dr_bob_bc

2007 Civic, 100,000 miles on it, owned since new. I change oil and filters religiously, but I don't remember the last time I pulled the cap to the radiator. It has never ran hot. Let mine be a cautionary tale!
First symptom was on 2 days in a row, a *very * momentary losses of power- just for a fraction of a second, at the very same spot in the drive, about 2 minutes into a 7 minute drive in subfreezing temperatures at highway speeds.
On a subsequent longer drive in -25 C/ -13 F, the cabin never heated up, and after about 20 miles there was a definite loss of power and the check engine light came on. Limped it home, temperature gauge at normal .
At home, coolant super low, oil smells burnt, and black burned oil on upper dipstick. So, changed oil and added coolant, still power is much lower than normal (drive-able but sluggish.) No knocks or other noise detected, no abnormal smoke from tailpipe, no coolant leaks found. Check engine light comes on after running a minute or so. Rough idle like missing on a cylinder, not constantly but somewhat intermittently.
Since it was the middle of Canadian winter, I bought another car, figuring I had fried the motor, and would deal with it in the spring.
Today, I did a compression test and was really perplexed: 190 178 172 168 psi on cool engine, without depressing accelerator. I was expecting lower numbers.
I have changed motors and trannies in older vehicles and had figured I would clearly need an engine swap, but today, after seeing those numbers, I am wondering if it is something much less severe.
Thoughts?

ezone

Coolant loss, now you refilled it: Is coolant oozing out, is the block cracked?


Your compression test results are not what I'd consider good enough IMPO

If it got as hot as you describe, I'd suspect the head is now warped as well

dr_bob_bc

Thanks for your reply.

My Honda Service Manual states a service limit of 128 psi, with maximum variation of 28 psi (my lowest is 168 with 22 psi variation.) Being a professional myself, I know that going by the book isn't always accurate and maybe you know more about compression?

Unfortunately, these complex motors have so many system components which I am ignorant of and I don't believe I am reasonably capable of trouble shooting much past this, other than finding/buying a code reader as my next step, and I'm not convinced that will sort it out. Limp mode? I have disconnected the battery in attempt to reset that, without any change. Just a bad plug or coil? That seems awfully optimistic given what the dipstick looked like.

I ran it for a a few minutes after filling up coolant and I never saw any coolant dripping/oozing out anywhere, but I can't really see the back of the motor, so if it was just oozing and no drips, I would not see that. I would see any drips that fell off the car onto the floor.

A call to Honda Consumer Relations assured me I wouldn't be getting a free motor replacement with a cracked block (past 10 years in service, which was the time period that Honda extended the warranty for cracked blocks.) so if it's cracked, it's of no help.

ezone

I always want to know about all fault code(s) and if possible, freeze frame data. From there I may learn a lot about what happened, and/or want to see more data, anything I can learn while sitting in the comfort of the drivers seat.

That spec is unrealistic to me.
Using my own tools and methods, I expect to see 180psi and above on just about any modern engine, with 10% variation or less. This engine I'd probably hope to see above 200 psi


Steady decline........maybe cranking rpm was dropping at each cylinder because the battery was being drained?

Every engine has the same basics,

and if there's a dozen different ways a head gasket can fail, then you need to know a dozen other different ways to test for it if passed your first check

You can buy a bluetooth dongle and a phone app pretty cheap and people find quite useful, google search 'torque pro'

Limp mode....or just runs bad?
If it's really in limp there's gonna be a code and data for it, but not all codes cause the computer to restrict engine power.

Did the dipstick melt?
I'd have my radiator funnel on it to burp the system, always watching for unusual rise and eventually 'air' bubbles that never end

So how did it lose coolant in the first place?
Where did it go?
Is it losing coolant now?


Is it the original engine?
I've posted pics (from google) in several threads in this forum showing where the blocks might crack, search

ezone

Link for research:

Amazon

Amazon

dr_bob_bc

I have no idea where the coolant disappeared to. Sadly, it was original coolant, like the motor, almost 12 years old, I should have changed it out. It may have gotten low over time, but in the summer my temp gauge was never high....

The dipstick didn't melt. There is black oil burnt on the top of it though, like it's glazed on, can't be wiped off.

I don't think it is losing coolant now, the rad looked like it had some in.. If it is losing, I don't know where it's going, exhaust is clean, no drips, oil looks pretty normal.

Bought a $100 code reader, Innova 3040e+- pretty cool. Code PO303, cylinder 3 misfire.

Put a new plug in #3 and swapped coils between #1 and #3 cylinder, cleared code.


Performed compression test with warm motor, accelerator floored:

#1) 205
#2) 205
#3) 190
#4) 182

Drove it around in the yard for 10 minutes, no power, took about 15 minutes to finally generate a new code: PO304, misfire on #4.

Swapped coils with #4 and #1, thinking I goofed on my earlier swap? Eventually get cylinder 1 misfire code.

Swapped #3 and #1 coils again, and got tired of waiting for a code after 15 minutes, running rough but no check engine light or code generated. Back to the forum...

Will try to understand "freeze frame data", run motor long enough to generate an error code, plus burp coolant and get back to you.

Thanks so much for your time and expertise!

dr_bob_bc

So,no codes on idling/parked after 10 minutes. No room for more coolant. So I went on the road a block and finally generated a code: misfire #1 cylinder. Swapped coils #1 and #2, and drove a block again, got more codes, cylinder #4 misfire, random misfire, cylinder #1 misfire, cylinder 4 misfire, random misfire, in that order.

Fuel Sys 1 OL-
Fault TPS 13.7%
Fuel Sys 2 N/A
O2Sloc O2S(lost this data off my screen)
Calc Load 41.2%
O2S B1 S2 0.79 V
ECT 205 F
STFT B1S2 0.0
STFT B1 0.0%
Command EGR 0.0%
LFT B1 -8.6%
EGR error 99.2%
MAP 9 inHG
Command Evap 0.0
RPM 800
Veh Speed 0
Spark Adv -4.5C
IAT 99 F
MAF 0.38 lb/min
TPS 13.7%

Watched a graph of the spark advance bounce around like crazy between 16 and -7 degrees during idling.

Maybe some of that helps?

I can post more data, not sure what else is of interest.

ezone

First, check out the pics in this bulletin---the crack locations are clear, and see the info about the ignition coils need to be checked

Link PDF (google sourced, this version is outdated but still useful): https://www.google.com/url?sa=t&rct=...Grz8Ntt13rtAnA




Newer tsb version link from google search but I did not see pics for coil inspection
https://static.oemdtc.com/TSB/A10-048.pdf


Spark advance will be all over the place, that's normal in the data list on a running engine. I've never really found that particular item very useful when troubleshooting problems I typically see at work

I assume the FF data you posted is associated with one of the misfire codes? Looks like hot engine, idle rpm,, no road speed
I was kinda hoping you'd still have the code that set during the original overheat event, but I suppose either that's gone now (I forgot about the battery being disconnected, seeing what the coolant temp was at the time of the overheat might be alarming LOL) or maybe it was a misfire code (was the CEL flashing during the overheat?)

Still low power? Possible exhaust restriction/cat clogged? Misfires and poor running can ruin a cat in a very short time

Low compression on the two cylinders is still troubling to me. #4(?) looks like it's far enough below the others to be the cause of a misfire code IMO.... Wet compression test?

Check valve clearances and adjust? Yes they are mechanical, not hydraulic...
If valves aren't tight, maybe a cylinder leakdown test would be a next step to see where the leakage is going....

Chasing misfires and swapping parts for testing..... #1 cylinder is nearest the serp belt, make sure you're not chasing the wrong cylinders (a very common mistake)

Inspect the ignition coils as mentioned in the bulletin, possible cause of misfire? (miss would follow a bad coil, not sure if you narrowed that down yet)

Maybe 'borrow' a cooling system pressure tester from autozone (or similar) and see if you can find a coolant leak that way? (looking for a root cause of all this)

I guess you're at the point of figuring out if this engine is really damaged and how bad is it, how much to fix it (include a machine shop resurfacing the cylinder head if it's warped), vs. installing a decent used engine? (try to get 2010-2011 engine)

dr_bob_bc

Update: Disconnected catalytic converter and shimmed it away from the exhaust manifold, and no improvement in performance.

Noticed 2 more symptoms: throttle response lag that isn't noticeable until engine warms up and idle drops down, which takes maybe 30-40 seconds in our warm weather. I suspect mixture is rich upon start- so wondering about a fuel issue?

Flooring throttle/holding it floored leads to a maximum 3500 rpm, then engine kind of surges regularly up and down about 300 rpm every half second or so.

2 ignition coils have the expansion damage indicated in the bulletin, and I am awaiting used replacements.

And thanks for the advice regarding cylinder numbering- I can't find that information anywhere else, not even in the factory manuals I have- I was definitely numbering them backwards.

ezone

Probably normal rev limit in park/neutral. What RPM will it reach on the road with the pedal floored from a standing start?

dr_bob_bc

Thanks, Ezone, you solved my problem- issue is resolved. Tried disconnecting exhaust, in case catalytic is blocked, no improvement. Replaced 2 coils that were abnormal in appearance, as per ezone's provided bulletin re cracked blocks, car runs perfectly and no more codes generated. Never have seen any coolant leak from car.

In summary, 2 bad coils, probably caused by overheating due to low coolant. Still not sure why coolant was low, suspect negligent owner not checking it for several years.

thanks again.

dr_bob_bc

Finally got around to insuring car and driving it. Runs fine, it's a nice driver, standard tranny which I enjoy. Went to change oil- contains coolant- about 10% of "oil" volume is coolant, I'd say. Saw some steam coming out of the dipstick hole and oil filler hole (when they were "uncorked") which was a clue before I got a actual look at the oil... I am guessing the engine got hot enough to boil off all the water in the oil on the initial "episode" as the oil just looked like burnt oil that time.

Head gasket kit at NAPA is over $300. Don't want to cheap out on a gasket kit online, really, it's far too much work to pinch pennies there. I can get a used engine for maybe $800 so that is probably the better route, I am thinking. The engine has probably been overheated, has been driven a bit on "poor quality" oil. I'm wondering what caused the head gasket to go in the first place, what's happened to the bearings and if the head warped at some time along the way.....

Again, thanks for your help.

Colin42

OEM head gasket is strongly recommended, and get the head checked by a machine shop

ezone

I think the block is likely cracked.
And it's probably why the car was for sale in the first place.

Go back to the post with the bulletin link that shows the pictures of the bare engine block showing four locations the block is known to crack. The cracks hidden behind the black steel cover on the back is the location that lets antifreeze leak into the crankcase and engine oil.

You say yours has been overheated.
Blowing a head gasket is not the usual cause on this engine. It's typically an after affect of the overheat caused by coolant loss though.
IF it's warped the head from a severe overheat (that's hot enough to melt the ignition coils), I would expect to find combustion leakage entering into the cooling system while the engine is running, which results in a seemingly endless (slow or rapid) stream of tiny bubbles coming up to the radiator neck while running, making it impossible to burp the cooling system completely......... i would expect to hear about the reservoir getting full but still finding air pockets in the radiator....or similar. (see overheating common causes reference thread in 7th gen area)
Or it might have a dead miss right after you start the engine.....Coolant leaks into a cylinder overnight, then at startup the engine misses on that cylinder until the antifreeze has worked itself out and the spark plug is dried enough to begin firing again.

I think if it had warped the head enough to let antifreeze pass into the oil passages, it would also be spilling antifreeze out to the ground, as it leaks out between the block and head. That literally happens, but usually seen after a driver ignores everything obvious and keeps driving until it simply quits running.

ezone