later)
         
6. While all this was happening, white smoke would come out in pulses
   
7. Turned off engine and gave up for a bit while researching
   

September 2018:

1. Cleaned Idle Air Control Valve; the spinny part inside moves more smoothly than before
   
2. Started engine; engine puts out a lot of white smoke ( → coolant???)
   
3. [NEW] (Video):
   Whooshing (sounds like rushing liquid or something)" target="_blank">Whooshing (sounds like rushing liquid or something)
   from somewhere on the engine; can’t pinpoint where it’s coming from.
   
4. [Not sure if there before] some liquid leaking out from the exhaust manifold - J-pipe interface; doesn’t feel oily and doesn’t try quickly → coolant? This is shown in the
   video linked to above at 0:19" target="_blank">video linked to above at 0:19
   , orhere as a still image.
   
5. Once engine reaches idle RPM it’d start shaking really badly (visibly rocking back and forth around 7-10 degree angle, which must be shaking pretty hard because I can’t get even close to moving the engine around that much manually)
   
6. No check engine lights came on (???)
   
7. 1 bolt broke off of the power steering pump; can see power steering fluid leak out lightly. Visible in the
   video linked above at 0:12" target="_blank">video linked above at 0:12
   , orhere as a still image. Is this an immediate issue?
   

October 2018:

1. Contacted HMotorsOnline; was advised to put on the ULEV valve cover, check timing, check distributor firing order
   
2. Planning to order new spark plug gaskets to replace the ones on the old ULEV valve cover; previous mechanic put liquid gasket all over the engine for some reason
   
3. [October 21, 2018] Checked TPS and MAP sensor connections. Had them backwards, resulting in the erratic behavior when getting on the gas at all.
   
4. [October 21, 2018] Saw coolant blast out of the exhaust leak between the exhaust manifold and J-pipe. Looked at oil dipstick, and there wasn't any milky stuff in the oil. Tentatively concluded that my head gasket is fine and I haven't yet developed a crack in my block (like my old engine), so the coolant must be coming into the combustion chamber via the intake. Turns out that the IACV was loose -- I didn't tighten it properly when I previously removed it for cleaning.
   
5. [October 21, 2018] Engine continued to shake for a little bit after starting it for about 20 seconds, then cleared up. Engine idled fine, throttle response was good, and coolant stopped coming out of the exhaust manifold leak. I put the car into drive, drove forward a little bit, put it into reverse, drove a little bit backwards, and confirmed that it works now (at least at speeds less than 10 mph).
   
6. Checked IACV hoses, replaced IACV gasket, still dumping coolant, and now have fault codes P0304 (current; cylinder 4 misfire), P0505 (pending; idle control system), P1399 (pending; random misfire) along with
   some awful screeching sounds" target="_blank">some awful screeching sounds
   . ? ? ? ? ?
   

November 2018:

1. Replaced short IACV coolant hose that's connected to the head
   
2. Cleared fault codes and started car; no more screeching, no fault codes came back up (not sure what exactly fixed the terrible screeching and idle control system fault code; could just be a simple IACV reinstallation or it could be the new coolant hose)
   
3. Drove around for a few hours; still leaking small amounts of coolant
   
4. Replaced the other IACV hose that's connected to the big coolant pipe behind the engine near the firewall
   
5. Drove around for another few days, passed a smog check on the first try, and was fine... for a few days: coolant started leaking out again, so replaced upper heater hose (the one higher up on the firewall without the heater valve) which connects to the big coolant pipe behind the engine on the side of the firewall. Probably best to drain the coolant first somehow, because an armful of coolant is never fun.
   
6. Drove around for another few days, and got another coolant leak; replaced the upper radiator hose metal tip thing that's bolted to the head (the upper radiator hose is attached to this) because the F23A one was used and it was bent the wrong direction which made the radiator hose bend in a weird way and leak
   
7. [Current!] Drove around for a few hours and things seem fine for now. Need to fix the exhaust leak.
   

Thanks for reading, and any help is appreciated.

Edit: Fixed some missing links in the timeline (the same ones linked to in the problem summary).

Edit 2 (November 12, 2018): Status update on the car

 

Hello, I just did this exact swap a month ago on a 99 LX. You must use the the USDM intake manifold... Did you remove the plenum and clean out the EGR passage? I aways use a honda intake gasket and clean the surfaces to near perfection. You do not need to swap the valve cover or the VTEC valve body. Just unscrew the plug and install the VTEC pressure switch from your old engine then make sure you plug in the green connector. You can test the VTEC solenoid by putting 12 volts on it and listen for the click. I suspect you have a vacuum leak, maybe at the IACV. The IACV gasket needs a little silicone grease and careful assembly. Chances are one of the o-rings is pinched, test by spraying carb cleaner around it. Check the vacuum line to the IACV and the purge valve lines. Did you connect the knock sensor?

The crank sensor on the JDM works, no need to swap it. My engine runs fine using the JDM distributor but inspect the connector, mine had a bent pin. Also test your A/F sensor, it should put out about 0.8 volts when heated with a torch and not have a slow response when the flame is removed.

schreps

 

ok, I just did this same job, replaced a f23a4 with jdm f23a.
I did not need to swap the valve cover, they are the same.
I used the 1) f23a4 intake manifold, TB (blue connector goes to the TPS) and plenum, 2) f23a distributor, 3) the f23a vtec solenoid with the f23a4 pressure switch (check, green connector goes vtec switch) 4) f23a4 exhaust manifold and f23a4 denso af sensor, 5) f23a thermostat housing and thermostat, 6) f23a crank senors, 7) f23a4 purge system and 8) f23a4 ECU.

If you are getting white vapor out the tail pipe then the head gasket is probably bad, you should let the engine vendor know but most wont honor their warranties unless you are an ASE certified tech... That's why I am really careful when picking out a JDM engine.

A cylinder leak down test is probably called for (with or without a tester). Watch these youtube videos to get an idea how to do it. and --- oldskool is no fool.
ETCG also has a good vid

 

Hi schreps, your thread outlining your engine replacement was helpful. It's how I found out I had the TPS and MAP sensor connectors reversed.

I used the USDM intake manifold and cleaned it out for sure. I think I did install the VTEC pressure switch; it was originally a bolt installed on the side of the VTEC solenoid on the F23A which I switched out for the one from the F23A4. I had no idea what it was at the time. I did have the TPS and MAP sensor cables reversed, so swapping that fixed the stalling issue when trying to drive the car as well as the surging engine speed. I used the F23A4 theromstat housing and thermostat because there was nothing inside the F23A thermostat housing for me. The F23A plastic distributor housing(?) was cracked, so I used the one from the F23A4. The rest of the parts used are as you've described.

About the white smoke, I'm not sure what I did since the original post that fixed the issues I was having, but initially the IACV was loose which allowed the coolant from the coolant passage in the IACV to go into the combustion chamber. I removed the IACV, cleaned it, put it back on, and the engine ran roughly for a bit while it cleared out the remaining coolant. After letting the engine run for about 5-10 minutes, the majority of the white smoke stopped coming out of the exhaust. After about 200-300 miles of driving, I don't have any more white smoke coming out of the exhaust. The car also passed its smog check on the first try.

After fixing that original problem, I still had coolant leaking. Seemed to come out of the IACV, so I replaced the IACV gasket and reinstalled it. Some intense screeching happened about 30 seconds after I started the engine, and I got idle control system fault codes as well as a misfire fault code. There was still a coolant leak, so I decided to replace the two coolant hoses attached to the IACV. After reinstalling the IACV, clearing all fault codes, then starting the engine again, I haven't had any fault codes since, but coolant was still leaking out here and there. Ended up replacing the heater hoses as well as swap out the JDM upper radiator hose metal tip thing that's attached to the head for the USDM one (which had a lot of rusty residue inside of it, so I had to clean it first), and I haven't had any coolant leaks in 2 days. Fingers crossed.

I still have a few small problems:

I have a broken stud bolt on the exhaust manifold, so the pipe between it and the catalytic converter isn't attached securely and there's an exhaust leak. Is it possible to remove that stud bolt and replace it with a new one? It's #12 here: http://hondapartsnetwork.com/assembl...il/3309514.png
I assume my current exhaust manifold doesn't have any other problems. I tried going to a local junkyard and getting some new exhaust manifolds, but the few that I've managed to get out have small cracks in them, so that's probably a no-go.

Similarly, I have a broken power steering pump bolt where the power steering fluid hoses attach to the main pump body. Half of it is still in there. Is it a good idea to use a bolt extractor to remove it and replace with a new bolt? Something like this:
Thanks for the help.

 

If you cant grip the broken stud with vise grips then buy a bolt extractor,the neiko set looks good. You may need to remove the manifold to have enough working room. Also, applying PB Blaster for 24 hours may help but heating with a torch may be required. And yes use an extractor on your broken power steering pump bolt, however I don't think its a good idea to apply heat to the pump housing... Whatever you do don't break the extractor off in the hole, its tool steel and will be a bitch to drill out.

BTW the IACV leaking coolant directly into the intake never occurred to me, good job finding and fixing!

On hondas all coolant leaks need to be fixed or air gets sucked in to the system when the engine cools, this leads to rough idle and eventually to head gasket issues. Its ok for a honda to drip a little oil but not coolant. My opinion...